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INTRODUCTION:INTRODUCTION:CB CB CTCTCVTCVTLALAWAVE TRAPWAVE TRAPISOLATORSISOLATORS
400kV CURRENT 400kV CURRENT TRANSFORMERTRANSFORMER
CURRENT TRANSFORMERCURRENT TRANSFORMER
I2
I1
PrimaryI1
Secondary I2
Current Transformer :
Kn
n
I
I
I.nI.n
1
2
2
1
2211
Ampere-TurnsConservation
Law
1n
2n
K : Transformation
ratio
TYPES OF CTTYPES OF CT LIVE TANK CT LIVE TANK CT
In 400kV : CGL makeIn 400kV : CGL make
DEAD TANK CT DEAD TANK CT
In 400kV : ABB,BHEL,AREVA makeIn 400kV : ABB,BHEL,AREVA make
TYPE OF DEAD TANK CT:TYPE OF DEAD TANK CT:
Hair pin design.Hair pin design.
Eye bolt design.Eye bolt design.
DEAD TANK & LIVE TANK CTDEAD TANK & LIVE TANK CT
LIVE TANK CTLIVE TANK CT
1. Diaphragm bellows2. CT cores3. HT primary terminal4. Primary conductor assembly5. Head housing6. Core housing7. Porcelain shell8. Bushing tube9. Capacitive grading layer10. Secondary terminal blocks12. Ground pad13. Secondary terminal box14. Base assembly15. Sealing plate
1. Oil filling plug
2. Dome
3. Nitrogen filling valve
4. Collar
5. Primary terminal
6. Porcelain insulator
7. Insulated primary
8. Cover plate for tank
9. Tank
10. Secondary cores
Eye bolt design
EYE BOLT DESIGN : Up to 245kVEYE BOLT DESIGN : Up to 245kV
1. Dome
2. Nitrogen filling valve
3. Primary terminal
4. Collar
5. Porcelain insulator
6. Primary conductor with insulation
7. Adaptor cylinder
8. Secondary cores
9. Base
10. Oil drain plug
HAIR PIN DESIGNHAIR PIN DESIGN
Hair-Pin design
IT 400 Cross section
HERMETIC SEALING:HERMETIC SEALING: Metallic bellows : Metallic bellows : **CT is hermetically sealed by the **CT is hermetically sealed by the
bellows. Oil filled metallic bellows bellows. Oil filled metallic bellows compensates for the oil volume compensates for the oil volume variation due to ambient temperature variation due to ambient temperature changeschanges
Nitrogen gas filled dome.Nitrogen gas filled dome.**The space above the oil is filled with **The space above the oil is filled with
nitrogen which acts as a cushion for nitrogen which acts as a cushion for changes in oil volume due to changes in oil volume due to temperature and load current temperature and load current variations.variations.
**The positive pressure of nitrogen **The positive pressure of nitrogen inside prevents contamination from inside prevents contamination from outside atmosphere, thereby provide outside atmosphere, thereby provide effective hermetical sealing. effective hermetical sealing.
FUNCTION OF CT :FUNCTION OF CT : Converts primary current in to Converts primary current in to
low magnitude secondary low magnitude secondary current for application of current for application of metering & protection metering & protection purposes.purposes.
Five Cores are present in CT Five Cores are present in CT
i) Core 1 & 2 for bus bar i) Core 1 & 2 for bus bar protection.protection.
ii) Core 3 for metering purpose.ii) Core 3 for metering purpose.
iii) Core 4 & 5 for distance iii) Core 4 & 5 for distance protection.protection.
CURRENT TRANSFORMERSCURRENT TRANSFORMERSRATINGSRATINGS
RATED CURRENT WITH EXTENDED RATED CURRENT WITH EXTENDED CURRENT LIMITSCURRENT LIMITS
RATED SHORT TIME CURRENTRATED SHORT TIME CURRENT INSULATION LEVEL.INSULATION LEVEL.NO. OF SECONDARIES.NO. OF SECONDARIES.BURDEN & ACCURACY CLASSBURDEN & ACCURACY CLASS
CT ACCURACIES
As per IEC-60044(1)
Metering Core – ±0.2 or 0.5%at rated Currents
Protection Cores – ± 1% at rated current
METERING COREMETERING CORE
ClassClass 5% of 5% of rated Irated I
20% of 20% of rated Irated I
100% 100% of of
rated Irated I
120% 120% of of
rated Irated I
0.20.2 0.750.75 0.350.35 0.20.2 0.20.2
0.50.5 1.51.5 0.750.75 0.50.5 0.50.5
PROTECTION CORES
ClassClass Current Error Current Error at rated at rated Primary Primary CurrentCurrent
Composite Error Composite Error at rated accuracy at rated accuracy
limit Primary limit Primary CurrentCurrent
5P5P ±1%±1% ±5%±5%
10P10P ±3%±3% ±10%±10%
RATIO & PHASE ERRORRatio Error = (KnIs- Ip)*100/ Ip
Kn = Rated transformation ratioIp = Actual primary currentIs = Actual secondary current
The difference in Phase between the Primary and Secondary current vectors is phase angle error.
Knee Point VoltageKnee Point Voltage10% increase in Voltage will lead to 50% 10% increase in Voltage will lead to 50% or more increase in Current.or more increase in Current.
Current TransformersCurrent TransformersSaturation curveSaturation curve
10 20 30 40
InductionB [T]
Primary currentIp/In
Protection CT
18500 gauss
Metering CT
8000 gauss
INSULATION LEVEL
For Windings having Um greater than 300kV, the rated insulation level is determined by rated switching and lightning impulse withstand voltage
For voltages < 300kV, insulation levels are decided by lightning impulse and power-frequency withstand voltages
System System VoltageVoltage
1 min 1 min Power Power Freq. Freq.
VoltageVoltage
Switching Switching Impulse Impulse
withstand withstand VoltageVoltage
Lightning Lightning Impulse Impulse
withstand withstand VoltageVoltage
220kV220kV 395kV395kV
460kV460kV-- 950kV950kV
1050kV1050kV
400kV400kV 630kV630kV 1050kV1050kV 1425kV1425kV
INSULATION LEVEL
Checks on CTChecks on CT Check for any transit damageCheck for any transit damage Check the nitrogen pressure on the top Check the nitrogen pressure on the top
chamber before commissioning.chamber before commissioning. Check oil level in CT.Check oil level in CT. Attend leakages on bushings immediately.Attend leakages on bushings immediately. Examine the porcelain for dirt deposits & clean Examine the porcelain for dirt deposits & clean
periodically.periodically. Prior to erection confirm the position of P1 & P2 Prior to erection confirm the position of P1 & P2
terminal of primary.terminal of primary.
Checks on CT ….(Contd)Checks on CT ….(Contd) Ensure that the terminals of unloaded Ensure that the terminals of unloaded
secondary are shortedsecondary are shorted Check that tank is earthed positively and Check that tank is earthed positively and
permanently. permanently. Use the lifting lugs provided on the bottom Use the lifting lugs provided on the bottom
tank for lifting the CT by slingstank for lifting the CT by slings Check the level of bellow.Check the level of bellow. Check earthing of star point of secondary at Check earthing of star point of secondary at
relay panel before commissioning of CT.relay panel before commissioning of CT. Check earthing of Tan delta point.Check earthing of Tan delta point. Secondary box cover is closed tightly.Secondary box cover is closed tightly.
Checks on CT Contd..Checks on CT Contd.. Testing of oil after one month of Charging.Testing of oil after one month of Charging. All the CT’s secondary TB’s must be properly All the CT’s secondary TB’s must be properly
tighten at CT’s JB,MB & at relay panel.tighten at CT’s JB,MB & at relay panel. Do not allow dirt and deposits on bushings. Clean Do not allow dirt and deposits on bushings. Clean
periodicallyperiodically Do not leave terminals of unloaded secondary openDo not leave terminals of unloaded secondary open Do not lift the CT by primary terminals or by Do not lift the CT by primary terminals or by
porcelain housing.porcelain housing. Carry out thermovision scanning after Carry out thermovision scanning after
commissioning of CT.commissioning of CT.
CURRENT TRANSFORMERSCURRENT TRANSFORMERSPRECOMMISSIONING TESTSPRECOMMISSIONING TESTS
INSULATION RESISTANCE MEASUREMENTINSULATION RESISTANCE MEASUREMENT CONTINUITY TESTCONTINUITY TEST SECONDARY WINDING RESISTANCESECONDARY WINDING RESISTANCE POLARITY TESTPOLARITY TEST TAN DELTA AND CAPACITANCE MEASUREMENTTAN DELTA AND CAPACITANCE MEASUREMENT CURRENT RATIO TESTSCURRENT RATIO TESTS MAGENTISING CURVES PERFORMANCEMAGENTISING CURVES PERFORMANCE CONTACT RESISTANCE MEASUREMENTCONTACT RESISTANCE MEASUREMENT
CURRENT TRANSFORMERSCURRENT TRANSFORMERSMAINTENANCE MONTHLYMAINTENANCE MONTHLY
CHECK OIL LEAKAGE FROM CTCHECK OIL LEAKAGE FROM CT
CHECKING BELLOW FOR EXPANSIONCHECKING BELLOW FOR EXPANSION
CHECK OIL LEAKAGE FROM SECONDARY CHECK OIL LEAKAGE FROM SECONDARY TERMINALSTERMINALS
CHECKING HEALTHINESS OF GASKETSCHECKING HEALTHINESS OF GASKETS
CURRENT TRANSFORMERSCURRENT TRANSFORMERSMAINTENANCE YEARLYMAINTENANCE YEARLY
CLEANING CLEANING
TIGHTENING OF TERMINAL TIGHTENING OF TERMINAL CONNECTORS AND SECONDARY CONNECTORS AND SECONDARY TERMINALSTERMINALS
THERMOVISION SCANNINGTHERMOVISION SCANNING
CURRENT TRANSFORMERSCURRENT TRANSFORMERSMAINTENANCE 1 YEARLYMAINTENANCE 1 YEARLY
1. TAN DELTA & CAPACITANCE MEASUREMENT1. TAN DELTA & CAPACITANCE MEASUREMENT
ACCEPTABLE LIMIT FOR TAN DELTA 0.007ACCEPTABLE LIMIT FOR TAN DELTA 0.007 INCREASE IN PRE-COMM VALUE AT 0.001 INCREASE IN PRE-COMM VALUE AT 0.001
PER YEAR UPTO 0.007PER YEAR UPTO 0.007 IF VALUE IS BETWEEN 0.007 TO 0.01 THEN IF VALUE IS BETWEEN 0.007 TO 0.01 THEN
HALF YEARLY MONITORINGHALF YEARLY MONITORINGABOVE 0.01 REPLACE THE CTABOVE 0.01 REPLACE THE CT
NITROGEN PRESSURE CHECKING (3 Yearly )NITROGEN PRESSURE CHECKING (3 Yearly )
CAPACITIVE VOLTAGE CAPACITIVE VOLTAGE TRANSFORMERTRANSFORMER
CVTCVT(Measurement of HV)(Measurement of HV)
Capacitor Voltage TransformersCapacitor Voltage TransformersLine protectionLine protectionHF transmissionHF transmission CVT are used to convert higher primary voltage CVT are used to convert higher primary voltage
to lower secondary voltage for the protection & to lower secondary voltage for the protection & metering purpose.metering purpose.
CVT provide least resistance path to higher CVT provide least resistance path to higher frequency signals for PLCC functions.frequency signals for PLCC functions.
CAPACITOR VOLTAGE CAPACITOR VOLTAGE TRANSFORMERTRANSFORMER
Capacitance potential divider connected between phase and ground of power circuit.
CAPACITOR VOLATGE CAPACITOR VOLATGE TRANSFORMERTRANSFORMER
Capacitor STACK(or stack)
Capacitor STACK(or stack)
Assembly of elements to reach higher voltage levels : ± 800 kV
HV Power line
Ground
In general, the termCAPACITOR
stands for a capacitor elementas well as a capacitor stack.
Capacitor Voltage Divider( or CVT )
Capacitor Voltage Divider( or CVT )
Connecting an MV inductive voltage transformer to a tap.
HV Power line
Ground
IntermediateVoltage :
10 to 20 kV/3
S1
S2
P1
P2
C1
C2
CVT CIRCUIT
Capacitor elements
Capacitor column
Insulating oil
Insulator flange
Secondary terminal box
Inductance
MV Transformer
Oil expansion device
Damping circuit
CVT SECONDARY VOLATGECVT Secondary Voltage v = k * V * C1/ (C1+C2)
V – Primary Voltage
k – Secondary Transformation ratioThere are 280 – 300 elements in C1 & C2 C1 will be about 260 to 280 elementsC2 will be 15 to 20 elements
NOTE:Puncturing of C1 – Secondary Voltage will increase
Puncturing of C2 – Secondary Voltage will decrease
SECONDARY VOLATGE
Periodic measurement to be carried out. In case of doubt, simultaneous measurement to be carried out with another feeder/ Bus CVT.
For 400kV CVTs puncturing of one Capacitor element in C1 side is likely to increase Secondary Voltage by about 0.35 – 0.45% (0.22 – 0.28V)
Failure of one Capacitor element in C2 side is likely to decrease Secondary Voltage by 5 – 6% (3.2 – 3.8V)
CVT RATINGCVT RATING
RATED PRIMARY VOLTAGERATED PRIMARY VOLTAGE
RATED SECONDARY VOLTAGERATED SECONDARY VOLTAGE
RATED BURDEN OF CORESRATED BURDEN OF CORES
CAPACITANCE IN pF (FOR CVT ONLY)CAPACITANCE IN pF (FOR CVT ONLY)
CLASS OF ACCURACYCLASS OF ACCURACY
CVTCVTREQUIRMENTSREQUIRMENTS
3 SECONDARIES (2 FOR PROTECTION 3 SECONDARIES (2 FOR PROTECTION AND ONE FOR METERING)AND ONE FOR METERING)
OUTPUT BURDEN 50 VA MINIMUM FOR OUTPUT BURDEN 50 VA MINIMUM FOR EACH SECONDARYEACH SECONDARY
3P ACCURACY CLASS FOR PROTECTION 3P ACCURACY CLASS FOR PROTECTION CORESCORES
0.2 ACCURACY CLASS FOR METERING 0.2 ACCURACY CLASS FOR METERING CORECORE
CVT CVT PRECOMMISSIONING TESTSPRECOMMISSIONING TESTS
INSULATION RESISTANCE MEASUREMENTINSULATION RESISTANCE MEASUREMENT
CONTINUITY OF WINDINGCONTINUITY OF WINDING
SECONDARY WINDING RESISTANCESECONDARY WINDING RESISTANCE
VOLTAGE RATIO TESTVOLTAGE RATIO TEST
TAN DELTA AND CAPACITANCE TAN DELTA AND CAPACITANCE MEASUREMENTMEASUREMENT
CVTCVTMAINTENANCEMAINTENANCE
MONTHLY:MONTHLY: LEAKAGE OF OIL.LEAKAGE OF OIL.QUARTERLY:QUARTERLY: SECONDARY VOLTAGESECONDARY VOLTAGEYEARLY:YEARLY: CHECKING OF EARTHING OF HF POINTCHECKING OF EARTHING OF HF POINT
DAMAGE TO BUSHING OF HF POINTDAMAGE TO BUSHING OF HF POINT
CLEANING OF PORCELAIN INSULATOR STACKS AND CLEANING OF PORCELAIN INSULATOR STACKS AND TIGHTNESS OF TERMINAL CONNECTORTIGHTNESS OF TERMINAL CONNECTOR
THERMOVISION SCANNINGTHERMOVISION SCANNING
CHECKING OF NEUTRAL EARTHINGCHECKING OF NEUTRAL EARTHING3 YEARLY3 YEARLYTAN DELTA MEASUREMENTTAN DELTA MEASUREMENT
CHECKS FOR CVT CHECKS FOR CVT
Check for any transit damage.Check for any transit damage.Check oil level in EMU Unit.Check oil level in EMU Unit.Check leakages on CVT .Check leakages on CVT .Examine the capacitor porcelain for Examine the capacitor porcelain for
dirt deposits and clean periodically on dirt deposits and clean periodically on de-energized and safely earthed CVT.de-energized and safely earthed CVT.
Check that the primary and secondary Check that the primary and secondary terminal box covers are in position terminal box covers are in position and sealed properly.and sealed properly.
II
CHECKS FOR CVT CHECKS FOR CVT Check NHF point is earth when not used for Check NHF point is earth when not used for
PLCC.PLCC.Check all the secondary wiring connections Check all the secondary wiring connections
are tightly secured at the terminal box.are tightly secured at the terminal box.Units must be short circuited with a bare Units must be short circuited with a bare
wire between head & bottom flange until wire between head & bottom flange until erection and connections are completed.erection and connections are completed.
The Tank of CVT should be earthed properly.The Tank of CVT should be earthed properly.Regularly monitor secondary voltage of Regularly monitor secondary voltage of
CVT’s w.r.t each other to identify any CVT’s w.r.t each other to identify any discrepancy in CVT secondary voltage.discrepancy in CVT secondary voltage.
II
CAUTIONS FOR CVT CAUTIONS FOR CVT Never keep the units horizontally.Never keep the units horizontally.Do not energized CVT from the Do not energized CVT from the
secondary side.secondary side.Discharge CVT prior to climbing.Discharge CVT prior to climbing.While removing connector from the While removing connector from the
CVT ensure local earthing on CVT ensure local earthing on conductor as well as on CVT.conductor as well as on CVT.
SURGE ARRESTORSURGE ARRESTOR
SURGE ARRESTORSSURGE ARRESTORS
PROTECTS SUBSTATION EQUIPMENTS PROTECTS SUBSTATION EQUIPMENTS FROM TRANSIENT OVERVOLTAGES FROM TRANSIENT OVERVOLTAGES
CONNECTED BETWEEN PHASE AND EARTH CONNECTED BETWEEN PHASE AND EARTH
PROVIDES LOW RESISTANCE PATH TO PROVIDES LOW RESISTANCE PATH TO EXCESSIVE HIGH VOLTAGE.EXCESSIVE HIGH VOLTAGE.
RATING IN PHASE TO EARTH VOLTAGERATING IN PHASE TO EARTH VOLTAGE
SURGE ARRESTORSSURGE ARRESTORS
GAPPED SILICON CARBIDE SURGE GAPPED SILICON CARBIDE SURGE ARRESTORSARRESTORS
GAPLESS ZINC OXIDE ARRESTORS GAPLESS ZINC OXIDE ARRESTORS
(PREFERRED THESE DAYS DUE TO HIGHER (PREFERRED THESE DAYS DUE TO HIGHER ENERGY ABSORPTION CAPABILITIES) ENERGY ABSORPTION CAPABILITIES)
MADE OF SMALL DISCS OF NON-MADE OF SMALL DISCS OF NON-LINEAR RESISTANCE MATERIAL ZnO LINEAR RESISTANCE MATERIAL ZnO WHICH PROVIDES LEAST RESISTANCE WHICH PROVIDES LEAST RESISTANCE PATH DURING SWITCHING SURGES OR PATH DURING SWITCHING SURGES OR LIGHTENING STROKELIGHTENING STROKE
ARRESTER ARRESTER FUNDAMENTALFUNDAMENTAL
Need for High Resistance to limit Discharge Current
Need Low Resistance during flow of lightning current to limit Surge Voltage A non-linear resistance material required
EQUIVALENT CIRCUIT OF SURGE EQUIVALENT CIRCUIT OF SURGE ARRESTERARRESTER
Concept of Leakage Current
Resistive Current
In phase with voltage
Increase with temperature
Increase with aging
Capacitive Current
In 90 Deg phase with voltage
Insignificant change with temperature and voltage
does not affect due to aging
SURGE ARRESTORSSURGE ARRESTORSPRE-COMMISSIONING TESTSPRE-COMMISSIONING TESTS
INSULATION RESISTANCE INSULATION RESISTANCE MEASUREMENTMEASUREMENT
LEAKAGE CURRENT MEASUREMENTLEAKAGE CURRENT MEASUREMENT
SURGE COUNTER CHECKSURGE COUNTER CHECK
SURGE ARRESTORSSURGE ARRESTORSMAINTENANCE YEARLYMAINTENANCE YEARLY
CLEANING CLEANING
LEAKAGE CURRENT MEASUREMENTLEAKAGE CURRENT MEASUREMENT
SURGE COUNTER CHECKSSURGE COUNTER CHECKS
WAVE TRAPWAVE TRAP
LINE TRAPLINE TRAP
LINE TRAP OFFER HIGH RESISTANCE LINE TRAP OFFER HIGH RESISTANCE TO HIGH FREQUENCY PLCC SIGNAL TO HIGH FREQUENCY PLCC SIGNAL AND LOW RESISTANCE TO POWER AND LOW RESISTANCE TO POWER FREQUENCY SIGNAL.FREQUENCY SIGNAL.
BLOCKING FREQUENCY RANGE WITH BLOCKING FREQUENCY RANGE WITH COMBINATION OF INDUCTANCE AND COMBINATION OF INDUCTANCE AND CAPACITANCE : 50Khz TO 500Khz.CAPACITANCE : 50Khz TO 500Khz.
COMPRISES OF INDUCTOR,TUNNING COMPRISES OF INDUCTOR,TUNNING CIRCUIT,LA.CIRCUIT,LA.
LINE TRAPSLINE TRAPSRATINGSRATINGS
INDUCTANCE IN MhINDUCTANCE IN Mh
RATED CURRENTRATED CURRENT
BLOCKING BANDWIDTHBLOCKING BANDWIDTH
Checks for Wave trap.Checks for Wave trap.
Tuning circuit and arrestor are Tuning circuit and arrestor are properly tightened.properly tightened.
Connectors are properly tightened.Connectors are properly tightened.Bird Guards are properly fixed.Bird Guards are properly fixed.Check for any physical damage.Check for any physical damage.
LINE TRAPSLINE TRAPSPRE-COMMISSIONING TESTSPRE-COMMISSIONING TESTS
INSULATION RESISTANCE INSULATION RESISTANCE MEASUREMENTMEASUREMENT
CONTACT RESISTANCE CONTACT RESISTANCE MEASUREMENTMEASUREMENT
LINE TRAPS MAINTENANCELINE TRAPS MAINTENANCEYEARLY CHECKSYEARLY CHECKS
TIGHTNESS & CLEANLINESS OF LINE TIGHTNESS & CLEANLINESS OF LINE TRAP INCLUDING TUNING UNITTRAP INCLUDING TUNING UNIT
TIGHTNESS OF TERMINAL TIGHTNESS OF TERMINAL CONNECTORCONNECTOR
ISOLATORSISOLATORS
Operate under no load condition.Operate under no load condition. Isolate the zone which is under Isolate the zone which is under
maintenance.maintenance.Three types of Isolators :Three types of Isolators :
A) Pantograph.A) Pantograph.
B) Horizontal center break.B) Horizontal center break.
C) Double Break.C) Double Break.
TYPE OF ISOLATORS BASED ON TYPE OF ISOLATORS BASED ON LOCATION OF USELOCATION OF USE
Line IsolatorLine IsolatorBus IsolatorBus IsolatorReactor IsolatorReactor IsolatorTransformer IsolatorTransformer Isolator
TYPE OF ISOLATORS BASED TYPE OF ISOLATORS BASED ON E/SON E/S
Without Earthswitch (Used where Without Earthswitch (Used where earthing is not required)earthing is not required)
With one Earthswitch (Commonly With one Earthswitch (Commonly used for earthing the equipment for used for earthing the equipment for which Isolator has been provided)which Isolator has been provided)
With two earth switch (Generally With two earth switch (Generally used for Bus earthing)used for Bus earthing)
Checks on IsolatorsChecks on Isolators
Proper alignment.Proper alignment.Proper fixing of limit switch.Proper fixing of limit switch.Proper closing of Isolators to avoid hot Proper closing of Isolators to avoid hot
spot.spot.Check mechanical/electrical interlock.Check mechanical/electrical interlock.Ensure twin earthing of Isolator MB.Ensure twin earthing of Isolator MB.Proper closing of Isolators MB.Proper closing of Isolators MB.
HCB ISOLATORSHCB ISOLATORS
HCB ISOLATORS—MAIN HCB ISOLATORS—MAIN CONTACTSCONTACTS
DOUBLE BREAK ISOLATORSDOUBLE BREAK ISOLATORS
DB ISOLATOR---CENTRAL ROTATING DB ISOLATOR---CENTRAL ROTATING STACK STACK
DB ISOLATOR--CONTACTSDB ISOLATOR--CONTACTS
PANTOGRAPH ISOLATORPANTOGRAPH ISOLATOR
PANTOGRAPH ISOLATOR--PANTOGRAPH ISOLATOR--CONTACTSCONTACTS
Checks on Isolators…Checks on Isolators…
Ensure proper position of NO/NC contact Ensure proper position of NO/NC contact in closed & open condition of Isolators.in closed & open condition of Isolators.
Apply grease regularly in Gear box.Apply grease regularly in Gear box.Check pole discrepancy function is Check pole discrepancy function is
working properly.working properly.
ISOLATORS AND E/SISOLATORS AND E/SPRECOMMISSIONING TESTSPRECOMMISSIONING TESTS
INSULATION RESISTANCE MEASUREMENTINSULATION RESISTANCE MEASUREMENT
INTERLOCKS CHECKINGINTERLOCKS CHECKING
OPERATING TIMEOPERATING TIME
AUXILIARY CONTACT CHECKINGAUXILIARY CONTACT CHECKING
CONTACT RESISTANCE MEASUREMENTCONTACT RESISTANCE MEASUREMENT
ISOLATORS AND E/SISOLATORS AND E/SMAINTENANCEMAINTENANCE
CLEANING & LUBRICATIONCLEANING & LUBRICATION
TIGHTENINGTIGHTENING
ALIGNMENTALIGNMENT
CONTACT RESISTANCE MESUREMENT CONTACT RESISTANCE MESUREMENT (ONCE IN A 4 YEARS)(ONCE IN A 4 YEARS)
THANK YOUTHANK YOU