shahnawaz report print

8/17/2019 Shahnawaz Report Print

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Mission Statement

Mission

Our Mission is to provide our customers with high quality electricity and water services, whilst creating value for our shareholders.

Objectives

Our objectives are to:

Efficiently meet our obligation to supply Qatars need for electricity and water.

Operate on a commercial basis.

Comply with local and international health, safety, and environmentalstandards.

Maximize the employment of capable Qatari nationals and develop them tothe competence level of employees in leading international companies.

History

Introduction

Qatar General Electricity & Water Corporation,was established in July, 2000f th t th E i i L b 10 t l t d i t i l f


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f th t th E i i L b 10 t l t d i t i l f

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The Board of directors at Kahramaa is granted extensive authorities toachieve the corporation’s goals mainly, the setting, and implementation and

follows up of general policies, plans, programs and projects.The board main responsibilities are the approval of corporationsorganizational structure, endorsement of the financial, administrative andtechnical internal rules and regulations, employees policies and regulations,as well as approving the corporation investment plans, its annual budgets andclosing fiscal year and approves loans with the Government and other parties,in addition to review of the operational and strategic performance.

b. The Financial Resources

The main financial resources of Kahramaa is the annual allocated funds fromthe state (government), services fees and revenues, the return of its capitalinvestments on its assets as well as the value of its shares and loansextendedtoothers.

The Electricity Sector

The Electricity transmission networks consist of approximately 100primary High Voltage sub-stations with total 660 km of overhead linessupported by 600 km of underground cables across the country. Thenetwork is coupled with 6500 low and medium voltage sub-stations(11kv) and more than 4500km of cable lines.The National ControlCenter (NCC), which contains state-of-art technologies, manages allnetwork demand and data acquisition from generation plants and

primarysub stations


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GENERAL OVER VIEW

Kahramaa distribution Network consists of about 10000 Nos substation. They

are either Indoor type or Out door type.

Max demand - 3025 (27.06.2006) till date

The domestic consumption is more predominant in the system and domestic

load contributes major portion of the total demand. Remaining are industrialand they contribute very less, near about 15% of the load (approx. 450

mw).Seasonal variations are predominant because of the extreme climatic

conditions. In summer, hot season begins from May – September, the

demand reaches its maximum value But in winter season, (Nov- Feb), the

demand reaches its minimum value.

In summer season demand is about 3000 MW

In winter season demand is about 1000 MW

But the Repaid economical & industrial development brings, Qatar power

sector a demand growth of about10% every year.

KAHRAMAA’S distribution Network consists of about 10000 Nos substation.


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3) Outdoor Substation

4) Under ground cables5) Over head lines - OH/L.

1) Primary Substation

Main incoming supply to the Primary Substation is fed from 66

KV system. Two main incoming transformers are generally provided to feedthe 11 KV Distribution system. 11 KV Bus is provided with a Bus

Coupler(A120) for oparational flexibility and is normally in closed condition..

All Switchgear panels for incoming feeders,transformers and outgoing feeders

are equiped with Circuit Breakers,Isolators and Earth switches. Current

transformer and Voltage transformers are also provided in each circuit for

protection & metering. Earthing transformers are provided for stable neutral

and for station supply. Circuit breakers are of either VCB/SF6 / OCB types are

used.DC System is 110 V DC with Battery and Charger. The primary

substatoin are well equipped with Control panel,protection panel,Switch gear

panel and Axilliary facilities. Local and remote control is possible for all


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Selector switches are in Grid position where Out going feeders are in DCC

control and Incomers and Bus Coupler are in NCC control.A Senior Authorised person can change the Selector switch position for work only with

the consent of Contrl Engineers of NCC/DCC.

2) Indoor Substation

All Indoor Substations are well equipped with Switchgear panelswith Circuit Breakers,isolating & eathing facility,control and protection circuitry

and metering facility for the smooth operation and control of feeder and Local

distribution transformers. All Feeders and L/Tx are connected to the common

bus of the Indoor substation through the respective circuit breaker. DC

system available is 30V DC with Battery and Charger.Station LT supply for

station lighting and Battery Charger is taken from L/Tx. All of the switchgeer

panels, L/Tx and Communication systems are protected inside a room.

Circuit Breakers used

1) OCB- Oil Circuit Breaker –Oil (Medium)- Vertical isolation

Types available are


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Control and protection circuitry is provided with the Switchgear panel

for the control and protection of Feeders and L/Txs.Local control facility isonly available for CB.

Metering

Ammeters are provided in each circuit to measure the load current

Status indicators are provided for circuit Breakers

DC voltmeter is provided to measure the DC voltage.

Operation and Maintanance

Presently no remote control is possible. Local operation &

Maintenance is always done by the Field engineers(Senior Authorised

Person) of Distribution Department with proper consent from System Control

Engineer on duty.

3) Out Door Substations

In Outdoor substations, Main Switches and Transformer

switches along with Earthing facility is provided for oparational, maintanance


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Main Switches for Feeders

Earth Switches for Feeders and TransformersTransformer Switches (OFS & TXS)

Current Transformers provided for EFI

Local Transformers - 11KV/433 V

Bolt on Feeder Pillar (BOFP) /Free Standing Feeder Pillar (FSFP)

HT and MV cables.Earth fault Indicators

Gas Pressure Indicators (only in SF6 Outdoor s/s)

Classification according to Insulation Medium

In outdoor s/s, all feeder switches and TX switches are provided with either oil

or SF6 Gas as insulation medium for breaking/making load current.

Oil Switches:- Oil is used as insulation medium for breaking /making the load

current. All switches are rated for breaking/ making load current and not

intended to break /make the fault current.But for transformer circuit Oil Fuse


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the CT across a shunt coil. Normal condition the current will flow through the

TLF( low impedence path) Any abnormality comes the fuse will blown out andit will results the flow of current through the shunt coil (high impedence trip

coil) which in turn trips the circuit breaker.Different types used are :-

Tamco

Merlin Gerin

ABBW Lucy

Fuse rating for different rating transformer

Oil Fuse rating available - 40A,63A,70A& 90A

Standard TLF Rating available – 5A,7.5A,10A,12.5A &15A

Voltage Transformer

Voltage Transformers (VT) are provided for metering, protection and

synchrocheck. VT is always part of Cable and is provided in all Primary

substation and in some Indoor Substation.In Primary all Feeders ,Incomers

and Bus sections are equipped with VT. VT’s are consider as part of the


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Ring Main Unit(RMU)

A single unit with two feeder switches and one T-off transformer switch. Oil and SF6 switches are available. Only one Transformer

circuit is available .Normally Transformer is connected to the T-off circuit and

two feeder switches provided on both sides.

Semi Extensible RMU

The outdoor substation with one RMU unit and which has a

provision to extend its Bus bar towards one side to add more circuits (Feeder

Switches/Tx switches) depending upon the Bus Bar current carrying

capacity.The extensible side of the RMU is provided with an Endcap.

Extensible RMU

The outdoor substation with one RMU unit and which has a provision to

extend its Bus bar towards both sides to add more circuits (Feeder

Switches/Tx switches) depending upon the Bus bar current carrying

capacity.Endcaps provided on both sides.


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•Main Switches are intended to making /breaking load current only andthere is no associated protection circuitry. These switches are not

designed to break / make fault current.

• Status indication windows are available for Main swtches,Earth

switches and TXS to indicate the current status of operation.

Main Switch Closed condition - "ON" with red backgroundTX Switch Closed condition - "ON" with red background

Earth Switch Closed condition - "ON" with yellow background

Earth Switch /Main Switch /TX Switch - Opened condition -

"OFF" with green background

•TX Switches are provided with Oil Fuse/ TLF for tripping the circuitunder overload / abnormal condition.

Inter locking

1) Inter locking facility is provided between Earth Switch ON and Main

S it h ON diti


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Manual type –Manual reset is required after the Flag ON condition due to fault

Auto type - LT supply is provided to EFI and it automatically reset the Flag

due to the fault after a delayed time period when supply resumed.

Gas Pressure Indicator for SF6 RMU

The Gas Pressure Indicator reading should be in the green zone for the safe

oparation of SF6 RMU.

Filling Pressure at 20 degree cent.- 0.4 BARG

Minimum oparating Pressure - 0.05 BARG

Red zone - operation of RMU is not allowed.

Green zone - Operation is allowed

If it is in red zone, refilling is required for further operation and is allowed only

with PTW.

HV and MV cable of Distribution Transformer

11KV HT Single run 3 core cable connect the TX Switch to the Transformer


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Bus Bar (R,Y,B and Neutral)

MV side cut out fuses ( 100A,200A,315 A)MV outgoing Cable (4 or 6 circuits)

Eatrhing Bus

Current Transformer

In Feeder Pillar MV links are provided for LT Outgoing Cables (3 Phase 4 wire

with separate Earth wire ) HRC fuses are provided in LT cable for overload

protection rating depends on the load current. In some consumer MV panel is

available with ACB and REF protection.

Maximum Demand Indicator

Ammeter is provided in MV panel with two needles. One is for the real

time load current measurement and the other one is for all time Meximum

Demand.This indication is more usefull tripping/fault analysis.

LT Transformer – ( 11 / 0.433 KV ) Dyn 11


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- Cut out fuses are provided depending upon the load.

Safety during shut down• The working section should be dead , isolate & Earth at both ends

before doing any work

• Test OH/L line before starting work by using an HV Tester for

confirmation

•If the OH/L found Dead,apply Portable Earth at the point of work

• Always instruct the workforce to wear

Safety Belt

Safety Shoe

Helmet

Gloves

• Field Engineer should collect the original copy of safety document

(PTW) signed by the competent person

• OHL work should be stopped immediately when the atmosphere

b l d d h f li ht i d th d h


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- A visual check is reccomended after each operation whether the

contacts are properly inserted/seperated.- Arcing Shields are provided to minimise the arcing of blades.

- If ABS is deffective , jumper connections are used to bypass it.

Test OH/L, If Dead, Apply Portable Earth

An HV OH/L Tester used to test the isolated line to make sure that the line is

electrically Dead and is always applicable before applying Portable Earth to

commence a work. After isolating & earthing( if facility is available) both ends,

then test the OH/L , If found dead apply Portable Earth at the point of work by

a copetent person with the precense of a senior authourised person.

If the OHL is dead - tester making normal low beep

If OHL is live - tester making high beep

( Before and after the tester itself should be check )

Portable Earth(PE):-Before doing any kind of work on OH/L, the Portable

Earth must be applied at point of work and is very essential to give a Permit to

Work(PTW) . So before issuing PTW, the System Control Engineer should

confirm that the PE is applied at the point of work and simillarly he should


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• Drop Out fuses are provided for the transformer

protection.Replacement of D.O fuses is permitted under live condition..• Out going cable with Fuse Cut – outs are used to feed the LT 3phase 4

wire system. Ratings available are 100 A, 200 A , 315 A .

• Earthing arrangement for PMT – Normally two Earth pits are provided,

one for ground /Body Earthing and the other one is for system neutral

earthing.Pole Box

Termination in a pole which provides connection between OH/L

circuit and UG Cable circuit is called a Pole Box. The HT cable may be either

from any I/D Substation / Out Door Substation or from another OH/L portion

due to crossing of road / EHT line.• CT and Earth Fault Indicators are provided in some Pole Box to

indicate earth fault passage

• LA’s are provided to protect the cable termination from lightning surges.

• Separate Earthing is needed for pole Box.


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point of isolation. According to the operation and control, two types of

Recloser are used in OH/L System. Auto reclosers with manual control

During fault, the auto recloser trips the circuit. But after the first opening, the

recloser attains Lock-Off. Manual operation is needed for closing the Auto

recloser and this is done by using an insulated operating rod. First the

operator should manually reset the switch and then close.

Auto reclosers with auto control

A microprocessor control is provided along with the Auto recloser and is

mounted on the pole (bottom). The operator can operate it from the ground

itself. This type of Auto recloser trips the OH/L faulty section and attains to

lock off. Closing after patrolling and clearing the fault is possible from the

automatic control installation. This type of auto recloser should protect the

OH/L section from O/C, short circuit, E/F and sensitive E/F.

Main Components


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RAS ABU ABOUD - 107 MW

SATALLITE STATIONS

i. AL WAJBAH

ii. SALIYAH

iii. DSS - 473 MW

Q- POWER - 699 MW

TOTAL 3528 MW

Transmission network

Kahramaa transmission grid consists of the following voltage levels.

Transmission Network

220 KV

132 KV

66 KV

Distribution Network

11KV

0.433 KV


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The National Control Centre (NCC) controls the QGEWC’S power

system in an efficient way. The smooth, stable and efficient grid control is

achieved by the automated control system (SCADA / EMS). Two control

desks are available, they are (I) Generation Desk and the other is (ii)

Switching Desk.

(i)Generation Desk.

Controlling the Active and Reactive power flow to maintain the

system voltage & frequency to a predetermined value.

Act according to the surplus & deficit condition.

Act according to the abnormal condition.

Merit Order Dispatch is observed

Automatic Generation Control is in operation.

(ii) Switching Desk.

Coordinating & controlling to all Switching operations.

Give Sanctions ( PTW & SFT ) to all switching operation

Executing load rearrangement programmes during shut down /

abnormal conditions.


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A spinning reserve equal to the capacity of the largest unit in service is

to be maintained as far as possible.

Operation with less than above or zero spinning reserve is allowed

when there is a short fall of generation capacity during summer peak,

or due to agreed plant maintenance programme, or units purposefully

kept off to avoid plants running winter nights or when generation unit

are agreed to be kept stand by ,to save running hours for anticipated

usage in next summer peak.

Voltage Control

(I) Generator MVAR Control

System Voltage is maintained by controlling the reactive power flow.

Due to the highly inductive nature of load, a larger capacity of MVAR is

required. The main MVAR generation source is the generator and all

generators are normally supplying about 50% of the active power as MVAR.

Then the major source and control point of MVAR is generator source.

Voltage is maintained by controlling the MVAR output of generators. The VAR

control can be achieved either through SCADA control or by local control.


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Immediate improvement in voltage to a limited extent is possible by changing

the tap of transformers in the system.

The Remote tap changing cubicle (RTCC) is having different ways of control.

They are:-

(i) Automatic control (with AVR)

(ii) Supervisory control (NCC)

(iii) Manual control (local)

For Grid Transformer - control is done from the NCC (supervisory mode only)

- ON Load Tap changing is possible.

For Primary Transformer (66 / 11KV) – Automatic control mode operation is

enabled with AVR(ON Load Tap Changing)

For Distribution Transformer – OFF load, manual control only permitted.

Operation at Abnormal Conditions

There are generally two conditions where the system runs on bellow target

frequently.

Condition 1 - When all the plants on bar (POB) are fully loaded and the


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if necessary this is continued with next list and so on. Next load shedding list

for cyclic shedding is # 23.

Note: DCC should be informed before domestic shedding, and they inform the

stand by offices concerned. Maximum load shedding time is limited to 2 hrs.

First domestic load and then furnaces are restored and later import of energy

is stopped as frequency improves.

Condition 2 - A Sudden drop in frequency due to an unexpected major

generation loss. This is an unanticipated frequency drop situation.

Action required – In this case automatic under frequency load shedding takes

place at various stages.

1. Automatic under frequency Bulk load shedding.

2. 11KV feeders at Primary s/s (domestic load) are kept selected at

predetermined frequency levels as below for automatic shedding.

Stage 1 A - Setting 49.2 HZ

Stage 1 - Setting 48.8 HZ




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Objective

Monitors and ensures continuous electricity supply for the distribution

network, within the prescribed values of limit violations, giving priority to

security and safety.

Major functions

Controls Active & Reactive power flow in the network and there byregulate the voltage.

Confirms to all the operation are done in strict compliance with the

department safety rules and regulations and there by ensuring system

safety and security.

Control , coordinate and direct to all switching operations by givinginstruction to field engineers for switching in the 11 KV network for

maintenance / repair of network components and for after fault

restoration.

Co-ordinate with NCC, in case of generation shortage or other system

contingency to shed the load in accordance to the prearranged


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Breaker status are transferred to DCC for monitoring and controlling. It also

provided alarm and limits violation condition to remind the Control Engineer to

act accordingly. The available data’s in the DCC computer console can be

utilized to originate different report for the smooth functioning of DCC.

Available Data’s & facilities

Loading Values of different Primary transformers.

Loading values of different outgoing feeders of PRY

Bus voltages of PRY

Breaker and VT status of PRY

Limit violation, alarm and important events.

All the data’s available in the DCC console can be utilized for past and

present system analysis and also helpful for the contingency analysis. The

data’s available in the database also helps to originate various technical report

& statistics.

Role of System Control Engineer


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Check whether all the safety aspects are taken care of before

execution.

Study the load rearrangement during the shut down, possible way of

back feeding, loading values of feeders and Transformers involved.

Check the load of feeders involved in paralleling at the time of

isolation and live phasing.

Analyze the paralleling involved in the programme and check

whether it is a bad paralleling or not.

Scrutinize the point of isolation, back feeding arrangement in terms

of system security and safety.

Study the loading condition due to the shut down and check whether

the shut down causes any overloading to any feeders and primary

transformers involved in the programme.

Check the substation planning Number and Name, Sequence of

operation and safety aspects related to the programme, date of

execution and duration of shut down etc.

Study the Live phasing route ,loading during Live phasing and


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Check the load of feeders involved before paralleling.

Check whether it is a bad paralleling.

Check the bus voltage of the Primaries involved.

If possible, request NCC to minimize the voltage difference

between Primaries involved.

Block the tap changing in order to avoid furthers changes in

voltage and thus the unwanted circulating current. This will

minimize bad paralleling effect.

If there is a bad paralleling history then arrange two field engineers

for make & break operation (if possible) or break and make

depending upon the consumer affected.

Check the load on feeder involved after paralleling in order to

confirm the paralleling is successful and is not interrupted the

consumer.

Supply confirmation from the field engineer is very essential after

paralleling.

• Before energizing a transformer, study the present loading of feeder


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• For collecting additional information about the tripping, the Control

Engineer can utilize the help of SSA and Stand by Technicians.

• Convey all information collected to the Distribution Stand by Engineer

and also give the Tel. No. of SSA who attending the fault. Control

Engineer should instruct the field engineer to proceed to the Indoor /

Outdoor / PRY where the fault is suspected.

•If OH/L is involved, then inform ABU HAMUR OH/L section to arrangethe patrolling.

• Report the matter to the top officials with details.

• Study the possible back feeding arrangement.

• Collect all information from the SSA at site and from the Stand by

Engineer like relay indication, EFI status, station supply (Battery) andabnormalities etc.

• With the above information locate the fault as early as possible.

• While test charging, keep the relay time setting to the minimum.

• Isolate the faulty section, apply C/N, L/ off and apply CME at point of


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• Always tell the name and planning No. of location and circuit to the

Engineer.

• Note down the time of instruction and time of confirmation of operation.

• Before issuing PTW and SFT confirm that the working section is

isolated, Earthed at both ends. And also confirm that the S/L and C/N

applied at the point of isolation.

• Always confirm switching positions after cancellation of SFT.Confirming switching positions after SFT is mandatory because of the

Field Engineer has the approval for the operations of earth switches

under SFT. He has the temporary control over Earth switches during

SFT for the purpose like HV injection, signal injection, colour phasing

etc.

• If OH/L involved in the isolated section, apply CME at point of isolation

(if possible) and test OH/L line, if found dead apply Portable Earth at

the point of work. After confirming the above, issue PTW. Before

cancellation of PTW confirm that all CME and portable earth are

removed from the line.


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• When multi permits issued to the same Field Engineer or to different

Field Engineers within the same point of isolation, then the energisation

shall be done only after the cancellation of all holding PTW’s within the

isolated section. When multi permits issued to different field engineer,

cross reference numbering is recommended (# CR).

• A field engineer can’t hold more than one SFT at a time. SFT is issued

by the field engineer to himself and his direct supervision involvement

is required to perform the test.

• Proper informational tags must be placed on single line diagram to

avoid any wrong operation.

• The field engineer can’t suspend the SFT. He has to cancel SFT before

he leaves the site. Any inconvenience occurred to complete the test,

then he should cancel the SFT and also confirm the switching positions

before the leaving the site.

• The field engineer can’t hold PTW and SFT together.

OTHER IMPORTANT ACTIVITIES

Load shifting / rearrangement as per NCC advise.


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In case of PMT, remove the HT fuse and then adjust the tap

position as required.

NOP Shifting:

Paralleling between same or different sources is required

Different Situations:-

• Load balancing among same or different Primary transformers.

• Load balancing among Feeders.

• During shut down works – to back feed the load to avoid interruption.

• During fault restoration.

• To avoid over loading of Feeders and Transformers.

Important Considerations required

Before paralleling, study the voltage profile of sources and block thetap if required.

Before and after paralleling study the real time loading values of

Feeders and Transformers involved.

Always confirm the supply status and this is necessary to find out

any load loss due to tripping in between.


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3. PTW and SFT Cards.

Prepared in prescribed form separate for PTW and SFT and which is serially

numbered with brief details particularly about CME, Name of Engineer,

Section isolated, work, Date and Time etc.

4. Station Log

All events recorded by the Control Assistant in a chronological order during

the shift. This includes all the switching operation instructions given by the

Control Engineer.

5. Control Engineer Log Book

Brief reports about the Operations during the shift.

6. Daily Report – system statistics

7. Weekly Maximum Demand Log

8. Daily peak print out.

Communication facility available

Q-Telephone, KM’s Pax phone, Hot line telephone and Fax

Construction & Reinforcement section -Distribution,


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section after obtaining the proper consent from governmental authorities. ROA

wing should arrange the approval from the governmental agencies (Qtel,

Sewerage, Civil engineering Department, Road Division and Water

Department of Kahramaa).

Role of Construction Engineer

• Estimates the material requirement and coordinate the same with the

suppliers & ABUHAMUR work shop• Coordinate with consumer for execution of scheme

• Allocate the work to different contractors and coordinate with them for

final execution.

• Prepare an action plan for the proposed work.

• Prepare shut down notices before execution, if any supply interruptionanticipated.

• Prepare switching programme for shut down and Commissioning. The

switching programme along with the alteration proposed to the existing

system is required to get proper consent from the system control (DCC)


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• The system control engineer should arrange for possible back feeding

and load transfer in order to avoid interruption during the execution of

work.

• The switching programme and other activities involved during the

execution shall comply the Safety Rules and Operation memorandum

of QGEWC high voltage system. The system operation memorandum

D15 is followed in this aspect.

• Before Commissioning a New Substation / Transformer

- Check the new label and fix it properly and confirm the same to

control (DCC)

- Protection and fault level of CB. Verify and inform to DCC.

- Check the operation of CB.

- Check the station lighting

- Check the trip circuit healthiness

- Check station Battery and Charger.

- Check the transformer before energizing (oil check, tap setting,

name plate, abnormalities etc.)


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1. Cable Identification.

2. Spiking

3. Colour phasing ( core phasing )

4. 11 KV Jointing work & Termination work on HT cable )

5. HV pressure test for 11 KV cable and Bus Bar

6. Dead phasing check – 11 KV system

7. Live phasing check - 11 KV system

8. Phase rotation check for MV side.

9. MV voltage check.

10.Trip / test check for CB.

11.Relay inter trip check

12.Transformer, Switchgear panel, Switches and Substation observation.

13.Relay setting & fault level.

Cable Identification

During construction and maintenance, the existing cable has to be cut

for fault rectification and for commissioning new substations in between the

existing cable. Then the Field Engineer should confirm the cable which is


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after removing the earth. Keep remote end of cable as earthed for return path

.Then by using the Audio receiver and head phone, we can identify the cable

in which signal is generated. When the receiver is put nearer along the cable

gives a clear beep but varying sound from the cable trough which transmitted

the signal. Sound variation is obtained only from the injected cable due to the

twisting of cable pairs. But for other cables, humming sound is obtained from

live cables and clear beep but not varying is obtained from dead cable if any.

The Cable Identification test is done by the field engineer himself in charge of

work. See the figure.

Spiking

After identifying the cable, before cutting, spiking has to

require for 100% confirmation that the cable is absolutely dead and safe for

cutting. Spike gun is a special arrangement, where the iron bullet is used for

firing. The spiking gun with bullet is placed over the cable and firing is done

remotely with the help of a rope. If the cable is the correct one, there is no

heavy sound. But for live cables heavy flash over and tripping may occur.

Thus spiking will helps to avoid dangerous situation and it provide more safety


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of jointing / termination works to transfer the same system phase(R, Y, and B)

from one point to other point. Colour crossing of the cable is serious and to

avoid this colour phasing is required during jointing and termination work.

Different methods for colour phasing

1. Banana Resistance and Megger

Connect the three different resistances (known value) to the RYB phases of

one cable end (Star connection with star point earthed) then by using a

Megger, which connected to the other end of cable and measures the

resistance. The corresponding values of resistance obtained on phases will

give the correct phase.

Uni directional LED with Battery set.

Connect the battery between any two phases of cable at the known end. Then

the lamp glow will indicate the phases where the battery connected and it also

indicate the direction of current flow. Then from the lamp glow and direction

we can easily confirm the three phases.

Safety

Before doing test, the cable should be isolated, earthed at


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together for same point of isolation is not permitted. If PTW is issuing after the

SFT, then the Control Engineer should always confirm the switching position

and also confirm that both ends of the cable is isolated and earthed.

Competent person - Kahramaa certified HV Cable jointer / Fitter with

Identity card of Kahramaa

Straight joint kit - XLPE cable to similar XLPE or PILC to similar PILC

Transit joint kit - XLPE cable to PILC or PILC cable to XLPE

Dead joint - Jointing work on Dead cable

Breaking a Termination – Removing an existing cable at a termination point

Making a Termination - Connecting a new cable at a termination point

Break & Make Termination - Breaking and making termination of cable at a

Point during construction / maintenance work

Safety

Before doing any work on cables, the cable section must be

isolated & earthed at both ends.

Any work on cables like Break & make terminations, Cable


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between Phases(R-Y, Y-B, and R-B). The duration of HV injection is about 15

minutes for each test. Pressure test is also required to test the perfection of

terminating & jointing work.

Pressure Test Kit

In the testing instrument, meters are provided to indicate the applied KV and

leakage mA of the circuit. If the leakage current value during injection is in

between 0.1 and 1.5 mA, then the cable is declared as healthy. The leakage

current higher than 3mA indicates the breakdown of the circuit. That means

excessive leakage current or tripping indicates that the dielectric strength of

insulation, jointing work / termination work is not up to the standard. If there is

a new bas bar is involved in the circuit, then HV Pressure test for Bus Bar is

also compulsory. For safety, discharge rode is provided with the test kit to

discharge the capacitive charge of cable after the test.

Phase to Earth Test

Voltage applied = 11 KV DC (Negative)

(R-E, Y-E and B-E)

Duration - 15 Minutes


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After the Pressure Test, the SFT taken should return and cancelled

with the consent of system control engineer. Confirm switching

position is mandatory.

11 KV DEAD PHASING

This is a method of checking R, Y, B, phasing of the newly constructed

elements from known end to the other end before live phasing. Dead phasing

will not disturb the existing system. This is a pre - confirmation test before live

phasing.

11 KV LIVE PHASING

After all type of constructional / maintenance activities on cables,

terminations, the 11 KV live phasing is required. This is essential for meeting

same RYB sequence condition before paralleling between two systems. It

always conducted at I/D substation and it prove that the added network

elements in same phase sequence with respect to the existing. The I/D

Substation nearer to the newly commissioned Substation should be taken in

order to minimize interruption to the consumers.

Live phasing proving the there statements below:-


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Bar spout phases and the Cable spout phases. While observing the live

phasing between the two system available at Bus bar spout &

Cable spout, for correct live phasing the voltage should be as follows:-

R of (Bus bar spout) to R (Cable Spout) – 11 KV

Y of (Bus bar spout) to Y (Cable Spout) – 11 KV

B of (Bus bar spout) to B (Cable Spout) – 11 KV

R of (Bus bar spout) to Y (Cable Spout) – 5.5 KV

Y of (Bus bar spout) to B (Cable Spout) – 5.5KV

B of (Bus bar spout) to R (Cable Spout) – 5.5KV

If any mistakes happened during work, then the voltmeter will indicate

incorrect reading. Then the Field Engineer should rectify the mistake.

At Indoor substation, the CB towards the new circuit should be kept opened.

Then Bus Bar spout is having the existing supply and cable spout is having

the existing system through the new circuit. By inserting live phasing sticks

between bas bar spout & cable spouts, we can confirm whether the live

phasing is correct or not.

Safety during live phasing


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bad paralleling etc. We can conduct live phasing at any I/D substations

( existing or new one )

• If the supply is taken through the new circuit includes an existing O/D

substation, then the existing and new phase rotation has to be check

for consumer safety.

Phase Rotation & MV voltage check for MV side

11 KV live phasing only proving that the new HT network elements are

in correct phase with respect to the existing system. But for transformers MV

phase rotation & voltage check is required to ensure that the consumer supply

is not affected due to the alterations and modifications done during the work.

This is required to ensure proper MV voltage and phase rotation to the

consumer.

Methods

1. Phase Rotation meter

2. LED Flickering meter

Phase rotation can be checked either by using a phase sequence check

meter (rotating dial with arrow indication) or by using an LED flickering


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LT side fuse replaced only after the successful commissioning of

transformer.

Close, Trip-Test and reclose

Trip-Test

If any CB is Rack out for any operational purpose, then it must be checked for

trip test. This is for a confirmation that all the auxiliary contacts are healthy as

before. Trip test is done by rotating the disc manually and it ensure the

following

Circuit Breaker auxiliary contacts are healthy and okay as before.

Trip circuit is healthy.

Close

If the live phasing is correct, for proving the same the Field Engineer

should close the CB between two systems.

Reclose

After proving the live phasing, the system NOP should be as per the

direction of System Control Engineer. That means the close or reclose is

according to the system condition.


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- Trip circuit healthiness.

Panel - Circuit labeling.

- Meters to be check for its functioning.

- provide operational locks.

- relay setting & trip circuit status.

Substation and Switchgear room - Planning Number.

- Door Lock.

- DC Battery Voltage check.

- Battery charger healthiness.

- Station lighting.

Operation & Maintance section, Distribution, Kahramaa

Introduction

The smooth functioning of distribution system is always in

accordance with the performance of its operation & maintenance team. So

continuous and reliable supply is ensured only through the better and efficient


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i. Preventive Maintenance: - Preventing a future breakdown and

ensure continuous supply. All periodic scheduled maintenance

on the 11 KV Distribution system is comes under this category.

Regular systematic maintenance, all preventive action taken for

the smooth & efficient operation of the system. Servicing,

Overhauling and routine oil and gas check are examples.

ii. Corrective maintenance or Breakdown Maintenance:- This is the

corrective actions taken for the smooth and efficient operation of

the system. The Break down or corrective maintenance

activities are conducted after the failure of an equipment. Such

maintenance results in outage of circuit and supply. In general,

it consists of locating the trouble, repair and recommissioning.

General duties of O&M Field engineers

All switching operations for O&M work are done by field engineers on duty

1) Periodic repair & maintenance – Preventive works-oil /gas

changing, servicing etc.

2) Break down Maintenance -TX replacement, Faulty Cable


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(DCC). So for all the work (operational, repair and maintenance ) the field

engineer should obtain proper consent from System Control Engineer (DCC).

Immediate supply Restoration:-

Immediate supply restoration always gives better service to

consumers and is important in distribution system. The kahramaa distribution

system has adopted an efficient and effective way for overcoming the

emergency breakdown condition. The field engineer are posted on a round

the clock rotation basis for the stand by duty in order to attend the emergency

tripping conditions and restoration thereon. During the tripping and emergency

condition, the system control engineer should co-ordinate and directs the field

engineers for immediate restoration. The system control engineer should

direct and co-ordinate by giving instructions to the field engineer as per the

relay indication and other field information. First, he should find out the faulty

portion and then isolate it from the healthy system and then restore the

remaining healthy system as early as possible. After that, DCC Control

engineer has to direct and coordinate the field engineer to rectify the faulty

section as early as possible. All the above switching operation must be done


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provided for some important distribution consumers. But mostly all I/D and

O/D substations are feeding from one source at a time and there is always

one or more alternative sources (either from same or different PRY) are

available as NOP. Some Radial feeding s/s and multiple source feeding s/s

are also available (same primary). The location of NOP decides the loading of

the 11 KV feeders which in turn reflects the loading of the transformers of the

Primary Substation.

NOP shifting will always helps to balance the loading among 11 KV feeder/

primary transformers and also helps to back feed the system at the time of

supply failure. There NOP shifting can be execute either by a pre-planned

manner (prior switching programmers) or for an emergency situation like over

loading / tripping of feeder / transformer (PRY). If it is in urgent nature, then

the field engineer on stand by duty has to attend the NOP shifting. The pre-

planned NOP shifting programme is normally executed by the field engineer

on system operation duty.

For system operation load shifting (NOP- Shifting), the DCC

should prepare the switching programme and the switching is


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Stand by offices are under the system operation department (DCC).Their

primary duty is providing service to the consumers (MV / side service). Supply

interruption of the consumer is attended by the stand by office Staff.

Depending on their availability, the O&M, Construction and DCC can

utilize them for finding Substation location and for collecting informations from

site etc.

1. DOHA STAND BY / EMERGENCY CALL CENTRE

2. KHALIFA TOWN STAND BY

3. RAYYAN STAND BY

4. WAKRAH STAND BY

5. M. SALAL STAND BY

6. KHORE STAND BY

7. AL- GHOWAIRIYA STAND BY

8. SHAHANIYA STAND BY

9. RUWAIS STAND BY

Substation Assistant –SSA

Controlling from NCC / DCC


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programme after obtaining proper data from DCC and send to the DCC

prior to the execution(48 hrs before).

For emergency break down / tripping work the field engineer should

operate according to the proper instruction from control engineer on

duty ( DCC).

Distribution System Protection

IntroductionThe function of a protection scheme is to ensure the maximum continuity of

supply. This is done by detecting the faults and isolating the minimum

possible part of power system during fault and abnormal condition. Protective

relays are the devices that detect abnormal conditions in the Electrical power

system by constantly monitoring and measuring Electrical quantities as wellas various other parameters to discriminate between Normal and abnormal

conditions. The basic Electrical quantities which are monitored for detecting

abnormal conditions are

Voltage

Current


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3) Phase to phase (L-L)

4) Phase to ground (L-G)

5) Phase to Phase with ground (L-L-G)

Faults in system

Cable faults – Joint faults, termination faults and third party damage

Transformer faults – Incipient faults, over loads, terminal faults, winding

faults and through faults

Switch gear faults – Flash over due to insulation failure

Bus bar faults

Natural events

Physical accidents

Mal operation

Kahramaa Distribution system protection

The protection scheme used in Distribution Network including the Primary

substation, Indoor substation and outdoor substation are detailed below.

Primary Substation protection


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It always directed towards transformer LV winding. Protects the transformer

from heavy circulating current occurred at the time of tap changing and it also

protect the other source in the same Bus from the internal LV fault of the

transformer.

6) Temperature, Gas and oil surge protection for transformer

Main TX Bucholz /PRV trip

Tap changer Bucholz surge/gas trip

Earthing TX Bucholz surge trip

Main Transformer winding temp trip

Eathing TZ Bucholz Alarm

Earthing TX low oil level

Main TX Bucholz Alarm

Main TX winding temp alarm

Main TX low oil level

Other Relays

Master trip Relay-All relays are wired to the master trip to initiate the tripping

signal for Circuit breaker. Type –F8H trip relay.


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Used to provide Auxiliary supply to primary substations (415 volts)

Stand by Earth fault Protection

Stand by earth fault relay is provided in the secondary circuit of earthing

transformer neutral CT. If an earth fault is not cleared by appropriate Circuit

breaker of 11KV feeder in the Primary substation, the earth fault current will

continue to flow through of the 66/11KV transformers in the Primary

substation.

If the fault persists without clearing by the feeder earth fault protection the

fault will be cleared by the SBEF stage 1 and 2 timer relays. Stage 1 will trip

the bus section and stage 2 will trip the transformer. Main features are as

follows.

o Protects the 11 KV distribution systems including the Primary

transformer LV winding from Earth fault and the maximum earth fault

clearing time is limited 3 seconds.

o The SBEF relay will initiate “Flag ON” condition for all earth faults

(magnitude higher than the set value). Current setting depends on the

independence of the Earthing transformer.


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11 KV Bus bar Protection

1. Partial Bus bar Protection

2. SBEF where there is no partial bus bar protection and in the substations

with partial bus bar, SBEF act as a back up protection.

Partial Bus bar protection

Partial bus bar deferential protection employed in the 11 KV feeders of

primary substation equipped with bus section breaker. This relay works on

deferential principle and the relay is connected across the secondary CT’s of

bus coupler and incomer with an overlapping arrangement. The feeder CTs

are not involved in this scheme of protection causes relay operation during

through fault condition. To avoid this, discrimination between Bus Bar fault

and 11 KV feeder faults is provided. Main features are as follows.

♦ It protects a portion of Bus Bar from bus Bar faults and provides a back up

protection for the 11 KV feeders. For 11 KV system faults feeder protection

act first and when it fails partial bus bar protection will act as back up.

♦ The phase fault element of the partial Bus Bar protection is graded with the

feeder phase fault protection and Earth fault element is graded with feeder


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send blocking signal, PBDP (50 high set)will trips the LV ,HV side breakers of

transformer along with the Bus coupler breaker.51 elements act as a back up

protection for the feeder

Grading

50element -100 milli sec time delayed operation.

51element (O/C) – graded with the feeder IDMT O/C and TX HV side O/C

(Time grading only possible - 300 milli sec)

51 element (E/F) - graded with feeder E/F (IDMT) and SBEF

(Magnitude grading only possible)

CT is -2000/1; current setting is normally 7% (300 m sec time grading)

Primary substation feeder protection

Normal protection scheme consist of the following relays.

1. Pilot wire protection

2. Standard IDMT Relays (2 O/C +1E/F)

Pilot wire protection

A type of unit protection

Solkor R instantaneous protection (60 milli sec)


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• The padding Resistance to set to a value such that, the total loop

resistance of the pilot wire cable is 1000 Ω. Let RL be the Pilot wire

lead resistance. There the padding resistor to be provided at each end

is , RP =1000-RL Ω (RL is normally about 10 Ω).

• Current Check Relay (B 69 Relay) is used in series with the SOLKOR

Relay and it will prevent the tripping of the 11 KV cable feeder on

account of any pilot wire open condition or pilot wire shorted condition.

For the current check Relay the O/C setting is provided with more than

the O/C setting of the IDMT O/C relay on the feeder.

• Pilot wire supervision relay is also used to detect any fault in the pilot

wire circuit and for any type of fault in the pilot wire

• If pilot wire supervisor Relay or current check relay is not provided

along with SOLOKOR R Relay, the following situations can occur

SOLOKOR R unit protection acted and the Feeder trips only at receiving end,

it can be assumed that it is pilot wire problem and in this Situation, the feeder

not to be put in service until the Pilot wire unit protection is decommissioned.


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100 milli sec –300 milli sec delayed operation is provided for this type relay in

order to avoid tripping during heavy inrush currents (100 m sec –300 m sec) is

the decaying time required for inrush. In some cases, SOTF protection is also

provided with Harmonic Restraint feature (100 millisecond delay ) or with out

Harmonic Restraint feature (300 millisecond delay ). The 2nd Harmonics from

magnetizing inrush currents or switching surges will decay with in 300 milli

second.

51- Normal IDMT element with grading.

Stage-2

50 element - Initiate blocking signal to the Partial Bus bar high set element

and the signal will reach within 60 milli sec. during a fault in the out going

feeder. The High set element of IDMT relay is not used for tripping but it

sending blocking signal to the partial Bus bar relay.

Relay Operation

For Three phase balanced fault – R&B O/C relay will operate.

For Three phase earth fault - R&B O/C relay will operate

Phase to phase fault - R or B phase O/C relay will operate


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LV side winding and cable up to the CT point is protected by Restricted

Earth fault protection. (In case of consumer MV panel with ACB and

REF relay available)

From MV panel REF relay to HV panel, intertrip cable used for the

connection for 11 KV inter tripping.

IDMT relay with EI Characteristic is used. This Provides better grading

with the MV fuses. Type TJM 31 &2TJm31.

Separate High set instantaneous element is provided to protect

transformer from heavy fault

Current setting and CT ratio required is as per the transformer capacity

High set relay setting is as per the short circuit fault current of the

transformer. (To avoid the unwanted tripping due to magnetizing inrush

current, 130% of the expected fault current is taken for relay current

setting)

MV side protection - Fuse protection is available.

- ACB with REF is provided in some consumer panel

Time and Current grading


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1000 KVA - 60A

1600 KVA - 90A

Transformer with SF6 TX switch

Time lag fuses are provided in the CT secondary circuit to protect HV side.

TLF required for Transformers with different CT is shown below.

Voltage

KV

TX Rating

KVA

CT Ratio

A

TLF rating

A

Max.distributor

fuse link rating

A

11 200 50/5 3 160

11 300 50/5 5 250

11 500 50/5 7.5 315

11 800 50/5 12.5 400

11 1000 100/5 7.5 500

11 1250 100/5 10 630

11 1500 100/5 12.5 630

11 1600 100/5 12.5 630


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IN OH/L, the earth path resistivity is very high and then the normal E/F relay

will not detect the earth fault of the system. To overcome, this condition OH/L

are provided with sensitive earth fault relay (current setting is 3% with a long

definite time lag of 3 seconds).

CT Ratio - standards

Primary substation

LV side of TX and Bus bar - 2000/1 for PBDP

-2000/1 for D O/C and D E/F

Out going Feeders - 400/1 or 300/1 for IDMT, SOLOKER R & Metering

Earthing Transformer - 750/1 (Neutral CT)

Indoor substation

Feeders - 300/5 or 400/5 for SOLKER R, IDMT and

metering.

Transformers - 150/100/50/5, 80/40/5, 60/30/5, 100/50/5

for IDMT & Metering

Out door substation

Transformer with SF6 TX Switch – 100/5 or 50/5


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• Circuit Breakers – Method of isolation.

• Pot End & Cap End Cables.

Operational & Safety Locks with Keys.

For better operational and system safety, kahramaa provided Operational and

Safety locks with keys to their Field engineers. Apart from operational & safety

lock, Substation keys are also available and is provided to all field engineers

and to some contractors.

Operational lock with key

Indoor and Outdoor Substations

All Switches, Circuit Breakers, Panels, Isolating and Earthing devices are

provided with Operational lock with key. Normally two types available and

given to all Field Engineers.

1) 246 Type

2) Den ( Department of electricity network )- small size

Strictly follow kahramaa’s Safety Rules, while using the operational locks

during the work.


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where the circuit on which work is to be carried out could be energized. The

keys for such locks shall be kept in a key safe, if provided, or in some other

safe place preferably in the possession of the Senior Authorized Person in

charge of the work. See Kahramaa Safety Rules12.3

Locking facility available for Indoor VCB

• Bus Bar spout shutter

• Feeder spout shutter

• Earth Switches

• Push Button ( Trip / Close )

• Panel Door

Interlocking features available

• Without opening the OCB, the inter locking lever will not be

disengaged.

• The Isolating lever entry is possible only when the OCB/VCB in opened

condition.

• Closing of Earth Switch is allowed only when the VCB is in Racked

Out/Test position.


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A data transfer is provided to transfer the operation status of CO2 spraying

system (Automatic / blocked / manual) to NCC and it will gives alarm for the

changes in operation. So the field engineer should inform NCC before doing

any operation.

Confirm Supply

Out Door Substation

Check the humming sound of Local Transformer.

Check the vibration of transformer.

Ammeter Indication from MV panel / Feeder pillar.

Indoor Substation

Check Transformer humming sound & vibration.

Check Meters indication in the switchgear panel

Check Station Battery charger voltage.

Station lighting

Location Map

An up to date location route map is provided to all Field Engineers for helping

them to find out the Location of Substation.


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identification failed and then close the main switch one by one. Then

identify the circuit from the feeding source by checking the station

supply.)

Pot End & Cap End Cables

Pot End ( P.E ) - Idly charged cable without connected load.

One ends of the cable is connected to the 11KV Bus and the other end is kept

free ( not terminated but the terminals are made and covered with a pot

termination kit ). Pot End cable is idly charged from one end.

Cap end ( C.E ) - Earthed Cable

One end of the cable is connected to the 11 KV Bus and the other end is kept

free, not terminated but only covered with a cap. The cap End cable is always

in earthed condition from its 11 KV Bus side.

Parallel Operation

Condition for parallel operation of two systems

1. frequency,

2. Voltage and

3. Phase sequence should be same


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The power transfer from a source to load is always depends on

the total impedance (transformer + line + generator) and the voltage angle /

load angle of the system. Here Reactive power transfer is always depends on

the magnitude of the voltage, that is always higher voltage to low voltage. The

active power transfer is always depending on the load angle / voltage angle

’’δ’’ irrespective of the magnitude of the voltage. So magnitude of the voltage

is depends on the voltage regulation and in turn depends on the impedance of

the system. Therefore the percentage impedance and voltage phase angle /

load angle are the determining factors of load flow from a source to a load at

remote end. The following factors determine the power transfer and thus the

current through a line.

1. Percentage impedance of transformers

2. Impedance of the line up to the load.

3. Load angle at different load centre or the phasor

displacement of voltage between source end and load end.

Bad paralleling


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paralleling. Otherwise, the voltage difference cause to produce high circulating

current and this trips the weaker portion.

One another reason for tap blocking is the tap changer is designed to

operate on load condition and not for operating on fault condition. One reason

for blocking the tap during paralleling is to avoid flow of fault current through

the tap changer while tap changing takes place.

Isolation and Earthing for Different Switchgears

Oil Circuit Breaker - Vertical isolation.

1. Service position - OCB, connect the Bus bar to the feeder /

transformer circuit when OCB is in closed condition , the live Bus bar is

connected with the feeder / Transformer.

2. Circuit Earth Position ( CK/E )

OCB provides connection facility between feeder / transformer circuit and

earthing system (station earth) .When OCB is in closed condition , the feeder /

transformer circuit is in earthed condition.

3. Bus bar Earth Position

OCB provides connection facility between Bus bar and earthing system. When


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TAMCO VCB

1 L/TX – 1000 KVA

4345 – I/D –OCB

9899 I/D – VCB.

termination for the new s/s. After

the work cancelled t he PTW. SFT

issued to HV / pressure test for the

cable between the I/D including

new s/s. P/ Test done at new I/D.

and cancelled SFT& confirmed

SW/ position. Live phasing done at

new s/s (11325- I/D).

Commissioned new s/s and local

TX.

05-06-2006

Eng. Dharam

Commissioning of new O/D

substation, Semi extensible 12603

with 1250 KVA transformer,

LABOUR CAMP –O/D in between

9935 I/D and 3828 O/D substation.

RMU is TAMCO ( SF 6 )

After proper back feeding, the

working portion isolated and

earthed as per switching

programme. Issued SFT to

identify, spike and color phasing

the cable. Cancel SFT & confirm

SW/P. Issued PTW to break and


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A400 is Connecting to the 10811

SALWA RD SHML I/D ( VCB – EPE

make )

confirm SW/P. Issued PTW to

make one No. ST. joint for the

cable A400 between the two I/D’s

after the work cancelled PTW.

Issued SFT for P/T and cancelled

SFT confirm SW/ P. After checking

11 KV live phasing, cable A400

commissioned.

07-06-2006

Eng Nizamudeen

Commissioning of 10132 KSW- I/D

in between 4180 (O/ D) and 4160

(O/D) substation.

Commissioned the new I/D and one

local TX (1000 KVA) commissioned

after checking the existing MV

Shifted the load as per switching

programme. Isolated & Earthed the

working section at both end.

Issued SFT for identification, spike

and colour phasing. Cancelled

SFT & confirmed SW/ position.

Issued PTW for 2 Nos. straight


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Extendible type

Commissioned new RMU with an

additional feeder switch.

PTW. Issued SFT , cancelled SFT

& confirm SW/P.11 KV Live

phasing done at 5167 DN- 13 I/D.

13-06-2006

Eng. Nizamudeen

Replacement of Defective RMU at

10313 KR – 6 O/D and to close the

ring with spare cables of 10313 KR-

6 O/D between 9787 KHORE EAST

-5 and 10319 KHORE SOUTH O/D

After MV check and phase rotation

commissioned the s/s and TX’s.

After isolation, applied CME at

both ends. SFT issued for colour

phasing. cancelled SFT , PTW

issued to make 3 Nos ( Break and

make ) termination at 10313 O/D

and for I No. Termination at 9787

O/D and also for one ST joint

between 10319 KR-9 O/D and

120313 O/D. Cancelled the PTW.

Issued SFT for HV P/Test,

Cancelled SFT& confirmed the

SW/ P. Live phasing done at

10320 I/D

14-06-2006 11 KV cable diversion between After load shifting and isolation,


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Progress report on Distribution Protection

18.06.2006

Eng. Shahul

Location- 11456 Villagio -11 I/D

ABB Make numerical relay

Replacement of SPAJ135C by

new high set SPAJ140C for L/TX’s

19.06.2006

With technicians

Pre commissioning test for I/D Attended magnetization test,

Primary injection, Trip circuit

healthy test for breakers

20.06.2006

Eng. Shahul

1.Abu Hamur North PRY

SIEMENS-SIPROTEC-7SJ61

2.Indoor substations

After fault maintenance- Setting

change for feeders

Relay setting change- as per DCC

advice

21.06.2006

With technician

1671- O/D- Industrial area

Old L/TX is 500 KVA

Setting change for L/TX (1000

KVA)

CT Ratio changing

22.06.2006

With technician

Saliya PRY A200 Tripped, Solkor

operated

Solkor decommissioning attended

25-05.2006 to

28.06.2006

NCC Attended routine activities

01.07.2006 Transmission protection Commissioning

69


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Progress report (O &M)

Date Engineer Work Remark Safety

22-05-06 Mr. HAKKIM

Mr. Raju

Replacement of faulty TX4 (Due to oil leak )at

(9649) City Centre -1-1/D

VCB – TAMCO

1.Replacement of faully TX (Due to oil leak)atan O/D substation.

2.Replacement of transformer(BOFP) by aNew TX ( FSFP) at an O/D substation.

VCB – TAMCO

E/S – available for eachcircuit consumer MV panelwith ACB available and REFrealy provided for MV sideprotection.Inter trip for HT isprovided.Before restoringMV side,Checked MVvoltage & Phase rotation

O/D extensible RMU ( oil )Yorkshire type.

Semi Extensible RMU ( Oil).Before restoring MV sidechecked MV voltage &phase rotation.

Operational safety as per

switching programmeinstruction from systemcontrol engineer.

After proper isolation &Earth, issued PTW for Break and make 11 KVtermination.

Operational safety as per SW/ProgrammePTW issued for breakand make HTtermination to New TX.Operational safety as per SW/ProgrammePTW issued for breakand make HTtermination to New TX.

70


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Date Engineer Work Remark Safety

23.05.06

24.05.06

25.05.06

Mr.Rajivkumar

Mr. Hakim

Mr. Raju(Stand by Duty)

NOP shifting programme toLoad DUHAIL PRYsystem operation duty.

1) Rectification of faulty cable by makingstraight joint& charging the cable.(Cable bitween 1036 city BANK s/s I/Dand 5716 O/D )

2)Rectification of faulty cable between (2462 ) SH EID BIN MAD No: 3 s/s andan O/D S/S

Fault restorationSFT & PTW issued for an HT Cablebetween NDC,PRY & an I/D S/S

3nos1/D&5nosO/D Substation visited as apart of NOP shifting.

VCB - EPE, TAMCOOCB - south walesRMU -

Tiger oil switchVCB – AGEStraight jiont fault

Third party damage

NDC, PRY visitedOCB Panel,Co2 Blasters provided for safety

Operation as per systemcontrol ( DCC )switchihng programme.Confirm supply isimportant in each

operation.

Issue SFT for Identification, Spike&Colour phasing .Issue PTW for onetermination & one No:ST joint nearer to 5716O/DIssue SFT for

spike,colour phasing the

cable.Issue PTW for straight

joint the cable

SFT issued for Identification,Spike&Colour phasing. IssuedPTW for 2 Nos stright

joint.

71

27.05.06 Mr. Raju Transformer replacement ( BOFP ) -1000KVABy new one at 725 I/D

Ray Rolle OCBMV Voltage & Phase rotation checkedbefore MV restoration

PTW issued for Break &make 1 No.HTtermination to loop thetransformer


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28.05.06

29.05.06

30.05.06

31.05.06

Mr. Mahmood

Mr. Inose

Mr.Rajivkumar

Mr. Hakkim

11 KV OHL – Maintenance-Redial circuit from ( 9757 ) new Al QayanO/D ( Al Khore lnd.Area)Replacing ABS (S-144 ) , (S- 145) & 8Nos. LA installation at Pole box and PMT

Cable fault Rectification

1.Replacemant of faulty O/D substation(package type) at 4362 O/D – HV P/Testpending

2. SF6 gas pressure Low -Refilling at5484 O/D Substation ( Lucy SF6 )

1.Fault rectification of an HT cablebetween SH . ABDULLA FARM-1 1/Dand pole BoxPole Box termination faulty.

RMU at O/D s/s isSF6 ( TAMCO )

Ray Roll OCB

HV Pressure Test done for new O/Dsubstation.Live phasing done at 2569 1/D. Before the

Live phsing Existing and new phaserotation checked at 2420 O/D.

Checked 11 KV line phasing at 1/D

Over head line involved

transformer.

After isolation &Earthissued PTW to thecompetent person( Before issueing PTW,test OHL,if Dead,Apply

Portable Earth )

Issued SFT for colour phasing the HT cableIssued PTW for making2 No Stright joint for thefaulty cable.

Issued SFT for HVP/Test for the new O/D

subatation.Issued PTW for refillingSF6 Gas at 5484 O/Dsubstation.Issued PTW for MVtermination.

Issued SFT for colour phasing thecable.Tested the OHL,found Dead then appliedthe protableEarth.Issued PTW for

722 Fault restoration 1/D – E/F relay operated

one No. Jumper connection and for raisethe Pole box.Noticed all indication


71/71

01.06.06

2.Fault restorationKHORE A300- tripped at an 1/Dsubstation, the OHL lodial line ( with twoTEE off -circuit ) Total supply failure.Indication - stand by E/F flag ON at PRYand alarm initiated at NCC for both TX

ABU HAMUR WORK SHOP VISIT

2) Fault restorationIndustrial area 1671- MI 1/D

Substation, one TX ( 500KVA ) tripped

on over loadTX -replaced by ( 1000 KV )

1/D E/F relay operatedEFI flagged at one pole Box(Radial TEE-off circuit )

Hands on training on different types of switches ( Oil & SF6 ), VCB & OCB’S

Indication R&B O/C

Noticed all indicationand after proper petrolling found that theearth wire(1 span)snapped in the radialTEE-off circuit.Isolated &earthed the faultyportion. Then charged

the healthy circuit fromthe 1/ D (All Relays andindications resetted.Keptthe relay setting TSMminimum for testcharging.).PTW issuedfor fault rectification.Issued PTWfor transformer replacement.Informedprotection department to

change the relaysettings.

shahnawaz report print

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