Condition based MaintenanceCondition based Maintenance

Condition based MaintenanceCondition based Maintenancenn ConditionCondition--based maintenance (CBM), shortly based maintenance (CBM), shortly

described, is maintenance described, is maintenance whenwhen need need arisesarises.i.e..i.e. to maintain the correct equipment at to maintain the correct equipment at the right time. This maintenance is performed the right time. This maintenance is performed after one or more indicators show that after one or more indicators show that equipment is going to fail or that equipment equipment is going to fail or that equipment performance is deteriorating.performance is deteriorating.equipment is going to fail or that equipment equipment is going to fail or that equipment performance is deteriorating.performance is deteriorating.

nn CBM primarily uses non destructive testing CBM primarily uses non destructive testing techniques,visual inspection & performance techniques,visual inspection & performance data to assess machinery condition thus data to assess machinery condition thus replacing arbitarily timed maintenance tasks replacing arbitarily timed maintenance tasks with appropriate maintenance tasks at only with appropriate maintenance tasks at only when warranted by equipment condition.when warranted by equipment condition.

Advantages of CBM over Preventive Advantages of CBM over Preventive maintenance & Corrective maintenancemaintenance & Corrective maintenance

nn CBM identifies incipient faults before they become CBM identifies incipient faults before they become critical, thus enabling more accurate planning of critical, thus enabling more accurate planning of preventive maintenance.preventive maintenance.

nn CBM enables the user to take maximum CBM enables the user to take maximum advantage of useful life of a component such as advantage of useful life of a component such as bearing because the equipment can be left in bearing because the equipment can be left in bearing because the equipment can be left in bearing because the equipment can be left in service if it meets the desired performance service if it meets the desired performance standards.standards.

nn Decreased number of maintenance operations Decreased number of maintenance operations causes a reduction of human error influences causes a reduction of human error influences

nn Decreased maintenance costs Decreased maintenance costs

Comparison of CBM,Preventive maintenance & Comparison of CBM,Preventive maintenance & Corrective maintenanceCorrective maintenance

General Condition Monitoring categoriesGeneral Condition Monitoring categoriesnn Temperature measurements (e.g. temperature Temperature measurements (e.g. temperature

recording with the help of laser gun , thermography) recording with the help of laser gun , thermography) helps detect potential failures related to a helps detect potential failures related to a temperature change in equipment. Measured temperature change in equipment. Measured temperature can indicate problems such as excessive temperature can indicate problems such as excessive mechanical friction (e.g. faulty bearings, inadequate mechanical friction (e.g. faulty bearings, inadequate lubrication), degraded heat transfer (e.g. fouling in lubrication), degraded heat transfer (e.g. fouling in heat exchanger) & poor electrical connections (e.g. heat exchanger) & poor electrical connections (e.g. loose corroded or oxidized connections).loose corroded or oxidized connections).heat exchanger) & poor electrical connections (e.g. heat exchanger) & poor electrical connections (e.g. loose corroded or oxidized connections).loose corroded or oxidized connections).

nn Dynamic Monitoring (e.g. signature analysis of Dynamic Monitoring (e.g. signature analysis of vibration)vibration)

nn Oil Analysis: e.g. Oil analysis (e.g. ferrography, Oil Analysis: e.g. Oil analysis (e.g. ferrography, particle counter testing) particle counter testing) --indicates problems such as indicates problems such as machine degradation, oil contamination ,improper oil machine degradation, oil contamination ,improper oil consistency & oil deterioration. Oil analysis falls into 4 consistency & oil deterioration. Oil analysis falls into 4 main areas: main areas:

ØØ a) fluid physical properties(viscisity,appearance).a) fluid physical properties(viscisity,appearance).ØØ Fluid chemical properties (Viscosity, appearance)Fluid chemical properties (Viscosity, appearance)

General Condition Monitoring categoriesGeneral Condition Monitoring categories

ØØ Fluid contamination (ISO cleanliness, ferroraphy)Fluid contamination (ISO cleanliness, ferroraphy)ØØ Machine Health (wear metals associated with plant Machine Health (wear metals associated with plant

components)components)qq Nondestructive Testing: NDT involves performing Nondestructive Testing: NDT involves performing

tests (e.g. xtests (e.g. x--ray, ultrasonic)ray, ultrasonic)qq Electrical Testing & Monitoring: e.g. power signature Electrical Testing & Monitoring: e.g. power signature

analysis, high potential testinganalysis, high potential testing--involve measuring involve measuring Electrical Testing & Monitoring: e.g. power signature Electrical Testing & Monitoring: e.g. power signature analysis, high potential testinganalysis, high potential testing--involve measuring involve measuring changes in system properties such as resistance changes in system properties such as resistance ,conductivity,conductivity--helps detect electrical insulation helps detect electrical insulation deterioration, broken motor rotor bars.deterioration, broken motor rotor bars.

qq Observation & Surveillance: Visual, audio & touch Observation & Surveillance: Visual, audio & touch inspectionsinspections

qq Performance Monitoring: Monitoring changes in Performance Monitoring: Monitoring changes in variables such as pressure,temperature,flow variables such as pressure,temperature,flow rate,electrical power consumptionrate,electrical power consumption

Condition Based Maintenance task intervalsCondition Based Maintenance task intervals

nnCBM task intervals must be properly CBM task intervals must be properly understood & should be determined based on understood & should be determined based on expected Pexpected P--F interval i.e. Potential failureF interval i.e. Potential failure--Functional failure interval.Functional failure interval.

Condition Based Maintenance task intervalsCondition Based Maintenance task intervals

nn CBM task intervals must be determined based on CBM task intervals must be determined based on the expected Pthe expected P--F interval. Following sources may F interval. Following sources may be referred to as an aid to determine Pbe referred to as an aid to determine P--F F interval:interval:

ØØ Expert opinion & judgments (i.e. manufacturer’s Expert opinion & judgments (i.e. manufacturer’s recommendations)recommendations)recommendations)recommendations)

ØØ Published information about condition Published information about condition ––monitoring tasks.monitoring tasks.

ØØ Historical data (e.g. current condition Historical data (e.g. current condition ––monitoring task intervals)monitoring task intervals)

qq Initial CM task intervals:Initial CM task intervals:--i) If existing CM task i) If existing CM task interval has proved effectiveinterval has proved effective--use it. ii) If using use it. ii) If using existing CM task interval failure has occurred existing CM task interval failure has occurred lower the interval.lower the interval.

Condition Monitoring Practices

for

Critical EquipmentsCritical Equipments

BBGS

Major AreasMajor Areas

nn Lubricating oil Lubricating oil nn Transformer oil Transformer oil nn Process Parameter Monitoring of Process Parameter Monitoring of nn Process Parameter Monitoring of Process Parameter Monitoring of

Boiler and Boiler and nn Circuit breakersCircuit breakersnn Rotating equipments like all load Rotating equipments like all load

bearing pumps and fansbearing pumps and fansnn SwitchyardSwitchyard

Type of test

Major Eqp / oil

Population of m/c

Freq. of

testing

Testing agency

Data owners

hipReporting

Moisture & TAN

TG lube oil 3 Monthly

In-house BBGS Ops Home PageBFP oil 7 Monthly

Draught fans oil 16 180oil 16 180

FRF 3 Weekly

WDA, moisture,

TAN, viscosity

TG lube oil 3

Six monthly

IIPM BBGS Ops

Report of M/s IIPM is kept in Dy Mgr Ops room.

FRF 3

HP LP bypass 3

BFP oil 6

Draught fans oil 16

Coal mills 17

Type of test Major Eqp

Population of m/c

Freq. of

testing

Testing agency

Data ownershi

pReporting

BDV, Neutralization factor, Moisture content, Specific

resistance, Interfacial tension,

Flash point, Tan delta, Sludge content, DGA

GT 7

2 years Shanthala BBGS -EMD Home page

ST, UT 3 each

CHT 6

BDV,Moisture, Acidity 180 days In-house BBGS -EMD Home Page

AHT, CTT 4 each

WST,DMT, IAPAT, IWT 2 each

HCSS 1ESP 62

Tan Delta132 KV

Switchyard all CT,PT

96 5 years T/D BBGS -EMD Home Page

DGA132 KV

Switchyard all CT,PT

96 5 years Shanthala BBGS -EMD Home Page

Type of test Major Eqp

Population of m/c

Freq. of testing

Testing agency

Data ownership Reporting

Combustible Analysis

Fly Ash and

Bottom Ash

3 7 days Lab BBGS -Ops. Home Page.

PF Grading Coal Mill 17 15 days Lab BBGS -Ops. Home Page.

CT and Condenser

performance test3

Bi-annual. (Apr to

In house -Ops BBGS -Ops.

performance test(Apr to Sep.)

Ops

Boiler efficiency test

3 3 months interval

In house -Ops BBGS -Ops.

Corrosion measurement

(CT/CW) 3 Monthly Chembond BBGS -Ops.

Corrosion measurement

(DMCW) 3 Quaterly Chembond BBGS -Ops.

Major Equipment Populatio

n of machines

Frequency of

reading

Measuring Equipmen

ts used

Mode of reading Agency

Report Generatio

n

Cooling Tower Fan 52 Monthly

PA Fan 6 Monthly

Coal Mill 17 Monthly

SKF Analyzer

Frequency based

vibration measurement and analysis

Under AMC of M/s SKF

Report submitted

by M/S SKF.

Available in Home

Page.

SA Fan 8 Monthly

CEP 6 Monthly

Compressors 20 Monthly

FD Fan 6 Monthly

Rotary Breaker 2 Monthly

DMCW Pp. 12 Bimonthly

BFP 7 Bimonthly

CW Pp. 7 Bimonthly

ACW Pp. 6 Bimonthly

ID Fan 8 Bimonthly

SlSl NoNo Readings taken inReadings taken in

ISO 10816ISO 10816StandardsStandards

Velocity (mm/sec) in RMSVelocity (mm/sec) in RMS

Present Present VibrationVibrationVelocityVelocityMm/secMm/sec

Health Health ConditionCondition

NormalNormal AlertAlert AlarmAlarm

11 < 4.5< 4.5 4.5 4.5 --11.211.2 >11.2>11.2

FEB FEB -- 20112011 14.214.2 AlarmAlarmMARCH MARCH --2011 (Decoupled 2011 (Decoupled Reading) Reading) 1.51.5 NormalNormalReading) Reading) 1.51.5 NormalNormal

MARCH MARCH --20112011 20.420.4 AlarmAlarm

Action Plan: Suggested by SKFCheck the pump impeller for unbalance issue & for proper clearance in its casing.Check the pump shaft for bend or eccentricity issue. Check the pump shaft bushes for proper fitment & in proper condition.Also check the internal clearance of the pump bearing & for defects with respect to the raceways & if required replace them.Also once verify the alignment between motor & pump.

MMD’s Observation : Bend shaft , impeller unbalance and damage to all the bushes.

Location of test Freq. of testing

Testing agency

Testing M/c

Reporting

Thermal insulation checking for Boiler

casing, steam piping Turbine casing

Pre-survey and post survey

In house –Planning

Dept

IR Gun / FLIR IR Camera

Report is submitted to MMD for corrective

action.

In house – IR Gun / Report is submitted

High energy drains valves and steam traps

Pre-survey and post survey

In house –Planning

Dept

IR Gun / FLIR IR Camera

submitted to MMD for corrective

action

Outdoor Electrical switch yard joints and

connectors.

Pre-survey and post survey

In house –Planning

Dept

FLIR IR Camera

Report is submitted to EMD for corrective

action

Type of test Major Eqp

Population of m/c

Freq. of testing

Testing

agency

Data ownershi

pReporting

Bearing health monitoring of load bearing

motors

Vital motors

Partial Discharge Important

Equipment arrived recently (Ultraprobe10000). Implementation planning in

progress.

Partial Discharge Monitoring in

Electrical Boards

Important HT and LT

boards

Partial Discharge Monitoring of 132KV/220KV

CT, PT

All

Partial Discharge Monitoring in transformers

(Dry, Oil filled)

All

ElectroElectrostatic static CleaniCleani

ngng

Coal millsCoal mills 1717

ELC m/c ELC m/c remains remains

always ON. always ON.

Turbine Turbine MOTMOT

33

WTWT--1,SAC1,SAC 22

Present Status

Continuous running of ELC machines in coal mills have resulted in :

Reduced wear and tearReduced oil consumption (Earlier oil had to be replaced after every two

months, at present done only after running for 10000 hrs) Less maintenanceHigher availabilityPlan is to fit the same in all ID/FD/PA gearboxes. Already fitted in FD-3A and PA-3A.

Sample ELC test certificateSample ELC test certificate

Transformer OilTransformer Oil

§§ The following tests are carried out on Transformer Oil of GT (1 The following tests are carried out on Transformer Oil of GT (1

& 2), UT (1 & 2) and ST (1 & 2) once a year by CPRI / Shanthala: & 2), UT (1 & 2) and ST (1 & 2) once a year by CPRI / Shanthala:

-- BDV, Neutralisation factor, Moisture content, Specific BDV, Neutralisation factor, Moisture content, Specific

resistance, Interfacial tension, Flash point, Tan delta at 90resistance, Interfacial tension, Flash point, Tan delta at 90°°C, C, resistance, Interfacial tension, Flash point, Tan delta at 90resistance, Interfacial tension, Flash point, Tan delta at 90°°C, C,

Sludge content, DGA Sludge content, DGA

§§ BDV, Moisture and acidity of the following transformers are BDV, Moisture and acidity of the following transformers are

carried out incarried out in--house bihouse bi--annuallyannually-- SATs, UATs, CHTs, ACTs, CWLTs, AHTs, and ESP SATs, UATs, CHTs, ACTs, CWLTs, AHTs, and ESP

TransformersTransformers

Audiometric studyAudiometric study

§§ Audio metric study at different zones of the boilers of both Audio metric study at different zones of the boilers of both

the units is carried once every week.the units is carried once every week.

§§ This study is primarily carried out to preempt any boiler tube This study is primarily carried out to preempt any boiler tube §§ This study is primarily carried out to preempt any boiler tube This study is primarily carried out to preempt any boiler tube

leak.leak.

§§ All records are maintained and studied for and deviation. All records are maintained and studied for and deviation.

§§ Any increase in noise level by 5 dB is investigated.Any increase in noise level by 5 dB is investigated.

Illumination StudyIllumination Study

§§ Illumination at different pre defined spots covering the entire Illumination at different pre defined spots covering the entire

station is checked once every month.station is checked once every month.

All data obtained from the checking are tabulated and reports All data obtained from the checking are tabulated and reports §§ All data obtained from the checking are tabulated and reports All data obtained from the checking are tabulated and reports

published.published.

§§ Corrective action are taken based on the reports.Corrective action are taken based on the reports.

Case studies on failure analysisCase studies on failure analysis1) Vibration analysis of Fans & pumps:

üReduced excessive vibration with SKF CMXA 70 Analyzer in SA Fan 1A-Seal Air Fan.Issue: High vibration observed of around 8.1 mm/sec Issue: High vibration observed of around 8.1 mm/sec at Motor bearing. Spectrum analysis reveals at Motor bearing. Spectrum analysis reveals misalignment between drives and bearing inaccuracies misalignment between drives and bearing inaccuracies observed in fan bearing. observed in fan bearing. observed in fan bearing. observed in fan bearing. Solution: SA Fan for maintenance during a planned Solution: SA Fan for maintenance during a planned shut down and precision alignment done between shut down and precision alignment done between drives and vibration come down to 2.2 mm/sec.drives and vibration come down to 2.2 mm/sec.üüReduced excessive vibration with SKF CMXA 70 Reduced excessive vibration with SKF CMXA 70 Analyzer in DMCW Pump Analyzer in DMCW Pump --3A3AIssue :High vibration observed of around 8.3 mm/sec Issue :High vibration observed of around 8.3 mm/sec at Pump NDE bearing. Spectrum analysis revels at Pump NDE bearing. Spectrum analysis revels looseness at Pump baselooseness at Pump base

Case studies on failure analysisCase studies on failure analysisfixing location along with rotational looseness observed fixing location along with rotational looseness observed

at Pump DE & NDE bearing. at Pump DE & NDE bearing. Solution: Tighten the Pump base fixing location and Solution: Tighten the Pump base fixing location and

tighten the Pump DE & NDE bearing sleeve and tighten the Pump DE & NDE bearing sleeve and vibration come down to 2.8 mm/sec. vibration come down to 2.8 mm/sec.

2) 2) Thermography study of high energy drainsThermography study of high energy drains::--upstream & down steam temperature of high energy upstream & down steam temperature of high energy motorized drain valve are measured to ascertain motorized drain valve are measured to ascertain upstream & down steam temperature of high energy upstream & down steam temperature of high energy motorized drain valve are measured to ascertain motorized drain valve are measured to ascertain passing of valves. Valves if found passing the passing of valves. Valves if found passing the upstream manual isolating valves are kept upstream manual isolating valves are kept closed.closed.Thermography 12Thermography 12--1313\\MC_drain_2013_2.xlsMC_drain_2013_2.xls

3) 3) Infra red thermography study of hot spots on grid: Infra red thermography study of hot spots on grid: Infrared Thermography is the science of acquisition Infrared Thermography is the science of acquisition and analysis of thermal information by using non and analysis of thermal information by using non contact thermal imaging devices. The Infrared contact thermal imaging devices. The Infrared THERMOGRAPHY locates the Hot Spots in Grids thus THERMOGRAPHY locates the Hot Spots in Grids thus making possible elimination of root making possible elimination of root

Case studies on failure analysisCase studies on failure analysiscause of abnormalities. This process resulted in cause of abnormalities. This process resulted in reduction of hot spots & inadvertent network tripping. reduction of hot spots & inadvertent network tripping. It has become important because of following : It has become important because of following : 1. 1. It It is nonis non--contact contact ––uses remote sensing; 2. It is two uses remote sensing; 2. It is two dimensional ;3. It is real time; dimensional ;3. It is real time; nnIn BBGS we carry out IRT by In BBGS we carry out IRT by numbering each and every joint in our 132 KV numbering each and every joint in our 132 KV ••numbering each and every joint in our 132 KV numbering each and every joint in our 132 KV switchyard , so that we can easily identify any switchyard , so that we can easily identify any joint;joint;Thermography1Thermography1\\SLD 132kv Feeder Bay.docSLD 132kv Feeder Bay.doc•• We carry out thermography of every point , after We carry out thermography of every point , after ensuring that the point is carrying load. ensuring that the point is carrying load. ••We keep a record of temperatures of all points so that We keep a record of temperatures of all points so that we have a historywe have a history••We save images for points which are having hot spotsWe save images for points which are having hot spots

The THERMOGRAPHY program The THERMOGRAPHY program

Temperature Temperature measuredmeasured CategoryCategory ActionsActions

<70<7000 CC NormalNormal Keep monitoringKeep monitoring

Preventive Maintenance: Rectification of identified HOT SPOT

707000 C<**<100C<**<10000 CC AlarmAlarmSchedule Schedule

Preventive Preventive MaintenanceMaintenance

>100>10000 CC CriticalCritical Immediate actionImmediate action

Thermographic assessment of Busbar Condition

Tests are done to identify looseness in joints which cause

huge heat loss and result premature breakdownpremature breakdown

After necessary maintenance the same IR Thermography was taken and the results are shown

Case study Case study --1 (Before Survey)1 (Before Survey)Drg No: 61Drg No: 61 Bay:Bay: GTGT--22 SLD Point SLD Point

No:No:2020

Location:Location:

YY--Phase Isolator Phase Isolator pad to 3” IPS ( pad to 3” IPS (

flexibleflexible ))

Max Temp:Max Temp:220 220 °° CC

Action On:Action On: 06.01.1006.01.10Action On:Action On: 06.01.1006.01.10

Action taken:Action taken:

ØØCopper flexible connectors Copper flexible connectors were found to be prone to were found to be prone to temperature rise due to temperature rise due to sulfation at the contact area sulfation at the contact area between Al and Cu although bi between Al and Cu although bi metallic strip was present, metallic strip was present, resulting in high resistance, resulting in high resistance, heating and pit marks so heating and pit marks so Copper Connectors were Copper Connectors were replaced with AL flexible replaced with AL flexible connectors.connectors.

Case study (After Survey)Case study (After Survey)

Drg No: 62Drg No: 62 Bay:Bay: GTGT--22 SLD Point SLD Point No:No:

2020

Location:Location:

29A B29A B--Phase Phase Isolator pad to 3” Isolator pad to 3”

IPS ( flexible )IPS ( flexible )

Max Max Temp:Temp: 43.6 43.6 °° CCTemp:Temp: 43.6 43.6 °° CC

Action Action On:On:

16.02.1016.02.10

Analysis:Analysis:

It was observed that the It was observed that the abnormal temperature abnormal temperature rise in this case was due rise in this case was due to mismatch in ALto mismatch in AL--Cu Cu joint.joint.

Maintenance Planning & OptimizationMaintenance Planning & Optimization

üü In BBGS we follow a Routine maintenance schedule In BBGS we follow a Routine maintenance schedule which are periodically reviewed & changed based which are periodically reviewed & changed based on feed back received from checklists of previous on feed back received from checklists of previous R/Ms.R/Ms.

üü For carrying out Routine maintenance we have a For carrying out Routine maintenance we have a schedule & accordingly planning department schedule & accordingly planning department schedule & accordingly planning department schedule & accordingly planning department convenes planning meeting everyday in the convenes planning meeting everyday in the afternoon ,where personnel from OPS & afternoon ,where personnel from OPS & Maintenance departments meet & chalk out plan Maintenance departments meet & chalk out plan for maintenance of equipments to be carried out in for maintenance of equipments to be carried out in the next day. the next day. maintenance planning meeting.docmaintenance planning meeting.doc

üü By following the above mentioned procedure we By following the above mentioned procedure we are able to reduce unscheduled disruptions and are able to reduce unscheduled disruptions and technical breakdowns thus ensuring equipment technical breakdowns thus ensuring equipment availability above 96%.availability above 96%.

Capital overhaulCapital overhaul

vvMeticulous planning is done before every capital Meticulous planning is done before every capital overhaul, to minimize cost involvement & down overhaul, to minimize cost involvement & down time of equipments.time of equipments.

vv Planning for annual overhauling referred to as Planning for annual overhauling referred to as Survey is done based on feedback received from Survey is done based on feedback received from Survey is done based on feedback received from Survey is done based on feedback received from OPS department & from previous R/M checklists.OPS department & from previous R/M checklists.

vv Details of execution on hourly basis is planned Details of execution on hourly basis is planned involving the contractors who will be actually involving the contractors who will be actually carrying out the job. carrying out the job. unit1 2012_Survey plan.xlsunit1 2012_Survey plan.xls