applying the predictable maintenance approach to dc
TRANSCRIPT
APPLYING THE PREDICTABLE MAINTENANCE APPROACH TO DC TRACTION SUBSTATIONS
IN SOUTH AFRICA
By
WILLEM SPRONG
THESIS
presented in partial fulfilment of the requirements for the degree
DOCTOR INGENERIAE
(D. Ing)
in the
FACULTY OF ENGINEERING
of the
UNIVERSITY OF JOHANNESBURG
SUPERVISOR: PROF. JHC PRETORIUS
JANUARY 2008
ABSTRACT This dissertation deals with the important issue of reliability management for 3kV DC Traction
Substations used by the national railway company in South Africa. Maintenance is one of the critical
and most costly phases in the lifecycle of any plant. It looks at the total life cycle of the equipment in a
typical substation, but the focus in the latter chapters is on the maintenance.
Through improved maintenance management, the reliability of the system can be improved. The
approach to maintenance is addressed as a predictive strategy, avoiding even more costly non-
productive time due to downtime caused by failure or induced by maintenance. Condition monitoring
and assessment is described as one of the effective tools in the maintenance engineer’s armoury to
apply a predictive approach.
A direct link between predictable maintenance and reliability is explored. In the definition of reliability,
concepts such as time and expected performance can be linked to a predictable delivery of the
designed function. In other words, if down time is expected and can be prepared for, it is more
acceptable than the unexpected. In essence, the system is still reliable as it performs according to
expectation.
The concept of predictable maintenance can be applied wider than just the 3kV traction substation.
The process of identifying critical equipment, to measure the condition and to take decisions based on
the rate of change in the condition can be used in any maintenance environment, even outside
electrical. The crucial ingredient to this is to understand that condition monitoring is not based on fixed
values, but the rate at which these values change. This is called Fuzzy logic.
Can we predict the future? If yes, how accurate will the predictions be?
ACKNOWLEDGEMENTS
I hereby wish to express my sincere thanks to the following people for their inputs to help me
complete this study:
• To my promoter, Professor JHC Pretorius, for his support.
• To my colleagues, Danie Barnard, Thys Grové, Oelof van Niekerk and George Roets, for
helping me with the research and all the equipment you borrowed me.
• To my parents, thank you for the opportunities to further my education.
• Thank you to my family, Sarita, Andé and Huibrecht, for you patients and support.
• Last but not least my Heavenly Father, without Him at my side I would never have been able
to complete this study.
CONTENTS
Chapter Description Page
ABSTRACT
ACKNOWLEDGEMENTS
ACRONYMS 1
LIST OF FIGURES 2
LIST OF TABLES 3
1 INTRODUCTION 4
1.1 Problem statement 4
1.2 The organisation of the dissertation 11
1.3 Research objectives explained 13
1.4 Conclusion 16
2 ELECTRICAL TRACTION SYSTEMS 17
2.1 Introduction 17
2.2 Electrical systems for Railway power supply. 17
2.3 Overview of the 3kV DC system 20
2.4 The schematic layout of a 3kV DC substation 23
2.5 Summary 33
3 RELIABILITY STUDY OF A 3KV DC SUBSTATION 34
3.1 What is reliability? 34
3.2 Probabilistic reliability 37
3.3 The reliability function 39
3.4 The Bathtub curve 41
3.5 Reliability component relationships 42
3.6 Block diagram analysis of a 3kV DC substation 45
3.7 Failure mode, effect and criticality analysis 48
3.8 The influence of workload on reliability 66
3.9 Summary 68
4 VISUAL INSPECTION FOR 3KV DC SUBSTATIONS 69
4.1 Introduction 69
4.2 Inspection form for 3kV DC substation 70
4.3 Importance of different components on the form 73
4.4 The physical inspection 74
4.5 Influence of the level of expertise and experience 75
4.6 Substation inspections on sample stations. 79
4.7 Interpreting the data 82
4.8 Summary 83
5 TECHNOLOGY TO MEASURE CONDITION 84
5.1 Introduction 84
5.2 General scope for condition monitoring of 3kV DC traction substation. 87
5.3 Monitoring interface for critical components 88
5.4 Block diagram of the condition monitoring system 106
5.5 Summary 108
6 ANALYSING MEASUREMENTS 109
6.1 Setting engineering limits 109
6.2 Surge Arrestors 110
6.3 Primary Circuit breakers 113
6.4 Traction Transformer 116
6.5 Rectifier 119
6.6 High Speed Circuit breaker 120
6.7 Batteries and chargers. 121
6.8 Summary 122
7 FUTURE DEVELOPMENT FOR REAL BUSINESS NEED –PREDICTIVE MAINTENANCE 123
7.1 Real business need. 123
7.2 Sustaining development 124
7.3 Key trends for condition monitoring in the future 128
7.4 Software development 129
7.5 The fuzzy logic program 137
7.6 Summary on fuzzy logic 139
7.7 Vibration measurement as an alternative. 140
7.8 Summary 143
8 CONCLUSION 144
8.1 Why sustainable condition monitoring 144
8.2 What are the obstacles that prevent sustainability? 144
8.3 How to implement a maintenance program. 146
8.4 How to sustain the maintenance program. 147
8.5 Objectives of this study 148
8.6 Future study 148
8.7 Final word 149
9 BIBLIOGRAPHY 150
10 ANNEXURES 154
10.1 Substation Logbooks 154
10.2 Substation Power Usage 165
10.3 Substations Condition Assessments 169
10.4 Electrical Fault list 171
1
ACRONYMS
λ Number of failures θ Mean life A Ampere AC Alternating current C Capasitor 0C Degrees Celsius DC Direct current EL Earth Leakage Ea activation energy FMECA Failure mode, effect and criticality analysis F(t) Probability of failure over specified time f(V) applied voltage HSCB High speed circuit breaker H.C. Holding Coil IQR Interquartile range kV kilovolt km kilometer kwh kilowatt-hour MOD Motor operated disconnects mH milihenry mov Metal oxide varistor MTBF Mean time between failure MTTF Mean time to failure OHTE Overhead track equipment O/L Overload OCB Oil circuit breaker PCB Primary circuit breaker R Reliability r Resistor RDB Reliability block diagram t Time T Temperature in Kelvin T/B Track breaker UVP Undervoltage potentiometer V Volt γ Instantaneous failure rate
2
LIST OF FIGURES Figure 1.1 Iceberg of cost Figure 1.2 PDM Cycle for critical equipment Figure 2.1 Typical feeding arrangement for DC systems Figure 2.2 Typical feeding arrangement for AC systems Figure 2.3 Block Diagram : Typical feeding arrangement for DC systems Figure 2.4 Schematic layout of a 3kV DC Traction Substation Figure 3.1 Reliability curve for the exponential distribution Figure 3.2 Typical failure-rate curve. Figure 3.3 A series network Figure 3.4 A parallel network Figure 3.5 Some combined series-parallel networks Figure 3.6 Reliability block diagram of a 3kV DC traction substation Figure 3.7 Reliability block diagram of a 3kV DC traction system Figure 3.8 Total power usage over 12 months Figure 4.1 Inspection form for 3kV DC traction substations Figure 4.2 Distribution plot of test results Figure 4.3 Quantile plot of test results Figure 4.4 Boxplot for test results Figure 4.5 Results of substation inspections Figure 4.6 Average of inspections per month Figure 4.7 Average of inspections per substation Figure 5.1 Age distribution for traction transformers in South Africa Figure 5.2 Pulse Rating Curves Figure 5.3 Current, energy and power derating curve Figure 5.4 Electrical representation of a ZnO varistor Figure 5.5 Increase in avarage leakage current Figure 5.6 Typical zinc-oxide varistor characteristics Figure 5.7 Typical oil flow Figure 5.8 Bucholtz Relay Figure 5.9 Typical High Speed Circuit Breaker Figure 5.10 Maximum allowable contact wear Figure 5.11 Blockdiagram of condition monitoring system. Figure 6.1 Surge count on lighting arrestor Figure 6.2 Leakage current tested on Metal Oxide Surge Arrestor. Figure 6.3 Operations during fault conditions Figure 6.4 Count of all operations. Figure 6.5 SF6 level as a percentage Figure 6.6 Top and bottom oil temperature – Transformer A Figure 6.7 Top and bottom oil temperature – Transformer B Figure 6.8 Current vs top temperature Figure 6.9 Accumulative calculated energy Figure 6.10 Contact wear Figure 7.1 PDM Cycle for critical equipment Figure 7.2 Typical failure-rate curve Figure 7.3 Typical time waveform for a traction transformer Figure 8.1 Team scheduling
3
LIST OF TABLES Table 2.1 The basic parameters for a 3kV Substation Table 2.2 The Legend of figure 2.4 Table 2.3 Different types of high voltage circuit breaker drive mechanisms Table 3.1 The key to figure 3.6 Table 3.2 FMECA for a 3kV DC traction system Table 3.3 Substation visits Table 4.1 Component description for Inspection form Table 4.2 Assessment scale for inspections Table 4.3 Scoring during test on eight people with different levels of experience and
expertise Table 4.4 Background on each person taking part in the test Table 4.5 Quantiles of the test results Table 4.6 Distance between base depot and substation Table 4.7 Summary of weather at each substation
Table 5.1 Different types of high voltage circuit breaker drive mechanisms Table 7.1 Equipment variables
4
1 INTRODUCTION 1.1 Problem statement A quote from an article written by Sandy Dunn (2005) [1] called Condition Monitoring in the 21st
Century - “Predicting the future is fraught with danger. Many wiser heads than mine have made
bold predictions of the future, only to be proved hopelessly wrong.” – maybe why the art of
predicting maintenance requirements never evolved. According to her the field of condition
monitoring was only established with any significance during the last quarter of the last century.
Condition monitoring is taken to mean the use of advance technologies in order to determine
equipment condition and potentially predict failure (Dunn, 2005) [1][2][3]. It includes, but is not
limited to technologies such as:
• Vibration measurements and analysis
• Infrared thermography
• Oil analysis and tribologie
• Ultrasonics
• Motor and transformer current analysis.
Condition monitoring is most frequently used as a predictive or condition-based maintenance
technique. However, there are other predictive maintenance techniques that can also be used,
including the use of the human senses (look, listen, feel, smell etc.), machine performance
monitoring, and statistical process control techniques. Chapter 3 describes a statistical
technique called Failure Mode, Effect and Criticality Analysis (FMECA) and chapter 4 explores
the use of human experience to obtain an accurate indication of condition.
The 3kV direct current substation is part of an electrical system that is needed to run electrical
locomotives. This electrical power is very cost effective in comparison with other forms of
energy [4], but only if the maintenance cost of this system can be held to the minimum. With the
volatile international economy it is important to make use of sustainable resources like the
locally produced electricity. This will reduce the risk of being dependant on oil prices that are
influenced by political stability in other countries.
It is not good practice to cut down on the maintenance itself, because of the very high repair
cost of substations once a catastrophic failure has occurred. To define a catastrophic failure it is
necessary to look at the types of failure that might occur.
5
The cost involved in repairing these failures and the consequent loss in production must be
analysed to find a proper definition of such a failure. The FMECA is based on a proper
understanding of the different modes of failure [5][6] and what caused it.
However, what changes occur within the field of condition monitoring will, in the long run,
only be sustained if it successfully address real business needs. In this area, condition
monitoring has a long way to improve, according to research from the USA. Repeated
surveys have led to very similar findings that: [1][7][8][9][10][11][12][13]
• Organisations are reluctant to invest in new manufacturing technologies because
they and their management aren’t convinced of the return on investment.
• In a survey of 500 companies, less than 3% of respondents were able to achieve a
measurable return on their investment in predictive maintenance technologies.
What is the real business need that will drive sustainable change in condition monitoring in
the new century? In these studies, mentioned above, the view is that asset effectiveness
will dominate the industrial maintenance scene for the first part. Effectiveness is the need
to extract maximum profits from the minimum investment in plant and equipment.
It is proposed to achieve this through the use of condition monitoring technologies in one of
five ways [1][12][13]:
• By improving equipment reliability through the effective prediction (and then
avoidance) of equipment failures.
• By minimising downtime (Mean-Time-To-Repair) through the integrated planning
and scheduling of repairs indicated by condition monitoring techniques with those
indicated by other techniques
• By maximising component life by avoiding the conditions that reduce equipment life
(for example, preventing over heating).
• By utilising condition monitoring techniques to maximise equipment performance
and throughput (for example, running close to thresholds).
• By minimising condition monitoring cost.
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The basic rule still remains that more must be done with less. This study will apply the
above ideas to provide a solution to the maintenance need for traction substations in South
Africa.
It is not good practice to spend lots of money on maintenance only and not to use the
opportunity to improve the overall condition of the assets, resulting in increased life
expectancy and reduced life cycle cost. There must be a change in the thinking and
method of working towards a more effective and efficient result. Simply going in the same
direction year after year will result in the available money not being spent in the best way.
In the case of Spoornet, the age distribution of staff shows that most members employed in
the technical field are older than 50 years with almost 60% being older than 55 years. It is
commonly accepted that older staff are more resistant to change than younger ones.
Unfortunately the experience that these staff members has also work against change
[4][14].
During a survey done by the author [15], 100 members were interviewed, of which 85%
that were against change, were older than 50 years. They felt that proven methods should
not be changed and that “most change just occurred for the sake of change”. The
challenge in this study was not just to look at new strategies for maintenance, but also how
to implement it effectively.
But why the need for a radical change in the railway industry? According to Petkoon
(1999)[16], railway transportation in South Africa has undergone some significant and
fundamental changes over the past ten to fifteen years. Some of these changes were
thrust upon the organisation by external developments and a number of them were by
design. The company had to adapt to some new positional and mindset changes to
compete in a highly competitive environment (Petkoon, 1999) [16].
Traditionally the organisation had national and social responsibilities towards the people in
South Africa [4]. One of these responsibilities was the so-called Common Carrier task. This
meant that all goods that they were requested to transport had to be catered for,
irrespective of the volume or the distance involved. An example of this was the old milk can
that had to be picked up at every station or even between two stations. Then, with the
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development of new transport technology, a paradigm change had to take place to keep up
with the new competition.
The railway transportation companies previously operated in a regulated market where the
competitors had to apply for a permit before any goods could be transported. It was up to
the government-owned railway company to decide to oppose such an application, and the
applicant then had to prove that existing service was inadequate for the market
requirements. As deregulation became a reality truckers were allowed to enter the market
freely and a substantial percentage of the market share was lost to the road. Railway
transport’s survival now depended on its ability to render a superior service at a
competitive price (Petkoon, 1999) [16].
The old South African Transport Services, an enterprise of the state under control of the
Minister of Transport, transformed into the company called Transnet. This company is still
owned by the state, but for the process of privatisation to take place it must become
profitable. Tariffs can no longer be adjusted to offset projected expenditure. The converse
became a glaring reality: expenditure budgets must be based upon the expected revenue
generating activities of the organisation. Maintenance will always remain a very important
and big expenditure to a company such as Spoornet. Throughout South Africa most of the
equipment in use on the railways were designed with the idea in mind that the state will be
able to pay for repairs if necessary. That is no longer the case and engineers are left with a
great challenge to do cost effective-maintenance on very old equipment.
This implicates that the railway and its operating there off are no longer a job-creating
organisation like in the past. With competition came the painful task of optimising resources
to match the task at hand in such a manner that customers would choose to transport their
goods via the railway on merit. It also implies that railway companies need to focus on
retaining important skills needed for maintenance. To be able to do maintenance on a
substation, highly trained people must be deployed. It is important to consider feeding
channels to fill vacancies with competent staff. Safety of workers may be compromised if
inexperienced people are appointed in the wrong positions.
Railway engineering have a proud tradition of technological innovations [4][14][16]. The
problem with this, however, is that these inventions were unique to the railways and its
8
requirements. This was no problem during the construction days of the infrastructure.
Equipment was manufactured in great numbers and manufactures were willing to spend
money on building plants and factories to meet the demand for these equipment. Since the
end of the construction era it became more of a daunting task to find the right components
to repair these great inventions. So, even excellent equipment simply cannot be repaired
anymore due to the lack of spare parts. It became even more important to do proper
maintenance, so as to prolong the life of this equipment.
Against the background of all these changes, Spoornet had to position themselves in such
a way that they would be successful in the long term. For most companies “long term” is
probably not more than five to ten years, but for railway companies it is probably between
twenty and forty years. The very nature of the equipment that is in use (cost, lead-time and
technical life) implies that decisions must be taken that span decades (Petkoon, 1999)[16].
With this in mind it is a great challenge to design solutions based on technology that will
not only be “timeless” on the one hand, but also be swiftly adaptable. To prevent some of
the problems that occurred in the past, adaptability must be a very important philosophy
when considering new ways to improve the service delivery, because in the end all railway
companies will remain service-delivery companies and would not be able to survive if they
have dissatisfied clients.
The substation forms an integral part of the entire transport system that must be
maintained. Without a proper power supply to the locomotives the competitive edge will be
lost, because by making use of electricity, trains are utilising the cheapest form of energy
available in South Africa. According to du Plessis (1999)[4] electrical energy is 3.83 times
cheaper than diesel. The cost to maintain diesel locomotives is also much higher compared
to that for electrical locomotives. The study to compare these types of energy is a very
interesting field but can take up pages of calculations and motivations, and is not part of
this investigation.
The next issue that must be discussed is the importance of maintenance. It might argued
that a good design is more important than a good maintenance plan. That might be the
reason for the very low interest in maintenance during past training of engineers and
technical staff at institutions across the globe. But since the big construction era worldwide
9
is something of the past it is now very important to focus on maintenance. The final goal of
any maintenance must be to prolong the lifecycle of any piece of equipment. There are
many factors that play an important role in decisions on when and what must be done to
get better value for money. Even during the design stage, the lifecycle engineers need to
look at the maintainability of the design. They need to consider the problem of component
obsolescence which affects all products and equipment throughout the total life cycle and it
is not limited to certain hardware.
Obsolescence also effects test and support equipment, software, tools and processes.
Obsolescence is the non-availability of spares for the specific component or that the
component is no longer manufactured by the original supplier. [17][18][19]
The lifecycle of traction power supply (substation) equipment consists of the following
phases :
The operational and maintenance phase for traction equipment are typically 30 years for
coastal and 50 years for inland areas (Du Plessis, 1999) [4]. The first three phases are
relatively short compared to the operating and maintenance phases. It is important to
remember that mistakes made during the design phase will have great influence during the
operating phase and might cause some major maintenance problems. It might even cause
the renewal phase to occur much faster than expected. So even though it might be a very
short period of time in the entire lifecycle, the design phase still remains one the most
important phases. To understand the cost involved, Figure 1.1 must be considered.
In 2007 the acquisition cost of a typical 3kV DC substation is in the order of R6M per unit
while the maintenance and operating cost will be approximately R120 000 per annum.[15].
Design
Test
Construction
Operate
Maintain
Renew
10
Based on a life expectancy of 40 years a substation will cost anything in the region of
R3.6M over its useful lifespan, if no inflation is taken into account. Training normally
constitutes 5% of the maintenance cost while for a DC substation and overhead track
equipment, the operating capital is about R10.15M per year (Du Plessis, 1999)[4].
The big challenge today is to decide on what maintenance must be done to keep the
substation as cost-effective as possible. It is not acceptable to spend large amounts of
money trying to maintain something while it will be better to replace it with new technology.
Methods must be found that will enable the maintenance engineers to do better
maintenance on old equipment so that the availability of the system is increased. This will
result in a more reliable system that will enable a more predictable service. It is necessary
to satisfy the clients who will keep the companies competitive in this changing environment.
Figure 1.1 : Iceberg of cost (Du Plessis, 1999) [16]
Operating capital
Acquire
Training
Operating cost
Maintenance cost
Scrap
Lifecycle
11
1.2 The organisation of the dissertation
To address the business need described earlier is important for this study. This need can
be summarised as improving the availability of traction substations over an increased life
expectancy without drastically increasing the required resources. A process must be
developed that will enable the maintenance engineer to make decisions that will be efficient
and effective.
The working of the 3kV DC substation must first be understood and is therefore explained
in chapter 2 where a discussion on the different electrical traction systems is followed by
the schematic layout of the 3kV DC traction system. This chapter is important to help the
reader understand the major components inside a substation and to get an overview of
how they work together for an entire system that has the ultimate function of supplying 3kV
DC to the locomotive running on the railway track. Schematic diagrams will help illustrate
this concept.
In chapter 3 the theory of reliability management will be discussed. The concept of
reliability and availability will be detailed. This will be followed by an analysis of the 3kV DC
system. The main output of any maintenance effort should always be to increase the
reliability of the component that is maintained. To understand what decision must be taken
towards maintenance, the concept of reliability must be understood. The FMECA is a
statistical method to help the decision makers understand where inherent risk is the
biggest. It was used in this study to determine the important components that should be
monitored and inspected to enable the best possible outcome.
After the discussion of statistics in chapter 3, the design of an inspection form will be
discussed in chapter 4. Some analysis was done to check the data that is obtained from
the human senses and to scientifically verify the usefulness of the information. Some
factors that might influence the outcome are investigated and described. The method used
to design this form can be implemented to design any similar type of form for different
application other than traction substations.
In chapters 5 and 6 the technology that was used to obtain the information required for
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condition analysis is explained. The outcome of tests done on a typical 3kV DC traction
substation is shown. Due to monetary constraints these tests, unfortunately, could only be
performed on selective substations, but the discussion in chapter 6 will assume
implementation in most of the 593 3kV DC traction substations in the network across South
Africa. The implementation of these tests is discussed and some critical obstacles in the
successful implementation are looked at.
Chapter 7 describes the future development of these techniques that can improve the
ability of engineers to make decisions on maintenance input based on business
requirements as described earlier in this chapter. An application in the use of vibration
theory for condition measurements of a transformer was developed and is discussed in this
chapter.
The measurement and analysis of vibrations is common method used in the mechanical
industry to identify problems on rotating machines. In this chapter the theory is explored to
apply this technology to transformers. If the vibration signal can be analysed as a voice
recording, then the transformer might just be able to “tell” you what is wrong.
The development required to ensure the sustainability of condition monitoring is discussed
in chapter 8. The implementation of knowledge gained in 3kV DC traction substations
across the high voltage environment and the added advantages like risk assessment for
insurance companies is finally discussed to put the icing on a groundbreaking experience
in this study.
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1.3 Research objectives explained
The objective of this study is to implement a new strategy towards planned maintenance.
There are currently four strategies being used in the field of maintenance engineering.
These are major breakdown, minor breakdown, routine corrective and preventive
maintenance. There is also a fifth strategy to redesign the system or specific components
in the system.
Maintenance during major breakdowns is very expensive and time sensitive. When this
strategy comes into play the system is down and must be repaired as quickly as possible
to prevent production losses. Minor breakdowns occur when certain components of the
system fails and cause the system to be down. It is easy to replace the components and
cost is lower compared to that of major breakdowns. Remember that one of the business
needs to ensure sustainability was to reduce the down time or MEAN-TIME-TO-REPAIR
(MTTR).
Routine corrective maintenance is a strategy where less critical components are
replaced after they failed. The failure of these components does not cause the system to
fail entirely. These three strategies are reactive of nature and are the unscheduled repair
of failed components to restore its functional capabilities. With certain components it
might be feasible to follow this strategie where the failure will not influence the ability of
the system to perform at the designed output. From the FMECA in chapter 3 it will
become clear how this can be determined.
Pro-active strategies are less costly and time consuming. Preventive maintenance is
such a strategy where components are replaced before they fail using a planned
maintenance schedule. These schedules have historically been based on
recommendations from original component manufactures. To date this has been the
preferred strategy by most companies due to a lack of precision knowledge on the
condition of the components. The objective of this study is to change all of that and make
information available to take away the guessing in preventative maintenance.
14
The fifth strategy that can be considered is that of redesigning the system or some
components in the system. The need for this arises from the fact that the required
function of the system changed through, for example, an increase in production. Some of
the components might become unavailable which will render the system un-
maintainable. Redesign is the only option in cases like these.
According to Bobrow (1996) [20] many utility companies across the world apply time-
based and condition-based maintenance to preserve the function of a specific device of
piece of equipment. In this study a sixth strategy is introduced based on this. It is called
predictable maintenance and makes use of information gathered during condition
assessments to apply engineering intelligence before arriving at a plan to do effective
and efficient maintenance. [3][21]
Micheal V Brown (2003)[12][13] defined predictive maintenance (PDM) in an article he
wrote for the New Standard Institute as a comparative of the trend of measured physical
parameters against known engineering limits for the purpose of detecting, analysing and
correcting problems before failure occurs. This approach can be applied to any
equipment problem if, a physical parameter like vibration, temperature, pressure,
voltage, current, or resistance can be measured. An engineering limit for the measured
physical parameter must be established so a problem can be detected during routine
monitoring. This limit should be low enough to detect a problem before destructive failure
occurs. Correcting the root problem is the key to most predictive efforts.
According to Brown (2003)[12], all critical equipment that is added to the program, enters
the cycle shown below in figure 1.2. [12]
15
Figure 1.2 : PDM Cycle for critical equipment (Brown, 2003)[12]
From Brown’s definition it is clear that the measurement of a physical parameter in itself is
not enough to detect the destructive effects on the equipment. It is important to establish a
limit or rate of change in the parameter that may be excessive or damaging.[12][13].
One method of determining a limit requires that a number of failures be observed before a
safe limit is established. Due to a lack of data on such observations the information had to
be based on personal objective experience from technicians that work on the equipment for
years. The manufacturers have already established many of the engineering limits for the
equipment. The objective in chapter 6 is to look at the limits and define them for the
equipment under discussion.
The research in this dissertation should open the door to the sustainability of predicting
maintenance requirements for 3kV DC substations. It should also not be limited to this
application only, but can be used throughout the high voltage installations and applications
in the industry. The fundamentals discussed for electrical equipments can also be applied
to other disciplines in engineering.
To change mindsets are just as important as changing technology. Without the acceptance
of the new strategies, maintenance will remain dependant on the human input and will be
16
performed objectively according to experience. People experience problems differently and
learn to react on faults based on previous experience.
One of the most common excuses to resist change that was brought to the table during the
survey was the shortage of trained staff. Whatever the different opinions were, most felt
that their experience and loyalty, towards the company, been abused by senior discussion
takers who had only one objective. They were chasing numbers and not sustainability. This
will be discussed in later chapters.
1.4 Conclusion This study explores the possibility to predict maintenance requirement for high voltage
electrical equipment through the analysis of information obtained from condition monitoring.
New applications will enable the maintenance engineer to accurately predict what the
maintenance requirement for his/her plant will be and to act accordingly.
Although the study focuses on the 3kV DC Traction system, it can be applied to various
different installations where the same principals will be used.
The successful implementation of predictable maintenance will ensure the sustainability of
a company that is heavily dependant on effective and efficient maintenance of its
infrastructure network.
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2 ELECTRICAL TRACTION SYSTEMS 2.1 Introduction The detailed layout for a 3kV DC traction system is very complex. However, for the
analysis that will be done in the following chapters it is necessary to understand only the
most important components and how they are working. This chapter forms the basis for
an analysis of the reliability of the 3kV system.
2.2 Electrical systems for Railway power supply. Electric power for the operating of electrified traction systems are mainly supplied by the
local utility company at voltages ranging from 11kV to 220kV. In some areas supplies are
also obtained from the local municipalities, for example in Durban, Cape Town and
Newcastle. The supply from the municipalities is not always that well-regulated and may
fluctuate as the demands of factories and other users on the same line may vary. If the
substation is not well-protected against sudden voltage increases and decreases, major
damage may occur when these fluctuations take place.
The power is normally distributed amongst the various substations via the utility
company’s network, although the transport company’s distribution networks are providing
its own power to some areas. The nominal voltage of these networks is either 33kV (Cape
Peninsula) or 42kV (Pretoria). In some rural areas the electrical network of the areas next
to the railways is also supplying power to local users, like farmers and sawmills from the
6.6kV distribution network that is used for power supply to the signals. This is, however
not an ideal situation because it influences the quality of the supply. It also creates
problems when billing must be done and is not a very cost-effective approach because its
means that extra staff must be paid and trained to keep the records up to date and to
make sure that these private users receive bills on a regular basis. [4][13]
There are three basic traction systems in use on the railway lines in South Africa at
present. These are 3kV DC, 25kV AC and 50kV AC. The three systems differ from each
another in respect of the method of feeding the overhead track equipment (Spoornet
Engineering Instruction : EP.001 Issue 1)[14]. The 3kV traction substations are all
connected to the overhead track equipment (OHTE) in parallel feeding arrangement. The
feeding arrangement implies that each substation supplies the complete 3kV network, in
18
contrast to the AC system where generally each substation feeds a dedicated section of
line. A typical feeding arrangement for DC systems can be seen in Figure 2.1.
Figure 2.1 : Typical feeding arrangement for DC systems (Spoornet Engineering Instruction : EP.001 Issue 1)[14]
There are many advantages and disadvantages of AC over DC, but to summarise, the
main advantage of using AC is that the substations can be placed much further apart.
Where the typical distance between two DC substations may vary between 8 to 15km,
25kV AC Substations can be placed up to 30km and 50kV substations up to 50km apart.
An AC substation is much less complicated and therefore much cheaper to maintain. One
of the big disadvantages is that an AC locomotive is far more expensive than a DC
locomotive. According to the latest values available from the local railway company an AC
locomotive will cost 80% more than its counterpart in the DC locomotives. But with the
development of new technology it is becoming better and better to use AC. In fact, all the
latest designs are AC systems, of which the newest example is the electrification of the line
between De Aar and Kimberley. [4][13][15]
One of the other main advantages is that it is much easier to get a regulated voltage for the
direct current, because only the IR (losses due to the internal resistance of the copper wire)
drop is involved. The current carrying capacity of the DC line is also greater than that of AC
cost-wise. In other words, there will be a greater capacity available on the DC line if the
19
same amount of money were spent to build a DC and an AC line. [4][13].
In order to balance the loading on the three phase supply network, it is essential that
alternate sections of the AC traction systems be supplied from different phases and that
phase breaks be provided between different sections. Traction sectioning stations are
provided at phase breaks with a circuit breaker connected across the phase break. This
circuit breaker is normally open and will only be closed in the event of power failure on one
section in order to restore the supply from an adjacent healthy section. Figure 2.2 shows a
typical feeding arrangement for AC systems. [4][15]
Figure 2.2 : Typical feeding arrangement for AC systems (Spoornet Engineering Instruction : EP.001 Issue 1)[14]
20
2.3 Overview of the 3kV DC system
In the case of the 3kV DC systems, which comprise approximately 80% of the total
electrified system, the utility’s high voltage supply is stepped down and rectified by AC to
DC power through silicon rectifiers. The 3kV DC is fed into a substation busbar from
which high-speed DC circuit breakers feed the various overhead track equipment
circuits. Tie stations are sometimes provided between substations or at line junctions for
the purpose of increasing the trip settings of the substation breakers.
Figure 2.3 shows what a block diagram for a typical DC feeding arrangement looks like.
It is important to note the major components shown in the diagram. These are discussed
in the following paragraphs.
Figure 2.3 : Block Diagram : Typical feeding arrangement for DC systems (Spoornet
Engineering Instruction : EP.001 Issue 1)[14]
21
The power is supplied by the local utility company (Eskom in this case) and firstly passes
through their isolators. This isolator enables the utility to switch the power to the
substation when work must be done on the AC disconnects. These disconnects belong
to the railway company that uses it to isolate the substation. Note that when opening the
disconnects the primary side of the transformer is automatically earthed.
The Primary Circuit Breakers form a very important part of the protection circuits in the
substation. It must switch the supply when a fault situation inside the substation occurs.
Locally two types of Circuit Breakers are used, namely the oil and SF6 filled breakers.
The supply from the utility company must then be stepped down and passes through the
main transformer. This transformer is the single most expensive piece of equipment in a
substation and will cost R1.5M to replace [15]. All the above equipment is situated
outside the building. From the secondary side of the transformer the electricity is fed
inside the building to the rectifier. All modern rectifiers are built with silicone diodes.
The 3kV DC then runs via a busbar to the high-speed track breakers. These breakers
must protect the substation on the DC side from faults that might occur on the overhead
track equipment. Just before the direct current is fed onto the line it passes through the
track switches outside the building close to the line. These switches can only be
operated by hand. From there it is fed onto the line. All of this will be discussed in greater
detail later on in chapter 2.
The function of the tie station shown in figure 2.3 can be seen as a remotely operated
switch. It gives extra protection on the 3kV side and allows greater currents to be drawn
from the substations. It is not always found between substations.
The basic laws of electricity demand that a return path for the current must exist. Figure
2.3 shows that the rail forms this path, called the negative return for 3kV DC electrified
systems. However, in some instances the rail is enhanced or supplemented by negative
conductors and earth wires. The complete negative return circuit must be insulated from
the ground to minimise the likelihood of return currents to the substation passing through
water pipes, fences, reinforced concrete foundations, et cetera, in contact with earth.
This will cause corrosion of these steel structures. The electrolytic corrosion or
22
electrolysis can cause foundations of structures to crack. Cases where fences that
became red hot due to these stray currents, have been reported as well. [14][21]
The resistance between the negative return circuit and the ground should always be
more than 25 ohms when measured on the negative cable at any substation (Spoornet
Engineering Instruction : EP.001 Issue 1). [14]
The basic parameters for a 3kV DC traction substation are given in Table 2.1. The
substation spacing indicates that the substations are situated 8 to 15km from each other
along the railway line.
Table 2.1 : The basic parameters for a 3kV Substation
(Spoornet Engineering Instruction : EP.001 Issue 1)[14]
2 hour rating 1.5 x continuous
0.5 hour rating 2 x continuous
Continuous output current 1500 amperes
Nominal output voltage 3000 volts
Approximate total cost R2 500 000
Substation spacing 8 to 15km
23
2.4 The schematic layout of a 3kV DC substation
To understand the reliability and availability of a 3kV DC substation, a thorough look at the
different components of this system is necessary. In this chapter a better understanding of
the main components will be created by explaining the schematic layout of such a system.
Figure 2.4 shows the layout of a typical single unit 3kV Direct Current substation in
schematic form. A single unit substation has only one supply, while a double unit will have
two supplies (two transformers).[14][21]
Figure 2.4 : Schematic layout of a 3kV DC Traction Substation (Spoornet Engineering
Instruction : EP.001 Issue 1)[14]
24
Table 2.2 : The Legend of figure 2.4
M.O.D. Motor operated disconnects V Voltmeter
EL Earth leakage (DC) A Ampere meter
C/T Current transformer T/B 3kV high speed circuit breaker (H.S.C.B.)
1 Mechanical interlocking F Fuse
O/L Overload MOV Metal oxide varistor
C Capacitor S Micro switch
R Resistor H.C. H.S.C.B. holding coil
mH Inductance coil U.V.P. 3kV DC undervoltage potentiometer
2.4.1 Supply from the utility company
From the utility company’s supply line, lightning arresters are connected between the three
phases and earth to protect all the equipment in the outdoor section of the substation
against lightning surges. Lightning is one of the biggest hazards for any electrical
installation. There are a great number of methods to protect equipment against strikes but
none of them are failure proof. There is always a possibility of a lightning strike and it must
be taken into account when calculating risk.
2.4.2 Disconnect switches
The disconnect switches are provided directly beyond the lightning arrestors for the
purpose of isolating the substation from Eskom supply to carry out maintenance work.
These switches are electrically and mechanically interlocked with the primary circuit
breakers to prevent them from being operated under load. The electrical interlocking
circuit is controlled by a set of contacts which, when the handle is turned to the open
position, make contact before the main blades open. This places 110V DC from the
battery supply on the main high voltage circuit breaker trip coil thus preventing operation
under load.
In some of the new types of disconnecting switches, a mechanical latch has been
provided, which must be operated manually before the opening handle will be released.
As soon as this latch is lifted, it in turn closes a set of contacts which operate the primary
25
circuit breaker trip coil. Some of the other types have a mechanical key interlocking
system whereby the key must be released by first taking the substation offload.
The three phase disconnects that is in use at 3kV DC substations operate the three
phases together. The switches are mechanically coupled and the majority of these
switches have automatic earthing facilities, while some must be earthed manually.
During switching operation it must be ensured that the mechanical action is operating
freely and that the live and earth contacts are properly made.
2.4.3 Primary circuit breakers
The primary circuit breakers are provided on the primary side of the main transformer for
the purpose of protecting the substation from overloading and from high fault currents.
The breaker are capable of interrupting fault currents of the order of 30 000 ampere.
The circuit breaker tripping mechanism is operated by protection relays which is driven
by current transformers. These relays are provided with contacts which close when the
relay is operated and so make the circuit to energize the 110V main circuit breaker trip
coil. The circuit breaker will be tripped but not locked out.
The primary circuit breaker is also tripped by a battery undervoltage relay. This relay is
normally calibrated to operate when the battery voltage falls below 90V. This prevents
the substation from staying onload while the batteries are not charging. This is very
important because the batteries are the heart of the protection circuits in the substation.
In the case of a SF6 breaker, protection is also provided for gas pressure and air
pressure.
There are basically four types of high voltage circuit breaker drive mechanisms. A
comparison of these is shown in Table 2.3 below.
26
Table 2.3 : Different types of high voltage circuit breaker drive mechanisms (Spoornet
Engineering Instruction : EP.001 Issue 1)[14]
TYPE USED ON ENERGY
STORAGE
MECHANSIM
STORED
ENERGY
(closed or
charged)
ADVANTAGES DISADVANTAGES
Solenoid Bulk oil circuit
breakers
Nil (open) 1. Simple and
cheap
2. Manual closing
possible
High burden on
battery
Spring 1. Minimum.
Oil
2. SF6
3. Vacuum
Springs O-CO Manual spring
charging possible
Complicated repair
Hydraulic SF6 circuit
breaker
Compressed
nitrogen
O-CO-CO Low burden on
battery
1. No manual closing
possible
2. Hydraulic system
with its associated
problems
Pneumatic SF6 circuit
breakers
Compressed
air
O-CO-CO 1. Low burden on
battery
2. Simple
1. No manual closing
possible
2. Pressure vessel
requires periodic
inspection, or drilling
of tell tale holes
Note : O = open, C = closed
The solenoid type is very simple and straightforward. For closing, a solenoid driving the
closing mechanism is connected directly to the 110V battery. Due to the heavy current
drain from the batteries, repeated closures cannot be attempted because the protection
will operate as soon as the battery voltage drops below 90V. This will cause the
substation to go on lockout and will require a technician to go out and reset the
substation.
In the spring drive mechanism the opening and closing of the circuit breaker is driven by
springs. The springs are wound by means of a small 110V DC motor. The springs can
also be wound using a crank handle. As soon as the breaker is closed, the 110V motor
27
starts to rewind the closing spring. The opening spring is tensioned during the closing
operation. Starting from a closed position and with the closing spring charged, the
breaker can perform the following sequence without any battery supply:
OPEN -> CLOSE -> OPEN
The hydraulic drive mechanism uses the principal of compressing nitrogen gas (N2). This
is done by trapping the gas in a cylinder (accumulator) and pressurising it with hydraulic
fluid oil working on the other side of the piston. In this way energy is stored in the
compressed nitrogen gas. The hydraulic fluid provides the drive mechanism between the
stored nitrogen and the electrical contacts. The fully charged nitrogen and hydraulic
pressure is in the order of 250 bar and can perform the following sequence of operation:
OPEN -> OPEN CLOSE -> CLOSE OPEN
In the pneumatic drive mechanism the energy is stored as compressed air and the drive
mechanism between the stored energy and the electrical contacts is also compressed
air. To prevent corrosion forming in the air receiver and other working parts and to
ensure smooth operation, the air must be clean and dry. Special precautions are built
into the circuit breaker to ensure that the air is dry by provision of an air drier at the
intake of the air receiver. When this receiver is charged to 10 bar, it has the capacity to
perform the following operations without recharging:
OPEN -> CLOSE OPEN -> CLOSE OPEN
The high voltage breaker in use at Spoornet must be able to interrupt fault currents in the
order of 30 000 ampere on the primary side of the main transformer. Due to the
increasing fault levels of the Eskom system, the new breakers must be faster and able to
withstand levels of up to 5 000MVA.
2.4.4 Main transformer
Main transformers are provided with three phase primary windings with supply voltages
ranging from 11kV to 220kV. The secondary windings usually consist of six phases to
provide 12 pulse full-wave rectification at 3kV DC. Vector groupings are used on the
secondary side with varying voltages to obtain the required output voltages. Leonard
28
Bobrow describes the vector theory in his book, Fundamentals of electrical
engineering.[20]
The standard for main transformers is a 4.5MW unit with a star primary and with two
secondary windings. The secondary windings are connected either as
• two extended deltas, each secondary phase shifted either 150 plus or 150 minus
relative to the primary (ASEA transformer) or
• a star and a delta secondary (GEC) (EP.001 Issue 1).[14]
These transformers are interchangeable provided, that the secondary voltages are the
same. The output voltage of each secondary phase is approximately 1220V, which,
when rectified and connected in series, will give low load voltage of approximately
3150V.
A 5-tap position tap changer is provided on the primary winding of the transformer to
adapt to the specific utility supply voltage. This tap changer can only be operated under
no-load conditions. Therefore the tap changer handle should be kept locked to prevent
operation under load. The tap switch should always be left in a position to give a low
load (100 amperes) voltage of about 3150V. Otherwise the tap switch should be left in a
position giving a DC voltage as close as possible to this value.
On both types of transformers, one secondary winding is rated at 50kVA more than the
other, as the 50kVA auxiliary transformer is fed off the one secondary winding of the
main transformer. This auxiliary supply is used inside the substation to provide power to
the battery charger and other low volt equipment inside the substation. It is also used
during the calibration of the switching equipment.
The main transformer is normally provided with the following :
• conservator tank with a silica-gel dehydrating breather
• a dial type thermometer for registering top oil temperature
• a Buchholz relay
• two drain cocks and an oil sampling cock.
29
Despite conventional wisdom, transformer life is a controllable factor and should not be
less than fifty years [10]. A transformer consist of a laminated iron core, paper insulation
and windings in a tank filled with liquid insulation. The paper provides mechanical
(structural insulation) and dielectric strength. Transformer oil protects the paper
insulation, is an insulation medium and coolant and provides the means to monitor
transformer condition and operation.
Some of the stresses that a transformer is exposed to are short circuit stress, 50Hz
excitation, lightning and switching surges. Most of the transformer failures are due to a
failure of some sort in the insulation system. The life of a transformer greatly depends on
the life of the insulation system inside it. If the solid insulation is properly maintained, one
should get more than fifty years of reliable transformer operating life.
Being essentially static devices, transformers require relatively little maintenance. It is
very important, though, to have good maintenance programme. This must allow for the
periodic check on the condition of the transformer so that deterioration of any kind can
be detected in time and corrected before it gets out of hand. Deterioration of oil and
insulation within the transformer is a function of moisture, time and temperature. These
transformers normally are subjected to relatively short load currents and have a low
average oil temperature. In the past it was considered adequate to test oil only every
four years. But due to the age of the transformers (some as old as 30 years) and the
increased demand by the heavier trains, it became necessary to rethink the testing
intervals. As soon as the temperature consistently starts rising above 600C, testing must
be done more frequently. For every 80C rise in temperature the remaining life of the
paper insulation will be halved. [9][10]
Transformer oil dissolves more moisture at higher temperatures than at lower
temperatures. If the oil and water combination is cooled, the water will precipitate out
and be absorbed by the insulation. The temperature profile in most transformers is not
uniform. Most of the aging will occur in the warmest regions of the transformer, like near
the top of the windings. More than 95% of transformer water is in the insulation material.
An operating transformer should have no more than 1% moisture at dry weight
(M/DW).[10] The paper in the transformer acts like a filter, attracting the products of
30
decay through adsorption. If it is not cleaned, the decay products will eventually destroy
it.
The oxidation of the oil causes acids and asphalts to form, which form sludge deposits
inside the transformer on the windings and the core. This will influence the adequate
cooling of the transformer and will in turn cause an increase in the average temperature
of the transformer. Combined with the fact that trains are running more and more
frequently this will lead to a shortened lifespan for the transformer. It will also cause a
breakdown in the insulation between the windings. The transformer will last ten times
longer at the same temperature if oxygen is kept below 300 parts per million. [10][22]
Experience has shown that when new oils of different kinds are mixed, the properties of
the mixture will not be better than those of the lowest grade. When replacing oil which
has been drawn off or leaked, it is satisfactory if the oil to be added is dry and pure, and
of at least the same quality as the bulk oil (EP.001 Issue 1). [14]
It is very important that the correct procedures are followed and correct containers used
for oil sampling. The oil temperature must be recorded as samples are taken to measure
the moisture content and determine the wetness of the solid insulation. Oil test results
are used to classify the oil. The oil classification, the results of the Dissolved Gas
Analysis and the relevant electrical tests will determine the correct oil treatment
procedure. Transformer oil can be given practically unlimited life.
2.4.5 High Voltage Current Transformers
The high voltage current must be measured to be able to monitor the system and detect
any faults or overloads. It is also necessary to measure the energy that is used for billing
purposes. The current is measured with the high voltage current transformers.
The signal from the current transformers is fed into a protective relay which compares it
with a pre-set value and if this value is exceeded, a further signal will be sent to the
primary circuit breaker to trip. For measuring purposes the signal is fed into a meter that
belongs to the electricity supply authority. This authority in most cases is Eskom.
31
Separate current transformer windings are used for protection and metering purposes
because the requirements differ. These windings are housed in the same unit. Because
the current exceeds 100A, we make use of the toroidal current transformer type. It
consists of a laminated ring-shaped core that carries the secondary winding. The primary
is simply the conductor running into the main transformer that passes through the centre
of the ring. The position is not that important, just as long as it passes through close to
the centre.
The ratio of the transformer is equal to the number of windings in the secondary. The
nominal secondary current is usually 5A, irrespective of the primary current rating (Wildi,
2000). [23] This means that a transformer having a 1000A/5A ratio has 200 turns on the
secondary winding.
In new designs the current transformers are mounted separately. This prevents the
withdrawal of the main transformer or circuit breakers in the event of failure of the current
transformer.
2.4.6 High voltage surge arresters
Surge arresters are installed on the transmission lines to protect equipment against
overvoltage surges. Lighting surges are generally caused both by direct strikes on, as well
as indirect lightning strikes near the transmission lines. The arrester is designed to block
the progress of a voltage surge moving through a system. It accomplishes this objective by
drawing sufficient current to dissipate the energy associated with the surge. [7][24].
High voltage surge arresters are always provided on the high voltage busbar feeding the
substation outdoor yard. One of these arresters is placed on each phase and must
protect the equipment inside the substation from surges on the Eskom side of the line.
Smaller surge arresters are also mounted on the track switch structure on the 3kV side
between the overhead track equipment and earth. The purpose of these arresters is to
serve as protection against any surges that might come from the track side.[14][21]
32
The 3kV feeder cables that run from the substation to the track switches are also
protected against surges through the 4 micro farad capacitors that is mounted between
the negative and the cables. The capacitor stores some of the energy from the surge
and releases it afterwards. This gives a smoothing effect on the surge.
The surge arresters should be located as close as possible to the equipment that must
be protected. The arresters must be connected to earth by means of an earth spike that
has a resistance smaller than 5 ohm to earth (EP.001 Issue 1). [14].
The two basic types of surge arresters used in the traction substations are the silicon
carbide (Si C) and Zinc Oxide (Zn O) arresters. The last type is the newer design that is
currently used. These lighting arresters are designed to clip off all voltage peaks that
exceed a specified level of 400kV. This means that all equipment in the substation must
be designed to withstand an impulse voltage of 500kV. Due to aging and damage to the
arrester it will not function to its designed specification. [7] After some time it will not limit
the voltage to under 500kV and a big enough surge will then cause major damage to the
substation.
2.4.7 Batteries
Batteries are installed at substation for control and protection purposes. The batteries form
the heart of the substation. Without proper operating batteries there will be no protection in
the substation. Running a substation without protection is almost impossible. Due to the
design of the substation to fail to a safe mode, a loss in the 110V supply from the batteries
will cause a loss of the main power supply to the overhead track equipment.
The battery supply is used for various purposes in the substation. It is used for closing
and tripping the primary circuit breaker, as a supply to the protection relays, for
emergency lighting inside the substation and as a closing and holding coil supply for the
high speed circuit breakers.
A typical battery bank will consist of 53 cells of 2.2V each. The batteries are rated in
terms of the voltage and ampere-hour capacity. The latest capacity for most lead acid
batteries in use is 100 ampere-hours. [14][21]
33
2.4.8 Rectifier
The six phase full wave bridge rectifier is the basic design on most new traction
substations. Two 1.5kV 6 pulse units, phase displaced by 300 are connected in series to
make up a 3kV 12 pulse unit.
Multiple phase 12 pulse rectification is preferred because of the very much smoother DC
output voltage and less harmonic noise.
In the actual design of the power rectifier, single diodes are seldom used. The required
voltage and current rating can be more economically obtained by using lower rated
diodes in series and in parallel.
The rectifier is situated inside the substation building and behind protective fencing to
prevent accidental shock. The entry to this enclosed bay is controlled by the interlocking
system in the substation.
Appendix 4 contains a copy of the Engineering Instruction EP.001 Issue 1 [14] that
contains detail information on the design of rectifiers for the use in 3kV DC traction
substations.
2.5 Summary
The chapter started with a discussion of the different types of traction systems that are in
use and explained the advantages and disadvantages of each system. The discussion
continued on the entire 3kV system and then the focus moved to the substation itself.
The important concept that must be understood is that all the components function together
to enable the system to provide 3kV DC power to the locomotive. More detail could have
been provided on each component that is a system in itself. It is not necessary to analyse
everything in detail because the data that is available on the failures are only at the level as
discussed in this chapter.
34
3 RELIABILITY STUDY OF A 3KV DC SUBSTATION 3.1 What is reliability? In the previous chapter a good understanding was created of how the 3kV DC traction
substation works. With this information, the ways in which the substation fails, the effects of
failure, and aspects of design, manufacture, maintenance and use which affect the
likelihood of failure, can now be described.
The task of the engineer is to design and maintain the product so that the failed state is
deferred (Covino, 2000). [25]. Covino et al. stated that reliability is one of the key factors
in product quality. According to British Standard, BS4778, failure means the termination
of the ability of an item to perform a required function. A study of the function of the 3kV
DC substation is necessary before the reliability can be investigated. According to
BS4778 [26] the reliability of a substation is the ability to perform a required function
under stated conditions.
According to Wolter J. Fabrycky [27] reliability as described in his book, Systems
Engineering And Analysis, can be defined simply as the probability that a system or
product will perform in a satisfactory manner for a given period of time when used under
specific operating conditions. This definition stresses the elements of probability,
satisfactory performance, time and specified operating conditions.
O’Connor described reliability as the probability that an item will perform a required
function without failure under stated conditions for a stated period of time. This definition
contains the same elements, namely probability, required function, stated conditions and
time. [28]
3.1.1 Probability
Probability, the first element in the reliability definition, is usually stated as a quantitative
expression representing a fraction or a percent specifying the number of times that an
event can be expected to occur in a total number of trials. For example, if the probability of
survival of an item for 80 hours is 0.75 (or 75%), it indicates that the item can be expected
to function properly for at least 80 hours 75 times out of a hundred.
35
When there are a number of supposedly identical items operating under similar
conditions, it can be expected that failure will occur at different points in time. Failures
are therefore described as probabilistic. For example, the 3kV system consists out of
many substations that are feeding into it. These substations have similar equipment
inside which operate under similar conditions. Failure of the equipment will not occur at
the same time. Probabilistic reliability is described in paragraph 3.2. [27]
The fundamental definition of reliability is heavily dependent on the concepts derived
from probability theory. In the FMECA done in this chapter, probability indicates the
frequency at which the incidents occur. A probability of 50% means that the incident
occurs at a frequency of once every two months. Monthly periods were taken to
calculate the probability.
This is adequate for the conclusions that had to be reach after the analysis. Once the
major components of the substation were identified, the most important once had to be
highlighted to proceed with further analysis.
3.1.2 Satisfactory performance
The second element in the reliability definition is satisfactory performance, indicating that
specific criteria must be established, which describe what is considered to be
satisfactory. It can also be described as the required function of the item in the system. A
combination of qualitative and quantitative factors defining the functions that the system
or product are to accomplish, usually presented in the context of the system
specification, are required. For the 3kV DC traction substation the basic requirement is to
provide a regulated supply of 3000V DC to the traction system. [27]
The satisfactory performance of any piece of equipment or component can, therefore, be
described as achieving the delivery requirement that it was designed for. In other words,
the system delivers what is expected from it.
36
3.1.3 Time
The third element, time, is one of the most important because it represents a measure
against which the degree of system performance can be related. The time parameter
must be known in order to assess the probability of the system to complete a task or
given function as scheduled. Of particular interest is the ability to predict the probability
of an item operating without failure for a designated period of time. In this chapter, all
data were analysed against a period of one month as described in the definition for
probability.
Reliability can also be defined in terms of mean time between failure (MTBF) or mean
time to failure (MTTF), making time critical in reliability measurement. [27] MTBF is the
average time between failures and MTTF is the average time until the first failure.
If the time is not probably defined in a study of this nature, it will create confusion on the
perception of reliability. It is important to remember that reliability was defined earlier as
the ability of the equipment to perform according to expectation. If the equipment
performs as expected, the operator would perceive it as being reliable.
37
3.1.4 Specified operating conditions
The specified operating conditions under which a system or product is expected to
function constitute the fourth significant element of the reliability definition. These
conditions will include environmental factors, such as the geographical location where
the system is expected to operate, the operational profile, temperature cycles, humidity,
vibration, shock, and so on. [27] The input from the operator is one of the factors
influencing the condition as mentioned. It cannot be expected to operate a system out of
the designed condition parameters. In substations, according to the fault list on annexure
10.4, and the analysis done on the impact of seasonal change in chapter 4 and 6, the
environmental condition plays an important role.
These factors play a very important role in the reliability of the 3kV DC substation.
Coastal and inland substations operate under very different environmental conditions.
Humidity and temperature play a major role in calculating reliability. Being close to the
railway lines, the equipment is also exposed to different vibration and shock factors than
in other applications. Some substations work harder than others due to the topography
of the environment. Trains need more current to pull a load over an incline and less
when coming down on the other side. A substation situated close to such place will be
exposed to bigger sudden changes in the amount of current being drawn from it, than
one that is on a flat piece of track. [15]
The four elements discussed above will be considered when determining the reliability of
a typical 3kV DC substation later in this chapter.
3.2 Probabilistic reliability
O’Connor discussed the concept of reliability as a probability involving the use of
statistical methods in his book, Practical Reliability Engineering. [28]
When reliability is 100 percent it means that the product will never fail and when it is zero
it means that it will never work. For practical purposes a hammer might be 100% reliable
if used for driving in nails, but would have zero reliability if used to stop a train. If used to
break rocks, its reliability for a given period of time might have some value between 0
38
and 100 percent. This is for illustration only because it is impossible to achieve 100% or
0% reliability.
When planning maintenance, the engineer, try to ensure 100% reliability, but experience
showed that it does not always materialise. Therefore reliability statistics are usually
concerned with probability values which are very high. Quantifying such numbers brings
increased uncertainty, since we need correspondingly more information. More
uncertainty is also introduced because reliability is also about people who maintain and
people who use the product. The varying environments in which substations must
operate also introduce great uncertainty when calculating the reliability.
The analysis of failures by different engineers will also cause uncertainty because of the
subjective nature of people. Questions like if a failure should be counted or not and what
the cause was will influence the statistical data being captured.
Reliability can be specified as the mean number of failure in a given time (failure rate), or
as MTBF for items that can be repaired and returned to use, or as the mean time to
failure (MTTF) for items which are not repaired but replaced. For items that can be
repaired it is often assumed that the failures occur at a constant rate, in which case the
failure rate λ = (MTBF)-1. Due to the constant usage of power from the substation it will
be assumed to be true for the major components. [28][29]
The application and interpretation of the statistics in the case of a 3kV substation are
less straightforward than in, for instance, public opinion polls or measurement of human
variations such as height, length and mass. The biggest problem with the statistics of
failures in substations is the amount of data that is available. There will not be nearly as
much data as in the other cases, like human study. Data is very expensive and variability
is hard to quantify. The integrity of the data is also very dependant on the experience
and knowledge of the person capturing it. To date, the human interface in the capturing
of data played a major role in Spoornet. This study introduces a technical interface after
looking at the human role.
It is also difficult to apply statistical theories to reliability calculations due to the fact that
variation is a function of time and time-related factors such as operating cycle and
39
seasonal changes. Different maintenance periods cause different inputs into the
condition of the substation. This has a major influence on the reliability of the substation.
Maintenance engineering is primarily concerned with change for the better. It does not
help if the reliability is not increased during maintenance. Therefore the data from any
past situation cannot be used to make good forecasts of the future behavior, without
taking into account changes that took place to increase reliability. These are the realities
that the maintenance engineer is faced with on a daily basis.
This provides a big challenge to the engineer, because of the fact that his statistical data
is influenced by various actions taken. By making simple, but intelligent, decisions on
maintenance inputs, a big change in the reliability can take effect.
3.3 The reliability function
The reliability function is derived by Blanchard and Fabrycky, System Engineering and
Analysis, 1981. [27]
The reliability function is determined from the probability that a system will be successful
at least for some specified time t. The reliability function, R(t), is defined as
R(t) = 1 – F(t) (3.1)
where F(t) is the probability that the system will fail by time t. F(t) is basically the failure
distribution function or unreliability function. If the random variable t has a density
function of f(t), the expression for reliability is
R(t) = 1 – F(t) = ∫∞t f(t) dt (3.2)
If the time to failure is described by an exponential density function, then
f(t) = 1/θ e-t/θ (3.3)
where θ is the mean life and t the period of interest. The reliability at time t is
40
R(t) = ∫∞t 1/θ e-t/θ dt = e-t/θ (3.4)
Mean life (θ) is the arithmetic average of the lifetimes of all items considered, which for
the exponential function is MTBF. Thus
R(t) = e-t/M = e-γλt (3.5)
where γ is the instantaneous failure rate and M the MTBF.
If a component has a constant failure rate, the reliability of that item at its mean life is
approximately 0.37. Thus, there is a 37% probability that the system will survive its mean
life without failure. Mean life and failure rate are related as
γ = 1/θ (3.6)
Figure 3.1 illustrates the exponential reliability function, where time is given in units of
t/M. The illustration focuses on the reliability function for the exponential distribution,
which is commonly used in many applications.
Figure 3.1 : Reliability curve for the exponential distribution. (Benjamin S. Blanchard,
Systems Engineering and Analysis, 1981) [27]
41
The failure rate is the rate at which failures occur in a specified time interval. The failure
rate per month is expressed as
λ = Number of failures / total operating months (3.7)
The failure rate may be expressed in terms of failures per month, percent failures per 12
months or failures per million hours. In the case of a 3kV DC traction substation the
failure rate was best expressed as failures per month. For the analysis in this chapter,
the rate was taken as the number of months during which events take place.
The relationship between the failure rate and the MTBF is
MTBF =1/λ (3.8)
The failure rate is important when determining corrective maintenance actions. All
system failures must be addressed to include failures due to primary defects, failures
due to manufacturing defects, failures due to operator defects, and so on (Blanchard,
1990).
3.4 The Bathtub curve
Figure 3.2 shows a curve indicating the relationship between failure rate and time.
Figure 3.2 : Typical failure-rate curve (Benjamin S. Blanchard, Systems Engineering and
Analysis, 1981). [27]
42
This curve may vary considerably depending on the type of component inside the
substation. Because of all the activities that can influence the reliability of a substation,
for example the replacement of certain defective components, this curve will not be
constant.
During the procurement process, companies need to take this into consideration. The
analysis later in the chapter can be used to provide important guidelines to ensure that
reliability is taken into account when purchasing equipment or components. It is not
always true that money can buy reliability. It is important to look at the design
specifications and make sure that the reliability will not be compromised due to utilisation
without the design parameters.
By examining the curve it can clearly be seen that it has a bathtub shape with three
distinct regions. The first region corresponds to early failures during debugging. As the
debugging rate continues, the failure rate decreases. The second region corresponds to
the useful lifetime of the component where the failure rate remains quite constant and
the failures are very nearly random. The third region corresponds to the wearout or
fatigue phase during which the failure rate increases rapidly with time. These three
regions are easily distinguishable in the plot of the failure rate function. (Ramakumar,
1985) [6]
3.5 Reliability component relationships
Given the basic reliability function and the measures associated with failure rate, it is
appropriate to consider their application in series networks, parallel networks and
combinations of these. These networks will be used in the reliability block diagrams and
static models for the analysis of the 3kV DC traction system. The development of the
reliability block diagram for the traction substation will evolve directly from the functional
flow diagrams for the system as described in chapter 2.
43
3.5.1 Series Networks (Benjamin S. Blanchard, Systems Engineering and Analysis, 1981) [27]
The series relationship is probably the most commonly used and is the simplest to
analyse. Most of the major components in the 3kV DC substation are related this way. A
basic series network is illustrated in Figure 3.3. In a series network all components must
operate in a satisfactory manner if the system is to function properly.
Figure 3.3 : A series network
Assuming that a system includes subsystem A, subsystem B and subsystem C, the
reliability of the system is the product of the reliabilities for the individual subsystems
expressed as
R = (RA)(RB)(RC) (3.9)
3.5.2 Parallel Networks (Benjamin S. Blanchard, Systems Engineering and Analysis, 1981) [27]
A pure parallel network is one where a number of the same components are in parallel
and where all the components must fail to cause total system failure. A parallel network
with two components is illustrated in Figure 3.4. Although not exactly the same, 3kV DC
substations are arranged in parallel on the system as in Figure 2.1. This arrangement is
not possible with AC traction systems because the AC cannot be exactly in phase, which
is not a problem with DC.
Figure 3.4 : A parallel network
A B C Input Output
A
B
Input Output
44
If components A and B are identical, the system will function if either A or B, or both are
working. The reliability is expressed as
R = RA + RB – (RA)(RB) (3.10)
3.5.3 Combined Series-Parallel Networks (Benjamin S. Blanchard, Systems Engineering and Analysis, 1981) [27]
Various levels of reliability can be achieved through the application of a combination of
series and parallel networks. Consider the two examples illustrated in Figure 3.5.
The reliability of the first network is given by
R = (RA)(RB + RC - RBRC) (3.11)
For the second network the reliability is given by
R = (RA + RB – RARB)(RC + RD – RCRD) (3.12)
(a)
B
C
Input Output
A
45
(b)
Figure 3.5 : Some combined series-parallel networks
Under certain conditions in system design it may be necessary to consider the use of
redundancy to enhance reliability by providing two or more functional paths in areas that
are critical for successful functioning. This is accomplished through the use of parallel
networks. In Figure 3.5(a) subsystem B and subsystem C can be used to illustrate the
redundancy of the system if they are considered to be exactly similar. In this case it will
be called duel redundancy because there are two backup systems that are performing
the same function. For the system to fail either subsystem A or subsystem B and
subsystem C must fail.
3.6 Block diagram analysis of a 3kV DC substation
The failure logic of a system can be shown as a reliability block diagram (RDB), which
shows the logical connections between components of the system. The RDB is not
necessarily the same as a block schematic diagram of the system’s functional layout.
The block schematic diagram of a 3kV DC traction substation is shown in Figure 2.4.
Keeping that in mind, the RDB for a traction substation is shown in figure 3.6. [15]
C
Input Output
A
D B
46
Figure 3.6 : Reliability block diagram of a 3kV DC traction substation. [15]
Table 3.1 : The key to figure 3.6
Supply AC Supply from the utility company
AC Disconnects Disconnect supply from substation
PCB Primary Circuit Breaker
Protection All protection circuits in substation
HSCB High Speed Circuit Breaker
OHTE Overhead track equipment
As can be seen in Figure 3.6, all the subsystems are in series. The subsystem that is
illustrating the protection is actually functioning alone. Each subsystem consists of many
components or even subsystems themselves, but to discuss everything in detail is
beyond the scope of this study. What is very important to notice is that failure of any one
of the major subsystems will cause the substation to fail. The effect that failure at
different levels will have, will be discussed during the analysis of the failures later on.
Surge Arrestors
Measurements
Voltage Transformer
Protection
Current Transformer
OHTE
Track Switch
HSCB DC Earthleakage
Rectifier
Transformer
PCB
AC Disconnects
Supply
47
To improve the reliability of the 3kV system, the arrangement of substations is illustrated
in Figure 3.7. Note that it is a parallel arrangement and that there will still be a supply of
3kV DC to the overhead equipment if one substation fails.
Figure 3.7 : Reliability block diagram of a 3kV DC traction system.
If substation B fails, substations A and C, which are the adjacent substations to B, will
still provide 3kV DC to the system. If, for example, substations A and B should fail, the
system will fail. The 3kV DC system can therefore be described as a dual redundancy
system.
Since almost anything is possible in the engineering world, it can happen that two
adjacent substations fail. It can happen that two substation are on the same supply
circuit from the utility company and that the supply fails. In the unlikely event of
something like this happening, there still is an alternative source of traction, namely
diesel locomotives. This is, however, a very expensive option and it must be insured that
it is implemented as little as possible.
3 2 1
4 5 6
48
3.7 Failure mode, effect and criticality analysis
The FMECA (failure mode, effect and criticality analysis) is performed to identify possible
problems that could develop as a result of system failures. The FMECA is oriented to
equipment and does not cover the effects of human actions on equipment. The objective
is to determine the ways in which equipment can fail, and the effects of such failures on
other elements of the system, (Benjamin S. Blanchard, Systems Engineering and
Analysis, 1981). [27] Failure effects can be considered at more than one level, for
example, at subsystems or the entire system.
FMECA can be based on a hardware or a functional approach. In the hardware
approach actual hardware failure modes are considered, for example a resistor that goes
open circuit or a bearing seizure. The functional approach is used when hardware items
cannot be uniquely identified, (O’Connor, Practical reliability engineering). [28] A
combination of the two approaches can also be used.
To perform an effective FMECA, a thorough knowledge of the system is needed. The
first step therefore is to obtain all information available on the system. The information in
the previous chapters should be enough to do a good analysis on the 3kV DC system.
The functional block diagram in figure 2.4 and the reliability block diagram in figure 3.6
and figure 3.7 will be used for the FMECA of a 3kV DC system. The data captured in
annexure 10.1 and 10.4 was used to calculate the probability of the fault occurring.
An FMECA can be performed from different viewpoints, such as safety, mission,
success, availability, repair cost, failure mode, etc. Although things like safety and cost
are very important for the maintenance of substations, the availability will be considered
during this analysis of the 3kV DC system.
The required outcome must be considered when deciding how to approach the FMECA.
For the purpose of this study, the important components had to be identified. Which
components failed frequently, what is the effort required to repair and what influence
does such a failure have on the system. The substation forms part of a bigger system
and should not be considerd and analysed in isolation. Consideration was given to the
effect that the failure would have on the entire system.
49
The FMECA must include the following information:
1. Item identification – Identify each significant system component that is likely to fail.
2. Description of failure modes – Define the most probable modes of failure for each
identified item. Failure modes are related to the operational modes that the system
experiences through the performance of its designed function.
3. Cause of failure – The anticipated cause of failure should be described for each
instance.
4. Possible effects of failure – Describe the most probable effects as a result of each
failure. Effects may range from complete system destruction to partial system
operation.
5. Probability of occurrence – Through statistical means, estimate the probability of
failure occurrence. Probabilities of occurrence may initially evolve from experience
factors or through reliability allocation and will be based on reliability prediction data
as more date is captured as the system progresses.
6. Criticality of failure – Failures may be classified in terms of criticality in any one of
four categories, depending on the defined failure effects as follows.
• Minor failure – Any failure that does not degrade the overall performance and
effectiveness of the system beyond acceptable limits.
• Major failure – Any failure that will degrade the system performance and
effectiveness beyond acceptable limits but van be controlled.
• Critical failure – Any failure that will degrade the system beyond acceptable limits
and could create a safety hazard if immediate corrective action is not taken.
• Catastrophic failure – Any failure that could result in significant system damage, such
as to preclude functional accomplishment, and could cause deaths and personnel
injuries.
50
7. Possible corrective action or preventive measures – Describe the action than can be
initiated to reduce the probability of failure occurrence or to minimize the effect of
failure, (Benjamin S. Blanchard, Systems Engineering and Analysis, 1981). [27]
In Table 3.2 a thorough FMECA was done on the major components of the 3kV traction
system. Because of a lack of data, most of the information follows from interviews with
two supervisors with forty-two years of experience amongst them and one electrical
engineer with twenty-one years of experience. Some of the information was double
checked with the data given in annexure 10.1 and 10.4, which contains the inscriptions
of logbooks taken from six substations over a period of one year and data collected from
the information system used by Spoornet to capture all maintenance effort on their
infrastructure. [15]
Some very important observations can be made from the FMECA done in Table 3.2 that
will help to identify areas of concern. Each of the items identified can be broken down
into smaller components and a FMECA can be done in greater detail but for the purpose
of developing a condition assessment, this is good enough.
The first observation made was that a lack of proper data prevented the accurate
calculation of the probability of occurrence. The values in Table 3.2 had to be
approximated on the basis of pure experience. It is imperative for good engineering
decisions on maintenance that a good record must be kept of all failures that occurred in
the system. These records must include the type of fault, cause of the problem, date and
time when it happened and how long it took to repair. This is the basic information
needed for most statistical analysis.
Secondly, it is important to note that the 3kV traction system is not an isolated system.
Adjacent systems, which may not even belong to the same company, have a big
influence on the availability. The supply from the utility company is one of these systems.
The substation cannot perform its desired function if there is no supply. This fact just
complicates the reliability calculations for the substation. From the FMECA experience
has proven that the supply can be quite unreliable in some cases.
51
One of the most important conclusions from this analysis, thirdly, is the importance of the
protection circuits that must minimise damage in the event of a failure. Note that it is not
always possible to completely prevent damage, but the ultimate goal is to have as much
control as possible over the amount of damage. The protection circuits must isolate the
fault to prevent damage to other components. In nearly all the identified items one of the
causes noted was the failure of protection. When the protection actually failed the
criticality of the failure increased to catastrophic. It is clear that the testing of protection
circuits must have a very high priority in the routine maintenance of a substation.
Human error plays a major role in the reliability of this system. All corrective actions were
based on a human effort that must be put into the maintenance. If this effort is not up to
standard and according to specified standards it can increase the probability of failure.
Human safety is one of the biggest consideration in some of the protection features
inside a substation. The interlocking on the AC disconnects form part of an interlocking
system protecting the technician that must work on the equipment. It is designed to
prevent access to potentially dangerous areas by the power to be switched off before
entrance to the enclosure can be gained.
53
Table 3.2 : FMECA for a 3kV DC traction system
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
Supply Supply the
substation with
88kV/132kV AC
Total Power
failure
Phase failure
Voltage spike
Voltage drop
Theft, loose
connection, etc.
Theft. Loose connection, etc.
Surge caused by nearby
switching on the system or
lighting
Shortage on
national grid.
Switching by
nearby industries on
the network.
Substation will
not have supply
and will not be able to work at
all.
Unbalanced load on the
Transformer
which can cause serious
damage if protection is
not working
properly.
Damage to substation
equipment
Due to energy
demand this can cause
sudden spike in
current drawn by the
substation.
Approx. 0.02
Approx. 0.04
Approx. 0.5
Approx. 0.3
Major failure
Critical failure
Major failure
Critical failure
The utility
company must
make sure that there is a ring
feed available.
Protection against phase
failure must be
working properly and
tested regulary.
Ensure surge arrestors are in
proper working condition.
Ensure
operational testing and
calibration of
undervoltage relay.
54
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
Surge Arrestors Protect equipment
inside
substation against any
power surge from the supply
Short circuit
Open circuit
Tracking of current
Age, external damage, over
current,
lightning strike
Lightning strike, leakage of
isolating material,
deterioration of
isolating layers
External dirt on porcelain,
damage to
porcelain insulator due to
vandalism or direct lightning
strike
Short circuit directly to
ground. Supply
will fail.
Protection against any
surge will not be possible.
Current leakage can cause
protection to
operate and will switch off the
substation.
Approx. 0.001
Approx. 0.01
Approx. 0.02
Major failure
Minor failure
Major failure
Proper cyclic testing of the
capacitive
characteristics.
Proper cyclic testing of the
capacitive characteristics.
Visual inspections for
damage and
frequent cleaning of the
porcelain.
55
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
AC Disconnects Used to isolate substation from
supply
Broken insulators
Opening Mechanism
failure
Interlocking
failure
Hot connection
Vandalism, lightning strike,
water in the
base plates causing
cracking
Rust, broken operating
handle, rotating
bearing broken
Broken keys,
mechanism not functioning
properly, loose connection on
electrical protection from
opening the
disconnects under load.
Dirty contacts,
contacts not
aligned correctly
Disconnects will not close or
open at all.
No operation will be possible.
Safety risk to
operator. Disconnects can
be damaged due to the
operating of it under load.
Contacts will
disintegrate and
conductors will be burnt.
Approx. 0.01
Approx. 0.015
Approx. 0.008
Approx. 0.02
Critical failure if occurring while
in open position
Minor failure
when closed
Critical failure if occurring while
in open position
Minor failure
when closed
Major failure
Critical failure
Visual inspection and
immediate
action when needed
Frequent corrective and
preventive
maintenance.
Visual and
mechanical inspection
before operating
commences.
Frequent
maintenance
and visual inspections for
any signs of over heating.
56
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
Voltage Transformer
Monitor the voltage on the
incoming
supply
Open circuit
Short circuit
Loose connection,
burnt wires
Burnt wires,
over current
No measurement
possible
No
measurement possible
Approx. 0.002
Approx. 0.002
Minor Failure
Minor Failure
Frequent testing
Frequent
testing
Measurements Take
measurement for billing and
protection
No
measurement
Incorrect
measurement
Damage to
measuring electronics or
faulty feed from voltage
transformer
Incorrect feed
from voltage transformer
No
measurements available for
billing
Incorrect
readings and calculations for
billing
Approx. 0.001
Approx. 0.005
Minor Failure
Minor failure
Calibrate and
test frequently. Compare
measurements to previous
ones
Frequent
calibration and testing
57
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
PCB (Primary circuit
breaker)
Protection switch between
supply and
substation
Not opening
Not closing
Current
Leakage to earth
External
damage
Operating mechanism
faulty, faulty
opening rely, protection
circuits not working
properly
Operating
mechanism faulty, faulty
Closing rely, protection
circuits not
working properly
Dirty porcelain
or breakdown of isolating
material and oil
Vandalism,
lightning, water
Substation will suffer damage
because PCB
did not open under fault
conditions
Substation off
load because there is no
supply
Damage to
breaker and possible trip of
substation if
leakage is detected by AC
earth leakage
Current leakage
and possible disintegration
Approx. 0.001
Approx. 0.001
Approx. 0.002
Approx. 0.0005
Catastrophic failure
Critical failure
Critical failure
Catastrophic
failure
Testing, maintenance of
breaker and
protection circuits
Testing of
protection circuits and
maintenance
Testing of oil
and isolation, frequent
cleaning of
porcelain
Do frequent
visual inspections
58
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
Current Transformer
Monitor the current into the
main
transformer
Short Circuit
Open circuit
Incorrect feed
Damage due to overcurrent.
Lightning, dry
without oil
Faulty windings, loose
connections
Loose
connection, damage due to
lightning or any other surge
No protection on equipment,
can cause
serious damage to transformer
if mounted in it.
Incorrect feed to protection
circuits
Protection
circuit will receive
incorrect feed and will not
operate properly
Approx. 0.001
Approx. 0.015
Approx. 0.002
Catastrophic failure
Catastrophic failure
Catastrophic
failure
Make sure that transformer is
tested
frequently and earthed
properly
Frequent testing of
transformer and
protection circuits. Install
to fail to safe mode
Testing and calibration of
protection. Do frequent ratio
tests on the current
transformer
59
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
Protection Circuits that must protect
the substation
from damage in the event of
any failure that might result in
major damage
Incorrect operation
No operation
Feed from
current transformer not
correct
Failure of DC
Eartleakage
Fault Protection rely failure
Feed from current
transformer not
correct, faulty rely, latching
mechanisms not functioning
Faulty rely,
battery supply
not working properly, No
feed from current
transformer
Loose
connection, faulty current
transformer
Loose
connections
Incorrect calibration
Not all equipment is
connected
Line faults are not isolated
Damage to substation due
to fault not
being isolated fast enough
Damage to
substation due
to fault not being isolated
fast enough.
Damage to
substation due to fault not
being detected
DC fault not
isolated before damage to the
substation occur.
Approx. 0.001
Approx. 0.001
Approx. 0.001
Approx. 0.002
Approx. 0.01
Catastrophic failure
Catastrophic
failure
Catastrophic
failure
Catastrophic
failure
Catastrophic failure
Monthly functional
testing, annual
calibration
Monthly
functional
testing, annual calibration.
Annual
calibration and frequent testing
Weekly
functionality testing.
Annual
calibration by
testing technician
Same as for DC earthleakage
60
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
Main Transformer
Step down of the supply
voltage to
1500V
Low oil level
Bucholtz rely operation
Over temperature
Short circuit
Leakage at gaskets
Gas formed inside the
transformer due to some kind of
fault like arcing
or low oil level.
Extensive arcing inside
transformer,
over current drawn due to
fault in system
Isolation material got
damaged due to water or
arcing, Isolating properties of
the oil not up to
standard any
If protection operate the
supply will be
switched off. If no operation
from the Bucholtz, the
transformer will blow up.
Supply is switched off
Protection will cause supply to
be switch off. If
not, there will be major
damage to transformer
Protection should detect
earth leakage or unbalanced
load and must switch the
supply.
Approx. 0.0015
Approx. 0.01
Approx. 0.002
Approx. 0.0025
Critical / Catastrophic
failure
Critical failure
Critical / Catastrophic
failure
Critical / Catastrophic
failure
Weekly check on oil level and
immediate
repair of any leaks.
The Bucholtz form an
important part of the
protection
circuits and must be tested
frequently.
Make sure that protection
works and that
over temperature
rely is set correctly
Do frequent ratio test and
isolating tests on the
transformer. The isolating
properties of
the oil must be
61
Open circuit
more.
Loose
connection, burnt windings.
The fault will
have various effects on the
transformer
that will cause gas and heat to
build up inside the
transformer. The protection
should detect
this and switch off the supply.
Approx. 0.0015
Critical /
Catastrophic failure
tested as well.
Make sure that
protection is in working order
and calibrated
to react as fast as possible.
62
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
Rectifier AC input to DC output
Open circuit
Short circuit
Over
temperature
One or more diodes not
working, Loose
connection, filter circuits
faulty.
Faulty diodes, fault current
causing
ionization of the air, support
circuits faulty
Arcing inside
rectifier, loose connection, bad
contact between diode
and heat sink, cooling fans not
working.
No output from rectifier.
Protection should detect
earth fault and
isolate the rectifier.
Over
temperature protection
should switch off the supply.
If not, major damage can
occur to
rectifier.
Approx. 0.003
Approx. 0.0025
Approx. 0.0035
Critical
Critical / Catastrophic
Critical /
Catastrophic failure
Frequent diode testing and
checking for hot
connections on the rectifier.
Make sure protection is
working and do
frequent diode testing.
Over
temperature protection must
be calibrated and tested.
Make sure that cooling fans are
working and
that hotspots are detected in
time.
63
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
HSCB Protection switch between
substation and
OHTE
Not operating
Operating too
slowly
Not good
connection to
busbar
Burnt contacts, opening and
closing circuits
faulty, broken spring
Tension on
opening mechanism not
correct
Tension on
contacts not
enough or to much, trolley
not properly aligned
Will not be able to isolate
substation from
fault on the OHTE
Contacts will be
damaged. If fault is big
enough, there
will be damage to substation.
Hot connection
will cause
arcing and damage to
contacts
Approx. 0.004
Approx. 0.0035.
Approx. 0.003
Catastrophic failure
Catastrophic
failure
Critical failure
Clean breaker frequently and
calibrate
annually.
Check tension
frequently and adjust if
needed.
Use correct
procedure to
set tension on contacts.
64
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
DC Earth leakage
Part of protection
circuits. Detects
any leakage of DC current in
the substation.
Not operating
Not locking out
substation
Faulty rely, no detection, loose
connection
Faulty latch or
rely
No protection for substation
against any DC
faults
Supply can be
switched back while fault is
still existing.
Approx. 0.0005
Approx. 0.001
Catastrophic failure
Catastrophic
failure
Weekly functional
testing and six-
monthly calibration
Weekly
functional testing must be
done.
DC Earthing System
To provide earth potential
to the DC in the
substation
Poor connection
No connection
Due to electrolysis the
earth mat
corroded away and is causing
poor connection between the
equipment in the substation
and the mat.
Due to
electrolysis the earth mat
corroded away
and is and does not exist
anymore.
There is no earthing
available for the
DC system in the substation.
The ability to conduct faults
is not-existant.
Approx. 0.003
Approx. 0.001
Critical failure
Critical failure
Testing of all protection
equipment in
the substation on an annual
basis.
Routine
replacement after every 5
years.
65
Item
Identification
Function Failure modes Cause Effects of
failure modes
Probability of
occurrence
Criticality of
failure
Corrective
action
Track switch Manually operated switch
between
substation and OHTE. Isolate
above from each other.
Arcing
Not able to be closed
Not able to be
opened
Incorrect alignment of
the blades, dirty
contacts
Operating handle faulty,
dirty mechanism or
miss alignment
Burnt contacts,
faulty operating handle, locks
rusted
Hotspot on system where
conductors can
burn off.
No connection between
substation and OHTE.
There will be no
manual way to isolate the
substation from the OHTE
Approx. 0.001
Approx. 0.0005
Approx. 0.0005
Critical failure
Critical failure
Catastrophic
failure
Frequent maintenance
and inspections
must be done.
Make sure operating
handle is in good working
order and that
there are no loose bolts on
the switch.
Visual
inspection of the switch will
give early warning of
problems.
OHTE Overhead track equipment.
Carries DC to locomotive.
No continuity
Short circuit
Theft, vandalism,
damage due to passing train,
loose
connections, etc.
Fault caused by
object on line or loose
connections.
No feed to locomotive.
No feed to
locomotive
Approx. 0.1
Approx. 0.05
Catastrophic failure
Critical failure
Develop new methods to
protect line against theft
and vandalism.
Remove all
possible hazards, like
nearby trees.
66
3.8 The influence of workload on reliability Just like mechanical fatigue in moving components, there is also electrical fatigue for
equipment used in the substations. There should be more fatigue in a substation where
the load is higher. A distribution of power usage is shown in Figure 3.8 for the six
substations under investigation. This data is for a period of twelve months and shows the
amount of power that was drawn from the utility company every month.
This particular utility company charges for three different tariffs, depending on the time of
day that the power was used. A breakdown into off-peak, standard and peak power is
given in annexure 10.2. The data gives an idea of the time of day when the substations
draw the most power. This is very important when looking into ways to save on energy
cost.
Figure 3.8: Total power usage over 12 months [15]
Table 3.3 summarises the number of times that there were problems at these
substations where maintenance staff had to go and do repairs. The information is
extracted from annexure 10.1.
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
2001
04
2001
05
2001
06
2001
07
2001
08
2001
09
2001
10
2001
11
2001
12
2002
01
2002
02
2002
03
Month
kwh
BEECHWICK
KRAAL
PERDEKOP
SPRUCEWELL
STANDERTON
VOORUITSIG
67
Table 3.3: Substation visits
Substation Callouts Maintenance Inspections
Beechwick 5 15 14
Kraal 23 17 53
Perdekop 16 9 27
Sprucewell 14 23 52
Standerton 19 15 23
Vooruitsig 13 20 23
Table 3.3 gives an indication of the maintenance effort that went into each substation for
a period of twelve months. The number of callouts to a particular substation can be
related to the reliability of that substation. It is an indication of the number of times that
the substation failed and had to be visited to rectify the fault. The column indicating the
number of inspections done on that substation is not always a true reflection of the effort
put into preventative inspections because it can be influenced by the distance that the
technician responsible for the inspections need to travel to get to it. The closer the
substation is to the depot, the more it will be inspected. However, it does give a very
good idea of the number of inspections done at that place.
According to Figure 3.8, the substation Sprucewell is drawing the most power during
much of the year. The number of callouts to the substation is average but the amount of
maintenance done is the highest. Inspections took place quite frequently according to
the graph. The substation drawing the least amount of power is Standerton. Not that
many inspections took place, but quite a lot of callouts had to be attended to. From
annexure 10.1 it can be seen that there was one incident involving human error that
caused quite a few callouts.
68
3.9 Summary
Accurate data is needed on the maintenance history of a 3kV traction substation to
calculate the reliability. Obtaining this data is not easy and it must be accumulated over
a period of at least three years to yield sufficient information. A technique for capturing
the data automatically is required.
By doing a FMECA on the system a very good model of the reliability can be obtained
through the use of experienced people. The knowledge gained over twenty years might
not be very scientific, but it remains very trustworthy. Before doing an FMECA, the
engineer must decide on the level at which the analysis must be done. More detail can
be added, depending on the required outcome.
Detail analysis of the type of callouts, the amount of maintenance and the number of
inspections indicates that by adding additional preventative effort, the reliability of a
substation can be increased. When calculating reliability it is very important to look at
workload. Reliability must be used as the measure against which to balance effort. An
acceptable reliability must be decided upon and workload must then be used as a
starting point to determine the maintenance effort.
Maintenance is an essential part of the lifecycle of any component or system and must not
be neglected. However, by making use of frequent inspections most problems can be
identified at an early stage, which will prevent major damage to an entire system. The
advantage of inspections should never be underestimated.
69
4 VISUAL INSPECTION FOR 3KV DC SUBSTATIONS 4.1 Introduction From chapter 3 it is clear that visual inspections play a major roll in improving the reliability
of a 3kV DC traction substation. It gives an early warning of possible failure, which can
then be avoided by doing preventative maintenance. When one small component fails in a
system it may lead to total system destruction. For example, the failure of the over
temperature protection on a rectifier can cause the entire substation to be destroyed by
the fault current running through it. By detecting the possible failure early this can be
prevented. For a visual inspection to be effective there must be a clear set of guidelines to
help the inspector not to overlook small things. It must also be done without switching the
system off because this will cause a failure. Remember that a failure occurs when the
system cannot perform at its design standard. By switching it off it is no longer supplying
3kV DC to the overhead feeders. The inspection must also enable the inspector to be
efficient and not to waist time on unimportant detail.
In this chapter such an inspection process will be discussed and explained. This process
enables the inspector to get an objective view of the overall condition of the substation
without having to test or switch off any thing. It is safe and fast and can be done by any
person with a reasonable knowledge of substation maintenance. It allows the engineer
to compare inspections for determining trends and maintenance standards. The layout
allows the engineer to draw up a maintenance budget, focussing on problem areas.
This system was designed to make maintenance-orientated inspections more efficient and
reliable.
70
4.2 Inspection form for 3kV DC substation The form in Figure 4.1 contains all the important components of the 3kV DC substation that
can be visually inspected. The only measurement that must be taken is that of the earth
fault current which can be read from the meters on the panels. No switching, is needed
which means that any person familiar with the working of the system can do the inspection
without needing special authority.
The form that must be used for this process is shown in Figure 4.1 and was designed
during my study towards a Masters degree in electrical engineering.[15]. All the information
is contained on only one page, with just short descriptions of each component that must be
inspected. Table 4.1 contains a detail description of each component for better
understanding. The weights that were assigned to each component were calculated sing
the FMECA one in the previous chapter.
The design of the form will help the person doing the inspection to follow a set route
through the substation in order to minimise time spent on the inspection. The average time
for inspections on a standard substation where all the sections in the form had to be
completed, was thirty-five minutes. When taking into account that the average distance
between two substations is ten kilometers, travelling between two substations takes about
fifteen minutes. It takes about one hour per substation to do this thorough inspection. This
implies that by using this process, six substations can be inspected per day.
71
DATEPLACE
FENCING 0.11 FENCING 0.11 LIGHTNING ARREST ERS 0.17
EART HING 0.15 EARTHING 0.15 CAPASIT ORS 0.17
OCB MECHANISM 0.11 OCB MECHANISM 0.11 SPARKGAPS 0.17
T RANSFORMER 0.11 TRANSFORMER 0.1 LOCK MECHANISM 0.17
SILICA GEL 0.13 SILICA GEL 0.13 EART HING 0.2
OIL LEVELS 0.15 OIL LEVELS 0.15 AREA CLEAN 0.12
SAFETY SIGNS 0.07 SAFET Y SIGNS 0.07 T OTAL: 1
PAINT 0.09 PAINT 0.09
AREA CLEAN 0.08 AREA CLEAN 0.09
T OT AL: 1 TOTAL: 1
INDOOR INDOORLIGHTNING ARREST ERS 0.21
LIGHT ING 0.08 LIGHTING 0.21 SPARKGAPS 0.2
HSCB PANELS 0.08 PANELS 0.21 EART HING 0.24
L.T . PANELS 0.1 METERS 0.24 LOCK MECHANISM 0.2
RECTIFIERS 0.08 S/GAP + D/SWIT CH 0.21 AREA CLEAN 0.15
REACT OR 0.07 PER./LOG-BOOKS 0.13 T OTAL 1
BATT ERY CHARGER 0.07 TOTAL: 1
MET ERS 0.08
EART HFAULT 0.12
SAFETY SIGNS 0.07 3kV SUB 0.7 / 0.4
PER./LOG-BOOKS 0.12 HIGH VOLTAGE YARD 0.35 3kV SWITCH FRAME 0.3 / 0.15
AREA CLEAN 0.13 INDOOR 0.4 6.6kV SWIT CH FRAME 0.0 / 0.15
T OT AL: 1 BAT TERY ROOM 0.25
T OTAL:
BATTERY ROOM 6.6kV SUB 0.0 / 0.3
HIGH VOLTAGE YARD 0.55 PRODUCTION MANAGERWATER LEVELS 0.39 INDOOR 0.45
CONNECTIONS 0.39 MAINTENANCE MANAGERSAFETY SIGNS 0.22
T OT AL: 1
6.6KV SW ITCH FRAME
3KV SUBSTATION
HIGH VOLTAGE YARD
SUBSTATION INSPECTION SHEET
6.6KV.SUBSTATION
HIGH VOLTAGE YARD
3KV.SWITCH FRAM E
Figure 4.1 : Inspection form for 3kV DC traction substations [15]
72
Table 4.1 : Component description for Inspection form [15]
Component Description 3kV Substation The part of the substation that is producing 3kV DC as an output. This
includes all the equipment associated with performing the required function. 6.6kV Substation The portion of the substation that is involves in the supply of 6.6kV power to
the overheads. It is sometimes connected to a supply or in other cases it is just for control purposes.
3kV Switch frame The structure where the output from the substation is fed onto the overhead equipment is called the switch frame. This frame hosts the switches and lightning protection for the 3kV feed.
6.6kV Switch frame This is the structure where the 6.6kV is fed onto the lines. High voltage yard This is the outdoor portion of the substation for the 3kV and the 6.6kV. In
most cases the two voltages are divided into two different yards to prevent accidents. This is where the supply to the substation is controlled and measured.
Indoor All equipment that is in the substation building is part of this portion of the 3kV or 6.6kV substation.
Battery room The heart of each substation, namely the batteries, is kept in the battery room.
Fencing The fence surrounding the entire substation that is preventing unauthorised entry to the high voltage yard and the building.
Earthing All the equipment is connected to earth for protection purposes. OCB Mechanism The mechanism that opens and closes the primary circuit breaker. Transformer All the transformers in the high voltage yards. For the 3kV feed it is normally
a 4.5MW transformer and for the 6.6kV it is normally a 1MW transformer. Silica Gel The breather that keeps the air dry when the transformer is “breathing”
contains silica gel which must be kept in a working order. Oil levels Al oil levels on the equipment must be correct. Safety Signs Safety signs that warns people against the dangers inside the substation
must be in place at all entry points to the substation. Paint Structure must be painted to prevent rust. Area clean The area must be clean of any rubbish or plants. Lighting The lights inside and outside the substation must be in working order. HSCB Panels The panels for the high speed circuit breakers must be clean and tidy. L.T. Panels The panels housing the low voltage equipment, such as protection, must be
tidy and clean. These panels are inside the 3kV substation building. Rectifiers The rectifiers are situated inside the enclosure that is protecting against
unauthorised entry. Reactor The big coil that is protecting the rectifier against surges must be clean and
the bolts must not be loose. Battery charger The panel that contains the battery charger is situated inside the building. Meters Al meters on the panels must be in working order. Earthfault The readings for this are taken from the meters on the panels and give an
indication of the leakage current that is flowing to earth. It must be zero. Per./Log. Books The permit books are used to document all switching that are done at the
substation. The logbook must be used as a visitors’ book, documenting everything that is being done at the substation.
Water levels The water level inside the batteries must be correct. Connections The connections between the batteries must be tidy and clean. Panels The panels inside the 6.6kV substation must be clean. S/Gap + D/Switch The sparkgap and d-switch at the door to the 6.6kV building must be working
to protect people entering the building from being injured. Lightning arresters The lightning arresters on top of the switching structures must be working. Capasitors The capasitors are on the 3.3kV switching frame and protects the system
from electric surge. Sparkgaps A small, bell-like type, piece of equipment that is situated on all structures to
protect people against electric shock. Lock mechanism The mechanism prevents unauthorised switching of the track switches at the
frame.
73
4.3 Importance of different components on the form The entire process for this inspection is based on the fact that not all the components are
critical for the performance of the required function. In fact, the components have different
weights of importance when it comes to the functioning of the substation.
Some components are critical in performing the function needed, while others are critical
when it comes to human safety. That is why it is possible to assign different weights of
importance to each component.
In Figure 4.1 the different weights were added for illustration purposes. The actual form that
will be taken to the site will not have these weights on it. The substation can be divided into
four major areas, namely the 3kV substation, 6.6kV substation, 3kV switch frame and 6.6kV
switch frame. Each of these is assigned a different weight. Because some substations only
consist of the 3kV portion, there are two ways to calculate weight. For example, if it has all
four components, the 3kV substation will contribute 40% of the total mark. The 6.6kV
substation will contribute 30% and the switch frames 15% each. This means that the 3kV
substation is of greater importance than the 6.6kV substation.
The 3kV substation is then divided into smaller components with different weights. From the
FMECA in chapter 3 and the callout statistics in annexure 10.1, these values were determined.
Consideration had to be given to the fact that the assessment must stay visual only, and must
not include the use of any measurement equipment. It can be seen that oil levels and earthing
is very important for the visual inspection. Safety signs, painting and a clean area are not that
critical but do give the maintenance engineer a good idea of the maintenance effort that went
into the substation since the previous inspection. Remember that the purpose of this inspection
process is to determine the maintenance effort that was made and the effort that is required.
74
4.4 The physical inspection
All the components and different aspects of the substation that is shown on this form can be
inspected and evaluated without having to do any switching in the substation. No special
authorisation and prior arrangements are therefore needed to perform the inspections.
Because of the limited impact on the service, more frequent inspections can be done and
randomly selected substations can be inspected without anybody knowing about it
beforehand. This will give a better idea of the condition that the system is in and the
maintenance effort that was put into it.
The process follows a logical path through the substations, which minimise time-consuming
movement through it. By using this logic, the inspection time was cut by about 20%
compared to previous inspections. The process also ensures that all the important aspects
are looked at and that nothing is ignored.
The maintenance engineer can decide on the scoring method that must be used. Each
component must be rated the same way. A good method is to score everything out of a
possible ten. For example, if the fencing is in very good condition and does not need any
work it can be scored a good nine out of ten. The scoring will be adjusted according to the
weight that was assigned to that component when it is entered into the Excel database.[15].
The spreadsheet will calculate the final scoring. An example of what the spreadsheet looks
like can be seen in annexure 10.3. The scoring can also be out of five or even one hundred,
depending on the maintenance engineer. Table 4.2 gives a very good guideline of how to
decide on a scoring.
Table 4.2 : Assessment scale for inspections [15]
Score out of 10 Interpretation of the score 10 Excellent condition with no improvement possible 9 Excellent condition with only minor cleaning needed 8 Good condition with only cleaning needed 7 Good condition with some minor maintenance needed 6 Condition still acceptable but maintenance is needed 5 Condition unacceptable but repairable with corrective maintenance 4 Condition unacceptable but repairable with major maintenance effort 3 Still in working order but budget for replacement within one year 2 Still in working order but must be replaced urgently 1 Out off order and must be replaced immediately 0 Not applicable for particular substation
75
When a condition assessment of 4 is given to a component, the engineer will immediately
know that work on it must be budgeted for. This assessment will help the decision makers to
get the correct precautionary measures in place to prevent major damage to the equipment.
4.5 Influence of the level of expertise and experience
The level of expertise and experience of the inspector will make a difference in the scoring.
During a test done on eight people [15], the scoring on the same substation during the same
day was as shown in Table 4.3. Table 4.4 contains the information on the expertise and
experience of each person that took part in the test. All were male except for person H.
Table 4.3 : Scoring during test on eight people with different levels of experience and expertise.[15]
3kV
High Voltage
Yard
3kV Indoor
6.6kV High
Voltage Yard
6.6kV Indoor
Batter room
3kV Switch frame
6.6kV Switch frame
Total
A 7.2 7.4 7.8 8.2 8.5 6.7 6.2 7.37 B 7.6 7.4 7.9 8.1 8.8 7.2 6.4 7.57 C 6.8 7.2 7.5 7.4 8.2 6.2 6.3 7.04 D 7.1 7.3 7.6 8.4 9.0 6.4 6.1 7.33 E 7.6 7.7 8.0 8.3 8.9 6.2 6.5 7.53 F 7.3 7.1 7.5 7.8 8.5 6.1 6.2 7.14 G 7.4 7.5 7.9 8.4 9.0 6.8 6.4 7.55 H 8.1 7.8 8.2 8.5 9.0 5.8 5.4 7.46
Table 4.4 : Background on each person taking part in the test [15]
A Electrical Engineer with 5 years experience on substation maintenance B Electrical Engineer with 22 years experience on substation maintenance C Civil Engineer with no experience on substation maintenance D Technical supervisor with 16 years experience on substation maintenance E Electrical Engineering Technician with 1 year experience F Electrician with 14 years experience and working on substations daily G Electrical Engineering Technician with 26 years experience H Senior administrative official with no technical experience
Figure 4.2 shows a plot of the distribution of the test results obtained from table 4.3. All the
results were between 7.0 and 7.6 which in itself gives an indication that the level of expertise
and experience does not have a great effect on the outcome of this inspection procedure.
76
Figure 4.2 : Distribution plot of test results
The following definition was taken from Stephen B. Vardeman, Statistics for engineering
problem solving (1993).
For a data set consisting of n values that when ordered are x1 ≤ x2 ≤ . . . ≤ xn,
1. for any number p of the form (i - 0.5)/n where i is an integer from 1 to n, the p
quantile of the data set will be taken to be xi (The ith smallest data point will be
called the (i - 0.5)/n quantile)
2. for any number p between 0.5/n and (n – 0.5)/n that is not of the form (i -
0.5)/n, the p quantile of the data set will be obtained by linear interpolation
between the quantiles corresponding to the two values of (i - 0.5)/n that bracket p.
In both cases, the notation Q(p) will be used to symbolize the p quantile.
The quantiles according to the above defenition for the test results obtained in table 4.3 are
shown in table 4.5.
Table 4.5 : Quantiles of the test results
i (i - 0.5) / 8 ith Smallest data point 1 0.0625 7.04 = Q(0.0625) 2 0.1875 7.14 = Q(0.1875) 3 0.3125 7.33 = Q(0.3125) 4 0.4375 7.37 = Q(0.4375) 5 0.5625 7.46 = Q(0.5625) 6 0.6875 7.53 = Q(0.6875) 7 0.8125 7.55 = Q(0.8125) 8 0.9375 7.57 = Q(0.9375)
6.66.8
77.27.47.67.8
A B C D E F G H
PersonC
ondi
tion
77
The median, Q(0.5), is obtained by linear interpolation.
0.5 is (0.5 - 0.4375) / (0.5625 – 0.4375) = 0.5 of the way from 0.4375 to 0.5625.
Linear interpolation gives
Q(0.5) = (1 - 0.5)Q(0.4375) + 0.5Q(0.5625) = 0.5(7.37 + 7.46) = 7.415
The lower quartile, Q(0.25), and the upper quartile, Q(0.75) are obtained by using the same
mathematics.
Q(0.25) = 7.235
Q(0.75) = 7.540
Referring to table 4.5 for the (i - 0.5) / 8 quantiles of the test result distribution, figure 4.3
gives the graphical plot of the quantiles.
Figure 4.3 : Quantile plot of test results According to Stephen B. Vardeman [29] the assumption can be made that the underlying
data-generating mechanism would itself produce smoother quantile plots for larger samples.
Due to cost and time constraints the amount of samples used in this test is limited to only
eight. This, however, is sufficient to analyse it and to come to some important conclusions.
[2][27]
6.76.86.9
77.17.27.37.47.57.67.7
0.06
25
0.18
75
0.31
25
0.43
75
0.56
25
0.68
75
0.81
25
0.93
75
Quantile
Con
ditio
n
78
Another way of plotting the results is by making use of a boxplot. The boxplot carries
somewhat less information, but nevertheless conveys a fair amount of information about
distribution location, spread and shape. To analyse the role that expertise and experience
play in the inspection process it is important to look at the distribution location and spread of
the test results.
A box is made to extend from the lower to the upper quartiles and is devide by a line at the
median. The interquartile range (IQR) is calculated as follows.
IQR – Q(0.75) – Q(0.25) = 0.305
Determine the smallest data point within 1.5IQR of Q(0.25) and the largest data point within
1.5IQR of Q(0.75). The boxplot is shown in figure 4.4.
1.5IQR = 0.4575
Q(0.25) – 1.5 IQR = 6.778
Q(0.75) + 1.5IQR = 7.998
Figure 4.4 : Boxplot for test results
From Figure 4.4 it can be seen that no points fall outside the value of 1,5IQR. This means
that the results are close enough to each other in order to prove statistically that this process
is not influenced by to expertise or the experience that the inspector has. All that the person
needs is the information contained in Table 4.2, which will serve as a guide to do the
inspection.
The only requirement for such a person is that he or she must be familiar with the location of
the different components in the substation in order to know what must be inspected. The two
persons with no electrical experience had to be guided in this regard.
7.04 7.235 7.54
7.415
7.57
7.3 7.1 7.2 7.0 7.6 7.5 7.4
79
4.6 Substation inspections on sample stations.
Over a period of one year five inspections were done on six substations that are located over
a total track section of 200 km. The substations were randomly picked to see what the
difference will be when certain variables were built in.
The variables that were taken into consideration and investigated were the following:
1. The influence of different person doing the maintenance
2. The physical location with environmental variables
3. Different load requirements due to the topography.
The inspections were done during different times of the year to see if that will have an
influence on the condition. The inspections were done during April, August, December,
March and June. This meant that an inspection was done in all four seasons of the year.
The investigation focussed on the following:
1. Seasonal influence
2. Time in respect to the financial year.
The inspections done at each substation are given in Appendix 3. Figure 4.5 is a visual
presentation of the results that were obtained for each substation.
80
6.0
6.5
7.0
7.5
8.0
8.5
Apr-0
1
Jun-
01
Aug-0
1
Oct-01
Dec-0
1
Feb-0
2
Apr-0
2
Jun-
02
Month
Con
ditio
n
Heidelberg
Sprucewell
Standerton
Perdekop
Beechwick
Vooruitsig
Figure 4.5 : Results of substation inspections
The first observation that must be made is that there was a decline in the condition of most of
the six substations during the last inspection done in June. This is also notable in Figure 4.6,
which gives the average condition for each inspection. There was a steady climb in the
condition during the first five measurements and then a sudden drop to the lowest of all the
inspections.
Figure 4.6 : Average of inspections per month There was a drop in the assessment at five of the six substations for the last inspection. One
of these substations dropped from 7.6 to 6.9. This is a drop of almost 10%. When looking at
the data in appendix 3, it is clear that the problem was in the high voltage yard of the 3kV
substation. The transformer deteriorated from 6 to 4 from the previous inspection, while there
was a problem with the safety signs as well. Despite the drastic deterioration between the
Average
7.137.17
7.21
7.34
6.99
6.80
6.90
7.00
7.10
7.20
7.30
7.40
Apr-0
1
May
-01
Jun-
01
Jul-0
1
Aug-0
1
Sep-0
1
Oct-01
Nov-0
1
Dec-0
1
Jan-
02
Feb-0
2
Mar
-02
Apr-0
2
May
-02
Jun-
02
Month
Con
ditio
n
81
last two inspections, this particular substation had an average of 7.52 for all the inspections
over the year period. Figure 4.7 shows the average per substation for the five inspections.
Figure 4.7 : Average of inspections per substation
4.6.1 Influence of distance between base depot and substation
The six substations are maintained by four different persons. The information in table 4.6
gives the distance for each person between the substation and his base depot from where all
duties must be performed.
Table 4.6 : Distance between base depot and substation
Substation Maintained by Distance Heidelberg Person A 4km Sprucewell Person A 23km Standerton Person B 6km Perdekop Person C 32km Beechwick Person C 12km Vooruitsig Person D 8km
From this information it is clear that the distance that the person performing the maintenance
needs to travel, does not influence the condition of the substation. Person A might have a
problem with the distance that must be travelled because of the very low score on the
substation that is far from him. The results of this investigation will vary from person to
person and more data is needed to get a realistic result.
Average
7.18
6.61
7.14
7.377.52
7.19
6.00
6.20
6.40
6.60
6.80
7.00
7.20
7.40
7.60
Heidelberg Sprucewell Standerton Perdekop Beechwick Vooruitsig
Substation
Con
ditio
n
82
4.6.2 Influence of environment on condition To investigate the impact that environmental factors have on the condition a summary of the
weather at each substation for the year during which these inspections were done, is given in
Table 4.7. This information was obtained from the South African Weather Bureau and
indicates the information from the closest weather station to the substation.
Table 4.7 : Summary of weather at each substation
Substation Average Temp.
Max. Temp. Min. Temp. Rainfall Sunshine
days Heidelberg 20 0C 35 0C -4 0C 216mm 280 Sprucewell 19 0C 32 0C -3 0C 256mm 282 Standerton 18 0C 29 0C -6 0C 310mm 264 Perdekop 17 0C 29 0C 0 0C 280mm 270 Beechwick 19 0C 30 0C -1 0C 268mm 246 Vooruitsig 18 0C 28 0C -2 0C 254mm 258
The extreme temperatures during winter may be considered as one of the reasons why the
condition assessment during June showed a drastic decline in scoring. Most electrical
equipment does not function well in places where extreme temperature changes take place.
[23][24][31].That is why the highest average was achieved during March, when smaller
changes between day maximum and minimum temperatures were experienced.
4.7 Interpreting the data Experience in the use of the form will help the engineer with the interpretation of the data.
The best way to gain the experience is to personally do the inspection. There is no better
person to interpret the data and make decisions accordingly than the one who did the
physical inspections.
Table 4.2 gives the best indication of how the data can be interpreted. Any value more than a
7 should be an indication that the substation is in very good order and that the maintenance
on that system is up to standard. There should not be a score of 10. That will mean that the
system in perfect order, which is highly unlikely.
A scoring between 4 and 7 should be an indication that the substation needs work. The
maintenance is not up to standard and must be improved. The condition can, however, be
83
brought up to the required standard without major expenses. Only labour is required, along
with minor material items.
When the scoring is under 4, the engineer will know that there are major repairs needed and
that the budget must be adjusted accordingly. Some components in the substation need
replacement, which must be budgeted for. A scoring of 1 will indicate that it is already too
late and that the particular system has failed and must be repaired immediately. When the
particular component is not applicable for the substation, a scoring of 0 must be entered. The
spreadsheet onto which the data must be entered, is programmed to check for any 0 entries
and to change the formula so that the calculations do not take the 0 into account. This
applies when it comes to the scoring of the 6.6kV substations. Not all 3kV substations are
combined with a 6.6kV substation.
Once the data were fed into the spreadsheet, it is easy to perform different kinds of analysis.
A list of all components that have a scoring of under 5 can be displayed by making use of the
programmed abilities of Excel. This list will show where special attention is needed for
budgeting.
4.8 Summary Proper inspections of any system are an important step in the maintenance cycle. It is
therefore very important that there is a good system in place for the inspections. The form
described in this chapter gives the starting point for such a system. It is just the tool to obtain
the data, not to make decisions.
If the data is interpreted correctly, as described in this chapter, it will become one of the most
valuable tool in the maintenance engineer’s box.
84
5 TECHNOLOGY TO MEASURE CONDITION 5.1 Introduction Technology based predictive maintenance provides advance notice of failure. There is still
repair cost involved, but without the downtime. According to Amos C Kenna (November
2003) [2], predictive maintenance involve to monitoring of two or three critical variables in a
device that, with a 90% confidence level, will warn you that the device is going to fail in a
very short time.
The measurements must help identify where to improve or focus maintenance effort.
Predictive maintenance involves more than just device data, it is process centered data with
comprehensive asset health information which enables the best financial decision. In other
words, it provides the ability to predict where to focus maintenance effort.
A study that was done by Boeing in the early 1960’s during the development of the 747
proved to be quite interesting.[29]. Richard Overman wrote in a paper presented at the 2003
International Maintenance Conference [3], that he found that only 11% of the components
demonstrated a failure characteristic that supported a scheduled overhaul or replacement
(scheduled removal). Eighty nine percent exhibited random failure characteristics for which a
scheduled removal was not effective. Since a scheduled removal was the primary scheduled
maintenance program at that time, new ways were needed to deal with the 89% not
applicable to scheduled removal.
During the failure mode, effect and criticality analysis done in chapter 3, it was found that the
same problem exists in a 3kV DC traction substation. New technologies need to be
developed to predict the onset of failure for components that exhibit a random failure
characteristic. In this chapter, the results from the FMECA were used to determine which
components need to be monitored to provide sufficient data for prediction of failure.
Maintenance is not required during the in initial life of any equipment. New systems will be
able to operate without maintenance. At some stage during the lifecycle, maintenance will be
required to ensure that the system retains its reliability. One of the decisions that must be
taken is when to begin with maintenance and how to adjust the maintenance input as the
equipment ages. [31][32]
The only way to determine this is through proper statistical analysis. For this analysis it is
important to be able to obtain as much information as possible.
85
Another problem that exist in companies across the globe is the reduction of operating and
maintenance cost while maintaining and, in most case, improving standards of production.
The downside of this cost cutting approach is that the companies now may not have
adequate financial or labor resources to maintain the quality in the future with traditional
asset management methods as discussed in chapter 1. [1][2][3][31]
According to Cliff Walton and Ross Mackinlay (2003) [30], the reason for this is twofold.
There is an ever increasing age profile of installed equipment combined with a trend toward
reducing in house engineering and technical knowledge. The increasing age profile of
installed traction transformers in South Africa, as shown in Figure 5.1, show the need for the
application of on-line condition assessment as an asset management tool to extend plant life.
[4]
A large number of the transformers have already passed the original life expectancy of 25
years.[32]. This does not mean that all the equipment that have passed their life expectancy
are about to fail. It does mean that these assets should be managed with a condition-based
approach. To achieve an effective condition-based asset management policy, the plant
condition should be checked regularly and in a systematic manner.
0
50
100
150
200
250
300
10 20 30 40 50 60
Age
Num
ber
Figure 5.1: Age distribution for traction transformers in South Africa [4]
On line condition monitoring of equipment is becoming more widespread in the worldwide
electricity industry. Accurate condition assessment and the subsequant management of in
service, high voltage plants are becoming more economical viable, with continous advances
86
and cost reductions being made in sensor technology, data acquisition and processing (Cliff
Walton and Ross Mackinlay, 2003) [30]. Although technology improvements continue apace,
it is essential that the resultant data be risk managed. Chapter 6 will focus on the
management of the tremendous amount of data that can be accumulated by continues
monitoring. In this chapter, the technology used to obtain the information is discussed to
provide a background for understanding the principles to be applied in chapter 6.
During the failure mode, effect and criticality analysis of the 3kV DC traction substation, the
critical components was identified according to risk. According to Cliff Walton and Ross
Mackinlay (2003) [30], this should typically be less than 5% of the system. If more is
identified, the system should be redesigned to eliminate the unacceptable high risk of failure.
The design of the monitoring system, used in this study, for traction substations was directed
at these critical components in the substation.
An early warning system was designed to detect trend and predict failure. This can only be
fully implemented once a proper understanding of the resultant data is achieved. Further
discussion on this will take place in chapter 6. It is important to correlate the condition
parameters with operational data like load and voltage. A decision support system for asset
management and maintenance purposes, using fuzzy logic, was formulated as a result of
these findings.
The technology must allow on line testing without the need to take the substation off-load.
This means that the substation must perform to its designed output while being monitored.
The information must immediately be available from remote access.
87
5.2 General scope for condition monitoring of 3kV DC traction substation.
The following discussion covers the design of an on line condition monitoring system for 3kV
DC traction substation. The purpose of the system is to assist with the condition based
maintenance of the critical components inside the substation.
During the failure mode, effect and criticality analysis these components were identified as:
• Surge arrestors
• Primary Circuit breaker
• Traction transformer
• Rectifier
• High speed circuit breaker
• Battery and battery charger
The monitoring system must monitor these and provide advance notification of impending
failure. It must continuously update statistical data on the condition to provide information on
condition for the fuzzy logic model in predicting maintenance effort. [33]-[41]
Additional monitoring can provide information on failures to enable a shorter repair time. This
will decrease the mean-time-to-repair (MTTR) with a resultant increase in MTBF.
The remainder of this chapter will be divided into three sections, namely:
• Monitoring interface for critical components
• Data processing
• Communications and database
Some of the questions to be answered include the need for people at different levels in an
organization to view the information gathered with this system and the cost involved on
frequent communication between the system and the relevant parties. How must the
information be presented to the end users to make it understandable without compromising
on detail required during the discussion making?
It is important to understand the environmental condition under which the system must
operate. All the substations in South Africa are between 0m and 1800m above sea level with
a humidity of not more than 96%. The ambient temperature will be in a range between -10oC
and 55oC. The atmosphere may vary from clean to being salt laden to being polluted by
88
industrial sources and locomotive fumes. Protection against lighting must be considered as
the strike density for some of the areas are amongst the highest in the world.
The system in itself must be reliable and it is of paramount importance that these
environmental factors are taken in consideration when designing the system. Vibrations from
the close proximity to the track might cause mechanical problems and need to be taken into
consideration when selecting the components.
According to the engineering regulations for the design of these substations, the supply
voltage will vary from 87V DC to 130V DC. The components must not be susceptible to
electromagnetic interference from the high voltage components inside the substation.
5.3 Monitoring interface for critical components
5.3.1 Surge Arrestors
The condition of surge arrestors in Spoornet have never been continuously monitored before
and, according to the 3kv DC Substation Routine Maintenance Manual (November 2002)
[21], surge arrestors must be inspected and cleaned once every 720 days. The only
indication that was available was the installation of surge counters that would give an
indication of the amount of surges dissipated by the arrester. These were quite inaccurate
and unreliable.
Leakage current is caused by a parallel combination of capacitance and dc resistance
between a voltage source (ac line) and the grounded conductive parts of the arrestor. The
leakage current through the device into the earth can be measured and used as a parameter
of condition. There are a number of instruments available that can be used to perform the
test. Due to the high cost of these, according to an internet market survey in the region of
R30 000 upwards, a method had to be designed that can be applied throughout South Africa
at each of the 603 substations that is cost effective. Due to the high rate of theft in the coutry
it is not a viable option to install expensive equipment in any case.
According to Kenneth Brown (March 2004) [24], in his article on metal oxide varistor (MOV)
degradation, Mov’s are variable resistors primarily consisting of zinc oxide (ZnO) with the
function of limiting or diverting transient voltage surges. MOV’s exhibit a relative high energy
absorption capability which is important to the long term stability of the device. The growing
demand of ZnO varistors is due to the nonlinear charachterisitcs as well as the range of
89
voltage and current over which they can be used. If MOV’s are used used within their well
defined specifications, degradation due to environmental impact is not likely. [42][43]also.
However, the environment in which they are used is not well defined. The ac voltage supply
is subject to lightning stikes, switching transients, temporary overvoltage and other simular
disturbances. Due to this variety of disturbances, degradation or failure are possible in many
applications. When applied within their specified limits. MOV’s perform their designed
function relaibly at a low failure rate. For the MOV to perform like this, it must quickly
dissipate absorbed energy and return to its standby operating temperature. The ability to
dissapate energy to the environment will depend on the design of the environment itself, for
example the ambient temperature, ventilation, heat sinking, proximity of other components
and heatsources. [24][42][43]
Degradation and catastrophic failures may occur if an MOV is subjected to transient surges
beyond its rated values of energy and peak current. Brown used this theory to describe the
life of an MOV as the time required to reach a thermal runaway condition. He expressed the
relationship between ambient temperature and the life of the MOV by the Arrhenius rate
equation,
t = t0 exp[Ea - f(V)] / RT (5.1) [24]
where:
(t) = the time to thermal runaway
t0 = constant
R = constant
Ea = activation energy
T = tempreature in Kelvin
and f(V) = applied voltage
This Arrhenius rate model impose increased voltage and elevated temperature to accelarate
the reaction and do not adequatly address the detrimental effects of surge hsitory. Surge
history, especially transient surges beyond rated maximums, are perhaps the greatest single
contributor to reductions in varistor voltage, increased standby leakage current, and ultimate
thermal runaway. When increased voltage is applied for durations longer than microseconds,
physical and chemical changes occur within the many boundary layers of the device. Typical
pulse duration curves are shown in Figure 5.2.
90
Figure 5.2 : Pulse Rating Curves (Brown, March 2004)[24]
The term “varistor” is a generic name for voltage-variable resistor. The resistance of an MOV
decreases as voltage magnitude increases. An MOV acts as an open circuit during normal
operating voltages and conducts current during voltage transients above the rated voltage.
Modern MOV’s are developed using ZnO due to their nonlinear characteristics and the useful
range of voltage and current is far superior to silicon carbide varistors. Hence the move in
South Africa to replace damaged silicon carbide varistors with metal oxide.
MOV’s have a large, but limited, capacity to absorb energy, and as a result they are subject
to failure as discussed in the FMECA in Table 3.2. The significant MOV failures include
electrical puncture, thermal cracking and thermal runaway, all resulting from excessive
heating, in paticular, from non-uniform heating. Non-uniform heating occur as a result of
electrical properties that originate during the manufacture process or the properties that
occur in polycrystalline materials.
According to Table 3.2 (Failure Mode, Effect and criticallity analysis), there are three basic
failure modes for MOV’s used within surge protection devices:
1. The MOV fails as a short circuit.
2. The MOV fails as an open circuit.
3. The MOV fails as a linear resistance.
It is likely for the MOV that fails initaily as a short circuit to fail as an open circuit due to the
absorption of large continuous current within the MOV. The short circuit failure is ussually
91
confined to a puncture site between the two electroded on the disc. Large fault current can
create temperatures high enough to melt the ZnO ceramic which causes the short circuit.
Open circuit failures are possible if operation at steady state conditions occur above the
rated voltage. The exponential increase in current causes overheating and eventual
separation of the wire lead and disk at the solder junction.
The test results documented in Mardira et. Al. (2001) [42] show that MOV’s can be degraded
from an 8/20µs surge current at 1.5 times the rated surge current. This means that
degradation will take place if, for example, a 10kA surge current rated MOV dissapates a
15kA single pulse surge current. Lighting will cause degradation to the MOV. When the MOV
degrade it becomes more conductive after it had been stressed by either continuous current
or surge current.
Many MOV’s show no sign of degradation when operated below a specified threshold
voltage. A prediction on the level of degradation can be made if the operating conditions
were known. Temperature distribution in the material is due to the development of localised
hot spots during current impulse. Primary current and voltage can be compared to
temperature distribution. Measuring temperature distribution on a continuous basis is
expensive, therefor only a temperature constant was measured during testing.
One of the key parameters related to measure degradation is leakage current. Leakage
current in the pre-breakdown region of a MOV is important for two reasons :
1. Leakage determine the amount of watt loss an MOV is expected to generate upon
application of a nominal operating voltage.
2. The leakage current determiones the magnitude of the operating voltage that the
MOV can accept without generating an excessive amount of heat.
The leakage current is composed of a resistive current and a capacitive current. The resistive
component of current is thermally stimulated and is significant, since it is responsive for the
joule heating within the device. The capacitive current is a function of the MOV’s capacitive
value and the applied ac voltage. If the arrestor is subjected to an elevated voltage at a
specific temperature, the internal current increases with time. Conversely, if the MOV is
subjected to an elevated temperature at a specific applied voltage, the internal current
increases with time. This is accelerated by higher operating stress, and is futher aggravated
92
by elevated temperatures. According to Brown (2004) [24], the life of an MOV is primarily
determined by the magnitude of the internal current and its increase in temperature, voltage
and time. As the current increases, the amount of heat (if not allowed to dissiopate) can
rapidly raise the temperature of the device. This will result in thermal runaway that can cause
destruction of the MOV.
If the increase in power dissipation occurs more rapidly than the MOV can transfer heat to
the environment, the temperature will increase until the unit is destroyed. Standler (1989),
wrote that MOV’s degrade gradually when subjected to surge current above their rated
capcity. He said that the end of life is commonly specified when the measured varistor
voltage (Vn) has changed by ±10%. MOV’s usually are functional after the end of life as
defined, but if it experiences sequential surge events, each causeing an additional 10%
reductionin Vn, the MOV may soon reach a level below the peak recurring value for the
applied voltage. When this state is reached the MOV draws in excess of 1mA of current
during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway.
In nearly all cases, the value of Vn decreases with exposure to surge current. This
degradation manifests itself as an increase in leakage current at the maximum operating
voltage in the system. Excesive leakage current during normal operation will cause heating in
the varistor. The relationship between percentage of the rated current and the temperature is
shown in Figure 5.3 (Brown, 2004). [24] also [42][43][44].
Figure 5.3 : Current, energy and power derating curve (Brown, 2004)[24]
Accelerated testing by Kenneth Brown was used in reliability prediction models. Using the
Arrenius model in Equation 5.1, the testing results allow accurate reliability and failure
93
prediction in a relatively short period of time. Studies have shown that failure of electrical
components are due to chemical degradation processes which are accelerated by elevated
temperatures.
During this study the following parameters were monitored:
• Number of discharges
• Total leakage current
The electrical properties of the ZnO varistor in the leakage current range can be represented
by the simplified model in Figure 5.4 (Lundquist ed. al.,1989). [44]
Figure 5.4: Electrical representation of a ZnO varistor (Lundquist ed. al.,1989) [44]
According to Lundquist (1989)[44], the typical specific capacitance of a ZnO varistor is 75ρF.
Typical values of the capacitive current (Ic) range from 0.5 to 3mA depending on the varistor
diameter. The resistive component of the leakage current (Ir) is in the range of 50 to 250µA.
Figure 5.5. (Lundquist ed. al., 1989)[44] show the increase in total leakage current (It) in
relation to Ir.
94
Figure 5.5: Increase in avarage leakage current (Lundquist ed. al., 1989)[44]
Figure 5.6: Typical zinc-oxide varistor characteristics (ABB Technical Information, 2350en)
Figure 5.6. shows the typical ZnO varisitor characteristics of accoring to a well kown
manufacturer, ABB. Note the capacitive current as shown in the figure.
The instrument that was used for the measurements is the Surge Arrester Monitor (SAM),
manufactured and supplied by ABB. The SAM has the following specifications:
95
a) Waterproof
b) Temperature range of –30oC up to 85oC
c) Counting level (peak value) 10A
d) Measuring range of the current (peak value for It) 1mA to 20mA
e) Dead time between counting of impulses 500ms
f) Frequency range up to 62Hz
g) Shielded sensor cable with PUR coating.
h) Life span of battery is about 15 years
A temperature probe was atteched to the base of the arrester to get a measure of the
temperature. This measurement was used as a comparative measurement and did not need
to be extremely accurate The results of the measurements is discussed in the following
Chapter 6.
5.3.2 Primary AC Circuit Breaker
The primary circuit breakers are provided on the primary side of the main transformer for the
purpose of protecting the substation from overloading and from high fault currents. The
breakers are capable of interrupting fault currents of the order of 30 000 ampere. This
interruption must occur in very short time (t).
The circuit breaker tripping mechanism is operated by protection relays, which is driven by
current transformers. The current (I) measured by the current transformers is already
available and can be utilized in calculations to determine the energy dissipated through the
breaker contacts. [4][14][21]
In the case of a SF6 breaker, protection is also provided for gas pressure and air pressure.
This pressure is available for monitoring purposes and was incorporated in the
Programmable Logic Converter (PLC) setup that was used in the prototype testing assembly.
There are basically four types of high voltage circuit breaker drive mechanisms. A
comparison of these is shown in Table 5.1 below.
96
Table 5.1: Different types of high voltage circuit breaker drive mechanisms (Spoornet
Engineering Instruction: EP.001 Issue 1)
TYPE USED ON ENERGY STORAGE MECHANSIM
STORED ENERGY (closed or charged)
ADVANTAGES DISADVANTAGES
Solenoid Bulk oil circuit breakers
Nil (open) 1. Simple and cheap 2. Manual closing possible
High burden on battery
Spring 1. Minimum. Oil 2. SF6 3. Vacuum
Springs O-CO Manual spring charging possible
Complicated repair
Hydraulic SF6 circuit breaker
Compressed nitrogen
O-CO-CO Low burden on battery
1. No manual closing possible 2. Hydraulic system with its associated problems
Pneumatic SF6 circuit breakers
Compressed air
O-CO-CO 1. Low burden on battery 2. Simple
1. No manual closing possible 2. Pressure vessel requires periodic inspection, or drilling of tell tale holes
Note: O = open, C = closed
The solenoid type is very simple and straightforward. For closing, a solenoid driving the
closing mechanism is connected directly to the 110V battery. Due to the heavy current drain
from the batteries, repeated closures cannot be attempted because the protection will
operate as soon as the battery voltage drops below 90V. This will cause the substation to go
on lockout and will require a technician to go out and reset the substation. [14]
In the spring drive mechanism the opening and closing of the circuit breaker is driven by
springs. The springs are wound by means of a small 110V DC motor. The springs can also
be wound using a crank handle. As soon as the breaker is closed, the 110V motor starts to
rewind the closing spring. The opening spring is tensioned during the closing operation.
Starting from a closed position and with the closing spring charged, the breaker can perform
the following sequence without any battery supply:
OPEN -> CLOSE -> OPEN
The hydraulic drive mechanism uses the principal of compressing nitrogen gas (N2). This is
done by trapping the gas in a cylinder (accumulator) and pressurising it with hydraulic fluid oil
working on the other side of the piston. In this way energy is stored in the compressed
nitrogen gas. The hydraulic fluid provides the drive mechanism between the stored nitrogen
97
and the electrical contacts. The fully charged nitrogen and hydraulic pressure is in the order
of 250 bars and can perform the following sequence of operation:
OPEN -> OPEN CLOSE -> CLOSE OPEN
In the pneumatic drive mechanism the energy is stored as compressed air and the drive
mechanism between the stored energy and the electrical contacts is also compressed air. To
prevent corrosion forming in the air receiver and other working parts and to ensure smooth
operation, the air must be clean and dry. Special precautions are built into the circuit breaker
to ensure that the air is dry by provision of an air drier at the intake of the air receiver. When
this receiver is charged to 10 bar, it has the capacity to perform the following operations
without recharging:
OPEN -> CLOSE OPEN -> CLOSE OPEN
The high voltage breaker in use at Spoornet must be able to interrupt fault currents in the
order of 30 000 ampere on the primary side of the main transformer. Due to the increasing
fault levels of the Eskom system [15], the new breakers must be faster and able to withstand
levels of up to 5 000MVA.
The following parameters was monitored:
a) Contact wear (as a function of the energy dissipated, I2t)
b) SF6 gas level (same principals will work for oil)
c) Number of operations
In the traction substation most operation occur during maintenance activity when the
breakers are operated under no-load conditions. The expected wear on the breakers was,
therefore, must less than specified by the manufactures. According to the 3kV DC Substation
Routine Maintenance Manual [21], used by railway operators in South Africa, the breakers
must be dismantled and opened for maintenance every 180 days. No mention is made in this
schedule on energy dissipated.
There is a routine monthly check that must be performed on these breakers as well. This can
be reduced if the condition monitoring is in place to predict maintenance requirements.
The I2t value for each operation was calculated by the main processing unit described later in
the chapter. An analog signal converter was used to convert the signal from the secondary of
the current transformer to a 4 – 20mA or 0 – 10V signal that was suitable for the analog input
to the PLC.
98
The results of the monitoring and calculations is be discussed in the following chapter 6.
5.3.3 Traction Transformer
According to Roy Moxley and Armando Guzmán in their paper called, Transformer
Maintenance Interval Management (2005)[32], excessive heat and mechanical stress during
through faults on transformers are recognized as the two major causes of damage.
Standards organizations such as the American Standards Institute (ANSI) and the Institute
for Electrical and Electronic Engineers (IEEE) consider the life expectancy for transformers
to be between 20 and 25 years.[32]. According to Facilities Instructions, Standards and
Techniques (FIST) 3-30, October 2000) [45], this estimate is based on continuous operation
at rated load and service condition with an average ambient temperature of 40oC and a
temperature rise of 65oC. This is also based on the assumption that the transformer receives
adequate maintenance over this period. According to studies done by these institutes, the life
will increase if the transformer is operated at lower ambient temperatures and load.
From experience and transformer design notes, it is known that the amount of service a
transformer can provide is directly linked to the serviceability. Measurable indicators of
transformer serviceability include electrical load, oil and ambient temperatures, fault history
and dissolved gasses analysis.
One of the most important issues in a traction transformer is the quality of the transformer oil.
The oil must ensure proper cooling, isolation and rust prevention inside the main tank. This
can only be achieved with good clean oil. The following factors influence the quality:
• Moisture
Moisture is the number one enemy. It is an accelerator of chemical reactions inside a
working transformer. Water also influences the isolation strength of oil and penetrates
paper isolation between windings. Paper has a 3000 times higher affinity for water
that oil. Furthermore, transformer oil is hygroscopic and can absorb moist from the
air. Water is also a product formed from the oxidation process that is continuously
going on inside the transformer and cannot be prevented. The tempo can, however,
be controlled.
• Temperature
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Heat is an accelerator of any chemical process. High temperature reduces the
lifetime of oil drastically due to the acceleration of the oxidation process.
• Acid
Various acids, organic and an organic, are formed from the chemical processes
inside the transformer. These acids then attack the oil and paper isolation, which
cause sediment to form. This sediment has an acid base as well and accelerate the
chemical breakdown of the oil. It also settles on the windings and inside the cooling
fins which causes overheating. The acids make the paper isolation brittle. This
reduces the ability of the transformer to withstand high electric impulses like lightning.
All of these can be monitored continuously if required. Routine oil sampling and testing is
much less expensive and will provide enough information to make decisions on possible
interventions required. It is not necessary to install expensive equipment to monitor the
moisture and acid content of the oil. [14][15][21][22][32]
Winding and oil temperature of the transformer is already measured and can be used for
calculations during predictions. The primary current in measured by the current transformer
and this input is already used for calculations on the primary circuit breakers.
An additional alarm that can be useful is the contacts of the Bucholtz relay. This will,
however, not be of any good when applying predictive models to the calculations.
The theory is that the winding temperature is direct in relationship to the amplitude of the
current measured by the current transformers. If this relationship were to change for a
specific transformer, it would be an indication of something faulty in the transformer.
In Chapter 8 the possibility of measuring vibrations on the transformer tank is discussed as
one method of monitoring the condition of the transformer.
An interesting theory that was explored, was to measure the difference between the top and
bottom oil temperatures. It was expected to stay constant and any change should be an early
indication of internal failure starting to occur. The assumption in this is that such failure will
occur gradually over a period of time, which should allow enough reaction time to immanent
failure. Typical oil flow is shown in figure 5.7 (FIST 3-30, October 2005)[45]. If proper flow is
100
possible inside the transformer, the relationship between the top and the bottom
measurements should stay constant. Any variation that is detected will be an indication of
either flow problems or excessive heating through the windings.
As discussed previously, the installation of flow detectors was not considered. It should also
be noted that the traction transformers in South Africa are naturally air cooled without fans.
Figure 5.7 : Typical oil flow (FIST 3-30, October 2005)[45]
Other possibilities that were considered include the monitoring of flow inside the transformer,
real time monitoring of dissolved gasses and oil humidity, pressures and partial discharges. It
will be un-economical to install the technology to monitor these properties in the 4.5MVA
traction transformers that is in use. During the FMECA (Failure mode, effect and criticality
analysis) the effect of a transformer failing was investigated and it was found that for the total
service, the maintenance engineer can afford having it out for a period of time.
101
According to FIST 3-30 (October 2005)[45], operation of only 10oC above the rated
temperature of the transformer will cut the life by 50%. The best way to protect and extend
the life of a transformer is to collect information such as load and fault current, as well as oil
and winding temperature, and then to receive notification when any of the values reaches the
preset levels. When combining these values it will provide a tool to logically predict alarm
conditions and react. The challenge was to provide a means of collecting these values
without creating a massive new system that is expensive and require frequent maintenance.
Modern protection relays that can be permanently connected to the transformer current and
temperature inputs have a memory and recording capability with some logic decision making
capacity. This will be discussed later in the chapter.
One of the inputs into the PLC that was introduced during the testing was the dry outputs
from the Bucholtz relay. Figure 5.8 shows the position of the open and closed contacts. [22]
Figure 5.8 : Bucholtz Relay (FIST3-30, October 2005)[45]
The Bucholtz relay has two oil-filled chambers with floats and relays arranged vertically one
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over the other. If high eddy-currents, local overheating or partial discharge occur within the
tank, bubbles of resultant gas rise tot the top of the tank. These rise through the pipe between
the tank and the conservator. As gas bubbles migrate along the pipe, they enter the Bucholtz
relay and rise into the top chamber. As gas builds up in the chamber, it displaces the oil,
decreasing the level. The top descents until it activates a magnetic switch, which triggers the
alarm output. The bottom switch will be activated if the oil level in the transformer decreases
below the accepted volume. Both of these outputs were connected to the PLC. [14][21]
5.3.4 Traction Rectifier
Visual inspection is the most effective way to determine the condition of the rectifier [15].
During visual inspection the following must be noted:
• Examine the rectifier for any signs of damage or overheating, discoloration of
connections and busbars.
• Ensure that no dust is present on the diodes or the heatsinks. This will obstruct
proper heat flow and will reduce the ability to dispose of heat to the environment.
• Check the tightness of all securing brackets to ensure proper current conduction.
• Test the attenuation circuit protection by manually operating the micro switch of the
dropout fuse. [14][15][21]
These inspections can only be done by a certified person who is authorized to isolate the
rectifier. [14]This means that the substation must be taken off-load.
Most modern rectifiers have been designed with proper circuits to indicate the condition of
the diodes, protect the rectifier against over-temperature and monitor the cooling fan. During
this study the existing technology designed into the rectifier was used to provide inputs to the
PLC.
The diodes are monitored to indicate open or short circuit failure. Two outputs to the PLC for
this were used. Indications of one or two diodes that failed were sent as an alarm signal to
the main processor. An over-temperature alarm was the third output. It is important to know if
the cooling fan is working or not. This will give advance warning of probable failure. The
silicon diodes are very heat sensitive and operate within fairly narrow tolerances.
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Due to the fact that rectifiers are mainly designed using power electronic components, it is
very difficult to monitor parameters that will provide information to be used as to set up a
predictive maintenance model.
5.3.5 High Speed Circuit Breaker
High Speed Circuit Breakers (HSCB) are provided in 3kV DC substations to protect the
overhead track equipment (OHTE) against overloads, to isolate the OHTE sections and to
isolate the substation from feeds from adjacent substations in the case of protection
operations (Spoornet Engineering Instraction EP.001, 1993)[14].
These breakers are normally calibrated to operate at currents between 3000A and 4500A,
depending on the loop resistance of the section of OHTE and rail it protects [21]. In the case
of short circuits immediately outside the substation, fault currents can reach levels of 50kA.
The breaker will clear such fault currents between 0.025 and 0.08 seconds (25ms and
80ms). This causes a high amount of energy to be dissipated through the contacts shown in
figure 5.9.
Figure 5.9: Typical High Speed Circuit Breaker (EP.001,1993).[14]
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The circuit is interrupted by parting the contacts and controlling the resultant arc inside an arc-
chute. The function of the arc-chute is to increase the resistance of the arc, and hence the arc
voltage.
The energy dissipated in the arc chute can be calculated. These calculations were
accumulated in the main processor to indicated the energy dissipated during the life of the
arc-chute. If this information is combined with the number of times that the breaker operated,
it should give a very good indication of the remaining life of the arc-chute and the contacts.
During tests the contact wear was measured weekly. Figure 5.10 shows the maximum
allowable wear on the contacts.
Figure 5.10: Maximum allowable contact wear (EP.001, 1993).[14]
5.3.6 Battery and Battery charger
Batteries are installed at traction substation for protection and control purposes. It is vitally
important to make sure that the batteries a properly maintained. Loss of the 110V DC supply
will cause the substation to fail due to the fail-to-safe design standard of the protection. This
will mean a total loss of design functionality of the substation. In other words, total failure.
[14][21][43]
Visual inspections are used to assess the general condition of the battery, battery room and
safety equipment. Check the cleanliness of the battery, racks and room. Electrolyte leaks are
a serious indication of cracks in the cells and must be attended to immediately. The ambient
temperature must be checked and care must be taken to ensure proper functioning of the
ventilation equipment. [15]
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The battery supply is used for the following:
• Closing and tripping of the Primary Circuit breaker.
• Supply to protective relays.
• Emergency lighting in substations.
• Closing- and holdingcoil supply of the High Speed Track Breakers.
Most chargers used in South African traction substations is the silicon-controlled rectifier
(SCR) type. The charger has two important functions, a) to keep the batteries charged and,
b) to replace the batteries if the need arises. The size of the charger is very important to the
life of the batteries. The charger must be big enough the easily gas the batteries during
charging.
With the design of new chargers, more and more parameters are measured. The following
were used during the tests:
• Battery Bank Voltage (V)
• Battery Bank Ripple Voltage (% of nominal)
• Charging current (Aaverage)
• Charging current Ripple (% of nominal)
Additional measurements that were done are:
• Discharge current (Ah)
• Average Cell Voltage
• Internal Resistance
• Ambient temperature.
A battery monitoring system that was installed monitored the additional parameters. This
data was stored in the main processor.
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5.3.7 Additional parameters monitored
Additional parameters monitored were:
• Output contacts of the protection relays
• Undervoltage relay output
• Rectifier voltage output
• Rectifier current output
Although these parameters were monitored, they were not used in setting up the predictive
model in fuzzy logic because it is more an indication of corrective maintenance required.
5.4 Block diagram of the condition monitoring system The condition monitoring system that was developed for this study captured the following information according to the block diagram shown in Figure 5.11.
• Three analogue signals from the surge arrestor.
• Two IO signals from the Primary Circuit Breaker and a serial port.
• Three analogue signals from the Main Traction Transformer and one IO from the Bucholtz relay.
• Six IO signals from the Rectifier.
• Serial port from the High Speed Circuit breaker.
• Serial port from the Battery charger.
The data captured from these inputs to the Main processing unit was stored on a removable hard drive in data format. The data was transferred to Excel spreadsheets where all the calculations were done.
107
•
Figure 5.11: Blockdiagram of condition monitoring system.
1 x Analogue
1 x Analogue
RS485 serial
RS485 serial
M A I N
P R O C E S S I N G
U N I T
3 x Analogue
2 x Dry Contacts
6 x Dry ContactsTraction Rectifier
Diode State
Fan Monitoring
Rectifier temp
Surge Arrestor Leakage current measurement
Primary AC Circuit Breaker
I2t calculation
Traction Transformer
Oil temp
Outputs from Bucholz relay
Winding temp
High Speed Circuit Breaker
Calculation of Energy dissipated in the arc chute or I2t calculation
Battery and Battery Charger
Charging Current
Cell Voltage
Battery Bank Voltage
Battery Bank Temp
Internal resistance calculation
Discharge Current RS485 serial
SF6 gas level
Number of trips
Primary AC current
Number of trips
Ripple Voltage
1 x Analogue
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5.5 Summary As technology develops, the monitoring of equipment will become less expensive and more accurate. The price to store information is also dropping drastically. This enables the monitoring system to compare more information for the maintenance engineer to use. It is important to be able to know what to do with the available information, how to analyse it. In the next chapter this will be explored. Monitoring must occur continuous without disruption to the performance of the equipment. All techniques in this chapter had no influence on the performance of the equipment and was relatively easy to install. It must always be kept in mind that these monitoring devices need to be maintained as well. Care msut be taken not to over complicate matters when monitoring is done. Compatibility to new technology is also of paramount importance. The PLC used during these test can already be replaced with a much more effective one, for example.
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6 ANALYSING MEASUREMENTS 6.1 Setting engineering limits As mentioned previously, predictive maintenance compares the trend of measured physical
parameters against known engineering limits for the purpose of detecting, analysing and
correcting problems before failures occur. [1][2][3][31]
A predictive approach can be applied to any equipment problem if, a physical parameter like
vibration, temperature, current, voltage or resistance can be measured. An engineering limit
for the measured physical parameter must be established so that a problem can be detected
during routine monitoring. This limit should be low enough to detect a problem before
damage occurs. Correcting of the root problem is the key to predictive maintenance.[31]
The established parameters can be measured periodically, for example weekly, monthly or
annually. If the measurement exceeds the engineering limit it must be analysed further. The
idea is to set the engineering limit low enough to allow for enough time to do proper analysis
and determine the root cause of the problem before damage occurs.
There are several aging processes at work in the equipment, any of which may cause the
ultimate failure. These processes are usually related to the basic physics of the materials and
how they are used.[31][32]
Knowledge of the physical properties of the materials used in equipment comes from either
theoretical of empirically derived conclusions. To understand how failures can be predicted,
the mortality of the equipment and the finding of the parameter must be understood.
The measurement of a physical parameter in itself, as in chapter 5, is not enough to detect
the destructive effects on the equipment or component. It is important to determine a limit or
a rate of change in the parameter that may be excessive or damaging.
One method is to observe a number of failures before a safe limit can be established. For
this reason a number of failures was observed and investigated to check limits on some of
the components discussed later in this chapter. Statistics of failures inside traction
substations were used to calculate probabilities of failure of the specific equipment under
discussion. The limited amount of information from this system must be noted. One major
problem identified in South Africa was the reluctance of maintenance personnel to accurately
110
record information on failures and components replaced [15]. This will be discussed in
chapter 7.
Most engineering limits have already been determined by the manufacturers, professional
societies and industrial groups. The application in a traction substation might differ from the
designed environment for that specific equipment, but over the years, as knowledge on the
maintenance requirements increased, the user determined new limits to suit the specific
application.[24][52]
Predictive maintenance must, however, not just focus on the reliability of the equipment but
also on the quality of the product delivered. In this case, a regulated 3kV direct current
supply to the traction locomotives. During the failure mode, effect and criticality analysis, this
was taken into account to determine critical equipment in the substation.
6.2 Surge Arrestors
The function of a surge arrestor is to limit over voltages that could damage equipment. The
arrestor must bypass the surge to ground and discharge severe surge current of high
magnitude and long duration without being damaged itself. This means that the arrestor must
be able to continuously withstand the rated voltage for which it was designed, only allowing
minimum flow (leakage current) of the 50Hz current to ground. After the high frequency
lighting surge has been discharged, a surge arrestor, still functioning properly, will be
capable of repeating its protective function until another surge voltage must be
discharged.[24][42][43]
Since the surge is discharged to ground, it is imperative that a good grounding system be in
place with a low resistance between the system and natural ground.
Figure 6.1 shows the measurements taken over a period of 15 months by the author on a
metal-oxide type surge arrestor in a substation located in an area with a high frequency of
lighting occurrences. According to Weather South Africa, this substation is located in the
area with the highest density of lighting during December 2005 and February 2006 in South
Africa.
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Figure 6.1: Surge count on lighting arrestor
Modern surge arrestors requires very little operational maintenance and the degree to which
such maintenance can be done is usually limited by the lack of adequate testing equipment.
This limits the surge arrestor maintenance to visual inspections as described in chapter 4
and simple electrical test as described in chapter 5. It is recommended that units found to be
defective be replaced rather than repaired. Where an arrestor is composed of more than one
unit, each one must be tested individually to enable the maintenance engineer to replace the
damaged units and retain the good ones. [43]
Surge arrestors are almost always supplied with one terminal connected to an electrically
energised source and one connected to ground. No work must be done while the one
terminal is connected to the energised source. [24][42][43]
The periodic visual inspections should ensure that the line lead is securely connected to the
line conductor and the arrestor. The ground lead must be fastened to the arrestor terminal
and the grounding system. The inspections must, thirdly, ensure that the housing is clean
and free of cracks, chips, or evidence of external flashover.
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During the inspection the following must be noted if the arrestor is subject to:
a) Damaging fumes or vapors.
b) Excessive dirt or any other current-conducting deposits.
c) Excessive humidity, moisture, dripping water, steam or salt spray.
d) Abnormal vibrations or shock.
e) Ambient temperatures in excess of 40oC.
Finally, the visual inspection must be concluded by ensuring that any gaps are free from
foreign objects and set at proper spacing.
The electrical test performed on the surge arrestor to measure the leakage current yielded
the information analysed in Figure 6.2.
Figure 6.2: Leakage current tested on Metal Oxide Surge Arrestor.
When analysing the trend line, it is important to note the steady upwards trend. This indicates
that leakage current increases over time as the number of surge voltages discharged through
the arrestor increases. In chapter 5, failure of an arrestor was described as the loss off the
capability to dissipate thermal energy. If the leakage current increases for the designed
operating voltage, in this case 88kV, then it must be assumed that the physical properties of
the material inside the arrestor is changing. This means that the capability of the arrestor to
perform to its designed standard decreased. [42]
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During the test period the arrestor being tested never reached the limit where it destructed
because of incapability to dissipate the thermal energy. It is therefore recommended that the
rate of change be monitored to be able to predict possible failure and replace the arrestor.
During the FMECA it was found that the arrestor does not play an critical role in the
substation and that catastrophic failure of the arrestor will not lead to the same effect on the
performance of the substation.
It is important to be able to detect failure immediately to reduce the risk of catastrophic failure
of the substation during the next surge. All surge arrestors have an amount of leakage
current present that can be measured. If this suddenly disappears, it will be a indication of
failure and immediate action can be taken. This is corrective maintenance and not the ideal
situation.
As soon as the rate of change reaches a 25% higher value than the average calculated over
the period since the monitoring started, a visual inspection must be conducted at least once
a month. When that rate increases to 50% difference, it is recommended that the arrestor be
changed. This calculation will become more accurate as the amount of data increases.
Different arrestors of the same type can be compared to increase the accuracy even further.
All the arrestors in one substation can be compared as a benchmark against each other.
These arrestors will operate in very much the same conditions. If the rate of degradation of
one suddenly start differing from the others, the alarm should be send.
6.3 Primary Circuit breakers
The function of a primary circuit breaker is to interrupt the high voltage supply from the utility
when an overload or fault condition occurs. Figure 6.3 is an indication that primary circuit
breakers in traction substations are not exposed to the same operating conditions as to that
of a distribution substation. Most of the operations in Figure 6.4 were caused by manual
switching during maintenance or when it was tripped by the battery undervoltage relay. This
relay is calibrated to drop out when the battery voltage drops below 90 volt. [14][20][21]
In Graph 6.3 the operations were filtered to represent only those that occurred during fault
conditions. A total of 43 such operation occurred out of a total of 74 during the 12 month
period over which these test were conducted. The highest fault current level was measured
at 25.89kA with the interrupting time varying between 8ms to 19ms. Figure 6.3 shows the
resultant It2 calculation the determine the amount of energy interrupted.
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Figure 6.3: Operations during fault conditions for primary circuit breaker.
From the trend line it is clear that the energy dissipated increased over the period. This can
be contributed to the time of interruption that increased. The satisfactory operation of the
spring drive mechanism depends heavily on the closing and tripping latches being in a good
condition. It must be clean, well lubricated and free of corrosion and wear. The drive
mechanism must only be connected while connected to the breaker. During inspection all
these should be checked before a rating can be applied to the inspection form as described
in chapter 4.
Figure 6.4 is an indication that more operation occurred during the warmer months. Even
though higher incidents of lightning occurred during these periods, it is difficult to understand
the reason for more operations. According to the substation’s maintenance logbook, frequent
maintenance was done on equipment inside the substation not necessarily directly
associated with the breaker. But to be able to work under certain off-load condition manual
switching of the breaker had to be done. It is therefore concluded that most of the switching
during the months with higher occurrence of lighting took place in order to do maintenance
on other damaged equipment.
The primary circuit breaker is part of the interlocking system of a substation and must be
switched before the substation can be taken off-load and declared safe to enter the high
voltage areas.
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Figure 6.4: Count of all operations.
Figure 6.5 is a measurement of the SF6 level inside the breaker. The SF6 pressure is at a
level of 5.8 to 7.5 bar.
Figure 6.5: SF6 level as a percentage.
116
The alarm should be set to sound if the pressure drops below 80%. If it reaches a level of
70%, the breaker should be tripped an locked-out as a pressure of less than that is
inadequate to clear the arc and will cause damage to the breaker. Catastrophic failure might
be the result.
While the gas system is refilled, the rapid expansion of the gas will cause it to cool to a lower
temperature than the dew point of the surrounding air, and moisture will condense on the
hose fittings. This is quite normal and there is no cause for alarm. If the flow rate is to high
though, it will cause the gas itself to freeze and prevent further flow, giving the impression
that the cylinder is empty. To prevent this, the supply cylinder valve must be regulated so
that the gas flow does not exceed the SF6 gas pressure of the breaker by more than 0.5 bar.
6.4 Traction Transformer
Being essentially static devices, transformers require very little maintenance [14].
Nevertheless, it is important to be able to have a measure of deterioration, if any, and
evaluate the condition of the transformer.
Deterioration of the oil and insulation within the transformer is a function of moisture, time
and temperature and, hence, of load conditions. Currently periodic oil sampling and testing
provides an indication of the condition of the oil. [9][22][32]
As can be seen in Figure 6.8, traction transformers are subjected to usually short peak
currents. As a consequence, average oil temperatures are relatively low, as shown in Figure
6.6 and Figure 6.7. Where the temperature is constantly higher than 60oC, more frequent oil
testing must be done. Much has been written about transformer oil and the methods of
testing it [22]. It remains a very subjective process, depending on the skill and commitment of
the person taking the sample. A different condition assessment technique had to be found.
Figure 6.6 and Figure 6.7 show the difference between temperature measurements at the
top and the bottom of the transformer. It was expected to be very much the same with the top
temperature to be a little higher because of thermal flow inside the tank. The first graph
yielded the expected results. Because of the natural ventilation design, making use of
radiator fins, the bottom temperature is approximately 1oC lower and lagging by a few
minutes. This is perhaps more than what was expected, but can be explained.
117
According to figure 5.7, the natural flow of oil inside the tank is through the radiator in a down
wards direction. This is caused by the difference in pressure because of higher thermal
energy at the top. Oil with a higher temperature will have a lower density, in other words, a
lower pressure will be measurable at the top. Nature dictates flow to be from a high to a low
pressure system.
The measurements in Figure 6.7, might be an indication of some problem in the oil flow of
that specific transformer. At approximately 13h00 and 20h00 the top and bottom
temperatures did not follow the same pattern, indicating irregularity in the flow. Upon
investigation, it was found that a packing on the radiator was busy disintegrating, causing
blockage of the system. If proper flow measurements were available, the result could have
proven to be very interesting.
Figure 6.6: Top and bottom oil temperature – Transformer A
The bigger difference in the top and bottom temperature in Figure 6.7 at some instances also
caused concern. Analysis of the record for oil testing on this transformer showed that no
tests were conducted for a period of almost four years.
When the tap at the bottom was opened, it was clearly blocked by a build-up of slack. This
slack was caused by excessive arcing over a period of time. These results showed that a
simple oil temperature test and comparison can provide evidence of possible failure. This
enabled the maintenance engineer to take an informed decision and do predictable
maintenance before a catastrophic failure occurred.
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Figure 6.8 shows the comparison between the top oil temperature and the current. As
described earlier, traction transformers are subjected to very cyclic load currents because of
their application. During the period under consideration, 9 trains drew current form the
system in the direction of incline. Measurement were only taken at 15 minute intervals, thus
the unexpected pattern in the current being drawn. The current should gradually increase as
the train nears the substation. The current drawn should also be much more in the same
order.
The principal, however, can still be explained using this data. The increase in temperature is
expected to be relative to the current drawn. If the relationship between current drawn and
temperature changes, it will be an indication of increased losses in the transformer or
deterioration of the oil quality. This function will be build into the fuzzy logic principal
described in chapter 7.
Figure 6.7: Top and bottom oil temperature – Transformer B
Possible problem area
119
Figure 6.8: Current vs top temperature
6.5 Rectifier
A rectifier is designed to remain functional even if one diode in a rectifier branch becomes
defective. Failure of a diode (loss of blocking ability) will not immediately lead to breakdown
of the rectifier, because two diodes are in series per branch and the remaining one will be
able to withstand twice the applied reverse voltage. [4][14][21]
The rate of replacement for silicon diodes, calculated from the maintenance data obtained
from Spoornet, is 0.2 per 1000 per annum [4]. This figure also includes replacement during
commissioning.
The conditions of the diodes are monitored and this information is send to a dispay on the
rectifier. Two outputs form this display was used as inputs to the PLC to indicate any faulty
diodes on the rectifier.
During the test period no faulty diodes were registered. The theory is that is advance warning
can be given when the first diode fails, it can be replaced before the entire rectifier fails.
120
6.6 High Speed Circuit breaker
The actual fault level can be measured when a high speed breaker operates. This can be
expected to be in the region of 50kA. The interrupting time is between 0.025 and 0.08
seconds. This equipment is very expensive because it must measure direct current, and to
install a prototype in the system, the failure-to-safety had to be proven.
To proof the theory though, the calibrated level for each of the three breakers were used with
an assumption that the interrupting time would be the same for each breaker. Breaker #1
was calibrated at 3200A, breaker #2 at 4000A and breaker #3 at 3500A. The time was taken
to be t=0.08.
Operation counters was installed and the number of operations logged. Figure 6.9 indicate
the results from calculating the accumulative energy for these values. It is clear that the rate
at which the calculation increases is very much the same for the three breaker.
This was compared with the measurements of the wear for the moving and fixed contact of
breaker #3. There is a very good comparison between the energy and both the contact wear.
It is possible to estimate contact wear by calculating energy dissipated through the contacts.
This will allow the maintenance engineer to determine intervention before failure occur.
Scheduled shutdowns can be used to replace worn contacts to prevent untimely failure.
Figure 6.9: Accumulative calculated energy
121
Figure 6.10: Contact wear
6.7 Batteries and chargers.
With the design of new chargers, more and more parameters are measured. The following
were used during the tests:
• Battery Bank Voltage (V)
• Battery Bank Ripple Voltage (% of nominal)
• Charging current (Aaverage)
• Charging current Ripple (% of nominal)
Additional measurements that were done are:
• Discharge current (Ah)
• Average Cell Voltage
• Internal Resistance
• Ambient temperature.
122
A battery monitoring system that was installed monitored the additional parameters. This
data was stored in the main processor.
No further discussion will be done on this subject since the science of understanding battery
supply is a study on its own. It must just be noted that the parameters obtained from these
test can be used, in conjunction with the manufacturer, to increase the maintainable life of a
battery bank.
6.8 Summary
Condition monitoring is an essential part of maintenance. The challenge is to find a cost
effective method of obtaining the data required to make accurate decisions. To implement a
system in 603 substations will be very costly and difficult to motivate.
Through the thorough investigation and research done in the previous chapters to identify the
critical components to be measured, a cost effective system was developed as discussed in
this chapter. The data obtained from the condition assessment was analysed to determine
thresholds, or engineering limits, that will enable toe system to provide an alarm when critical
values are reached.
This reduces the level of experience required by the maintenance engineer and eliminates
unnecessary input on a human level. This interface will never disappear entirely, but the
system developed limits the risk involved when human intervention is required.
It is important to note that it will still be a human that setup and maintain the system. It will
still be a human that must react to alarms.
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7 FUTURE DEVELOPMENT FOR REAL BUSINESS NEED –PREDICTIVE MAINTENANCE
7.1 Real business need. As capital available for investment shrivels, manufacturing managers need to sqeez the last
useful drop of economic life from equipment. Traditional reactive and preventive
maintenance must be blended with today’s predictive maintenance tools. (C. Kenna Amos,
1993) [2]
A balanced between competing business considerations of trying to increase capacity,
maintain quality and reduce production costs must be found. Success for maintenance
practitioners, facing dwindling budgets and smaller staff, will mean finding a fresh
perspective on their function and communicating in business terms with the enterprise’s
higher levels. Manufacturing executives must grasp the criticality of adequately funded and
implemented maintenance programs and then act accordingly.
Optimizing asset utilization has its challenges. The enterprise must understand what
predictive maintenance is, and how and why it is used. Then the business must identify
which assets are best monitored predicatively. [2] This process was implemented for traction
substation during the study and proofed to be very successful. Over time the information
obtained from this will lead to a better understanding of the dynamics involved in 3kV DC
traction substation maintenance, which will enable an improved analysis to be carried out.
Using available technology, predictive maintenance provides advance notice of problems
With the predictive approach, one still have the repair cost, but not the downtime. It will allow
longer MTBF and higher level of utilization because you don’t have as much preventive
maintenance. Predictive maintenance depends on the monitoring of two or three critical
variables in a device that, with a 90 percent confidence level, will tell you that the device is
going to fail in a very short time.
Predictive maintenance allow manufactures to determine where they need to improve or
focus their efforts. Those would be maintenance, cost reduction and quality improvement. It
must be noted that predictive maintenance is one component of an asset management
strategy. The others would be performance monitoring, condition monitoring, quality
improvement and cost reduction according to C. Kenna Amos (1993)[2].
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In chapters 5 & 6 the focus was on device data and obtaining the information required to take
certain predictive decisions. Predictive maintenance involves more than just device data. In
fact, capturing the data proofed to be the easier part of the process. The data must be
analysed in the context of the users business needs. It must enable the owner or
manufacturer to take the best financial decisions.
While condition monitoring and performance monitoring feed into predictive maintenance,
businesses could benefit from acknowledging that automation systems and devices,
including wiring, as well as products themselves, are assets to be considered.
In the process industries, the next frontier for predictive maintenance is in the measuring
devices. The solution may be “self-validating” assets where the asset or equipment will give
indication that a problem exist. It will provide information on the root cause and the manner in
which the problem effects productivity. Also [1][3][5][6][17][27]
7.2 Sustaining development
As discussed in the previous section, the future must be in developing equipment and
components that will be able monitor itself and detect possible problems. Advance warning
must then be given to the maintenance engineer on the cause of the problem and the extend
that productivity is influenced. If possible, the equipment must try to rectify the problem as
good as possible. In other words intelligent equipment must be developed.
The cost savings possible through predictable maintenance is so significant that it will
become impossible to operate any system in future without it. Because of the age of the
average traction substation in South Africa, this will become the only way to keep the system
running without having to spend huge amounts of capital in a short period of time.
The savings will not only be in the avoidance of unnecessary preventive maintenance, but
also in the fact that less corrective maintenance, or unscheduled maintenance, is needed. In
chapter 1 the problem with these strategies were explained. The maintenance time required
can be reduced and predicted. Direct maintenance cost normally, according to C. Kenna
Amos (1993)[2], in some instances contribute to only about 30% of the actual cost incurred if
unscheduled loss in production occurs.
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During this study the focus was on developing a system that can be implemented on traction
substations. Only a few substations were monitored to test the system and obtain data for
the development of the analysis process. If this system is to be implemented in all of the 603
substations, maintenance effort calculations will surely show this to be true as well.
Sandy Dunn’s quote (2005)[1], that predicting the future is fraught with danger brings her to
the conclusion that changes in the field of condition monitoring only be sustained if they
address real business need.
What is this business need that will sustain development in condition monitoring? After
investigating a wide range of possibilities, it must be defined as the need to extract maximum
profits from the minimum profits in plant and equipment. The aging substation equipment
may be beyond this point already and need to be replaced, but due to the capital cost
involved, ways must be explored to stretch the remaining maintainable life of the equipment.
In the FMECA that was done in chapter three, the critical equipment was identified. The
criteria not only took the functionality into consideration, but also the cost to replace and
availability. A 5MVA traction transformer, for example, costs approximately R1.2mil. to import
with a delivery time of between 8 and 12 months. This increases the criticality of the
transformer.
According to Sandy Dunn (2005)[1], there are five ways to achieve the above through
condition monitoring.
a) Improve equipment reliability through the effective prediction of equipment
failures.
b) Minimising downtime thought integrated planning and scheduling of repairs
indicated by the condition monitoring.
c) Maximise component life by avoiding the conditions that reduce equipment life.
d) Utilize condition monitoring to maximise equipment throughput and performance.
e) Minimise the condition monitoring cost.
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7.2.1 The need to predict equipment failure
When the corrective strategy is in use, the main motivator to improve is to reduce failures.
The primary advantage of condition monitoring is to be able to predict unplanned equipment
failures. It is important to determine through a analysis like the FMECA, which failures need
to be predicted, and to implement condition monitoring to assist in this. The current
frequency at which monitoring takes place in traction substations, is far from optimal. To
determine the frequency, it is important to know what the lead time for each failure is.
Condition monitoring is very expensive and creates huge amounts of data. If the frequency is
not accurate, it will make the investment in monitoring equipment useless. [51][52]
7.2.2 Integrated planning and scheduling
There are other ways in which condition monitoring can improve maintenance through this
predictive approach. The total downtime can be reduced by taking a holistic view of all the
equipment in the system. Planned maintenance can be scheduled together and be done in
one shutdown. If one piece of equipment is nearing the possible failure condition, the
available information on the other equipment can be accessed to determine condition status
and a decision can be maid if this must be replaced at the same time.
This requires the effective integration of the following:
a) Condition monitoring results.
b) Visual inspection results.
c) Preventative maintenance schedules.
d) Equipment performance monitoring. [3]
The difficulty in this, for a major railway company, is that all of these information traditionally
have been kept in different places. During this research study, information from the various
departments were combined to produce the calculations on probability.
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7.2.3 Greater accuracy in failure prediction and the need to reduce cost of condition
monitoring
The most significant benefit from integrating the condition monitoring data and the process
control data is that root cause determination of failure can be done much more accurate.
Presently the cause investigation heavily rely on the experience of the analyst. Due to a rapid
decrease in the number of experienced personnel available in the market, the integration of
this data becomes essential.
The biggest challenge in this effort to integrate the data is to capture it in the same protocol.
In other words, a program must be developed to capture all the data in the same format to
enable accurate analysis.
The fact that the cost of signal processing technology is decreasing rapidly, makes the
development of such software much more economical. Manufactures must realise the benefit
of fitting this technology to their equipment and be guided by the rest of the industry to decide
on a protocol that will be used. Very much the same as the Bluetooth cordless technology.
This sensor technology is still too expensive to implement economically in the industry. If
implemented, this intelligent sensor technology will greatly reduce the complexity of putting
the outputs together and integrate the data. Although a PLC was used to capture the data in
this research, the information input was still greatly restricted by the output received from the
sensors. The data compiled for the high speed circuit breaker is a good example where
proper output would have required very expensive technology. The calibrated value for each
breaker was used during energy calculations, but with better sensors, the accurate measured
value could have been used. The principal was proven and can be applied when the
monitoring technology becomes economically available.
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7.2.4 The need to improve relaiblity
The algorithms used in these intelligent sensors must be accurate and reliable. The starting
point for these algorithms will be discussed later in this chapter. The process will be
described as a fuzzy logic algorithm.
The impact of the improvement in this failure diagnostics software must be two-fold. First it
must improve the consistency and accuracy of failure diagnoses. Second, it must reduce the
labour required to assess the condition of equipment.
7.3 Key trends for condition monitoring in the future
From the measurements taken in this study, it is clear that for predictive maintenance to be
sustainable, intelligent sensors and new cost effective monitoring techniques must be
developed. This is to enable continuous monitoring of critical components of the system. The
increased requirements to build sensors into equipments that can be connected to the
monitoring system in substations must be understood by the manufacturers.
To enable the engineer to understand and analyse all the information obtained from these
sensors, software will have to become increasingly more sophisticated and a rapid
development in the diagnostic capabilities is required to keep up with the evolving hardware.
Condition monitoring must be accepted by the maintenance and operation departments as a
day to day activity that cannot be neglected. The advantage to production managers must
become clear for them to support this strategy. Planning towards increased production must
make use of the available information to enable optimized planning.
Predictive maintenance must be incorporated into business plans and the advantage of
condition monitoring that can lead to better utilization and reliability must be integrated with
the need to produce.
During the visual condition inspections performed in chapter 4, it became clear that in some
instances acceptable standards were lowered to prevent loss of production . This is a very
short term solution which can be prevented by enforcing compliance to industry standards
through these monitoring techniques.
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In the railway industry the development of process control technology is much more
advanced than that of condition monitoring. The manufactures of the process control
equipment will have to understand the concept of integration with this maintenance strategy
flowing from condition monitoring, and start applying it to their technology.
7.4 Software development
From the above discussion it is clear that there will be an increased number of components
in the substation that can be monitored as the technology becomes more accost effective.
The focus will shift from obtaining the information, to applying the principles in the industry to
maximise the business benefit.
There will be less manual data collection an more sophisticated analysing software. The
basic start for any software developer is to understand the client need. To facilitate this
process, the predictive strategy, discussed to date, can be written into a fuzzy logic program.
7.4.1 What is fuzzy logic
According to Steven Keahler, Fuzzy logic – An introduction [46], the concept of fuzzy logic
was conceived by Lofti Zadeh, a professor at the university of California, and presented not
as a control methodology, but as a way of processing data by allowing partial set
membership rater than crisp set membership or non membership. This approach to set
theory was not applied to control systems until the 70’s due to insufficient small computer
capability prior to that time. Professor Zadeh reasoned that people do not require precise,
numerical information input, and yet they are capable of highly adaptive control. If feedback
controllers could be programmed to accept noisy, imprecise input, they would be much more
effective and perhaps easier to implement. Also [36][37][38][39][40][41]
In this context, fuzzy logic is a problem-solving control system methodology that lends itself
to implementation in systems ranging from simple, small, embedded micro-controllers to
large, networked, multi-channel PC or workstation-based data acquisition and control
systems. It can be implemented in hardware, software, or a combination of both. Fuzzy logic
provides a simple way to arrive at a definite conclusion based upon vague, ambiguous,
imprecise, noisy, or missing input information. It is the same approach to control problems as
to how a person would make decisions, only much faster.
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Fuzzy logic incorporates a simple, rule-based IF X AND Y THEN Z approach to solving a
control problem rather than attempting to model a system mathematically. The fuzzy logic
model is empirically-based, relying on an operator's experience rather than their technical
understanding of the system. For example, rather than dealing with temperature control in
terms such as "SP =500F", "T <1000F", or "210C <TEMP <220C", terms like "IF (process is
too cool) AND (process is getting colder) THEN (add heat to the process)" or "IF (process is
too hot) AND (process is heating rapidly) THEN (cool the process quickly)" are used. These
terms are imprecise and yet very descriptive of what must actually happen. Consider what a
person does in the shower if the temperature is too cold: he will make the water comfortable
very quickly with little trouble. Fuzzy logic is capable of copying this type of behavior but at
very high rate. [33][34][35][46]
Fuzzy logic offers several unique features that make it a particularly good choice for many
control problems.
1) It is inherently robust since it does not require precise, noise-free inputs and can be
programmed to fail safely if a feedback sensor quits or is destroyed. The output control is a
smooth control function despite a wide range of input variations.
2) Since the fuzzy logic controller processes user-defined rules governing the target control
system, it can be modified easily to improve or drastically alter system performance. New
sensors can easily be incorporated into the system simply by generating appropriate
governing rules.
3) Fuzzy logic is not limited to a few feedback inputs and one or two control outputs, nor is it
necessary to measure or compute rate-of-change parameters in order for it to be
implemented. Any sensor data that provides some indication of a system's actions and
reactions is sufficient. This allows the sensors to be inexpensive and imprecise thus keeping
the overall system cost and complexity low.
4) Because of the rule-based operation, any reasonable number of inputs can be processed
(1-8 or more) and numerous outputs (1-4 or more) generated, although defining the rule base
quickly becomes complex if too many inputs and outputs are chosen for a single
implementation since rules defining their interrelations must also be defined. It would be
better to break the control system into smaller chunks and use several smaller fuzzy logic
controllers distributed on the system, each with more limited responsibilities.
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5) Fuzzy logic can control nonlinear systems that would be difficult or impossible to model
mathematically. This opens doors for control systems that would normally be deemed
unfeasible for automation.
How is fuzzy logic used?
1) Define the control objectives and criteria: What am I trying to control? What do I have to
do to control the system? What kind of response do I need? What are the possible (probable)
system failure modes? This was done in the Failure mode, effect and criticality analysis in
chapter 3.
2) Determine the input and output relationships and choose a minimum number of variables
for input to the fuzzy logic engine (typically error and rate-of-change-of-error). With the
information obtained from the measurements described in chapter 5 and the resultant
discussion in chapter 6, it is possible to provide accurate relationships for the equipment that
was monitored.
3) Using the rule-based structure of fuzzy logic, break the control problem down into a series
of IF X AND Y THEN Z rules that define the desired system output response for given
system input conditions. The number and complexity of rules depends on the number of
input parameters that are to be processed and the number fuzzy variables associated with
each parameter. If possible, use at least one variable and its time derivative. Although it is
possible to use a single, instantaneous error parameter without knowing its rate of change,
this cripples the system's ability to minimize overshoot for a step inputs.
4) Create fuzzy logic membership functions that define the meaning (values) of Input/Output
terms used in the rules.
5) Create the necessary pre- and post-processing fuzzy logic routines if implementing in
S/W, otherwise program the rules into the fuzzy logic H/W engine.
6) Test the system, evaluate the results, tune the rules and membership functions, and retest
until satisfactory results are obtained.
This is a very shortened explanation of fuzzy logic. One of the goals of this study is to create
a fuzzy logic understanding of maintenance. The PDM (Predictive Maintenance) Cycle as
described by Brown (2003) [13] and discussed in chapter 1, is a very simple example of
fuzzy logic.
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Figure 7.1 : PDM Cycle for critical equipment (Brown, 2003)[13]
It must be understood what must be controlled with this fuzzy logic. The need for the
maintenance engineer to understand the requirements of a system and to react in time to
prevent unscheduled downtime, provides the answer to this question. With the development
of a fuzzy logic diagram, the focus will be on the monitoring, comparison of the
measurements to set engineering limits and the analysis of the problem if it exists. Also
[40][41].
7.4.2 Fuzzy logic for equipment being monitored
During this study, values were monitored for the following:
o Surge arrestors
o Primary circuit breakers
o Traction Transformers
o Rectifiers
o High Speed Circuit breakers
o Batteries and Chargers
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(a) Surge Arrestors
The following was measured during the tests:
o Surge Count
o Leakage current
According to the measurements the engineering limits for the arrestors must be set as
follows:
o Accumulative Surge count per annum eo<40
o Average Leakage current el<13mA
o Rate of change in leakage current over 24 hours er<0.1mA
o Leakage current ec>0mA
The rate of change can be taken over a shorter period if greater accuracy is required, the 24
hour period, however, provide a filter for high occurrences of surge dissipation through the
arrestor.
To provide an immediate alarm when the arrestor is destroyed, a limit is set that there should
always be some leakage current present. Hence the reason for the ec>0mA.
(b) Primary Circuit breakers
The following was measured during the tests:
o Energy dissipated during fault current operation (It2)
o Operation count
o SF6 Level
To calculate the accumulative fault current, operation under normal conditions, for example
when switching was required for maintenance purposes, were filtered out.
According to the measurements the engineering limits for arrestors must be set as follows:
o Rate in change for It2 over 10 operations er<0.2kJ
o Operations under fault conditions per annum eo<75
o SF6 level 70<esf6<95
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To prevent to much pressure in the SF6 breaker, a higher limit is also set for the SF6 level.
The will warn the maintenance engineer if the technician doing maintenance, used the
incorrect equipment of method to fill the breaker.
(c) Traction Transformer
The following was measured during tests:
o Top oil temperature
o Bottom oil temperature
o Current
In the analysis in chapter 6, the top and bottom oil temperature was compared to determine
any problems with the internal flow of the oil. The top temperature was also compared to the
current drawn through the transformer. This provide for a classic fuzzy logic input, as no
precise values are required to determine an outcome.
The engineering limits that must be set according to these comparisons are:
o Difference between top and bottom temperature ed<20C
o Rate of change for top temperature and current drawn er<30sec
o Comparison between current and top temperature must stay constant
A rise in current must result in a rise of the top temperature. The comparison must remain
constant. Minor alterations will be allowed due to difference in ambient conditions such as
wind and temperature. If the data base is populated over a prolonged period of time, the
accuracy of this comparison will become much higher.
(d) Rectifier
The following was captured on the rectifier testing:
o Diode failure
As explained in chapter 6, no faulty diodes was detected over the testing period. The input
will provide an alarm to the maintenance engineer should any failure occur. It will also
automatically log the information on the database to provide for accurate calculations on the
probability of failure.
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(e) High Speed Circuit Breaker
The following information was measured and captured onto the data base:
o Energy dissipated
o Fixed contact wear
o Moving contact wear
The idea of this study was to determine any relationship between the accumulated energy
dissipated and the contact wear. According to graph 6.9, showing the calculated
accumulated energy dissipated, and graph 6.10, depicting the fixed and moving contact
wear, there is a very strong relationship between the energy dissipated when operated under
load conditions and the wear on the contacts.
It is a very cumbersome task to measure contact wear because of the effort involve. It must
be done by a certified person who need to take the breaker out of service for a short period
of time. The idea of the preventive strategy is to do all measurements and determine
maintenance requirements without influencing the operation of the equipment. From the
graphs mentioned above it is clear that the possibility to estimate contact wear by measuring
the energy dissipated through them.
According to the calculated results, it is possible to set an alarm for contact replacement
when the accumulative energy reaches a level of ee=3500J. It must be noted that this is a
calculated value for the energy and that more expensive equipment might lead to a different
value.
Since predictive maintenance focus on the total downtime of a system and aims to reduce
that by scheduling tasks together, both contacts must be replaced simultaneously. According
to the results the moving contact have much higher tolerances towards wear, but to reduce
down time and maintenance effort, it must be replaced with the fixed contact.
When rep[lacing a contact, various time consuming tasks must be performed, including the
removal of the breaker from service, opening and cleaning of the breaker and the re-
calibration after replacements. All of this can be halved if the two contacts are to be replaced
during the same maintenance cycle.
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(f) Batteries and Charges
During the past couple of years, technology have been developed to monitor batteries and
charges. This technology provides the following outputs as discussed in chapter 6:
• Battery Bank Voltage (V)
• Battery Bank Ripple Voltage (% of nominal)
• Charging current (Aaverage)
• Charging current Ripple (% of nominal)
Additional measurements that were done are:
• Discharge current (Ah)
• Average Cell Voltage
• Internal Resistance
• Ambient temperature.
This information was added to the data base to provide valuable information on the condition
of the batteries. The manufactures of the technology already build in some alarms which can
be used to act upon problems before the cause failure.
The intention of this study was not to go into more detail on the monitoring of the batteries.
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7.5 The fuzzy logic program
When taking all the above into account, a fuzzy logic program for the equipment can be
designed. The table of variables are shown in table 7.1.
Table 7.1: Equipment variables
Equipment Variable Action
Surge Arrestor
eo<40
el<13mA
er<0.1mA
ec>0
No action required if number of operations is less than 40 per annum, compare with rate of change in leakage current if more than 40. Raise maintenance concern if tempo per day, week of month exceeds the average by more than 30%. Monitor to calculate rate of change. If the value exceeds 13mA, detail analysis by the maintenance engineer might show interesting result. Raise maintenance concern when value is exceeded. Raise maintenance concern when the rate of change exceeds 0.1mA over 24 hours. If no leakage current is present, immediate action is required by maintenance staff.
Primary Circuit Breaker
er<0.2kJ
eo<75
70<esf6,95
Raise maintenance concern if the rate of change over a moving average of 10 operations is more than 0.2kJ Raise maintenance concern if more than 75 operations occurred under fault conditions. Monitor the operation against the average per day, week and month, This will provide important information on other defects that might be present in the substation. The SF6 level must be between 70% and 95%. Raise maintenance concern if these limits are exceeded.
Traction Transformer
ed<2oC
er<30sec
Monitor difference between top and bottom oil temperatures and compare. Raise maintenance concern if this value exceeds 2oC The temperature of the oil must not lag the current spikes by more than 30sec. Compare average lag time to determine characteristic of each transformer.
Rectifier ediode Raise maintenance concern if a diode fail on the rectifier.
High Speed Circuit Breaker ee<3.5kJ Raise maintenance concern to replace both
contacts if calculated energy exceeds 3.5kJ.
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The program commands for each piece of equipment that were monitored are shown below. For the surge arrestor:
IF eo > 40 OR eo (day) > (AVERAGEday)+30% OR eo (week) > (AVERAGEweek)+30% OR eo (month) >
(AVERAGEmonth)+30%, THEN SEND MAINTENANCE CONCERN
IF el > 13mA, THEN SEND MAINTENANCE CONCERN
IF er > 0.1mA, THEN SEND MAINTENANCE CONCERN
IF ec < 0 OR ec = 0, THEN SEND MAINTENANCE CONCERN, FLAG FOR IMMEDIATE
ATTENTION
For the primary circuit breaker:
IF er > 0.2 kJ, THEN SEND MAINTENANCE CONCERN
IF eo > 75 OR eo (day) > (AVERAGEday)+30% OR eo (week) > (AVERAGEweek)+30% OR eo (month)
> (AVERAGEmonth)+30%, THEN SEND MAINTENANCE CONCERN
IF esf6 < 70% OR esf6 > 95%, THEN SEND MAINTENANCE CONCERN
For the traction transformer:
IF ed > 2oC, THEN SEND MAINTENANCE CONCERN
IF er > 30sec OR er > er (average) +30%, THEN SEND MAINTENANCE CONCERN
For the rectifier:
IF ediode > 0, THEN SEND MAINTENANCE CONCERN
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For the high speed circuit breaker:
IF ee > 3500J, THE SEND MAINTENANCE CONCERN
7.6 Summary on fuzzy logic During the development of a software program to aid in the decision making of the
maintenance engineer, the information in the data base on the all the conditions monitored,
must be compared to evaluate the rate of change in any of them. An abnormal rate will cause
an alarm to the engineer, who will be able to react.
If this strategy is followed, the system will be an intelligent tool that has the capability of
training itself. The more information in the database to compare, the higher the accuracy of
the system. It is not necessary to have accurate engineering limits and to program these into
the program. Even the rate of change, as defined in the chapter for each piece equipment,
will be calculated as the system evolves by adding data to its intelligence.
The theory is that if a specific piece of equipment nears the end of its operational life, the rate
of change will increase enough for the program to pick it up and send an alarm for urgent
replacement or repair.
This is not really a new theory. The historical bathtub curve already indicated this
characteristic of electrical equipment.
Figure 7.2 : Typical failure-rate curve (Benjamin S. Blanchard, Systems Engineering and
Analysis, 1981).
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The theory that the rate of change increases near the end of life, is also reflected in figure 7.2
where the probability of failure is presented. Maybe a co-incidence? Further development in
condition monitoring equipment and the availability of more data will enable the maintenance
engineer to test this theory with greater accuracy.
7.7 Vibration measurement as an alternative. 7.7.1 Introduction The use of vibration testing is used almost every day in normal life activities. Thumping a
watermelon to assess the ripeness by the sounds or vibration coming from it is but one
example. [49]
An interesting theory that was researched and experimented with, was to monitor the
vibration of a traction transformer. If a huge number of similar transformers could be
compared and a typical wave form for the vibration determined, then any substantial variance
from that could be an indication of latent defects. [50][51]
During the study, a accelerometer was used to provide input to a digital scope meter. This is
very basic equipment with a limited degree of accuracy. After the analysis of six similar
transformers a typical waveform could be determined.
The specifications for the accelerometer is shown below:
Range Velocity 200m/s2 : 0.5 to 199.9 m/s2
Acceleration 200m/s2 : 0.5 to 199.9 m/s2 Frequency range 10Hz to 1kHz
Accuracy ± (5% + 2d) reading, 160Hz, 80Hz. @ 23 ± 5oC
Three measurements were taken for each transformer at different places to determine the
typical waveform for that specific transformer.
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7.7.2 Basic vibration theory. The analysis of time waveform data is not a new technique. In earlier days of vibration
analysis the data was viewed on oscilloscopes and the frequency components calculated by
hand. According to Timothy A Dunton, time waveform analysis can be used for any vibration
problem. [47]
He wrote that the key to successful analysis of time waveform data is in the setup of the
instrument. The following elements have to be considered when setting up the instrument.
o Unit of measurement
o Time period sampled
o Resolution
Amplitude measurements units should be generally selected based on the frequency of
interest. Waveform data can be taken using displacement, velocity or acceleration. During
the tests performed on the transformers, acceleration was used. This emphasized the higher
waveform frequencies that were present in the vibration signal. [47][49]
The instrument used was set up to capture a time period of approximately 0.1 seconds. This
allowed for at least 4 cycles to be captured. This function was limited on the scopemeter that
was used to capture the data due to the fact that it only captured the display data that was
present on the screen of the meter.
The resolution of the meter was high enough to capture important events I the cycle.
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7.7.3 Test results
The waveform shown in figure 7.3 was taken at a 3kV DC substation.
Figure 7.3: Typical time waveform for a traction transformer
When observing a waveform it is important to look at the symmetry above and below the
centerline axis. This indicates that the motion inside the transformer is even.
It was important to observe a repetitive waveform to validate the accuracy of the data. Note
that the higher frequency component starts at the same point each time on the lower
component.
7.7.4 Summary on Vibration Theory
The use of time waveform analysis can be a valuable aid in condition assessment. This is a
typical example of where a increase in data can lead to more accurate analysis.
It was found that the basic high frequency components are always present. If this can be
determined by comparing a huge number of transformers to each other, a more accurate
waveform will be identified to analyse the measurements against.
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The identification of an abnormal condition will become increasingly easier. To be able to
identify the specific cause of the abnormal higher frequency component, it is important to
analyse faulty transformers in detail. The findings must be documented for future
comparisons.
Once the different irregularities are tied to specific causes of failure, it will allow the
maintenance engineer to take preventative action with greater assurance. Immediate action
can be taken without having to open the transformer to find the fault.
One of the great dis-advantages of this method is the amount of data that will be generated
and must be stored. A system must be developed where new data can be used to update the
existing wave profile for a normal transformer. Once the update was done, it can be
discarded after a period of time. It is important not to discard immediately, as this information
will still become necessary during analysis after failure occurred.
The amplitude of the waveform cannot be taken into account when analysing the data, as
this was found to change significantly during periods where current was drawn. It can,
however, be used to compare the change relative to the current that was drawn. As with the
comparison of the oil temperatures, any deviation of note from the normal can be used to
raise alarm with the maintenance engineer.
Constraint during this study was caused by a lack of funding to acquire instrumentation with
analysis capability. These are already available on the market and can be used with
immediate effect by a trained technician.
7.8 Summary Future business needs will dictate the urgency at which advancement into condition
assessment technology will take place. The use of fuzzy logic already makes it possible to
monitor certain parameters as discussed and provide advance warning when failure might
occur. Combining this information with maintenance history, the maintenance engineer can
plan his work with minimum disruptions on the performance of the system.
According to the definition of reliability, as discussed in chapter 3, the system will still
operated as expected, meaning that it will remain a reliable system even when shut down to
perform maintenance.
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8 CONCLUSION 8.1 Why sustainable condition monitoring When discussing condition monitoring and the subsequent predictive approach, the following
question comes to mind: what was first, the PM program or emergencies.
During this study, emergency work was analyzed to derive a model for visual inspections.
During a detailed failure mode, effect and criticality analysis this fault data was used to
determine the probability of failure for the equipment in question. The answer to this question
is therefore clear for this study. The need for a predictive approach was created by the high
cost of unscheduled maintenance.
During the study, one common problem was detected when interviewing maintenance
personele, specially the engineer responsible for managing the maintenance budgets. Too
many managers stated that there was no time for predictable maintenance since most of
their time was being consumed by emergency repair. Not only was their time wasted on
unscheduled maintenance, but also their money. And not just their money, but the lost in
production caused far greater losses, which is in most cases not easy to determine.
Most of these managers did, however, realized that if they had an effective and efficient
predictable maintenance plan, they would have had less emergencies. According to Micheal
Brown, 2003 [12][13], most companies can slowly but surely reap the gains of a PM program
by focusing their effort on the work rather than on the idea of a maintenance plan.
8.2 What are the obstacles that prevent sustainability?
The most common perception according to Brown [12], was that the predictable approach
had to be designed and sold from the top down in the company. The financial managers
imposed the requirement of a detailed cost versus benefit analysis on the total program
before it could be approved. The demand for justification is often dictated by the demand for
proof that such a program would work.
The advances in computer technology, according to Brown [12], can, if not implemented
carefully also become an obstacle to the implementation of the approach. Once the software
is approved and purchased at high cost, the drive for the initial data collection often
overshadows the predictable program.
145
Emergency work always has priority over planned work. If only the concept could be
understood that emergency work is the result of a lack of focus on planned or scheduled
maintenance.
During a survey done by the author under 100 staff members employed by Spoornet in the
technical maintenance environment, 85% resisted change because they believed in the
proven methods. They maintained that any change in the three important strategies would
cause serious reduction in reliability. These strategies, corrective, preventive maintenance
and replacement were used for all applications. [15]
A serious obstacle was found to be the reluctance off staff to complete the required
paperwork to enable the updating of the fault database. Analysis of data captured onto the
system by a typical maintenance depot showed two major problems, lack in consistency of
descriptions and incomplete information.
It was found that the system was to complex with to many possible variations on the
information required. The maintenance staff had to receive intensive training to understand
the information required, but due to the complex forms and administration involved to
complete the input into the database, they did not provide useful information.
The staff capturing this information was not competent to understand the complexity and,
when in doubt, used their own initiative to update the database. During a study, it was found
that out of 19 staff members country wide, only 2 had the relevant electrical experience to
capture the data and understand what they were doing. This was reflected in the accuracy of
the information that was captured by them onto the system. The ability to check the
correctness of the information did not exist and caused a corrupt database that did not really
provide any useful information.
146
8.3 How to implement a maintenance program.
The implementing of the program should be done step by step, starting at prioritizing the
work. Perform the FMECA to determine the equipment with high probability of failure and
frequent downtime.
Take only the top two or three pieces of equipment and attempt to identify the root cause of
the common failures. A good analysis of the work history can be a good indication of this. If a
lack of information is present, a good brainstorm between experienced staff can help solve
these issues. [2][3]
A maintenance program to focus on these root causes can then be drawn up to prevent it
from occurring.
In this study the top critical equipment was identified and analysed to determine the main
root causes of failure. This was then used to develop a condition assessment strategy for the
equipment. It is important to be able to look at the information and make decisions on the
maintenance requirements.
To enable the proper implementation of a predictable approach, teams must be set up with
two distinct responsibilities. One will react on faults and the other will focus on preventing
these faults from occurring. The maintenance engineer can schedule his teams as per figure
8.1 to allow for the opportunity to focus on predictable maintenance and reducing faults. Red
indicates the period for the team to focus on emergency work while the blue indicated the
focus period on scheduled maintenance.
One team will be responsible for all faults on three sections while the other two can focus on
pro-active maintenance. If this scheduling is strictly implemented and maintained over a
period of time, the number of faults should decrease, allowing for more time to do proper
maintenance.
147
Team A Team B Team C Week 1 Section 1
Section 2 Section 3
Week 2 Section 1 Section 2 Section 3
Week 3 Section 1 Section 2 Section 3
Week 4 Section 1 Section 2 Section 3
Week 5 Section 1 Section 2 Section 3
Week 6 Section 1 Section 2 Section 3
Figure 8.1 : Team scheduling
8.4 How to sustain the maintenance program. From the previous discussion, it is clear that the most important step that must be taken to
ensure sustainability is to reach an understanding between operations and maintenance.
This includes the following:
o Agree to a common goal for production efficiency.
o Focus on total reliability.
o Solve problems at the root cause without classifying it against departments.
o Include operators in basic inspection activities.
o Agree on priorities of work requests.
o Communicate production plans.
o Create a joint shutdown schedule.
The visual inspection process developed in this study can be used to train operators, such as
train drivers, platelayers and signal personele, to do the basic inspections required to create
a database on the condition of the substations.
With the right focus achieved in the relationship between the operator and the maintainer,
maintenance will not be seen as a service provider, but a deliverer of reliability.
148
The manager must learn to listen to these good performers and be able to downplay the
negative influence form the others.
The issue of staff competence and adequacy must be addressed. In the past policies were
written to ensure self-regulation by the railway company. These policies must be changed to
allow for external expertise to enter the market and assist where possible. The company
needs to allow itself to employ skills from external sources, and if necessary, from the
international pool of expertise. The tendency to employ people and train them to become
railway specific experts, must be limited to the really minimum.
The identification of tasks that can be performed by people with general electrical skills, will
enable outsourcing of those skills and reduce the staff risk inside the company. Only those
specialized maintenance task will be performed by skilled personele trained specifically for
that.
8.5 Objectives of this study
The objective of this study was to develop a predictive approach to maintenance of traction
substations for the South African conditions. An understanding into the working of a
substation was required to determine the process required.
The critical equipment in a substation was identified through a FMECA analysis. To
determine the condition of the substations a visual inspection process and a conditions
monitoring process was developed.
These were combined to draw up a program outline in fuzzy logic that will assist the
maintenance engineer when making his decisions.
8.6 Future study
The theory on vibration analysis was explored and must be developed in future. Expensive
equipment required to do initial test caused any such study to be halted for now.
The fuzzy logic outline can be used to write a program than can assist the maintenance
engineer on early warnings, decision making and record keeping. Such a program will
require extensive knowledge in database interfacing and programming.
149
The methodology that was used I this study can be implemented for any equipment, not just
electrical equipment. A future study in the general railway engineering will yield
unprecedented advantages to the industry in South Africa.
The depletion of experienced skills in South Africa must be studied. During this study it was
briefly discussed as a consideration in the visual inspections and the maintenance quality.
The development in sensor technology will make the implementation of the findings much
more cost effective. Ongoing study in the development must take place to take advantage of
any additions to the current ability.
8.7 Final word
Technology can be implemented to reduce the human factor in maintenance, but it will never
replace that input required for proper maintenance. The human maintenance manager must
still take the final decision to believe all the information available and to react.
It will always be a human that must go and do the work and be proud of what he or she did.
Although this study explored ways in reducing human objectivity when making maintenance
decisions, it also proofed that maintenance will always require an experienced input from
skilled staff members.
Recognition must be given to experience, to skills and to loyalty. This will serve as motivation
for the transfer of skills to new generation maintenance engineers.
The perception with South African people, that only a formal tertiary education can bring
success, must change. There will always be a place for skilled labor, artisans and
technicians in this maintenance world. This must start with the national government who
must provide enough financial backing to informal training institutions.
Structures outside the main railway company must be created to encourage an industry in
railways in South Africa. Railway experience should no longer be pinned to a specific group.
The national institutions, regulating the technical industry in South Africa must give
recognition to the railway industry and support growth in this challenging field.
150
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10 ANNEXURES 10.1 Substation Logbooks Vooruitsig Date Discription Code
13-Jun-01 Reset substation 2 13-Jun-01 Inspection 3 15-Jun-01 Inspection 3 18-Jun-01 Fill the oil on the OCB's 2 20-Jun-01 Inspection 3 17-Jul-01 Do testing on the OCB's oil 1 26-Jul-01 Site meeting Inspection 4
02-Aug-01 Do maintenance on the track breakers and batteries 1 15-Aug-01 Do maintenance on the transformer and the rectifier 1 17-Aug-01 Inspection 3 23-Aug-01 Inspection 3 31-Aug-01 Inspection 3 03-Sep-01 Take the work permit for private contractor 4 04-Sep-01 Assist private contractor 4 05-Sep-01 Reset substation 2 06-Sep-01 Inspection 3 06-Sep-01 Reset substation 2 07-Sep-01 Assist private contractor 4 13-Sep-01 Call out for low battery voltage 2 14-Sep-01 Call out for low battery voltage, all T/B's off load and eskom power failure 2 15-Sep-01 Refuel plant due to battery voltage low 2 15-Sep-01 Reset substation 2 04-Oct-01 Test W/F 1 10-Oct-01 Take the transformer oil sample with TSS 4 11-Oct-01 Do maintenance on the track breakers and batteries 1 17-Oct-01 Site meeting Inspection with HTSA 4 18-Oct-01 Do maintenance on substation 1 07-Nov-01 Do maintenance on the track breakers and batteries 1 15-Nov-01 Assist private contractor 4 20-Nov-01 Do maintenance on the transformer and the rectifier diodes 1 13-Dec-01 Do maintenance on the track breakers and batteries 1 14-Dec-01 Inspection 3 24-Dec-01 Inspection 3 29-Jan-02 Inspection 3 19-Feb-02 Do maintenance on the track breakers and batteries 1 25-Feb-02 Inspection 3 26-Feb-02 Do maintenance on the transformer and the rectifier 1 01-Mar-02 Inspection 3 13-Mar-02 Call out to faulty substation 2 10-Apr-02 Do repairs on track breaker B45 2 10-Apr-02 Inspection 3 11-Apr-02 Call out to substation 2 12-Apr-02 Do cleaning on Hipot track breakers 2
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15-Apr-02 Assist with substation maintenance 4 16-Apr-02 Replace track breaker at substation 2 19-Apr-02 Inspection 3 25-Apr-02 Do maintenance on the track breakers and batteries 1 25-Apr-02 Inspection 3
02-May-02 Fill in substation report book and clean substation yard 1 03-May-02 Inspection 3 10-May-02 Inspection 3 13-May-02 Do maintenance on the transformer and the rectifier 1 05-Jun-02 Do maintenance on the track breakers and batteries 1 06-Jun-02 Inspection 3 21-Jun-02 Inspection 3 25-Jun-02 Do maintenance on the transformer and the rectifier diodes 1 28-Jun-02 Inspection 3 04-Jul-02 Inspection 3 09-Jul-02 Do maintenance on the transformer and rectifier 1 12-Jul-02 Inspection 3 23-Jul-02 Do maintenance on the track breakers and batteries 1
01-Aug-02 Inspection 3 07-Aug-02 Do maintenance on the transformer and the rectifier 1 14-Aug-02 Do maintenance on the track breakers and batteries 1
1 Maintenance on substation 2 Callout or breakdown 3 Inspections 4 Other visits
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Heidelberg Date Discription Code
03-Aug-01 Inspection 3 16-Aug-01 Maintenance - schedule A + D 1 17-Aug-01 Inspection 3 31-Aug-01 Inspection 3 13-Sep-01 Call out to substation because breakers went on lock out 2 16-Sep-01 Call out to substation because telecontrol is not working 2 18-Sep-01 Call out to substation because telecontrol is not working 2 19-Sep-01 Check telecontrol 3 09-Oct-01 Maintenance - schedule A + D 1 10-Oct-01 Taking of transformeroil samples 4 15-Oct-01 Call out because train is standing 2 19-Oct-01 Inspection 3 22-Oct-01 Call out because of DC Earth leakage operation 2 25-Oct-01 Inspection 3 31-Oct-01 Call out to substation because telecontrol is not working 2 01-Nov-01 Call out to check trackbreakers 2 02-Nov-01 Call out to substation because telecontrol is not working and train was standing 2 03-Nov-01 Check if substation is still on load 3 06-Nov-01 Inspection 3 07-Nov-01 Call out to close track breaker because telecontrol is not working 2 08-Nov-01 Call out to close track breaker because telecontrol is not working 2 09-Nov-01 Check if substation is still on load and replace line card of telecontrol 2 12-Nov-01 Call out to check substation 2 12-Nov-01 Inspection 3 12-Nov-01 Call out to check substation because it is off load 2 16-Nov-01 Inspection 3 18-Nov-01 Call out to check substation because it is off load 2 29-Nov-01 Maintenance of track breakers, batteries and low voltage panels 1 30-Nov-01 Inspection 3 07-Dec-01 Inspection 3 11-Dec-01 Call out to check substation because it is off load 2 12-Dec-01 Maintenance of rectifier, maintransformer and OCB's 1 13-Dec-01 Call out to check substation because it is off load 2 16-Dec-01 Call out to check substation because it is off load and track breaker failed to close 2 18-Dec-01 Maintenance on track breakers 1 20-Dec-01 Collect substation information 4 21-Dec-01 Inspection 3 24-Dec-01 Inspection 3 27-Dec-01 Inspection 3 28-Dec-01 Do monthly readings 3 04-Jan-02 Inspection 3 06-Jan-02 Call out to check substation because it is off load 2 09-Jan-02 Work on telecontrol 1 10-Jan-02 Maintenance of track breakers, batteries and low voltage panels 1 11-Jan-02 Inspection 3 14-Jan-02 Inspection 3
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14-Jan-02 Call out for OCB. Replace no volt coil 2 18-Jan-02 Inspection 3 21-Jan-02 Inspection 3 22-Jan-02 Call out for OCB's. 2 25-Jan-02 Inspection 3 28-Jan-02 Inspection 3 01-Feb-02 Inspection 3 04-Feb-02 Call out to check substation because it is off load 2 08-Feb-02 Inspection 3 10-Feb-02 Inspection 3 15-Feb-02 Inspection 3 18-Feb-02 Maintenance of rectifier, maintransformer and OCB's 1 22-Feb-02 Inspection 3 25-Feb-02 Maintenance of track breakers, batteries and low voltage panels 1 28-Feb-02 Inspection 3 01-Mar-02 Inspection 3 05-Mar-02 Assist Escom in substation 4 08-Mar-02 Inspection 3 13-Mar-02 Maintenance on track breakers 1 15-Mar-02 Inspection 3 15-Apr-02 Maintenance of track breakers, batteries and low voltage panels 1 18-Apr-02 Inspection 3 19-Apr-02 Inspection 3 22-Apr-02 Take out permit for OHTE personel working outside 4 22-Apr-02 Call out for OCB's. 2 25-Apr-02 Inspection 3
02-May-02 Inspection 3 06-May-02 Maintenance of rectifier, maintransformer and OCB's 1 10-May-02 Inspection 3 15-May-02 Call out for OCB's. 2 16-May-02 Maintenance of track breakers, batteries and low voltage panels 1 17-May-02 Inspection 3 24-May-02 Inspection 3 29-May-02 Testing of diodes 1 31-May-02 Inspection 3 03-Jun-02 Inspection 3 07-Jun-02 Inspection 3 12-Jun-02 Maintenance of track breakers, batteries and low voltage panels 1 14-Jun-02 Inspection 3 21-Jun-02 Inspection 3 28-Jun-02 Inspection 3 05-Jul-02 Inspection 3 24-Jul-02 Inspection 3 25-Jul-02 Inspection 3
08-Aug-02 Inspection 3 14-Aug-02 Maintenance of track breakers, batteries and low voltage panels 1 16-Aug-02 Inspection 3
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Sprucewell Date Discription Code 02-Aug-01 Ajust OCB closing interlocks 1 08-Aug-01 Working in LT Panel 1 09-Aug-01 Complete Substation report 4 17-Aug-01 Inspection 3 21-Aug-01 Repair Telecontrol - PSU loose 2 22-Aug-01 Maintenance - schedule A + D 1 28-Aug-01 Unit off due to Escom failure 2 30-Aug-01 Check telecontrol and track breakers. Clean substation. 1 30-Aug-01 Inspection by Technical Supervisor. 3 31-Aug-01 Telecontrol is out. 2 31-Aug-01 Inspection and reading on substation 3 03-Sep-01 Repair Telecontrol - PSU (blackbox) faulty 2 10-Sep-01 Work on telecontrol cabinet. Control was advised that there is still a Transtel fault on the line 2 18-Sep-01 Telecontrol is out. 2 19-Sep-01 Telecontrol is out. 2 10-Oct-01 Take oilsamples with contractor of Main Transformer 4 12-Oct-01 Use substation phone to contact control 4 18-Oct-01 Voorsien noodvoedsel 4 19-Oct-01 Point out 6.6kV and 3kV cables 4 20-Oct-01 Track breaker fail to close 2 22-Oct-01 Maintenance - schedule B + C 1 24-Oct-01 Maintenance - schedule A + D 1 25-Oct-01 Inspection 3 05-Nov-01 Search for ladder and stagger guage but could not find any 4 06-Nov-01 Inspection 3 09-Nov-01 Inspection 3 12-Nov-01 Substation off laod 2 12-Nov-01 Inspection 3 14-Nov-01 Maintenance on Track breakers 1 16-Nov-01 Inspection 3 18-Nov-01 Check substation 3 30-Nov-01 Inspection 3 06-Dec-01 Maintenance on Main Transformer, Wavefilter equipment, rectifier and OCB's 1 07-Dec-01 Inspection 3 11-Dec-01 Call out to close track breaker 2 13-Dec-01 Inspection 1 20-Dec-01 Collect substation information 4 21-Dec-01 Inspection 3 24-Dec-01 Inspection 3 26-Dec-01 Call out to check substation 2 27-Dec-01 Inspection 3 28-Dec-01 Do monthly readings 1 31-Dec-01 Inspection 3 04-Jan-02 Inspection 3 07-Jan-02 Maintenance on Track breakers 1 11-Jan-02 Inspection 3
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14-Jan-02 Inspection 3 18-Jan-02 Inspection 3 20-Jan-02 Inspection 3 22-Jan-02 Call out for substation that is off laod 2 24-Jan-02 Maintenance on High voltage bays, OCB's and Maintransformer 1 25-Jan-02 Inspection 3 28-Jan-02 Inspection 3 01-Feb-02 Inspection 3 04-Feb-02 Replace fire extinguisher 4 08-Feb-02 Inspection 3 19-Feb-02 Maintenace on Trackbreakers, batteries amd low voltage panels 1 22-Feb-02 Inspection 3 01-Mar-02 Inspection 3 06-Mar-02 Maintenance to Track breakers, batteries and low voltage panels 1 08-Mar-02 Inspection 3 14-Mar-02 Busbar permit to do maintenance on busbars. 1 15-Mar-02 Inspection 3 18-Mar-02 Check functionality of interlocking keys 3 22-Mar-02 Inspection 3 28-Mar-02 Inspection 3 19-Apr-02 Inspection 3 25-Apr-02 Inspection of intruder alarm 2 25-Apr-02 Inspection 3
03-May-02 Inspection 3 09-May-02 Inspection 3 10-May-02 Inspection 3 13-May-02 Maintenance on Track breakers, batteries and low voltage panels 1 17-May-02 Inspection 3 27-May-02 Inspection 3 30-May-02 Testing of diodes 1 31-May-02 Inspection 3 03-Jun-02 Inspection 3 06-Jun-02 Maintenance on Track breakers, batteries and low voltage panels 1 07-Jun-02 Inspection 3 14-Jun-02 Inspection 3 20-Jun-02 Maintenance on High voltage bays, OCB's and Maintransformer 1 21-Jun-02 Inspection 3 28-Jun-02 Inspection 3 03-Jul-02 Remove substation plans for making of copies 4 05-Jul-02 Inspection 3 24-Jul-02 Inspection 3
05-Aug-02 Maintenance on Track breakers, batteries and low voltage panels 1 08-Aug-02 Inspection 3 08-Aug-02 Call out for Escom failure 2 12-Aug-02 Inspection 3 13-Aug-02 Maintenance on High voltage bays, OCB's and Maintransformer 1 13-Aug-02 Inspection 3 16-Aug-02 Inspection 3
160
Standerton Date Discription Code 03-Aug-01 Inspection 3 17-Aug-01 Inspection 3 20-Aug-01 Assist private contactors at substation 4 21-Aug-01 Assist private contactors at substation 4 22-Aug-01 Assist private contactors at substation 4 23-Aug-01 Assist private contactors at substation 4 23-Aug-01 Inspection 3 24-Aug-01 Assist private contactors at substation 4 24-Aug-01 Inspection 3 28-Aug-01 Inspection of track breakers 3 28-Aug-01 Take out busbar permit to disconnect faulty cable feeding to trackswitch 2 29-Aug-01 Do work on cable in High Voltage yard 2 30-Aug-01 Take out workspermit to find fault on cable 2 31-Aug-01 Take out workspermit to repair cable fault 2 01-Sep-01 Take basbar permit for repairs to 3kV DC cable 2 03-Sep-01 Assist in repairs 4 04-Sep-01 Take basbar permit for repairs to 3kV DC cable 2 05-Sep-01 Take basbar permit for repairs to 3kV DC cable 2 05-Sep-01 Do test work in substation 1 06-Sep-01 Work on the faulty cable 2 06-Sep-01 Assist in with cable permit 2 07-Sep-01 Do work on the feeder cable 2 10-Oct-01 Assist private contactors at substation 4 18-Oct-01 Work on faulty tele and T/B's 2 22-Oct-01 Work on the faulty tele 2 25-Oct-01 Inspection 3 09-Nov-01 Inspection 3 11-Nov-01 Do work in substation which was off load 1 20-Nov-01 Do work on substation 1 21-Nov-01 Replace batteries and switch T/B's locally 2 23-Nov-01 Inspection 3 12-Dec-01 Inspection 3 27-Dec-01 Replace silca gel to the transformer 1 04-Jan-02 Switch on one that failed to close 2 08-Jan-01 Inspection 3 31-Jan-02 Do task A and D in the substation 1 01-Feb-02 Do inspection and readings 3 08-Feb-02 Do inspection and readings 3 14-Feb-02 Do inspection and readings 3 22-Feb-02 Do inspection and readings 3 26-Feb-02 Do task B and C in the substation 1 26-Feb-02 Inspection 3 03-Mar-02 Do repairs on the burnt diodes bank 2 07-Mar-02 Do task A and D in the substation 1 08-Mar-02 Do inspection and readings 3 05-Apr-02 Do inspection and readings 3
161
12-Apr-02 Inspection 3 16-Apr-02 Do task A and D in the substation 1 19-Apr-02 Inspection 3 22-Apr-02 Do switching in the substation 4 22-Apr-02 Inspection 3 25-Apr-02 Inspection 3
03-May-02 Do inspection and readings 3 15-May-02 Do task A and D in the substation 1 17-May-02 Do inspection and readings 1 20-May-02 Do task B and C in the substation 1 24-May-02 Do inspection and readings 1 30-Jun-02 Calibrate and reclose tripped T/B 2 03-Jul-02 Service the T/B's 2 08-Jul-02 Calibrate the T/B's 2 09-Jul-02 Calibrate the T/B's 2 12-Jul-02 Inspection 3 18-Jul-02 Do inspection and readings 1 30-Jul-02 Take information at substation 4
16-Aug-02 Do inspection and readings 1 19-Aug-02 Service the T/B's and L-T panels 1
105
162
Perdekop Date Discription Code 05-Aug-01 Do inspection and readings 3 08-Aug-01 Phone control at substation 3 17-Aug-01 Do inspection and readings 3 21-Aug-01 Take 3kV permit out 1 21-Aug-01 Cancel 3kV permit 1 23-Aug-01 Take 3kV permit out 1 01-Oct-01 Take permit for the loose bolt on the transformer 2 02-Oct-01 Do task A and D at substation 1 03-Oct-01 Inspection 3 09-Oct-01 Fill substation report book 1 10-Oct-01 Assist private contractors at substation 4 19-Oct-01 Inspection 3 19-Oct-01 Call out for track breaker failing to close 2 24-Oct-01 Replace electronic closing relay 2 25-Oct-01 Inspection 3 28-Oct-01 Call out for track breaker failed to close 2 28-Oct-01 Assist in changing T/B B61 2 09-Nov-01 Inspection 3 15-Nov-01 Assist at substation 4 16-Nov-01 Inspection 3 06-Dec-01 Repair the tele box LMCU 2 07-Dec-01 Inspect and reset main overcurrent handle 2 12-Dec-01 Call out for faulty tele 2 13-Dec-01 Work on the tele box 2 13-Dec-01 Check tele box 3 19-Dec-01 Work on the tele box 2 29-Dec-01 Call out for track breaker which failed to close and replace latch card on the tele box 2 31-Dec-01 Call out for one unit and T/B B63 failed to close 2 07-Jan-02 Inspection 3 18-Jan-02 Call out for the substation off load 2 23-Jan-02 Check out substation 3 23-Jan-02 Inspection 3 29-Jan-02 Inspection 3 08-Feb-02 Inspection 3 22-Feb-02 Inspection 3 07-Mar-02 Do task A and D at substation 1 08-Mar-02 Inspection 3 13-Mar-02 Put substation on load 2 04-Apr-02 Inspection 3 12-Apr-02 Inspection 3 24-Apr-02 Inspection 3 25-Apr-02 Fill substation report book 1 29-Apr-02 Do task A and D at substation 1
02-May-02 Monitor substation 3 03-May-02 Inspection 3 17-May-02 Tele out of order and find T/B B62 off load 2
163
24-May-02 Inspection 3 31-May-02 Inspection 3 05-Jun-02 Inspection 3 06-Jun-02 Inspection 3 12-Jun-02 Phone control at substation 4 14-Jun-02 Inspection 3 19-Jun-02 Do task A and D at substation 1 26-Jun-02 Inspection 3 03-Jul-02 Do repairs to telecontrol 2
164
Beechwick Date Discription Code
15-May-01 inspection 3 21-May-01 Do maintenance on batteries and track breakers 1 26-May-01 Take work permit 1 28-May-01 Do maintenance on the transformer and the rectifier 1 15-Jun-01 inspection 3 20-Jun-01 Do maintenance on T/B's and batteries 1 20-Jul-01 Do reset at substation 2
06-Aug-01 Deliver material at substation 4 07-Aug-01 Do maintenance on T/B's and batteries 1 17-Aug-01 Inspection and do transformer leaks 1 20-Aug-01 Take work permit due to train standing 2 23-Aug-01 Inspection 3 22-Sep-01 Call out for substation off load 2 25-Sep-01 Do maintenance on track breakers 1 10-Oct-01 Take transformer oil sample with TSS 4 15-Nov-01 Do maintenance on track breakers and batteries 1 22-Nov-01 Do maintenance on the transformer and the rectifier 1 24-Jan-02 Inspection 3 29-Jan-02 Inspection 3 04-Feb-02 Do maintenance on the track breakers and batteries 1 01-Mar-02 Inspection 3 05-Mar-02 Do maintenance on the transformer and the rectifier 1 19-Apr-02 Inspection 3 24-Apr-02 Inspection 3 24-Apr-02 Replace phase failure relay at substation 2
09-May-02 Inspection 3 10-May-02 Inspection 3 20-May-02 Do maintenance on the transformer and the rectifier 1 06-Jun-02 Inspection 3 10-Jun-02 Inspection 3 11-Jun-02 Do maintenance on the transformer and the rectifier 1 18-Jun-02 Do maintenance on the track breakers and batteries 1 28-Jun-02 Inspection 3 03-Jul-02 Service the diode bank 1 10-Jul-02 Take the work permit and do repairs at substation 2 24-Jul-02 Take work permit to test the substation 4
01-Aug-02 Inspection 3
165
10.2 Substation Power Usage Sum of TOTAL-kwh DESCRIPTION MONTH BEECHWICK KRAAL PERDEKOP SPRUCEWELL STANDERTON VOORUITSIG 200104 160285 480800 551118 714440 103275 191314200105 159953 0 566083 817760 77150 187842200106 147659 501200 582476 243600 76390 185122200107 179516 226000 653772 241760 83615 248596200108 188317 233200 683976 418760 104765 240474200109 202121 226800 683751 1340440 83254 202590200110 223290 196800 724812 702520 83425 294292200111 195656 291600 693548 986440 101505 258995200112 169347 210000 619580 1134400 73710 212738200201 136443 218000 574512 704800 67470 213281200202 181297 203200 603543 797920 72585 326950200203 150422 207600 555864 892320 68765 250672
166
Sum of PEAK-kwh DESCRIPTION MONTH BEECHWICK KRAAL PERDEKOP SPRUCEWELL STANDERTON VOORUITSIG 200104 24207 62000 73404 100120 12430 28932200105 22647 0 74222 96240 7705 25688200106 24388 51200 89374 38480 10765 29713200107 25907 24000 85889 26200 8175 29591200108 30468 26000 109005 50240 12680 43462200109 32146 20800 108844 180440 11214 33063200110 33595 24800 95231 90600 8595 41739200111 26014 34800 93177 131000 10065 35176200112 25269 24800 87308 107440 9710 29200200201 20232 26000 81240 86520 8275 29745200202 28808 20800 88806 107880 9470 48038200203 21539 20000 76981 109000 8865 28272
167
Sum of STD-kwh DESCRIPTION MONTH BEECHWICK KRAAL PERDEKOP SPRUCEWELL STANDERTON VOORUITSIG 200104 53550 173200 186184 249160 34650 66467200105 51500 0 177906 281160 24000 57329200106 47969 204000 191653 89880 22090 57677200107 53621 76400 202307 87680 28330 81819200108 65597 74800 233463 137680 33635 81171200109 69994 78400 227631 469400 26723 65631200110 80211 63200 244751 253840 32215 97832200111 69307 83200 243940 355120 34495 98931200112 64253 71600 215251 636280 23605 84296200201 41194 56400 173368 246240 20815 63222200202 61164 70800 201475 299280 23545 96318200203 50221 73600 191142 405800 20935 85922
168
Sum of OFF-kwh DESCRIPTION MONTH BEECHWICK KRAAL PERDEKOP SPRUCEWELL STANDERTON VOORUITSIG 200104 82528 245600 291530 365160 56195 95915200105 85806 0 313955 440360 45445 104825200106 75302 246000 301449 115240 43535 97732200107 99988 125600 365576 127880 47110 137186200108 92252 132400 341508 230840 58450 115841200109 99981 127600 347276 690600 45317 103896200110 109484 108800 384830 358080 42615 154721200111 100335 173600 356431 500320 56945 124888200112 79825 113600 317021 390680 40395 99242200201 75017 135600 319904 372040 38380 120314200202 91325 111600 313262 390760 39570 182594200203 78662 114000 287741 377520 38965 136478
169
10.3 Substations Condition Assessments
170
171
10.4 Electrical Fault list Notifctn Notif.date Time Description FunctLocation Order MalfStrt Malf.end Malf.start MalfEnd Downtime
1000627305 04.04.2004 15:44:07 DLD SUB OFF LOAD C01-L035-UDLD 200797470 07:00:00 18:30:00 04.04.2004 04.04.2004 11.5
1000630771 18.04.2004 16:15:01 ALK SUB GCB L/OUT DU PLOOY PAGE 9790 C01-L030-UAMR 200847688 17:50:00 19:00:00 18.04.2004 18.04.2004 1.17
1000632526 23.04.2004 17:37:33 KU SUB L/OUT V RHYN PAGE 9803 C01-L044-UKU 200790859 17:45:00 23:50:00 22.04.2004 22.04.2004 6.08
1000635273 05.05.2004 05:29:09 TELE FAULTY,PALABORWA-OLIFANT A TRAIN IS C01-L065-UOLF 200790864 05:00:00 14:00:00 05.05.2004 05.05.2004 9
1000635573 05.05.2004 19:27:19 NO INDICATION ON T/B'S. STAFF TO RESET C01-L065-UBSG 200790867 19:40:00 21:30:00 05.05.2004 05.05.2004 1.83
1000636174 08.05.2004 06:51:42 SWITCHING FOR ESC AT PHALABORWA C01-L065-SPBA 200790879 07:45:00 16:00:00 08.05.2004 08.05.2004 8.25
1000639251 18.05.2004 12:57:58 KUDU SUB TELE OUT.HAZYVIEW SUB KEEPS TRI C01-L044-OKU2HZW 200847696 09:40:00 13:25:00 18.05.2004 18.05.2004 3.75
1000640498 21.05.2004 17:22:24 AKORNHOEK,B27 FAULTY,STAFF REPAIR C01-L044-UACH 200805150 11:12:00 15:30:00 21.05.2004 21.05.2004 4.3
1000643384 01.06.2004 22:41:02 WESTAFFIN-MAYFERN IN NELSPRUIT WERF C01-L0NL-ONST2NST 200805158 19:00:00 23:50:00 01.06.2004 01.06.2004 4.83
1000645179 07.06.2004 16:32:41 RIVULETTS U/B L/O C01-L030-URVR 200847699 07:15:08 12:00:40 06.06.2004 06.06.2004 4.76
1000645834 09.06.2004 13:51:09 ONDERVALLE B14 WEIER TOE C01-L030-SONV 13:53:34 00:00:00 09.06.2004 0
1000646344 10.06.2004 14:31:57 ONDERVALLE TELE OUT,B13+B14 FAIL TO R/C C01-L030-SONV 13:45:00 00:00:00 10.06.2004 0
1000646621 11.06.2004 10:33:12 NGODWANA RU FAIL C01-L030-SNGX 10:36:01 00:00:00 11.06.2004 0
1000648759 19.06.2004 16:35:33 WESTAFFEN UITGESLUIT C01-L030-UWFF 200847706 16:35:00 17:00:00 19.06.2004 19.06.2004 0.42
1000650633 27.06.2004 15:59:25 STAFF C/O TO SWITCH 11KV DUE ESC SHUT C01-L030-SNGX 200842646 07:20:00 09:40:00 27.06.2004 27.06.2004 2.33
1000651629 30.06.2004 21:18:18 WESTAFFIN SUB LOCKOUT. C01-L030-SWFF 200842641 19:10:00 21:00:00 30.06.2004 30.06.2004 1.83
1000655818 15.07.2004 23:29:24 IMPALA SUB L/O C01-L035-UMER 200847708 23:29:00 00:30:00 15.07.2004 16.07.2004 1.02
1000658107 24.07.2004 14:49:57 TELE AF LEGOGOTE-NUMBI-KUDU TREINE STAAN C01-L044-OLEG2NUM 200847660 14:49:00 17:00:00 24.07.2004 24.07.2004 2.18
1000658181 24.07.2004 19:41:39 LOW VOLTAGE ACORNHOEK-KLASERIE,STAFF C01-L044-SACH 19:15:00 00:00:00 24.07.2004 0
1000659121 28.07.2004 06:00:06 STAFF C/O TO SWITCH AT LEGOGOTE TO ISOLA C01-L044-OKOL2LEG 200871983 01:05:00 03:30:00 28.07.2004 28.07.2004 0
1000659503 29.07.2004 05:31:40 T/B B20 FAILS AT MKHUHLU.STAFF TO RECLOS C01-L044-UMUL 200847667 05:30:00 07:00:00 29.07.2004 29.07.2004 1.5
1000659725 29.07.2004 21:16:50 KAAP MUIDEN TIE L/OUT.STAFF C/O TO RESET C01-L034-SKM 200847669 21:16:00 22:30:00 29.07.2004 29.07.2004 1.23
1000660032 30.07.2004 18:06:10 WESTAFFIN RU LO C01-L030-UWFF 200847753 18:00:00 18:30:00 30.07.2004 30.07.2004 0.5
1000660177 31.07.2004 18:09:50 RIVULETS SUB L/O BATT BANK FAULTY STAFF C01-L030-SRVR 200842658 18:09:00 19:00:00 31.07.2004 31.07.2004 0.85
1000660336 02.08.2004 05:51:55 IMPALA SUB LO C01-L035-UIAL 200847751 05:51:00 06:30:00 02.08.2004 02.08.2004 0.65
1000663032 11.08.2004 07:54:44 NGODWANA 3KV SUB L/OUT.SCHLEICH CALLED C01-L030-SNGX 07:40:00 00:00:00 11.08.2004 0
1000667804 18.08.2004 16:47:05 WESTAFFIN L/O STAFF RESET C01-L030-UWFF 200842190 16:47:00 17:30:00 18.08.2004 18.08.2004 0
1000673349 02.09.2004 09:58:03 ESC OFF FROM KROKODIL TO MBUMBA,DUE TO C01-L044-UKU 09:18:00 00:00:00 02.09.2004 0
172
1000673365 02.09.2004 10:26:54 WATERVAL ONDER OCB, NO INDICATION C01-L030-SWVO 10:30:00 00:00:00 02.09.2004 0
1000673545 03.09.2004 05:14:41 ACORNHOEK SUB LOCKOUT. C01-L044-UACH 200842117 15:00:00 16:05:00 02.09.2004 02.09.2004 1.08
1000725114 13.09.2004 19:39:23 PALABORWA M/L45/5 DRAAD SPARK C01-L065-UPBA 200843811 20:15:00 21:00:00 13.09.2004 13.09.2004 0.75
1000769739 17.09.2004 08:46:16 AIRLIE SUB L/OUT,STAFF FOUND 11KV FUSE C01-L030-SARL 07:00:00 00:00:00 17.09.2004 0
1000769865 17.09.2004 17:31:47 AIRLIE SUB LOCKOUT. C01-L030-SARL 15:00:14 00:00:00 17.09.2004 0
1000770176 19.09.2004 18:03:53 BOULDERS SUB LOCKOUT. C01-L034-SBLD 19:26:34 00:00:00 18.09.2004 0
1000770211 20.09.2004 04:55:24 NUMBI BB05 FAIL. TELE FAULTY. LEGOGOTE C01-L044-UNUM 200908664 04:55:00 07:05:00 20.09.2004 20.09.2004 2.17
1000771786 23.09.2004 05:08:00 NUMBI BB05 FAIL. TELE FAULTY. LEGOGOTE C01-L044-UNUM 200908672 05:08:00 08:18:00 23.09.2004 23.09.2004 3.17
1000772153 24.09.2004 20:17:18 T/B'S TRIPPED MBUMBA--ROLLE,NO TRAINS IN C01-L044-URLE 200871992 08:00:00 12:15:00 27.09.2004 27.09.2004 4.25
1000772154 24.09.2004 20:23:49 TELE OUT NUMBI SUB.TRAIN STANDIN IN SECT C01-L044-OLEG2NUM 200908682 15:25:00 16:30:00 24.09.2004 24.09.2004 1.08
1000772440 26.09.2004 15:58:13 LEGOGOTE-NUMBI TREIN STAAN TELE AF C01-L044-UNUM 200908678 15:58:00 18:10:00 26.09.2004 26.09.2004 2.2
1000772455 26.09.2004 18:36:03 TELE OUT NUMBI SUB.TRAIN STANDIN IN SECT C01-L044-UNUM 200908692 20:55:00 23:00:00 24.09.2004 24.09.2004 2.08
1000772465 26.09.2004 19:09:02 TELE OUT NUMBI SUB.TRAIN STANDIN IN SECT C01-L044-UNUM 200908685 19:09:00 21:15:00 26.09.2004 26.09.2004 2.1
1000772641 27.09.2004 09:32:46 NUMDI TREIN STAAN C01-L044-OLEG2NUM 06:07:53 07:10:24 27.09.2004 27.09.2004 1.04
1000773665 29.09.2004 05:05:38 AIRLIE SUB L/OUT.STAFF C/O TO RESET. C01-L030-SARL 04:50:00 00:00:00 29.09.2004 0
1000774620 02.10.2004 06:16:56 AIRLIE SUB L/OUT.STAFF C/O TO RESET. C01-L030-SARL 06:17:24 00:00:00 02.10.2004 0
1000775209 04.10.2004 17:37:38 EWESTAFFIN SUB L/OUT.STAFF C/O TO RESET C01-L030-UWFF 200908718 17:10:00 18:30:00 04.10.2004 04.10.2004 1.33
1000776454 07.10.2004 16:40:02 NUMBI BB05 FAIL. TELE FAULTY. LEGOGOTE C01-L044-UNUM 200908272 16:30:00 18:00:00 07.10.2004 07.10.2004 1.5
1000776579 08.10.2004 05:15:33 WESTAFFINRU L/OUT.STAFF C/O TO RESET C01-L044-UNUM 200908285 15:00:00 15:30:00 08.10.2004 08.10.2004 0.5
1000777118 11.10.2004 04:55:07 ALKMAAR SUB LOCKOUT. C01-L030-UAMR 200908704 07:00:00 08:30:00 10.10.2004 10.10.2004 1.5
1000779488 16.10.2004 19:00:54 VIENA B41 FAILS TO RECLOSE,STAFF C/O TO C01-L065-UVIN 200871957 14:35:00 16:25:00 15.10.2004 15.10.2004 1.83
1000779632 17.10.2004 18:10:01 WESTAFFIN,OCB FAILS RECLOSE,STAFF TO R/C C01-L030-UWFF 200908731 06:00:00 06:30:00 17.10.2004 17.10.2004 0.5
1000779636 17.10.2004 18:19:41 MKHUHLU,OCB FAILS R/C.STAFF C/O TO RESET C01-L044-UMUL 200908737 15:45:00 18:00:00 17.10.2004 17.10.2004 2.25
1000781043 19.10.2004 15:35:32 GRANIETPOORT KARINO ESC FAIL. C01-L034-SGRP 12:48:18 00:00:00 19.10.2004 0
1000782838 25.10.2004 17:49:26 TELE OUT NUMBI,STAFF C/O TO RESET T/B'S C01-L044-UNUM 200908255 17:49:00 19:59:00 25.10.2004 25.10.2004 2.17
1000782918 26.10.2004 05:35:16 NUMBI 3KV FAIL. TELE UIT. C01-L044-UNUM 200908695 05:35:00 07:45:00 26.10.2004 26.10.2004 2.17
1000783736 26.10.2004 12:56:49 TELE OUT NUMBI,STAFF C/O TO RESET T/B'S C01-L044-UNUM 200908263 12:56:00 13:45:00 26.10.2004 26.10.2004 0.82
1000784471 28.10.2004 12:49:21 3LEGOGOTE CABLE BLOWN ON T/B B03 C01-L044-OLEG2NUM 200910112 07:30:00 16:00:00 25.10.2004 27.10.2004 56.5
1000785098 31.10.2004 16:37:24 WESTAFFIN SUB L/OUT,STAFF C/O TO RESET C01-L030-SWFF 07:00:00 10:00:00 30.10.2004 30.10.2004 3
1000785100 31.10.2004 16:44:47 WESTAFFIN SUB L/OUT,STAFF C/O TO RESET C01-L030-SWFF 12:00:00 14:30:00 30.10.2004 30.10.2004 2.5
1000788005 07.11.2004 14:25:57 TENBOSCH 3KV FAIL. TELE UIT. C01-L035-STCH 200932776 10:42:19 11:20:00 07.11.2004 07.11.2004 0.63
1000788180 08.11.2004 08:17:22 ACORNHOEK SUB TELE FAULTY. C01-L044-UACH 200908162 08:40:00 12:00:00 08.11.2004 08.11.2004 3.33
173
1000788728 08.11.2004 21:59:41 WESTAFFIN L/O C01-L030-SWFF 200932751 17:50:42 21:42:20 08.11.2004 08.11.2004 3.86
1000788732 08.11.2004 22:30:18 NGODWANA L/O C01-L030-UNGX 17:55:34 19:06:03 08.11.2004 08.11.2004 1.17
1000788758 09.11.2004 05:22:08 WESTAFFIN L/O C01-L030-UWFF 200932742 05:22:00 05:47:00 09.11.2004 09.11.2004 0.42
1000788982 09.11.2004 14:44:50 ALTHORPE SUB LOCKOUT. C01-L035-UALT 200889907 13:36:29 00:00:00 09.11.2004 0
1000790157 11.11.2004 04:43:17 IREACH SUB L.O C01-L044-UIRG 200905666 05:00:00 09:10:00 11.11.2004 11.11.2004 4.17
1000791215 13.11.2004 12:26:32 MBUMBA SUB L/O-ACORHOEK SUB TELE UIT C01-L044-UMUM 200932761 04:00:00 08:50:00 13.11.2004 13.11.2004 4.83
1000791219 13.11.2004 12:53:34 MBUMBA--TOT--NUMBE E.S.C 132KV AF C01-L044-SMUM 06:57:00 10:15:00 13.11.2004 13.11.2004 3.3
1000791239 13.11.2004 13:29:47 NUMBI+H/VIEW C01-L044-SNUM 200912494 13:29:00 15:39:00 13.11.2004 13.11.2004 2.17
1000791341 14.11.2004 13:09:38 WESTAFFIN SUB L/O C01-L030-SWFF 200912572 13:09:00 13:39:00 14.11.2004 14.11.2004 0.5
1000791484 14.11.2004 16:44:53 KROKIDIL SUB L/O C01-L044-SKOL 200912509 16:44:00 18:54:00 14.11.2004 14.11.2004 2.17
1000791559 15.11.2004 05:08:38 WATERVALBOVEN NOODWANA 3KV.FAIL. ESC C01-L030-SWTB 200932784 18:20:25 18:21:00 14.11.2004 14.11.2004 0.01
1000791581 15.11.2004 05:52:19 LEGOGOTE 3KV CABLE FAULT. TS.15 C01-L044-OKOL2LEG 200905453 21:30:01 00:30:00 14.11.2004 15.11.2004 3
1000791656 15.11.2004 09:10:35 TELE OUT,TRAINS STANDING,STAFF C/O IREAH C01-L044-UMUL 200932781 09:20:00 13:45:00 15.11.2004 15.11.2004 4.42
1000792070 15.11.2004 21:38:13 C01-L044-SACH 21:39:02 00:00:00 15.11.2004 0
1000792147 16.11.2004 06:19:21 ACORNHOEK OCB WEIERTOE C01-L044-SACH 200932767 06:00:00 08:41:41 16.11.2004 16.11.2004 2.69
1000792295 16.11.2004 10:16:50 MBUMBA- WEIER TOE.DC EARTH C01-L044-SMUM 08:46:18 10:31:47 16.11.2004 16.11.2004 1.76
1000792419 16.11.2004 15:13:44 MBUMBA- WEIER TOE.DC EARTH C01-L044-UMUM 200932796 08:45:00 10:10:00 16.11.2004 16.11.2004 1.42
1000792464 16.11.2004 16:17:27 LEGOGOTE-NUMBI TRAINS STANDING,W/P AT LE C01-L044-SLEG 200932788 13:39:00 15:35:00 16.11.2004 16.11.2004 1.93
1000793388 18.11.2004 23:32:32 LEGOGOTE 3KV CABLE FAULT. TS.15 C01-L044-OKOL2LEG 200932614 07:30:00 14:30:00 22.11.2004 25.11.2004 0
1000794031 21.11.2004 15:52:22 IREIGH SUB TELE OFF STAFF TO RESET C01-L044-UIRG 200932798 13:14:01 15:54:22 21.11.2004 21.11.2004 2.67
1000794096 21.11.2004 17:15:44 NGODDWANA SUB L/O C01-L030-SNGX 17:16:33 00:00:00 21.11.2004 0
1000795493 23.11.2004 05:29:57 REPORT OF SPARKS+ FLAMES IN RIVULETTS SU C01-L030-SRVR 01:25:00 03:00:00 23.11.2004 23.11.2004 1.58
1000796818 25.11.2004 15:44:50 L030-SNGX-Sub,L/OBatt-u b/loader tripped C01-L030-SNGX 200908155 18:00:00 20:00:00 08.11.2004 08.11.2004 2
1000798453 30.11.2004 13:02:17 TENBOSCH TRAINS ARE STANDING.STAFF C/O C01-L035-ODLD2TCH 200926020 13:15:00 15:30:00 30.11.2004 30.11.2004 2.25
1000798659 01.12.2004 05:34:51 NGODWANA ONTSPORING 1TROK C01-L030-ONGX2EK 200926028 05:20:00 07:20:00 01.12.2004 01.12.2004 2
1000798750 01.12.2004 10:04:10 KROKODIL 3KV FAIL. TELE UIT. (ROETS) C01-L044-UKOL 200932665 11:55:00 15:05:00 01.12.2004 01.12.2004 3.17
1000799063 01.12.2004 20:08:49 IREAH-ROLLE 3KV LAAG HERSTEL BREKERS C01-L044-URLE 200932672 20:10:00 21:15:00 01.12.2004 01.12.2004 1.08
1000799477 02.12.2004 23:53:11 MIRB -MKHUHLU 3KV AF C01-L044-UMUL 200926017 00:00:00 09:10:00 02.12.2004 03.12.2004 33.17
1000799656 03.12.2004 12:00:25 KROKODIL SUB L/OUT,STAFF C/O TO RESET C01-L044-SKOL 200925971 12:50:00 16:00:00 03.12.2004 03.12.2004 3.17
1000800050 04.12.2004 17:23:55 WESTAFFIN SUB L/OUT,STAFF C/O TO RESET C01-L030-SWFF 200925988 17:15:00 23:15:00 04.12.2004 04.12.2004 6
1000800213 05.12.2004 16:55:52 TELE OUT,REF283554,STAFF C/O TO RESET AL C01-L034-SKM 200926002 18:55:00 01:00:00 05.12.2004 06.12.2004 6.08
1000801193 07.12.2004 14:27:11 TELE OUT ACORNHOEK+KLASERIE,STAFF C/O C01-L044-SACH 200925911 08:30:00 10:00:00 07.12.2004 07.12.2004 1.5
174
1000801281 07.12.2004 17:58:53 KROKODIL TO MBUMBA ESC 132KV FAILED,STAF C01-L044-SMUL 200925951 18:45:00 23:50:00 07.12.2004 07.12.2004 5.08
1000801282 07.12.2004 18:03:04 LOW VOLTAGE NGODWANA STAFF TO RESET C01-L030-OARL2NGX 200934132 18:03:00 19:33:00 07.12.2004 07.12.2004 1.5
1000801822 09.12.2004 14:59:19 STAFF C/O TO IREAGH RELAY RM 110 OFF C01-L044-SIRG 200925981 18:24:00 19:05:00 03.12.2004 03.12.2004 0.68
1000801953 10.12.2004 08:22:08 PALABORWA-KLASERIE+ACORNHOEK TELE+3KVLAA C01-L044-UIRG 200927133 08:20:00 11:05:00 10.12.2004 10.12.2004 2.75
1000802495 13.12.2004 05:31:07 ACORNHOEK SUB L/OUT,STAFF C/OUT TO RESET C01-L044-UACH 200927136 09:35:00 10:00:00 13.12.2004 13.12.2004 0.42
1000802838 13.12.2004 16:05:34 KROKODIL SUB LOCKOUT. C01-L044-SKOL 200927124 14:15:04 17:15:00 13.12.2004 13.12.2004 3
1000803060 14.12.2004 10:19:39 ROLLE-HAZYVIEW TELE AF TREINE STAAN C01-L044-UHZW 200927129 10:00:00 11:10:00 14.12.2004 14.12.2004 1.17
1000803250 14.12.2004 15:34:03 KROKODIL L/O-LEGOGOTE TELE AF C01-L044-OKOL2LEG 200927095 07:30:00 12:30:00 15.12.2004 15.12.2004 5
1000803327 15.12.2004 05:03:15 TELE OUT WATER VAL BO,11KV TRIPPED,STAFF C01-L030-SWTB 200927119 18:45:00 21:00:00 14.12.2004 14.12.2004 2.25
1000804243 18.12.2004 17:00:03 RIVULETS MAYFERN 3KV FAIL. C01-L030-SRVR 200927088 16:40:00 20:10:00 18.12.2004 18.12.2004 3.5
1000804290 19.12.2004 12:40:08 PALMLOOP SUB LOCKOUT. C01-L065-UPLP 200927139 07:30:00 09:00:00 21.12.2004 21.12.2004 1.5
1000806342 27.12.2004 17:27:57 TELE OUT,KROKODIL SUB L/OUT C01-L044-SKOL 200931346 15:50:00 19:00:00 27.12.2004 27.12.2004 3.17
1000806525 28.12.2004 09:50:40 WESTAFFIN OCB L/OUT,STAFF C/O TO RESET C01-L030-OWFF2MYN 200931917 10:30:00 11:45:00 24.12.2004 24.12.2004 1.25
1000807659 02.01.2005 19:28:09 WESTAFFIN OCB L/OUT,STAFF C/O TO RESET C01-L030-OWFF2MYN 200931934 06:40:00 09:00:00 02.01.2005 02.01.2005 0
1000807662 02.01.2005 19:30:18 BRAKSPRUITBRUG TELE OUT/GVB COMPLAINS C01-L065-UBSG 200931943 06:45:00 09:45:00 02.01.2005 02.01.2005 3
1000807778 03.01.2005 07:44:50 LEGOGOTE SUB TELE UIT C01-L044-ULEG 200931941 07:50:00 14:10:00 03.01.2005 03.01.2005 6.33
1000808720 05.01.2005 04:16:15 HAZYVIEW SUB TRIPPED,TELE FAIL .STAFF R/ C01-L044-UHZW 200933930 18:00:00 20:55:00 04.01.2005 04.01.2005 2.92
1000808722 05.01.2005 04:25:56 KUDU SUB TELE OUT,STAFF FOUND SUB OFF C01-L044-UKU 200942292 20:55:00 23:30:00 04.01.2005 04.01.2005 2.58
1000809209 05.01.2005 16:40:45 KOMATIE WERF. TREINE STAAN C01-L035-GKTR 200933943 12:02:00 15:30:00 05.01.2005 05.01.2005 3.47
1000811202 11.01.2005 16:35:34 LEGOGOTE TELE FAULTY. C01-L044-ULEG 200934058 07:00:00 12:40:00 13.01.2005 13.01.2005 5.67
1000811297 12.01.2005 05:47:08 VIENA-BRAKSPRUIT 3V AF.COMMS REF300784 C01-L065-UPLP 200934064 20:25:00 20:50:00 11.01.2005 11.01.2005 0.42
1000813101 16.01.2005 15:44:11 WESTAFFIN RU FAIL TO CLOSE. C01-L030-SWFF 200933981 07:00:21 09:30:00 16.01.2005 16.01.2005 2.49
1000814400 17.01.2005 14:58:09 VIENA ACORNHOEK ATTEND TO TELE. C01-L065-UVIN 200942282 14:10:00 15:05:00 17.01.2005 17.01.2005 0.92
1000816485 23.01.2005 20:26:18 ELANDSHOEK RIVULETTS 3KV FAIL. BOOM OOR C01-L030-SEK 200940069 07:30:00 15:00:00 24.01.2005 24.01.2005 7.5
1000817464 25.01.2005 14:25:03 ALTHORPE SUB L/O C01-L035-OKM2ALT 200946191 17:00:10 10:49:52 24.01.2005 25.01.2005 17.83
1000817511 25.01.2005 16:17:33 BOULDERS3KV L/O+11KV V15 FAIL C01-L034-OBLD2KM 200945072 22:30:00 23:10:00 25.01.2005 25.01.2005 0
1000817537 25.01.2005 17:26:31 PALMLOOP-BRAKSPRUITBRUG LAE-SPAANING C01-L065-UPLP 200946218 11:00:00 13:45:00 26.01.2005 26.01.2005 2.75
1000817600 26.01.2005 05:05:46 KAAPMUIDEN 3KV FAIL. C01-L044-OKM2KOL 200946200 23:10:00 00:10:00 26.01.2005 27.01.2005 1
1000818311 28.01.2005 08:09:37 ONDERVALLE B16 FOULTY REPLACE ECR C01-L030-SONV 200945057 07:00:38 08:11:59 28.01.2005 28.01.2005 1.19
1000818607 29.01.2005 06:44:05 IMPALA SUB L/O C01-L035-SIAL 200946223 17:35:00 19:20:00 28.01.2005 28.01.2005 1.75
1000818613 29.01.2005 07:44:10 WATERVALBOVEN SUB L/O C01-L030-SWBW 200946229 07:30:00 10:00:00 29.01.2005 29.01.2005 2.5
1000818863 30.01.2005 17:59:57 PALMLOOP SUB L/O C01-L065-UPLP 200946221 18:34:00 19:55:00 29.01.2005 29.01.2005 1.35
175
1000824391 11.02.2005 23:21:28 KUDU NUMBI TELE UIT. 3KV FAIL. C01-L044-ONUM2KU 200951298 17:55:16 23:00:00 11.02.2005 11.02.2005 5.08
1000824459 12.02.2005 07:24:27 KUDU +NUMBI SUB L/O..TRANSTEL AF C01-L044-UNUM 200950932 11:25:00 14:10:00 11.02.2005 11.02.2005 2.75
1000824716 13.02.2005 18:34:53 LEGOGOTE KROKODIL 3KV. FAIL. TELE OUT. C01-L044-OLEG2NUM 200951307 18:12:35 23:15:00 13.02.2005 13.02.2005 5.04
1000825404 15.02.2005 08:26:47 KUDU-LEGOGOTE 3KV AF TELE AF C01-L044-UHZW 200951316 07:30:16 16:31:21 14.02.2005 14.02.2005 9.02
1000825847 16.02.2005 05:07:30 NUMBI TELE OUT. 3KV. FAIL. LEGOGOTE ESC C01-L044-SNUM 200955767 05:07:00 06:15:00 16.02.2005 16.02.2005 1.13
1000829365 24.02.2005 08:52:06 ALTHORPE RU FAIL TO CLOSE C01-L035-UALT 200964655 08:52:00 10:22:00 24.02.2005 24.02.2005 1.5
1000830426 25.02.2005 15:09:15 11KV AF WATERVAL BOVEN-NGODWANA C01-L030-UWTB 200979249 16:30:00 18:30:00 25.02.2005 25.02.2005 2
1000830708 26.02.2005 15:17:05 NUMBI B07 FAIL TO CLOSE. KUDU TELE OUT. C01-L044-SNUM 200964652 15:17:00 16:37:00 26.02.2005 26.02.2005 1.33
1000830751 26.02.2005 18:50:53 KUDU SUB L/O-HAZEYVIEW 3KV AF C01-L044-UKU 200964651 19:29:32 00:30:42 25.02.2005 26.02.2005 5.02
1000831329 28.02.2005 17:03:17 ALTHORPE SUB TELE AF C01-L035-SALT 200960648 17:03:00 18:33:00 28.02.2005 28.02.2005 1.5
1000831623 01.03.2005 12:34:23 BRAKSPRUITBRUG SUB .O.C.B. OOP C01-L065-UBSG 200960746 11:45:00 12:50:00 01.03.2005 01.03.2005 1.08
1000832558 03.03.2005 17:32:07 WATERVAL BOVEN SUB LOCKOUT. C01-L030-SWTB 200960642 17:30:00 18:00:00 03.03.2005 03.03.2005 0.5
1000833180 06.03.2005 15:51:48 IREAGH SUB L/O C01-L044-UIRG 200960656 07:20:00 09:45:00 04.03.2005 04.03.2005 2.42
1000833182 06.03.2005 16:00:47 WESTAFFIN SUB L/O C01-L030-SWFF 200960651 07:15:00 00:00:00 06.03.2005 0
1000835418 14.03.2005 13:04:10 HAZYVIEW B16 WEIER TOE. C01-L044-UHZW 200964624 08:15:00 11:10:00 14.03.2005 14.03.2005 2.92
1000835436 14.03.2005 14:13:44 OLIFANTS SUB NOINDICATION. POWER SUPPLY C01-L065-UPBA 200964607 11:10:00 13:50:00 14.03.2005 14.03.2005 2.67
1000836392 17.03.2005 14:37:13 GRANIETPOORT -KARINO 3KV AF C01-L030-OWFF2MYN 200964623 04:00:00 04:20:00 14.03.2005 14.03.2005 0.33
1000836804 19.03.2005 09:36:32 MBUMBA SUB LOCKOUT. C01-L044-UMUM 200964636 10:30:00 12:20:00 19.03.2005 19.03.2005 1.83
1000837229 22.03.2005 08:10:11 KLASERIE SUB LOCK OUT. B32 FAULTY. C01-L044-UKAX 200964641 08:00:00 10:40:00 20.03.2005 20.03.2005 2.67
1000837973 24.03.2005 15:53:09 HAZYVIEW RU OFF LOAD. B16 FAIL TO CLOSE. C01-L044-UHZW 200978961 15:40:35 16:13:00 24.03.2005 24.03.2005 0.54
1000837976 24.03.2005 16:17:43 VIENA SUB TELE UIT. C01-L065-UVIN 200978872 16:20:00 19:30:00 24.03.2005 24.03.2005 3.17
1000838314 27.03.2005 15:12:10 Telecontrol outstatioGRANIETPOORT RU L/O C01-L034-UGRP 200978901 17:00:00 23:30:00 27.03.2005 27.03.2005 6.5
1000839505 01.04.2005 08:09:10 WESTAFFIN SUB LOCK OUT. C01-L030-SWFF 200979250 07:30:00 10:00:00 01.04.2005 01.04.2005 2.5
1000839509 01.04.2005 08:15:23 HAZYVIEWVIENA 3KV FAIL. TELE OUT. C01-L065-SVIN 200978982 07:40:45 10:00:00 01.04.2005 01.04.2005 2.32
1000840912 06.04.2005 14:41:08 MKHUHLU SUB 3KV. CABLE FAULT. C01-L044-SMUL 200978995 07:22:00 16:10:00 07.04.2005 07.04.2005 8.8
1000841725 10.04.2005 15:08:36 VIENA BREKERS OOP C01-L065-UVIN 200979172 07:05:45 11:38:25 10.04.2005 10.04.2005 4.54
1000841906 11.04.2005 09:12:10 HAZEYVIEW SUB T/B16 F.T.C. C01-L044-SHZW 200979163 08:45:00 12:20:00 11.04.2005 11.04.2005 3.58
1000843501 16.04.2005 15:29:42 WATERVALBOVEN L/O C01-L030-UWTB 200979247 08:00:00 16:15:00 16.04.2005 16.04.2005 8.25
1000843692 18.04.2005 05:47:57 WESTAFFIN SUB /O C01-L034-OGRP2BLD 200978842 07:15:00 07:45:00 16.04.2005 16.04.2005 0.5
1000844706 20.04.2005 17:29:29 WESTAFFIN RU FAIL TO CLOSE. C01-L030-SWFF 200979248 14:00:00 16:50:00 20.04.2005 20.04.2005 2.83
1000844712 20.04.2005 17:51:23 DROOGLAND SUB LOCKOUT. LOW GAS. C01-L035-SDLD 200978850 16:30:00 19:45:00 20.04.2005 20.04.2005 3.25
1000845001 21.04.2005 14:22:17 OLIFANTS SUB B50 WEIER TOE. C01-L065-UOLF 200978803 13:32:59 15:08:00 21.04.2005 21.04.2005 1.58
176
1000847541 03.05.2005 10:43:53 LEGGOGOTE SUB TRF BUSCHING GEBREEK C01-L044-ULEG 200979242 08:50:00 14:00:00 28.04.2005 28.04.2005 5.17
1000849164 09.05.2005 16:09:30 HAZYVIEW MKHUHLU B16 AND B17 FAIL TO CL C01-L044-OHZW2MUL 201008116 14:23:55 15:15:00 09.05.2005 09.05.2005 0.85
1000849364 10.05.2005 15:36:56 WESTAFFIN B34 FAIL TO CLOSE. C01-L030-SWFF 200982541 14:00:00 16:30:00 10.05.2005 10.05.2005 2.5
1000851747 19.05.2005 14:42:58 LEGOGOTE SUB TELE UIT C01-L044-ULEG 200989801 07:40:00 11:30:00 19.05.2005 19.05.2005 3.83
1000851748 19.05.2005 14:45:53 HAZYVIEW SUB TB 14 F.T.C C01-L044-UHZW 200989806 11:30:00 13:15:00 19.05.2005 19.05.2005 1.75
1000852333 23.05.2005 05:55:34 ISOLEER VIR E.S.C BYTENBOCH C01-L035-STCH 200989733 09:09:00 14:20:00 22.05.2005 22.05.2005 5.18
1000852487 23.05.2005 12:33:33 IREAGH SUB LOCKOUT. C01-L044-UIRG 200989725 07:12:03 17:31:00 23.05.2005 23.05.2005 10.32
1000853706 27.05.2005 14:24:46 DROOGLAND SUB L/O C01-L035-UDLD 200989761 04:30:00 09:00:00 28.05.2005 28.05.2005 0
1000854227 30.05.2005 20:05:57 IMPALA LO C01-L035-UIAL 200989751 09:00:00 13:00:00 30.05.2005 30.05.2005 4
1000854863 01.06.2005 17:22:12 ALKMAAR SUB RU FAIL TO CLOSE. C01-L030-SAMR 200993899 17:12:40 18:36:00 01.06.2005 01.06.2005 1.39
1000855038 02.06.2005 14:21:02 WATERVAL BOVEN 3KV CABLE DAMAGED BY CONT C01-L0WB-OWTB2WTB 200991760 12:00:00 15:00:00 03.06.2005 03.06.2005 0
1000855439 04.06.2005 05:11:17 ALKMAAR SUB RU FAIL TO CLOSE. C01-L030-SAMR 200989745 04:30:40 05:04:00 04.06.2005 04.06.2005 0.56
1000855652 05.06.2005 19:04:15 DROOGLAND IMPALA 3KV. FAIL. C01-L035-SDLD 200989755 11:45:47 18:45:00 05.06.2005 05.06.2005 6.99
1000856630 08.06.2005 18:23:47 ALKMAAR EN WESTAFFIN RU FAIL TO CLOSE. C01-L030-SAMR 200993894 08:00:00 14:30:00 08.06.2005 08.06.2005 6.5
1000857376 11.06.2005 19:16:13 MACHADADOR-NGODWANE--E.S.C TOVOER AF C01-L030-UWTB 200992170 14:30:00 15:30:00 10.06.2005 10.06.2005 1
1000860579 24.06.2005 14:57:53 LEGOGOTE SUB RU OFF LOAD. C01 FAIL TO CL C01-L044-ULEG 200996836 14:05:00 15:50:00 24.06.2005 24.06.2005 1.75
1000860879 26.06.2005 17:15:18 KROKODIL--LEGGOTE E.SC. AF C01-L044-ULEG 200996832 13:10:00 16:47:00 26.06.2005 26.06.2005 3.62
1000860906 26.06.2005 21:52:45 WESTAFFIN TB.34 AND TB.35 FAIL TO CLOSE. C01-L030-OWFF2MYN 201003794 20:56:51 21:18:00 26.06.2005 26.06.2005 0.35
1000861473 29.06.2005 07:31:00 MAYFERN SUB L/O C01-L034-OMYN2KNO 201003789 18:06:00 19:45:00 28.06.2005 28.06.2005 1.65
1000862001 30.06.2005 20:53:48 KARINO SUB LOCKOUT. C01-L034-OKNO2GRP 201003811 18:04:13 20:15:00 30.06.2005 30.06.2005 2.18
1000865950 18.07.2005 05:01:22 MAYFERN WESTAFFIN 3KV FAIL. NO TRANSTEL C01-L030-OWFF2MYN 201008016 00:03:12 00:42:00 18.07.2005 18.07.2005 0.65
1000867515 23.07.2005 16:31:31 WESTAFFIN RU L/O BB UNSURE C01-L030-UWFF 201009377 10:00:00 15:00:00 24.07.2005 24.07.2005 5
1000869380 31.07.2005 19:17:23 11KV IMPALA TELE C01-L035-HIAL2KTR 201009365 21:06:29 02:27:47 30.07.2005 31.07.2005 5.36
1000869382 31.07.2005 19:23:22 PALMLOOP-VIENNA TELE AF RESET TOERUSTING C01-L065-UPLP 201009380 06:26:04 11:42:25 31.07.2005 31.07.2005 5.27
1000869721 02.08.2005 06:01:00 NGODWANA-KARINO-GRANIETPOORT TELE C01-L034-UKNO 201026880 07:50:00 12:35:00 02.08.2005 02.08.2005 4.75
1000869751 02.08.2005 08:22:06 ELANDSHOEK 20M NEG RETURN STOLEN. C01-L030-OEK2RVR 201009844 08:00:25 15:00:00 20.07.2005 20.07.2005 6.99
1000870755 06.08.2005 06:09:46 NGODWANE SUB LOCK OUT. C01-L030-ONGX2EK 201026890 16:41:24 17:47:00 05.08.2005 05.08.2005 1.09
1000871199 09.08.2005 05:41:31 ROLLE B23 FAIL TO CLOSE. C01-L044-URLE 201026908 06:00:00 08:25:00 09.08.2005 09.08.2005 2.42
1000873627 20.08.2005 17:17:22 KARINO 3KV CABLE FAULT. C01-L034-OKNO2GRP 201026962 16:25:00 12:00:00 20.08.2005 22.08.2005 43.58
1000875790 30.08.2005 11:04:08 KLASERIE SUB NEG AF C01-L044-UKAX 201026958 08:10:00 13:00:00 02.09.2005 02.09.2005 4.83
1000875900 30.08.2005 17:55:56 ACORNHOEK B31 FAIL TO CLOSE C01-L044-UACH 17:50:56 00:00:00 30.08.2005 0
1000878031 08.09.2005 17:34:16 WESTAFFIN SUB LOCKOUT. C01-L030-SWFF 201034791 10:00:00 11:30:00 08.09.2005 08.09.2005 1.5
177
1000880326 18.09.2005 17:16:57 MBUMBA SUB L/O C01-L044-UMUM 201034807 15:10:00 17:35:00 18.09.2005 18.09.2005 2.42
1000880671 20.09.2005 07:15:15 ONDERVALLE TIE U,V FAULTY C01-L030-TONV 201034787 07:00:00 16:00:00 20.09.2005 20.09.2005 9
1000881387 23.09.2005 07:39:06 DRAKENSIG-VIENA 3KV LAAG C01-L044-UDRK 201050982 14:35:00 15:00:00 23.09.2005 23.09.2005 0
1000886223 11.10.2005 05:43:06 NUMBI SUB OFF LOAD. NO TELE. C01-L044-SNUM 05:00:39 00:00:00 11.10.2005 0
1000889013 20.10.2005 15:35:17 HOEDSPRUIT 11KV. SWITCHING. C01-L044-SHDT 201050998 07:37:44 07:59:00 20.10.2005 20.10.2005 0.35
1000890122 25.10.2005 07:37:33 NELSPRUIT 3KV. FAIL MAYFERN WESTAFFIN. C01-L034-SNST 201056289 06:01:00 07:01:00 25.10.2005 25.10.2005 1
1000891691 29.10.2005 05:59:53 WESTAFFIN SUB C01 FAIL TO CLOSE.(EDWARD) C01-L030-SWFF 201056272 16:29:00 17:39:00 28.10.2005 28.10.2005 1.17
1000891916 31.10.2005 04:43:25 IMPALA SUB OFF LOAD. TELE FAULTY.(EDWARD C01-L035-SIAL 201056242 16:29:00 19:01:00 28.10.2005 30.10.2005 50.53
1000892288 01.11.2005 04:47:32 WESTAFFIN SUB C01 FAIL TO CLOSE.(EDWARD) C01-L030-SWFF 201056227 20:51:00 21:52:00 31.10.2005 31.10.2005 1.02
1000892340 01.11.2005 07:59:03 LEGGOTE E.S.C. ISOLEER C01-L044-SLEG 201056308 12:40:00 16:35:00 31.10.2005 31.10.2005 3.92
1000893325 03.11.2005 17:27:16 WESTAFFIN SUB L/O C01-L030-SWFF 201055749 17:11:00 18:14:00 03.11.2005 03.11.2005 1.05
1000893327 03.11.2005 17:30:15 WATERVAL BOVEN SUB L/O C01-L030-SWTB 201064150 14:00:00 15:15:00 03.11.2005 03.11.2005 1.25
1000893642 04.11.2005 12:36:21 IMPALA TELE UIT KRAG LAAG C01-L035-SIAL 201065170 11:25:00 12:40:00 04.11.2005 04.11.2005 1.25
1000894013 05.11.2005 08:14:58 RIVULETS TELE OFF POWER LOW C01-L030-SRVR 201064119 07:00:00 11:00:00 06.11.2005 06.11.2005 4
1000894716 07.11.2005 13:55:40 MBUMBA 90M NEG CABLE STOLEN. OB153 ROL C01-L044-ORLE2MUM 201068149 12:00:00 16:10:00 07.11.2005 08.11.2005 28.17
1000895898 10.11.2005 06:51:11 IMPALA SUB LO NO TELE C01-L035-UIAL 201065159 08:40:00 10:20:00 08.11.2005 08.11.2005 1.67
1000895967 10.11.2005 08:27:47 KARINO SUB L ARRESERS FAILTY C01-L034-UKNO 201064059 07:29:00 15:15:00 05.11.2005 05.11.2005 7.77
1000896360 11.11.2005 12:06:24 DRAKENSIG SUB LOCK OUT. C01-L044-UDRK 201068965 09:50:00 12:45:00 11.11.2005 11.11.2005 2.92
1000896610 12.11.2005 19:24:26 OLPHANT-PHALABORWA KRAG LAAG C01-L065-UPLP 201068948 20:00:00 01:30:00 12.11.2005 13.11.2005 5.5
1000897101 14.11.2005 17:09:26 NGODWANA SUB OCB FAIL TO CLOSE. C01-L030-SNGX 201130182 16:00:00 17:45:00 14.11.2005 14.11.2005 1.75
1000898437 19.11.2005 05:29:16 WESTAFFIN OCB. FAIL TO CLOSE. (EDWARD) C01-L030-SWFF 201068081 16:50:20 18:15:00 18.11.2005 18.11.2005 1.41
1000898547 19.11.2005 12:36:41 WESTAFFINSUB L/O C01-L030-SWFF 201068012 12:15:00 15:25:00 19.11.2005 19.11.2005 3.17
1000899713 22.11.2005 17:14:04 WESTAFFINSUB L/O C01-L030-SWFF 201076781 16:11:00 16:40:00 22.11.2005 22.11.2005 0.48
1000899797 23.11.2005 05:07:06 9OLIFANTS PALMLOOP 3KV FAIL. NO TELE. C01-L065-UPLP 201082384 20:00:00 15:00:00 22.11.2005 23.11.2005 19
1000900280 24.11.2005 11:20:44 3KV NUMB1 TELE AF TREINE STAAN C01-L044-SNUM 201083289 10:54:00 14:20:00 24.11.2005 24.11.2005 3.43
1000901329 28.11.2005 08:10:35 PALMLOOP SUB BATT CHARGER FAULTY C01-L065-UPLP 201082381 11:30:00 13:00:00 25.11.2005 26.11.2005 25.5
1000901440 28.11.2005 13:02:58 ROLLE TELE UIT KRAG LAAG C01-L044-SRLE 201082353 13:00:00 18:00:00 28.11.2005 28.11.2005 5
1000902982 30.11.2005 17:04:19 NUMBI KRAG LAAG C01-L044-UNUM 201082362 18:00:00 19:30:00 30.11.2005 30.11.2005 1.5
1000903282 02.12.2005 04:51:13 KROKODIL--MBUMBA E.S.C LYN FOUT C01-L044-UKOL 19:10:00 00:00:00 01.12.2005 0
1000903287 02.12.2005 04:58:21 NUMBI SUBTELE AF SUB T/B OOP C01-L044-UNUM 201082358 05:20:00 07:55:00 02.12.2005 02.12.2005 2.58
1000903366 02.12.2005 12:04:50 HAZYVIEW TO PALMLOOP CHECK ALL SUBS. C01-L065-UPLP 201082366 09:20:00 14:30:00 02.12.2005 02.12.2005 5.17
1000903449 02.12.2005 17:30:29 HAZEYVIEW sub tele out .power low,reset C01-L065-UVIN 201082369 19:20:00 22:00:00 02.12.2005 02.12.2005 2.67
178
1000903474 02.12.2005 23:57:33 VIENNA TELE OUT RESET SUD C01-L065-UVIN 20:26:55 20:52:37 02.12.2005 02.12.2005 0.43
1000903948 05.12.2005 15:36:58 WATERVAL BOVEN ONDERVALLE 3KV FAIL. C01-L030-SWTB 201085876 10:00:00 11:15:00 05.12.2005 05.12.2005 1.25
1000905506 08.12.2005 04:58:29 KOMATIPOORTSUB L/O C01-L035-UKTR 201085885 07:00:00 16:30:00 08.12.2005 08.12.2005 9.5
1000906256 12.12.2005 05:08:11 WESTAFFIN SUB LOCKUT. C01-L030-SWFF 201098780 08:00:00 10:30:00 12.12.2005 12.12.2005 2.5
1000906707 13.12.2005 05:08:20 RIVULETTS TB.30 AND 31 FAIL TO CLOSE. C01-L030-SRVR 201098771 11:00:00 14:00:00 13.12.2005 13.12.2005 3
1000908395 18.12.2005 13:54:19 KOMATIPOORT SUB B68 ,B69 FAIL TO CLOSE. C01-L035-SKTR 201098733 08:00:00 14:00:00 16.12.2005 16.12.2005 6
1000908398 18.12.2005 14:12:53 KOMATIPOORT SUB LOCKOUT. C01-L035-UKTR 201085882 06:00:00 16:00:00 18.12.2005 18.12.2005 10
1000909414 20.12.2005 21:11:01 W/V/BOVEN SUB L/O C01-L030-GWTB 201098744 10:00:00 10:45:00 20.12.2005 20.12.2005 0.75
1000910065 24.12.2005 17:08:38 RIVULETS T/ OOP C01-L030-SRVR 201089234 16:25:00 18:39:00 24.12.2005 24.12.2005 2.23
1000910068 24.12.2005 17:17:19 BOVEN SUB L/O C01-L030-SWTB 201098790 09:00:00 10:15:00 24.12.2005 24.12.2005 1.25
1000911572 30.12.2005 16:33:59 WESTAFFIN RU LO C01-L030-UWFF 201089397 16:10:28 21:10:00 30.12.2005 30.12.2005 4.99
1000911732 31.12.2005 21:51:56 KOMATIPOORT RU FAIL TO CLOSE C01-L035-UKTR 201089403 21:43:00 01:52:00 31.12.2005 01.01.2006 4.15
1000911791 01.01.2006 19:40:41 PALMLOOP KRAG LAAG C01-L065-UPLP 201089352 19:40:00 03:20:00 01.01.2006 02.01.2006 7.67
1000911949 02.01.2006 21:10:29 WESTAFFIN SUB LO C01-L030-UWFF 201089366 21:11:00 22:21:00 02.01.2006 02.01.2006 1.17
1000912964 06.01.2006 11:37:10 PALMLOOP RU LOCKOUT. TELE OUT. C01-L065-UVIN 201091598 10:15:00 14:30:00 06.01.2006 06.01.2006 4.25
1000914804 12.01.2006 16:03:37 ROLLE 100M SUB NEG. STOLEN. OB.765 C01-L044-ORLE2MUM 201094169 07:22:00 16:10:00 13.01.2006 13.01.2006 8.8
1000915395 15.01.2006 16:10:01 MALELANE SUB RU FAIL TO CLOSE C01-L035-UMER 201091628 15:30:00 20:00:00 15.01.2006 15.01.2006 4.5
1000915439 15.01.2006 16:59:30 WATERVALBOVEN L/O C01-L030-UWTB 201091632 20:15:00 21:00:00 15.01.2006 15.01.2006 0.75
1000915749 16.01.2006 15:42:21 ALKMAAR 3KV SUB LO C01-L030-UAMR 201098403 08:00:00 14:00:00 16.12.2005 16.12.2005 6
1000917319 20.01.2006 05:06:21 PALMLOOP SUB LOCKOUT. C01-L065-UPLP 201095982 08:40:00 11:45:00 20.01.2006 20.01.2006 3.08
1000917644 21.01.2006 06:40:50 3KV KOMATIPOORT BREKERS WEIER TOE C01-L0KT-OKTR2KTR 201098229 11:15:00 14:15:00 21.01.2006 21.01.2006 3
1000917893 23.01.2006 05:28:10 SYCAMORE LO C01-L030-USYC 201098178 17:30:00 22:30:00 23.01.2006 23.01.2006 5
1000917895 23.01.2006 05:34:32 ROLLE KRAG IAAG C01-L044-URLE 201095969 08:45:00 11:10:00 23.01.2006 23.01.2006 2.42
1000919113 25.01.2006 05:38:06 TENBOSCH RU FAIL TO CLOSE C01-L035-UTCH 201098165 08:00:00 17:00:00 25.01.2006 25.01.2006 9
1000919114 25.01.2006 05:39:38 MKHUHLU RU FAIL TO CLOSE C01-L044-UMUL 201095960 05:40:56 10:30:00 25.01.2006 25.01.2006 4.82
1000919418 25.01.2006 16:21:28 SYCAMORE SUB LOCK OUT. C01-L030-SSYC 201098250 16:30:00 22:30:00 25.01.2006 25.01.2006 6
1000919796 26.01.2006 20:32:12 VIANNA B41 FAIL TO CLOSE C01-L065-UVIN 20:28:02 20:52:59 26.01.2006 26.01.2006 0.42
1000919939 27.01.2006 11:05:34 WESTAFFN ALKMAAR 3KV FAIL. B33 BURNT. C01-L030-SWFF 201098202 11:30:28 15:30:00 27.01.2006 27.01.2006 3.99
1000920391 29.01.2006 19:44:18 SYCAMRE SUB L/O C01-L030-SSYC 201098279 08:30:00 15:30:00 27.01.2006 27.01.2006 7
1000921998 02.02.2006 09:58:11 LEGOGOTE TELE UIT C01-L044-ULEG 201100071 12:35:00 18:00:00 31.01.2006 31.01.2006 5.42
1000922234 03.02.2006 07:32:56 SYCAMORE SUB FTC C01-L030-USYC 201099910 13:00:00 14:00:00 03.02.2006 03.02.2006 1
1000922236 03.02.2006 07:52:38 KOMATIPOORT BREKERS OOP C01-L035-UKTR 201099747 07:30:00 14:19:00 03.02.2006 03.02.2006 6.82
179
1000922572 04.02.2006 05:47:15 KARINO SWITCHING FOR ESC. MAYFERN TELE O C01-L034-SKNO 201099754 14:25:00 16:56:00 03.02.2006 03.02.2006 2.52
1000922573 04.02.2006 05:53:10 ELANDSHOEK SUB LOCKOUT. NGODWANA B25 C01-L030-SEK 201099971 15:30:00 21:00:00 03.02.2006 03.02.2006 5.5
1000922597 04.02.2006 10:22:05 MALELANE SU L/O C01-L035-UMER 201099852 10:14:00 19:05:00 04.02.2006 04.02.2006 8.85
1000922803 05.02.2006 17:17:12 3 KV NGODWANA L/O C01-L030-UNGX 201103907 17:17:01 18:00:00 05.02.2006 05.02.2006 0.72
1000922873 06.02.2006 04:46:35 WESTAFFIN ALKMAAR 3KV FAIL. NO TRANSTEL. C01-L030-SWFF 201099891 23:31:00 00:45:00 05.02.2006 06.02.2006 1.23
1000923366 07.02.2006 13:27:46 PALMLOOP SUB TELEF EN OC.B. OOP C01-L065-UPLP 201103853 09:40:00 13:40:00 07.02.2006 07.02.2006 4
1000924822 10.02.2006 16:25:51 ALKMAAR-WESTAFFEN TREINSTAAN C01-L030-OAMR2WFF 201103902 16:19:00 19:31:00 10.02.2006 10.02.2006 3.2
1000926427 13.02.2006 22:50:31 VIENNA RU FTC B41 C01-L065-UVIN 201105301 22:45:00 01:35:00 13.02.2006 14.02.2006 2.83
1000926665 14.02.2006 14:58:04 HOEDSPRUIT 11KV. SUB TELE FAULTY. C01-L044-SHDT 201105312 12:10:00 15:45:00 14.02.2006 14.02.2006 3.58
1000927096 15.02.2006 20:13:28 PALMLOOP B45 FAIL C01-L065-UPLP 201105281 19:45:00 23:45:00 15.02.2006 15.02.2006 4
1000927105 15.02.2006 20:27:33 MALELANE TREIN STAAN KRAG AF C01-L035-SMME 201105292 19:14:00 02:30:00 15.02.2006 16.02.2006 7.27
1000927108 15.02.2006 20:33:46 GRANIETPOORT KRAG LAAG C01-L034-UGRP 201115940 20:33:00 21:45:00 15.02.2006 15.02.2006 1.2
1000928149 20.02.2006 05:29:26 SYCAORE SUB L/O C01-L030-USYC 201108700 15:20:00 18:29:00 19.02.2006 19.02.2006 3.15
1000929394 22.02.2006 05:24:30 BROHAM- WESTAFIN SUBS L/O TELE AF C01-L030-OAMR2WFF 201108703 22:00:06 24:00:00 21.02.2006 21.02.2006 2
1000929407 22.02.2006 06:40:18 SYCAMORE SUB LO C01-L030-USYC 201110946 13:40:00 15:00:00 22.02.2006 22.02.2006 1.33
1000929408 22.02.2006 06:41:32 PALMLOOPTELE OUT RU OPEN C01-L065-UPLP 201110941 08:00:00 09:50:00 22.02.2006 22.02.2006 1.83
1000930080 24.02.2006 06:03:52 3kv DROOGLAND SUB L/O C01-L035-UDLD 201110918 06:00:00 07:25:00 24.02.2006 24.02.2006 1.42
1000930406 25.02.2006 11:49:01 LEGOGOTE KRAG LAAG C01-L044-ULEG 201110894 12:01:00 16:18:00 25.02.2006 25.02.2006 4.28
1000930631 26.02.2006 16:38:58 HAZEYVIEW-KUDU TELE AF C01-L044-UKU 201110968 08:40:00 10:45:00 26.02.2006 27.02.2006 26.08
1000930699 27.02.2006 05:02:37 KAAPMUIDEN 3KV.FAIL. KROKODIL B.01 OPEN. C01-L034-SKM 201108787 03:15:00 08:00:00 27.02.2006 27.02.2006 4.75
1000930795 27.02.2006 09:30:24 HOEDSPRUIT TELE OFF C01-L044-UHDT 201110974 08:20:00 19:30:00 27.02.2006 28.02.2006 35.17
1000931767 01.03.2006 10:22:08 MBUMBA B26 FTC C01-L044-UMUM 201110992 11:30:00 16:55:00 01.03.2006 01.03.2006 5.42
1000931772 01.03.2006 10:59:15 HECTORSPRUIT BONDS AF C01-L035-OIAL2DLD 201110940 16:30:00 16:00:00 24.02.2006 03.03.2006 167.5
1000932388 03.03.2006 12:28:01 palmloop sub OCB OOP C01-L065-UPLP 201110950 07:35:00 11:05:00 03.03.2006 03.03.2006 3.5
1000932621 04.03.2006 18:09:54 WATERVALBOVEN LO C01-L030-UWTB 201128007 18:15:00 19:15:00 04.03.2006 04.03.2006 1
1000935258 14.03.2006 14:58:48 ALTHORPE SUB SEVEN BATTERIES EXPLODED. S C01-L035-SALT 201127981 08:00:00 13:00:00 14.03.2006 14.03.2006 5
1000935610 15.03.2006 21:13:58 W/V/BOVEN SUB L/O C01-L030-SWTB 201127999 21:30:00 22:15:00 15.03.2006 15.03.2006 0.75
1000936552 16.03.2006 21:16:49 WESTAFFIN SUB O.C.B. L/O C01-L030-SWFF 201118231 21:10:00 00:15:00 16.03.2006 17.03.2006 3.08
1000936862 18.03.2006 06:09:57 WESTAFFIN +MAYFERN 3KV OFF C01-L034-ENST2MYN 201115965 00:50:00 04:10:58 18.03.2006 18.03.2006 3.35
1000937100 19.03.2006 16:30:08 C01-L030-SSYC 201118713 15:40:00 17:00:00 19.03.2006 19.03.2006 1.33
1000937405 20.03.2006 17:04:34 AIRLIE B23 FAIL TO CLOSE. C01-L030-SARL 201135410 17:04:00 18:46:00 20.03.2006 20.03.2006 1.7
1000937414 20.03.2006 17:18:21 WATERVAL BOVEN SUB LOCKOUT. C01-L030-SWTB 201125127 15:29:00 18:15:00 20.03.2006 20.03.2006 2.77
180
1000937911 22.03.2006 16:36:21 MAYFERN SUB OFF LOAD. NO TRANSTEL. C01-L034-SMYN 201118243 16:25:00 21:10:00 22.03.2006 22.03.2006 4.75
1000938015 23.03.2006 04:27:41 AIRLIE L/O C01-L030-UARL 201127980 07:00:00 12:30:00 23.03.2006 23.03.2006 5.5
1000939156 26.03.2006 16:25:17 PALMLOOP SUB L/O C01-L065-UPLP 201121662 13:00:00 15:25:00 24.03.2006 24.03.2006 2.42
1000939159 26.03.2006 16:31:56 PALMLOOP SUB L/O C01-L065-UPLP 201121678 13:20:00 17:30:00 26.03.2006 26.03.2006 4.17
1000939528 28.03.2006 04:45:05 WESTAFFIN SUB LOCKOUT. C01-L030-SWFF 201121869 21:05:00 21:20:00 27.03.2006 27.03.2006 0.25
1000939529 28.03.2006 04:49:16 NUMBI B07 AND KUDU B11 FAULTY. NO.1 LINE C01-L044-SNUM 201121874 21:20:00 04:45:00 27.03.2006 28.03.2006 7.42
1000939530 28.03.2006 04:52:54 WATERVAL BOVEN SUB LOCKOUT. C01-L030-SWTB 201127991 07:00:00 07:45:00 28.03.2006 28.03.2006 0.75
1000939811 29.03.2006 04:58:48 MAYFERN SUB OFF LOAD. NO TRANSTEL. C01-L034-SMYN 201125102 20:10:00 21:50:00 28.03.2006 28.03.2006 1.67
1000939814 29.03.2006 05:31:33 MAYFERN SUB OFF LOAD. NO TRANSTEL. C01-L034-SMYN 201125087 20:10:00 21:50:00 28.03.2006 28.03.2006 1.67
1000939825 29.03.2006 07:10:51 WESTAFFIN T/B OPEN C01-L030-SWFF 201125094 07:10:00 07:59:00 29.03.2006 29.03.2006 0.82
1000939876 29.03.2006 07:17:37 DROOGLAND SUB T/B OOP..TELE AF C01-L035-SDLD 201121772 01:55:00 11:11:00 29.03.2006 29.03.2006 9.27
1000940741 30.03.2006 04:56:33 MBUMBA SUB LOCKOUT C01-L044-UMUM 201125036 23:00:00 02:30:00 29.03.2006 30.03.2006 3.5
1000940757 30.03.2006 06:56:33 MBUMBA SUB FAIL TO CLOSE C01-L044-UMUM 201125050 08:00:00 12:30:00 30.03.2006 30.03.2006 4.5
1000941059 31.03.2006 04:14:59 PALMLOOP SUB LOCKOUT. C01-L065-UPLP 201125057 18:05:57 21:09:00 30.03.2006 30.03.2006 3.05
1000941740 03.04.2006 13:13:19 RIVULETS OFF LOAD CHARGER FAULTY C01-L030-URVR 201127979 12:30:00 15:30:00 03.04.2006 03.04.2006 3
1000942325 05.04.2006 05:13:49 WATERVAL BOVEN 3KV SUB L/O C01-L030-GWTB 201127988 06:00:00 06:45:00 05.04.2006 05.04.2006 0.75
1000942353 05.04.2006 06:40:44 RIVULETS OFF LOAD CHARGER FAULTY C01-L030-URVR 201128004 07:00:00 10:00:00 05.04.2006 05.04.2006 3
1000944362 10.04.2006 19:03:10 RIVULETS BREAKERS FAIL TO CLOSE C01-L030-URVR 201127676 18:49:00 20:57:00 10.04.2006 10.04.2006 2.13
1000944578 11.04.2006 14:20:51 PALMLOOP SUB LOCKOUT. C01-L065-UPLP 201129773 13:00:00 16:35:00 11.04.2006 11.04.2006 3.58
1000944672 11.04.2006 21:28:12 ALKMAAR SUB NEG STOLEN C01-L030-OAMR2WFF 201128015 21:00:00 22:40:00 11.04.2006 11.04.2006 1.67
1000945905 13.04.2006 15:40:04 KUDU SUB B13 FAIL TO CLOSE. C01-L044-UKU 201129944 08:10:00 13:05:00 13.04.2006 13.04.2006 4.92
1000945907 13.04.2006 15:44:49 HAZYVIEW TELE OUT. C01-L044-UHZW 201129937 13:05:00 13:45:00 13.04.2006 13.04.2006 0.67
1000945908 13.04.2006 15:46:42 PALMLOOP SUB LOCKOUT. C01-L065-UPLP 201129960 15:35:00 20:00:00 13.04.2006 13.04.2006 4.42
1000946041 14.04.2006 12:10:31 W/V/BOVEN SUB L/O C01-L030-GWTB 201135710 12:20:00 13:40:00 14.04.2006 14.04.2006 1.33
1000946042 14.04.2006 12:14:01 LEGOGOTE SUB T/B OOP C01-L044-SLEG 201127725 09:49:00 13:59:00 14.04.2006 14.04.2006 4.17
1000946121 15.04.2006 06:25:00 WATERVAL BOVEN SUB LOCKOUT. C01-L030-SWTB 201135728 07:00:00 07:30:00 14.04.2006 14.04.2006 0.5
1000946262 16.04.2006 16:00:36 W/V/BOVEN UB L/O C01-L030-GWTB 201135733 16:00:00 16:45:00 16.04.2006 16.04.2006 0.75
1000946427 17.04.2006 17:28:59 W/V/BOVEN SUB L/O C01-L0WB-YWTB 201135739 17:30:00 18:15:00 17.04.2006 17.04.2006 0.75
1000946511 18.04.2006 09:26:50 ACORNHOEK SUB NEG STOLEN C01-L044-UACH 201128028 13:20:00 16:30:00 06.04.2006 07.04.2006 27.17
1000946512 18.04.2006 09:33:57 HOEDSPRUIT SUB NEG STOLEN C01-L044-UHDT 201128021 08:00:00 15:10:00 07.04.2006 07.04.2006 7.17
1000946637 18.04.2006 14:09:50 PALMLOOP RU FTC C01-L065-UPLP 201129779 14:00:00 18:00:00 18.04.2006 18.04.2006 4
1000946718 18.04.2006 17:00:13 W/V/BOVEN SUB L/O C01-L030-UWTB 201130143 16:00:00 16:45:00 18.04.2006 18.04.2006 0.75
181
1000947724 20.04.2006 17:29:37 palmloop sub l/o C01-L065-UPLP 201132744 07:00:00 00:00:00 20.04.2006 0
1000948087 22.04.2006 08:50:02 PALMLOOP RU FTC C01-L065-UPLP 201132745 12:50:00 18:00:00 22.04.2006 22.04.2006 5.17
1000949896 27.04.2006 14:57:17 SYCAMORE SUB TELE OUT POWER LOW C01-L030-USYC 201132613 16:15:00 18:00:00 27.04.2006 27.04.2006 1.75
1000950273 29.04.2006 16:27:55 NGODWANA TB.25 FAIL TO CLOSE. C01-L030-SNGX 201132723 12:30:00 14:30:00 29.04.2006 29.04.2006 2
1000950275 29.04.2006 16:36:02 DROOGLAND TELE OUT. CHECK SUB. C01-L035-SDLD 201132733 14:30:00 18:00:00 29.04.2006 29.04.2006 3.5
1000950400 30.04.2006 18:39:31 PALMLOOP RU FTC C01-L065-UPLP 201149886 07:30:00 12:30:00 30.04.2006 30.04.2006 5
1000950431 01.05.2006 05:16:31 KOMATIEPOORT 3KV SUB LO C01-L035-UKTR 201132728 05:00:00 12:20:00 01.05.2006 01.05.2006 7.33
1000956136 17.05.2006 15:31:36 Sub lock out fan failure C01-L034-SMYN 201149990 15:40:10 18:00:00 16.05.2006 16.05.2006 2.33
1000956347 18.05.2006 11:40:00 HOEDSPRUITSUB L/O C01-L044-UHDT 201147528 16:30:00 00:00:00 18.05.2006 19.05.2006 7.5
1000956438 18.05.2006 17:31:54 OLIPHANT SUB TELE RU FTC C01-L065-UOLF 201149864 07:00:00 19:10:00 20.05.2006 20.05.2006 12.17
1000956924 21.05.2006 15:37:27 Droogland sub no indication C01-L035-SDLD 201147471 07:21:00 12:54:00 21.05.2006 21.05.2006 5.55
1000957143 22.05.2006 10:54:19 OLIFANTS SUB BATTERY CHARGER FAULTY. C01-L065-UOFT 201147696 07:00:00 19:10:00 20.05.2006 20.05.2006 12.17
1000957635 23.05.2006 13:50:16 BREAKER B85 TRIPED C01-L035-UMER 00:00:00 00:00:00 0
1000959771 29.05.2006 07:42:09 ROLLE SUB L/O C01-L044-URLE 201147737 07:20:00 13:25:00 29.05.2006 31.05.2006 54.08
1000960032 30.05.2006 08:39:50 IMPALA SUB T/B OOP C01-L035-SIAL 201147634 07:30:00 14:00:00 29.05.2006 29.05.2006 6.5
1000962294 04.06.2006 15:02:49 WATERVALBOVEN RU FAIL TO CLOSE C01-L030-UWTB 201147679 08:30:46 12:15:00 04.06.2006 04.06.2006 3.74
1000962891 06.06.2006 16:36:39 WATERVALBOVEN SUB LO C01-L030-UWTB 201149981 15:00:00 16:15:00 06.06.2006 06.06.2006 1.25
1000963221 07.06.2006 19:19:16 W/V/BOVEN T/B F.T.C. C01-L030-GWTB 201221273 19:30:00 20:15:00 07.07.2006 07.07.2006 0.75
1000964657 10.06.2006 01:36:35 IMPALA L/OMALELANEB61+DROOGLANDB64 C01-L035-UIAL 201147461 01:00:00 04:00:00 10.06.2006 10.06.2006 3
1000964658 10.06.2006 01:40:20 W/V/BOVEN SUB L/O R/C CUP C01-L030-UWTB 201147454 04:00:00 07:50:00 10.06.2006 10.06.2006 3.83
1000965485 13.06.2006 16:46:25 THEFT ARL C01-L030-SARL 201152681 08:00:00 15:30:00 14.06.2006 15.06.2006 31.5
1000967386 19.06.2006 13:19:33 W/V/ONDER EARTH WIRE STOLEN C01-L030-UWVO 201150047 10:00:00 16:30:00 20.06.2006 20.06.2006 6.5
1000969410 24.06.2006 10:31:34 NGODWANA RU FAIL TO CLOSE C01-L030-UNGX 201152467 10:18:00 12:14:00 24.06.2006 24.06.2006 1.93
1000969704 26.06.2006 10:33:31 ALHORPE L/O C01-L035-UALT 201155569 09:00:00 14:00:00 26.06.2006 26.06.2006 5
1000974602 10.07.2006 13:25:12 HAZEYVIEW SHUNTING IN YARD C01-L044-OKU2HZW 201162986 13:45:00 16:10:00 10.07.2006 10.07.2006 2.42
1000974739 11.07.2006 05:25:16 WATERVALBOVEN SUB L/O C01-L030-UWTB 201162935 20:25:08 23:30:00 10.07.2006 10.07.2006 3.08
1000975362 13.07.2006 08:15:00 ACORNHOEK NEG STOLEN C01-L044-UACH 201162847 08:00:00 18:30:00 13.07.2006 13.07.2006 10.5
1000976334 15.07.2006 01:51:18 NGODWANA C01-L030-OARL2NGX 201163212 02:15:00 04:15:00 15.07.2006 15.07.2006 2
1000976516 16.07.2006 06:52:43 W/V/ONDER+SYCAMOR+ALTHORPE SUBS L/O C01-L030-SWVO 06:57:02 18:00:00 15.07.2006 15.07.2006 11.05
1000976517 16.07.2006 07:08:22 W/V/ONDER+SYCAMOR+ALTHORPE SUBS L/O C01-L030-UNGX 201162857 13:00:00 15:15:00 15.07.2006 15.07.2006 2.25
1000976911 18.07.2006 03:25:00 ALTHORPE SUB LO C01-L035-UALT 201163215 01:00:00 04:30:00 18.07.2006 18.07.2006 3.5
1000976912 18.07.2006 03:29:13 HOEDSPRUIT RU L/O C01-L044-UHDT 201162840 03:30:00 05:40:00 18.07.2006 18.07.2006 2.17
182
1000977790 18.07.2006 19:06:17 W BOVEN SUB LO C01-L030-UWTB 201163231 11:00:00 11:45:00 18.07.2006 18.07.2006 0.75
1000978114 20.07.2006 06:25:01 WATERVAL BOVEN SUB LO C01-L030-SWTB 201163234 15:30:00 16:15:00 20.07.2006 20.07.2006 0.75
1000978257 20.07.2006 15:33:28 KAAPMUIDEN T/B,S FAIL TO CLOSE C01-L034-TKM 201163221 18:00:00 22:00:00 20.07.2006 20.07.2006 4
1000978264 20.07.2006 16:09:52 IREAGH KRAG BAIE LAAG C01-L044-SIRG 201162834 16:02:00 20:40:00 20.07.2006 20.07.2006 4.63
1000978367 21.07.2006 08:09:58 ELANDSHOEK SUB T/B'S TC C01-L030-OEK2RVR 201172342 08:00:00 12:00:00 28.07.2006 28.07.2006 4
1000978717 23.07.2006 10:04:54 MKHUHLU SUB OPEN TELE NOT WORKING C01-L044-SMUL 201162993 09:42:00 15:00:00 23.07.2006 23.07.2006 5.3
1000978721 23.07.2006 10:29:34 ISOLATE SUB FOR ESC C01-L044-UACH 201172362 09:10:00 17:40:00 23.07.2006 23.07.2006 8.5
1000978725 23.07.2006 10:41:35 WATER VALBOVEN SUB L/O C01-L030-SWTB 201163238 08:00:00 08:45:00 23.07.2006 23.07.2006 0.75
1000978861 24.07.2006 07:13:37 MBUMBA T/B'S FTC C01-L044-SMUM 06:28:00 11:47:03 24.07.2006 24.07.2006 5.32
1000979196 25.07.2006 08:16:04 PHALABORWA 11KV SHUTDOWN FOR ESC C01-L065-UPBA 201172337 07:20:00 07:50:00 23.07.2006 23.07.2006 0.5
1000979200 25.07.2006 08:42:31 PHALABORWA 3KV DC SUB SHUTDOWN FOR ESC C01-L065-UPBA 201172367 06:50:00 19:15:00 23.07.2006 23.07.2006 12.42
1000979210 25.07.2006 08:47:53 MBUMBA T/B'S FTC C01-L044-UMUM 201172354 11:10:00 16:30:00 24.07.2006 28.07.2006 101.33
1000980599 26.07.2006 15:19:24 ALTHORPE SUB RU L/O C01-L035-UALT 201172079 15:13:00 17:35:00 26.07.2006 26.07.2006 2.37
1000980703 27.07.2006 06:58:46 WATERVALBOVEN T/B 10 C01-L030-UWTB 201172401 09:00:00 10:10:00 27.07.2006 27.07.2006 1.17
1000982031 02.08.2006 07:45:49 ALTHORPE SUB LOCK-OUT C01-L035-UALT 201174307 07:30:00 12:00:00 02.08.2006 02.08.2006 4.5
1000982818 02.08.2006 15:20:06 W BOVEN T/B FAIL TO CLOSE C01-L030-UWTB 201174374 12:30:00 13:15:00 02.08.2006 02.08.2006 0.75
1000983065 03.08.2006 11:19:35 W BOVEN T/B FAIL TO CLOSE C01-L030-UWTB 201174385 11:00:00 11:45:00 03.08.2006 03.08.2006 0.75
1000985893 10.08.2006 13:41:47 WEG SWAAT VOERE LGK C01-L044-SMARB 00:00:00 00:00:00 0
1000986468 14.08.2006 07:07:37 RESET WATERVALBOVEN SUB C01-L030-UWTB 201180233 10:00:00 10:45:00 14.08.2006 14.08.2006 0.75
1000988402 17.08.2006 13:39:43 WATERVALBOVEN SUB RU EN T/B/S OPEN C01-L030-UWTB 201180239 13:20:00 14:15:00 17.08.2006 17.08.2006 0.92
1000988499 18.08.2006 02:38:28 WATERVALBOVEN SUB RU EN T/B/S OPEN C01-L030-UWTB 201180245 09:00:00 09:45:00 18.08.2006 18.08.2006 0.75
1000988992 20.08.2006 20:35:38 BOVEN SUB L/O C01-L030-GWTB 201198649 20:30:00 21:15:00 20.08.2006 20.08.2006 0.75
1000990236 23.08.2006 12:32:18 CP068/05:50(SRLE)TB/23 FTC C01-L044-URLE 201177076 05:50:00 07:20:00 23.08.2006 23.08.2006 1.5
1000990901 24.08.2006 16:59:06 CP073/1647(AMR)T/BREAKERS FAIL TO CLOSE C01-L030-UAMR 201179265 16:47:00 00:00:00 24.08.2006 0
1000991248 26.08.2006 06:31:13 CP076/06:27(SAMR) T/B'S FTC C01-L030-SAMR 201176978 06:27:00 09:00:00 28.08.2006 28.08.2006 2.55
1000993278 31.08.2006 15:25:22 CP085/1515ALTHORPE SUB L/O C01-L035-UALT 201180386 15:15:00 18:00:00 31.08.2006 31.08.2006 2.75
1000993820 04.09.2006 04:47:08 CP087/0020(NST)3KV DC OFF NST LOCO&YARD C01-L034-TNST 00:20:00 01:30:00 04.09.2006 04.09.2006 1.17
1000994307 05.09.2006 19:46:25 CP091/1918(IAL)T/B FAIL TOCLOSE C01-L035-UIAL 201185303 19:18:00 21:23:00 05.09.2006 05.09.2006 2.08
1000995961 08.09.2006 13:16:22 CP097/13:11(SKTR)RU FTC C01-L035-SKTR 201198691 13:20:00 18:30:00 08.09.2006 08.09.2006 5.17
1000996283 11.09.2006 04:22:47 CP101/0213WATERVAL ONDER RU TRIPED C01-L030-UWVO 201198680 05:00:00 06:30:40 11.09.2006 11.09.2006 1.51
1000996489 11.09.2006 18:18:05 CP102/1816ALTHORPE SUB LO C01-L035-UALT 201185295 18:11:00 21:10:00 11.09.2006 11.09.2006 2.98
1000996660 12.09.2006 13:30:16 CP105/13:22(SAMR)T/B'S 32&33 FTC C01-L030-SAMR 201197785 13:22:00 15:00:00 12.09.2006 12.09.2006 1.63
183
1000998289 15.09.2006 10:25:31 CP113/1015(SYC)SYCAMORE NO TELE C01-L030-USYC 201209667 08:00:00 09:15:00 15.09.2006 15.09.2006 1.25
1000998623 16.09.2006 13:13:42 CP115/1249(AMR)T/BREAKERS FAIL TO CLOSE C01-L030-UAMR 201185641 07:00:00 11:00:00 17.09.2006 17.09.2006 4
1000999156 19.09.2006 08:21:41 CP119/0530ALTHORP L/O C01-L035-UALT 201198753 08:30:00 12:00:00 19.09.2006 19.09.2006 3.5
1001000184 20.09.2006 12:22:19 CP122/12:19(SOFT)T/B 50 FAIL TO CLOSE C01-L065-UOLF 201195775 12:45:00 14:30:00 20.09.2006 20.09.2006 1.75
1001000483 21.09.2006 10:47:09 CP1241016HOEDSPRUIT RU FTC C01-L044-UHDT 201196232 06:55:20 14:25:00 27.09.2006 27.09.2006 7.49
1001000596 21.09.2006 15:10:07 CP124/1502(AMR)SUB LOCK-OUT C01-L030-UAMR 201209666 09:30:00 12:00:00 21.09.2006 21.09.2006 2.5
1001001228 24.09.2006 15:55:14 CP1291540WESTAFFEN LO C01-L030-UWFF 201196533 19:50:00 23:45:00 24.09.2006 24.09.2006 3.92
1001001229 24.09.2006 15:59:47 CP1291547 BRAKSPRUITBRUG RU LO C01-L065-UBSG 201196267 16:30:00 19:50:00 24.09.2006 24.09.2006 3.33
1001001271 25.09.2006 05:54:49 CP1291700ALTHORPE SUB L/O C01-L035-UALT 201196713 23:45:00 04:00:00 24.09.2006 25.09.2006 4.25
1001001913 27.09.2006 19:04:54 CP133/18:22(SALT)UNIT AND T/B'S LO FTC C01-L035-SALT 201198760 19:15:00 23:00:00 27.09.2006 27.09.2006 3.75
1001001926 28.09.2006 01:56:53 CP134/01:17(SIAL)RU AND T/B'S LO FTC C01-L035-SIAL 201198762 07:00:00 14:00:00 28.09.2006 28.09.2006 7
1001003480 02.10.2006 05:29:53 cp139/0116(WTB)T/B FAIL TO CLOSE C01-L030-UWTB 201198830 06:00:00 07:00:00 02.10.2006 02.10.2006 1
1001003695 02.10.2006 16:58:44 CP141/16:55(SAMR)T/B'S LO FTC OELOF C01-L030-SAMR 201196723 16:55:00 19:00:00 02.10.2006 02.10.2006 2.08
1001003748 02.10.2006 21:43:38 CP141/2128(WFF)SUB LOCK-OUT C01-L030-UWFF 201196737 21:28:00 23:15:00 02.10.2006 02.10.2006 1.78
1001003775 03.10.2006 02:57:19 CP141/0252(WTB)T/B FAIL TO CLOSE C01-L030-UWTB 201198789 12:00:00 13:00:00 03.10.2006 03.10.2006 1
1001004137 04.10.2006 09:58:15 CP144/07:51(SIAL)T/B LOCAL IND OELOF C01-L035-SIAL 201209643 07:50:00 09:50:00 04.10.2006 04.10.2006 2
1001005128 05.10.2006 17:08:46 CP149/1700ALKMAAR LO C01-L030-UAMR 201198796 15:00:00 17:20:00 05.10.2006 05.10.2006 2.33
1001005503 07.10.2006 09:48:38 CP153/09:42(SSYC)NO SUPPLY ON OHTE DAVID C01-L030-USYC 201198542 09:15:00 10:30:00 07.10.2006 07.10.2006 1.25
1001007409 11.10.2006 17:03:50 CP162/1600 ZMYN-SWFF SUBS OOP DAWID C01-L030-UWFF 201203366 17:10:00 19:30:00 11.10.2006 11.10.2006 2.33
1001007617 12.10.2006 12:15:45 CP166/1149(IAL)B63 FAIL TO CLOSE C01-L035-UIAL 201203373 12:20:00 15:00:00 12.10.2006 12.10.2006 2.67
1001008149 14.10.2006 14:52:18 CP171/0955(KU)ESC SWITCHING OPERATIONS C01-L044-UKU 201198742 09:55:00 16:30:00 14.10.2006 14.10.2006 6.58
1001008274 15.10.2006 15:16:35 CP174/1425(DLD)SUB OFF-LOAD C01-L035-OIAL2DLD 201203288 15:00:00 18:45:00 15.10.2006 15.10.2006 3.75
1001008386 16.10.2006 05:59:06 CP175/0547(AMR)SUB L/O C01-L030-UAMR 201198641 07:00:00 09:00:00 16.10.2006 16.10.2006 2
1001008613 16.10.2006 15:23:40 CP176/15:41(GWTB)RU TB'S OPEN FTC DAVID C01-L030-GWTB 201209662 13:30:10 14:15:00 16.10.2006 16.10.2006 0.75
1001008908 17.10.2006 15:26:15 CP178/1523(DLD)T/B FAIL TO CLOSE C01-L035-UDLD 201203343 15:33:00 18:10:00 17.10.2006 17.10.2006 2.62
1001009143 18.10.2006 13:42:06 CP180/13:10(GWTB)RU AND T/B'SFTC DAWID C01-L030-GWTB 201209658 15:40:00 16:30:00 18.10.2006 18.10.2006 0.83
1001009201 18.10.2006 15:40:00 CP180/15:38(SKAX)11 KV OF JOHANN C01-L044-UKAX 201203438 15:45:00 18:30:00 18.10.2006 18.10.2006 2.75
1001009453 19.10.2006 16:33:11 CP181/0814(HDT)RECTIFIER DIODES BLOWN C01-L044-UHDT 201203453 08:00:00 11:20:00 19.10.2006 19.10.2006 3.33
1001009883 21.10.2006 05:55:22 CP185/05:53(SRVR)T/B 30FTC DAWID C01-L030-SRVR 201203354 07:00:00 09:10:00 21.10.2006 21.10.2006 2.17
1001010038 22.10.2006 06:09:59 CP188/06:04(SNGX)RU OPEN FTC DAWID C01-L030-SNGX 201203400 07:00:10 08:45:00 22.10.2006 22.10.2006 1.75
1001010444 23.10.2006 16:02:46 CP192/1407(SYC)B21C/COIL FLASH OVER C01-L030-USYC 201209655 08:30:00 10:30:00 23.10.2006 23.10.2006 2
1001011666 25.10.2006 07:07:27 CP194/1526IMPALA SUB L/O C01-L035-UIAL 201221285 07:30:00 17:30:00 25.10.2006 25.10.2006 10
184
1001012308 26.10.2006 18:48:58 CP199/18:45(SSYC)RU LOCAL IND T/B 20 FTC C01-L030-SSYC 201221295 19:00:00 21:15:00 26.10.2006 26.10.2006 2.25
1001012366 26.10.2006 23:54:56 CP199/23:40(SAMR)11KV OF DAWID C01-L030-SAMR 201221290 23:50:00 01:30:00 26.10.2006 27.10.2006 1.67
1001012875 28.10.2006 22:59:38 CP003/2004(TCH)HOOK-UP KM 203/9-10 C01-L035-ODLD2TCH 201212176 20:15:00 03:30:00 28.10.2006 29.10.2006 7.25
1001012967 29.10.2006 14:56:21 CP005/14:50(GWTB)RU OPEN T/B'S FTC DAWID C01-L030-GWTB 201212035 15:00:00 15:45:00 29.10.2006 29.10.2006 0.75
1001014755 04.11.2006 08:08:14 CP021/08:02(GWTB)UNIT + T/B'S OPEN DAWID C01-L030-GWTB 201212311 07:30:00 08:15:00 04.11.2006 04.11.2006 0.75
1001014942 05.11.2006 19:11:57 CP025/1907NUMBI SUB LO C01-L044-UNUM 201212289 19:08:00 22:00:00 05.11.2006 05.11.2006 2.87
1001016586 07.11.2006 11:19:46 CP030/1118(WTB)T/B FAIL TO CLOSE OELOF C01-L030-UWTB 201222298 11:18:00 15:30:00 07.11.2006 07.11.2006 4.2
1001018070 11.11.2006 13:49:13 CP041/1304(RVR)B34 FAIL TO CLOSE DAVID C01-L030-URVR 201221269 14:00:00 16:30:00 11.11.2006 11.11.2006 2.5
1001018339 13.11.2006 05:16:36 CP041/1740 VIENA T/B F.T.C. ANDRE +OELOF C01-L065-UVIN 201222342 07:00:00 13:00:00 12.11.2006 12.11.2006 6
1001018372 13.11.2006 06:31:13 CP043/0538(KOL)SUB L/O J V RHYN C01-L044-UKOL 201222369 07:40:00 19:30:00 13.11.2006 13.11.2006 11.83
1001021455 16.11.2006 18:07:02 CP053/1759(KOL)NO TELE TO T/B OELOF C01-L044-UKOL 201222365 17:59:00 21:00:00 16.11.2006 16.11.2006 3.02
1001022792 21.11.2006 15:54:28 CP063/1554ALKMAARRU FAIL 6 DIODES GEBLAA C01-L030-UAMR 15:13:24 00:00:00 21.11.2006 0
1001025083 27.11.2006 19:53:41 CP075/1736(ALT)OCB L/O DAVID C01-L035-UALT 17:36:00 20:15:00 27.11.2006 27.11.2006 2.65
1001025939 30.11.2006 05:07:04 CP078/2334(WTB)T/B FAIL TO CLOSE DAVID C01-L030-UWTB 23:34:00 00:10:00 29.11.2006 30.11.2006 0.6
1001026309 01.12.2006 00:02:44 CP080/0001(AMR)NO TELE TO CLOSE T/B C01-L030-UAMR 00:01:00 14:22:00 01.12.2006 05.12.2006 110.35
1001026614 02.12.2006 07:23:28 CP083/15:28(SVIN)T/B'41 FTC JOHAN C01-L065-UVIN 201268112 18:00:00 21:50:00 01.12.2006 01.12.2006 3.83
1001026801 03.12.2006 10:21:36 CP088/10:06(SIAL)TB'63 FTC KOOS C01-L035-OIAL2DLD 201269413 10:00:00 13:00:00 03.12.2006 03.12.2006 3
1001027448 04.12.2006 09:09:37 CP083/21:47(SHDT) SUB L/O JOHAN C01-L044-UHDT 201268097 21:50:00 23:11:00 01.12.2006 01.12.2006 1.35
1001027476 04.12.2006 09:14:20 CP083/23:09(SDLD)SUB L/O JOHAN C01-L035-UDLD 201268320 05:45:00 21:30:00 05.12.2006 05.12.2006 15.75
1001027526 04.12.2006 09:19:44 CP083/02:00(SRVR)I/B'S FTC JOHAN C01-L030-URVR 201268326 02:50:00 06:55:00 02.12.2006 02.12.2006 4.08
1001027546 04.12.2006 09:22:34 CP083/02:25(SWFF) TB'S FTC JOHAN C01-L030-USYC 201268328 06:55:00 08:05:00 02.12.2006 02.12.2006 1.17
1001027566 04.12.2006 09:24:33 CP083/06:57(SWVO) SUB L/O JOHAN C01-L030-UWVO 201268329 05:30:00 18:00:00 04.12.2006 04.12.2006 12.5
1001028062 04.12.2006 16:46:09 CP090/1255 IMPALA--KOMATIE E.S.C. AF GE C01-L035-STCH 12:55:00 15:55:00 04.12.2006 04.12.2006 3
1001028826 05.12.2006 12:02:17 CP092/1158(MYN)NO TELE TO CLOSE T/B ROET C01-L034-UMYN 11:58:00 00:00:00 05.12.2006 0
1001029993 09.12.2006 06:17:33 CP099/0430 SWFF SUB L/O GEORGE C01-L030-OAMR2WFF 201268138 05:00:00 08:00:00 10.12.2006 10.12.2006 3
1001030018 09.12.2006 10:12:10 CP099/0817(KAX)OCB FAIL TO CLOSE JOHAN C01-L044-UKAX 201268511 08:55:00 11:00:00 09.12.2006 09.12.2006 2.08
1001030235 10.12.2006 14:59:39 CP100/0647(TCH)RECTFIER BURNT JOHAN C01-L035-UTCH 201237273 06:47:00 12:00:00 10.12.2006 11.12.2006 29.22
1001030237 10.12.2006 15:03:07 CP100/0718(RLE)SWITCHING FOR ESCOM JOHAN C01-L044-URLE 201268343 08:25:00 10:20:00 10.12.2006 10.12.2006 1.92
1001030239 10.12.2006 15:07:56 CP100/1155(KTR)NO TELE JOHAN C01-L035-UKTR 201268334 14:15:00 20:40:00 10.12.2006 10.12.2006 6.42
1001032619 16.12.2006 14:09:19 CP109/14:03(GWTB)SUB L/O JOHAN C01-L030-UWVO 201268100 16:00:00 22:10:00 16.12.2006 16.12.2006 6.17
1001033039 18.12.2006 11:09:07 CP107/16:11(SIAL)SUB LO GEORGE C01-L035-UIAL 201268305 05:30:00 16:00:00 15.12.2006 15.12.2006 10.5
1001033562 19.12.2006 15:06:04 E812912311(AMR)SUB L/O G ROETS C01-L030-UAMR 201233719 13:15:00 14:15:00 19.12.2006 19.12.2006 1
185
1001033743 20.12.2006 05:25:19 CP113/0500WATERVALBOVEN SUB L/O C01-L030-UWTB 201271360 06:30:00 11:40:00 20.12.2006 20.12.2006 5.17
1001034786 21.12.2006 12:47:03 CP118/1228(MYN)LOW POWER ROETS C01-L034-EMYN2KNO 12:28:00 12:56:00 21.12.2006 21.12.2006 0.47
1001034856 21.12.2006 16:20:52 CP118/1336(AMR)OCB FAIL TO CLOSE ROETS C01-L030-UAMR 201269479 13:45:00 14:45:00 21.12.2006 21.12.2006 1
1001036011 27.12.2006 14:24:20 CP122/0557(WTB)SUB L/O BATT U/V JOHAN C01-L030-UWTB 201268737 05:57:00 13:45:00 27.12.2006 27.12.2006 7.8
1001036021 27.12.2006 14:37:20 CP123/1029(NGX)T/B FAIL TO CLOSE JOHAN C01-L030-UNGX 201268727 10:15:00 12:20:00 27.12.2006 27.12.2006 2.08
1001036027 27.12.2006 14:43:21 CP123/1157(WVO)SUB L/O JOHAN C01-L030-UWVO 201268733 12:50:00 13:10:00 27.12.2006 27.12.2006 0.33
1001036037 27.12.2006 15:01:03 CP123/1119(SYC)SUB L/O JOHAN C01-L030-USYC 201268664 16:50:00 18:05:00 27.12.2006 27.12.2006 1.25
1001036040 27.12.2006 15:16:46 CP123/1207(DLD)T/B FAIL TO CLOSE JOHAN C01-L035-UDLD 12:07:00 15:11:00 27.12.2006 27.12.2006 3.07
1001036043 27.12.2006 15:23:16 CP123/1213(KTR)GCB FAIL TO CLOSE JOHAN C01-L035-UKTR 12:13:00 15:43:00 27.12.2006 27.12.2006 3.5
1001036086 27.12.2006 18:48:11 CP123/18:10(YWTB)SUB L/O JOHAN C01-L030-UWTB 201268770 18:05:00 20:00:00 27.12.2006 27.12.2006 1.92
1001036332 28.12.2006 14:06:41 CP124/0859(ALT)SUB L/O J V RHYN C01-L034-TKM 201268772 08:30:00 09:40:00 28.12.2006 28.12.2006 1.17
1001036416 28.12.2006 19:03:08 CP126/18:35(SDLD)TB'S FTC JOHAN C01-L035-UDLD 201268782 19:00:00 22:50:00 28.12.2006 28.12.2006 3.83
1001036624 29.12.2006 19:48:52 CP127/1311(KTR) NOTELE TO CLOSE T/B JOHA C01-L035-UKTR 201268793 13:40:00 14:25:00 29.12.2006 29.12.2006 0.75
1001036734 30.12.2006 13:02:02 CP128/13:00(SWFF)SUB L/O GEORGE C01-L030-UWFF 201269490 13:15:00 14:00:00 30.12.2006 30.12.2006 0.75
1001037288 03.01.2007 05:33:25 CP130/0524(AMR)OCB TRIP NO TELE DAVID C01-L030-UAMR 201268679 08:00:00 08:50:00 03.01.2007 03.01.2007 0.83
1001037308 03.01.2007 08:15:16 CP124/08:59(SALT)SUB L/O JOHAN C01-L035-UALT 201268775 09:40:00 10:35:00 28.12.2006 28.12.2006 0.92
1001037310 03.01.2007 08:19:05 CP126/18:40(SIAL)T/B 63 FTC JOHAN C01-L035-UIAL 201268651 15:40:00 17:20:00 29.12.2006 29.12.2006 1.67
1001037445 03.01.2007 21:10:49 CP131/1928(ALT)NO TELE TO CLOSE T/B OELO C01-L035-UALT 201268717 19:28:00 22:28:00 03.01.2007 03.01.2007 3
1001039676 12.01.2007 11:52:46 CP141/1039(WTB)SUB L/O DAVID C01-L030-UWTB 201271986 10:40:00 12:15:00 12.01.2007 12.01.2007 1.58
1001039819 13.01.2007 05:30:13 CP1410528TENBOSH SUB LO C01-L035-UTCH 201271546 10:00:00 14:40:00 13.01.2007 13.01.2007 0
1001040213 15.01.2007 08:02:18 CP144/0735(KU)NEG RETURN B/BAR BROKEN C01-L044-UKU 201268548 12:00:00 19:00:00 12.01.2007 12.01.2007 7
1001040262 15.01.2007 10:44:20 CP144/1037(TCH)SUB L/O C01-L035-UTCH 201271322 10:40:00 15:00:00 15.01.2007 15.01.2007 4.33
1001040367 15.01.2007 14:31:20 CP145/14:25(SRLE)RU FTC JOHAN C01-L044-URLE 201268554 07:30:00 17:00:00 18.01.2007 18.01.2007 9.5
1001040693 16.01.2007 17:08:42 CP146/1205(KTR)SUB L/O C01-L035-UKTR 201269585 11:00:00 20:00:00 16.01.2007 16.01.2007 9
1001040815 17.01.2007 08:23:39 CP147/0636(AMR)OCB L/O DAVID C01-L030-UAMR 201270904 07:30:00 10:00:00 17.01.2007 17.01.2007 2.5
1001040975 17.01.2007 17:24:04 T/B 11 FTC (GWTB) DAWID C01-L030-OSYC2ARL 201253795 02:30:00 10:30:00 19.01.2007 19.01.2007 8
1001041541 19.01.2007 20:21:05 CP153/20:18(SALT)SUB LO OELOF C01-L035-UALT 201268517 20:18:00 22:30:00 19.01.2007 19.01.2007 2.2
1001041783 21.01.2007 16:47:30 CP154/0700 SALT SUB L/O JOHAN C01-L035-UALT 201268596 07:50:00 15:15:00 20.01.2007 20.01.2007 7.42
1001042889 24.01.2007 19:49:40 CP164/19:06(GWTB)SUB LO DAWID C01-L030-GWTB 19:06:20 19:49:00 24.01.2007 24.01.2007 0.71
1001043289 26.01.2007 06:26:39 CP168/06:24(SRLE)T/B'S FTC JOHAN C01-L044-URLE 201270581 07:25:00 20:00:00 26.01.2007 26.01.2007 12.58
1001043487 26.01.2007 22:56:36 CP170/2255(WTB)SUB L/O DAVID C01-L030-UWTB 22:55:00 23:13:00 26.01.2007 26.01.2007 0.3
1001043654 27.01.2007 21:58:09 CP170/1727(WTB)SUB L/O OELOF C01-L030-UWTB 201268619 21:39:00 00:30:00 27.01.2007 28.01.2007 2.85
186
1001043655 27.01.2007 22:01:55 CP170/2139(WTB)SUB L/O OELOF C01-L030-UWTB 21:39:00 23:20:00 27.01.2007 27.01.2007 1.68
1001043824 28.01.2007 20:30:37 CP171/1920(TCH)PCB L/O OELOF C01-L035-UTCH 201270115 19:20:00 22:30:00 28.01.2007 28.01.2007 3.17
1001043898 29.01.2007 09:04:30 CP170/0554ROLLE SHUTDOWN FOR ESC C01-L044-URLE 201267824 16:30:00 21:30:00 28.01.2007 28.01.2007 5
1001044163 29.01.2007 20:35:56 CP173/1815(ALT)T/BREAKERS L/O OELOF C01-L035-UALT 201267952 18:15:00 20:30:00 29.01.2007 29.01.2007 2.25
1001044386 30.01.2007 09:49:02 CP174/09:43(GWTB)SUB LO DAWID C01-L030-UWTB 09:43:47 13:30:00 30.01.2007 30.01.2007 3.77
1001045036 01.02.2007 05:21:53 CP178/0518(TCH)PCB L/O DAVID C01-L035-UTCH 201272503 06:00:00 10:30:00 01.02.2007 01.02.2007 4.5
1001046466 06.02.2007 05:23:24 CP192/2301 ALTHRPE SUB L/O ELOF C01-L035-UALT 201269599 23:01:00 01:30:00 05.02.2007 06.02.2007 2.48
1001046919 07.02.2007 06:07:46 CP195/05:49(SWFF)SUB L/O DAWID C01-L030-UWFF 201272452 06:00:00 08:15:00 07.02.2007 07.02.2007 2.25
1001047075 07.02.2007 11:34:33 CP197?11:31(SARL)T/B 23 FTC DAWID C01-L030-UARL 201272445 11:40:00 13:00:00 07.02.2007 07.02.2007 1.33
1001047108 07.02.2007 13:10:48 CP197/13:03(SPBA)T/B51 FTC JOHAN C01-L065-UPBA 201267742 13:15:00 13:55:00 07.02.2007 07.02.2007 0.67
1001047380 08.02.2007 09:44:42 CP1990945AIRLIE SUB NEG STOLEN C01-L030-ONGX2EK 201256439 08:00:00 15:30:00 09.02.2007 09.02.2007 0
1001047940 09.02.2007 17:41:29 CP002/17:39(GWTB)SUB LO RU FTC DAWID C01-L030-UWTB 201272565 14:40:00 18:30:00 09.02.2007 09.02.2007 3.83
1001047989 10.02.2007 06:02:22 CP002/06:00(SAMR)T/B'S FTC DAWID C01-L030-ORVR2AMR 201268462 06:00:56 20:00:00 11.02.2007 11.02.2007 13.98
1001048672 13.02.2007 02:04:53 CP07/02:00(GWTB)SUB LO DAWID C01-L030-OWTB2ONV 201260814 02:45:00 12:00:00 13.02.2007 13.02.2007 9.25
1001049387 14.02.2007 16:09:29 CP0131407WATERVALBOVEN B08 BLOWN C01-L030-UWTB 14:07:19 16:12:38 14.02.2007 14.02.2007 2.09
1001049527 15.02.2007 08:36:11 CP012/1102 MBUMBA NEG LOOSE C01-L044-ULEG 201268493 12:30:00 13:30:00 14.02.2007 14.02.2007 1
1001050211 17.02.2007 13:36:48 CP017/074 W/V/BOVEN -MACHADO3KV OFF OELO C01-L030-UWTB 201268466 07:24:00 11:45:00 17.02.2007 17.02.2007 4.35
1001050505 19.02.2007 06:26:14 CP021/1630 RIVULETS T/B OOP C01-L030-SRVR 16:30:00 00:00:00 18.02.2007 0
1001050507 19.02.2007 06:40:44 CP021/1712 TENBOCSH SUB L/O C01-L035-STCH 201268470 17:12:00 22:00:00 18.02.2007 18.02.2007 4.8
1001051603 22.02.2007 16:15:15 CP030/0600(TCH)SUB L/O G ROETS C01-L035-UTCH 06:00:00 09:04:00 22.02.2007 22.02.2007 3.07
1001051698 23.02.2007 07:15:52 CP031/0800 W/V/BOVEN L/L FAULTY C01-L030-SWTB 08:00:00 00:00:00 22.02.2007 0
1001051974 23.02.2007 19:43:29 CP036/1509(TCH)OCB L/O DAVID C01-L035-UTCH 201272509 15:20:00 20:00:00 23.02.2007 23.02.2007 4.67
1001052231 25.02.2007 16:50:17 CP040/1100 ROLLE SUB E.S.C. SHUTDOWN C01-L044-UNUM 201267838 13:00:00 20:00:00 25.02.2007 25.02.2007 7
1001052233 25.02.2007 16:53:04 CP040/1330 IREAGH SUBT/B OOP C01-L044-UIRG 201267845 15:10:00 16:50:00 25.02.2007 25.02.2007 1.67
1001052805 27.02.2007 21:35:10 CP044/1915(TCH)PCB L/O AUX XFR AC FAIL C01-L035-OTCH2KTR 201272688 19:45:00 00:15:00 27.02.2007 28.02.2007 4.5
1001053442 02.03.2007 07:19:57 CP046/0749AIRLIE SUB L/O C01-L030-UARL 07:49:40 00:00:00 01.03.2007 0
1001053707 03.03.2007 09:11:24 CP0480843ACORNHOEK RU LO C01-L044-UACH 201267236 09:00:00 12:30:00 03.03.2007 03.03.2007 3.5
1001053884 04.03.2007 13:26:04 CP0500859ALTHORPE SWITCHING FOR ESC C01-L035-UALT 201269587 15:00:00 17:00:00 04.03.2007 04.03.2007 2
1001053892 04.03.2007 13:31:04 BRAKSPRUITBRUG RU LO C01-L065-UBSG 201267222 11:00:00 14:00:00 04.03.2007 04.03.2007 3
1001054315 05.03.2007 15:30:23 CP047/0734(MYN)NO TELE TO CLOSE T/B OELO C01-L034-UMYN 07:34:00 07:51:00 02.03.2007 02.03.2007 0.28
1001054556 06.03.2007 13:23:47 CP054/0744(WTB)SUB L/O DC/E/LEAKAGE DAVI C01-L030-UWTB 201272630 08:00:00 08:45:00 06.03.2007 06.03.2007 0.75
1001055159 08.03.2007 13:21:23 CP060/0540(MUL)THEFT C01-L044-UMUL 201267171 06:00:00 12:20:00 08.03.2007 08.03.2007 6.33
187
1001055728 11.03.2007 15:50:32 CP068/0625(WTB)SUB L/OUT DAVID C01-L030-UWTB 201272562 07:00:00 07:45:00 11.03.2007 11.03.2007 0.75
1001056044 12.03.2007 16:37:29 CP071/1037(ALT)T/B FAIL TO CLOSE DAVID C01-L035-UALT 10:37:00 13:07:00 12.03.2007 12.03.2007 2.5
1001056062 12.03.2007 16:59:36 CP072/1512(WTB)SUB L/O DAVID C01-L030-UWTB 201272525 10:45:00 15:20:00 12.03.2007 12.03.2007 4.58
1001056429 13.03.2007 16:37:50 CP075/1455(ALT)T/B FAIL TO CLOSE DAVID C01-L035-UALT 14:55:00 17:40:00 13.03.2007 13.03.2007 2.75
1001056439 13.03.2007 18:12:00 CP072/1812 CYCAMORE-AIRLIE POWER OFF C01-L030-USYC 201272655 18:15:00 19:10:00 13.03.2007 13.03.2007 0.92
1001056851 15.03.2007 05:21:22 CP077/0111 CYCAMORE-AIRLIE POWER OFF C01-L030-USYC 201272515 04:00:00 05:30:00 15.03.2007 15.03.2007 1.5
1001057039 15.03.2007 16:32:52 CP079/1409(WTB)SUB L/O DAVID C01-L030-UWTB 201272536 14:15:00 15:15:00 15.03.2007 15.03.2007 1
1001057041 15.03.2007 16:37:22 CP079/1420(SYC)SUB L/O DAVID C01-L030-USYC 201272518 15:20:00 16:20:00 15.03.2007 15.03.2007 1
1001057436 16.03.2007 21:13:11 CP0821430(WTB)SUB L/O DAVID C01-L030-UWTB 201272543 14:30:00 15:15:00 16.03.2007 16.03.2007 0.75
1001057437 16.03.2007 21:21:46 CP083/1728(SYC)SUB L/O DAVID C01-L030-USYC 201272684 17:30:00 18:45:00 16.03.2007 16.03.2007 1.25
1001058562 21.03.2007 14:40:43 CP091/13:50 (SALT)T/B'S55&56 FTC OELOF C01-L035-UALT 201269591 13:50:00 14:30:00 21.03.2007 21.03.2007 0.67
1001058690 22.03.2007 05:17:54 CP092/0430(MUM)T/BREAKERS L/O JOHAN C01-L044-UMUM 201272440 07:40:00 16:00:00 23.03.2007 23.03.2007 8.33
1001059402 25.03.2007 08:40:23 CP099/0829 SYCAMORE L/O C01-L030-USYC 08:29:53 00:00:00 25.03.2007 0
1001059404 25.03.2007 08:43:28 CP099/0834 KOMATIPOORT RU FTC C01-L035-UKTR 08:34:52 10:38:56 25.03.2007 25.03.2007 2.07
1001060160 27.03.2007 18:48:21 CP102/14:15(GKTR)RU FTC DAWID C01-L035-UKTR 14:15:26 18:05:53 27.03.2007 27.03.2007 3.84
1001060824 30.03.2007 05:31:34 CP107/05:31(SALT)RU LOCK OUT DAWID C01-L035-SALT 05:31:35 00:00:00 30.03.2007 0