generator & transformer protection

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GENERATOR & TRANSFORMER GENERATOR & TRANSFORMER PROTECTIONPROTECTION

ELECTRICAL MAINTENANCE DEPARTMENTELECTRICAL MAINTENANCE DEPARTMENT

BYBY

K JACOB K JACOB JOSEJOSE

CLASSES OF PROTECTIONCLASSES OF PROTECTION

•CLASS A1CLASS A1

•CLASS A2CLASS A2

•CLASS BCLASS B

•CLASS CCLASS C

GROUPS OF PROTECTIONGROUPS OF PROTECTION

• Group-1 – Group-1 – DC source 1 from 1/2 FA DC source 1 from 1/2 FA section-1section-1

• Group-2 – Group-2 – DC source 2 from 1/2 FA DC source 2 from 1/2 FA section-2section-2

• In case of any In case of any DC supply failureDC supply failure in GRP in GRP inform Electrical Maintenance inform Electrical Maintenance immediatelyimmediately

CLASS A1CLASS A1

CAUSES OF CLASS A1CAUSES OF CLASS A1

1. GT & UT PROTECTIONS1. GT & UT PROTECTIONS

2. GENERATOR BACKUP PROTECTION2. GENERATOR BACKUP PROTECTION

3. OTHER BACKUP PROTECTIONS3. OTHER BACKUP PROTECTIONS

CLASS A1 – CAUSES – CLASS A1 – CAUSES – TRANSFORMER PROTECTIONSTRANSFORMER PROTECTIONS

TRANSFORMER PROTECTIONS-MECHANICALTRANSFORMER PROTECTIONS-MECHANICAL

• PRVPRV• BUCHHOLZ RELAYBUCHHOLZ RELAY• SUDDEN PRESSURE RELAYSUDDEN PRESSURE RELAY• FIRE PROTECTIONFIRE PROTECTION• UT OLTC SUDDEN PRESSURE RELAYUT OLTC SUDDEN PRESSURE RELAY

Note: UT A/B WTI/OTI will trip the Note: UT A/B WTI/OTI will trip the corresponding incomer from the transformer corresponding incomer from the transformer and change over to Standby Trf.and change over to Standby Trf.

CLASS A1 – CAUSES – CLASS A1 – CAUSES – TRANSFORMER PROTECTIONSTRANSFORMER PROTECTIONS

TRANSFORMER PROTECTIONS-ELECTRICALTRANSFORMER PROTECTIONS-ELECTRICAL

• DIFFERENTIAL PROTECTION(GT/UT) – 87GT/87UTDIFFERENTIAL PROTECTION(GT/UT) – 87GT/87UT• GT HV WINDING + O/H LINE DIFFERENTIAL-87HVGT HV WINDING + O/H LINE DIFFERENTIAL-87HV• RESTRICTED EARTH FAULT (UT’s only)87NUT A/BRESTRICTED EARTH FAULT (UT’s only)87NUT A/B• STANDBY EARTH FAULT (GT only)-51NGTSTANDBY EARTH FAULT (GT only)-51NGT• OVERCURRENT PROTECTION (UT’s only)-51UT A/BOVERCURRENT PROTECTION (UT’s only)-51UT A/B• BACKUP EARTH FAULT (UT’s only)-51 NUT A/BBACKUP EARTH FAULT (UT’s only)-51 NUT A/B• GT OVERFLUXING – 99GTGT OVERFLUXING – 99GT• EARTH FAULT BEYOND GCB – 64GTEARTH FAULT BEYOND GCB – 64GT• GT + O/H LINE DIFFERENTIAL – 87TLGT + O/H LINE DIFFERENTIAL – 87TL

CLASS A1 – CAUSES – BACKUP CLASS A1 – CAUSES – BACKUP PROTECTIONS FOR PROTECTIONS FOR GENERATORGENERATOR BACKUP PROTECTIONS FOR BACKUP PROTECTIONS FOR

GENERATORGENERATOR

• GENERATOR LBB (For GCB) – 50GLBBGENERATOR LBB (For GCB) – 50GLBB

• GENERATOR BACKUP IMPEDANCE – GENERATOR BACKUP IMPEDANCE – 21G21G

• DEAD MACHINE RELAY – 50GDMDEAD MACHINE RELAY – 50GDM

CLASS A1 – CAUSES – OTHER CLASS A1 – CAUSES – OTHER BACKUP PROTECTIONSBACKUP PROTECTIONS

• SWITCHYARD TEE DIFFERENTIAL – SWITCHYARD TEE DIFFERENTIAL – 87TTIGX/87TT2GX87TTIGX/87TT2GX

• 400 KV BREAKER LBB – X52Z400 KV BREAKER LBB – X52Z (8-52/9-52/13-52/14-52)(8-52/9-52/13-52/14-52)

• 400KV BREAKER POLE DISCREPENCY -400KV BREAKER POLE DISCREPENCY -X52PDXX52PDX

(8-52/9-52/13-52/14-52) – DEFEATED(8-52/9-52/13-52/14-52) – DEFEATED

CLASS A1 - ACTIONSCLASS A1 - ACTIONS

CLASS A1 CAUSES TRIPPING OFCLASS A1 CAUSES TRIPPING OF

• BOTH 400KV BREAKERS OF THE UNITBOTH 400KV BREAKERS OF THE UNIT

• GCBGCB

• FIELD BREAKERFIELD BREAKER

• STEAM TURBINESTEAM TURBINE

• UNIT TRANSFORMER INCOMERS – BA/BBUNIT TRANSFORMER INCOMERS – BA/BB

CLASS A2 - CAUSESCLASS A2 - CAUSES

GENERATOR PROTECTIONSGENERATOR PROTECTIONS

• DIFFERENTIAL – 87G1/87G2DIFFERENTIAL – 87G1/87G2

• OVERVOLTAGE – 59G1OVERVOLTAGE – 59G1

• 95% EARTH FAULT -64G195% EARTH FAULT -64G1

• INTERTURN FAULT – 64GITINTERTURN FAULT – 64GIT

• OVERFLUXING – 99GOVERFLUXING – 99G

• NEGATIVE PHASE SEQUENCE – 46GNEGATIVE PHASE SEQUENCE – 46G

• LOW FORWARD POWER – 30sec – 37G1/2LOW FORWARD POWER – 30sec – 37G1/2

.. Contd... Contd.

CLASS A2 - CAUSESCLASS A2 - CAUSES

GENERATOR PROTECTIONSGENERATOR PROTECTIONS

• POLE SLIPPING – 98GPOLE SLIPPING – 98G

• FIELD FAILURE – 40 G1/2FIELD FAILURE – 40 G1/2

..contd...contd.

CLASS A2 - CAUSESCLASS A2 - CAUSES

SIEMENS MULTIFUNCTION RELAY – SIEMENS MULTIFUNCTION RELAY – 96G96G

• 100% STATOR EARTH FAULT100% STATOR EARTH FAULT

• ROTOR EARTH FAULTROTOR EARTH FAULT

• OVER VOLTAGEOVER VOLTAGE

CLASS A2 - ACTIONSCLASS A2 - ACTIONS

CLASS A2 CAUSES TRIPPING OF CLASS A2 CAUSES TRIPPING OF

• GCBGCB

• FIELD BREAKERFIELD BREAKER

• STEAM TURBINESTEAM TURBINE

• UT INCOMER (if both 400kV breakers UT INCOMER (if both 400kV breakers are in tripped condition)are in tripped condition)

CLASS B PROTECTIONCLASS B PROTECTION CLASS B – GENERATOR TRIP FROM TURBINE CLASS B – GENERATOR TRIP FROM TURBINE

TRIPTRIP

THIS IS ACHIEVED THROUGH LOW THIS IS ACHIEVED THROUGH LOW FORWARD POWER RELAY – 2 SEC DELAY- FORWARD POWER RELAY – 2 SEC DELAY- 37 G1/237 G1/2

NEED FOR CLASS B TRIPNEED FOR CLASS B TRIP

PROTECTION OF TURBINE FROM PROTECTION OF TURBINE FROM OVERHEATINGOVERHEATING

CLASS B - ACTIONSCLASS B - ACTIONS

CLASS B CAUSES TRIPPING OF THE CLASS B CAUSES TRIPPING OF THE FOLLOWINGFOLLOWING

• GCBGCB• FIELD BREAKERFIELD BREAKER

(i.e. GT & UT will still be in charged (i.e. GT & UT will still be in charged condition from 400kV side – GRID)condition from 400kV side – GRID)

CLASS C PROTECTION - CLASS C PROTECTION - CAUSESCAUSES

CLASS C IS CAUSED ONLY BY – CLASS C IS CAUSED ONLY BY –

UNDERFREQUENCY- UNDERFREQUENCY- 81G/96G81G/96G

(GRID COLLAPSE)(GRID COLLAPSE)

Presently connected to Class B at 45Hz.Presently connected to Class B at 45Hz.

CLASS C PROTECTION - CLASS C PROTECTION - ACTIONSACTIONS

CLASS C CAUSES TRIPPING OFCLASS C CAUSES TRIPPING OF

• BOTH 400KV BREAKERSBOTH 400KV BREAKERS

(i.e. Unit will come on house load)(i.e. Unit will come on house load)

ACTIONS IF CLASS A1 TRIP ACTIONS IF CLASS A1 TRIP OCCURSOCCURS

THE FOLLOWING ACTIONS ARE THE FOLLOWING ACTIONS ARE NECESSARYNECESSARY

• Restore unit supply if auto changeover Restore unit supply if auto changeover from standby trf. does not take placefrom standby trf. does not take place

• Ensure DG set availabilityEnsure DG set availability

• Inform Electrical MaintenanceInform Electrical Maintenance

ACTIONS IF CLASS A2 ACTIONS IF CLASS A2 OCCURSOCCURS

THE FOLLOWING ACTIONS ARE THE FOLLOWING ACTIONS ARE NECESSAYNECESSAY

• Ensure unit supplies are healthyEnsure unit supplies are healthy

• Inform Electrical MaintenanceInform Electrical Maintenance

CLASS A2 – LOW FORWARD CLASS A2 – LOW FORWARD RELAYRELAY

THE FOLLOWING SEQUENCE OF THE FOLLOWING SEQUENCE OF EVENTS OCCURSEVENTS OCCURS

• CLASS A2 TRIP – TRIP TO STEAM CLASS A2 TRIP – TRIP TO STEAM TURBINETURBINE

• AFTER TRUBINE TRIP – CLASS BAFTER TRUBINE TRIP – CLASS B

CLASS A2 – LOW FORWARD CLASS A2 – LOW FORWARD RELAYRELAY

RESTARTINGRESTARTINGTHE FOLLOWING SEQUENCE OF EVENTS THE FOLLOWING SEQUENCE OF EVENTS

MUST BE FOLLOWEDMUST BE FOLLOWED

• RESET BOTH CLASS A2 TRIP RELAYSRESET BOTH CLASS A2 TRIP RELAYS• RESET STEAM TURBINE TRIPRESET STEAM TURBINE TRIP• RESET BOTH CLASS B TRIP RELAYSRESET BOTH CLASS B TRIP RELAYS• SYNCHRONISE USNIG GCBSYNCHRONISE USNIG GCB

Note: Reset trip relays only when Note: Reset trip relays only when starting to rollstarting to roll

CLASS B TRIP - RESTARTINGCLASS B TRIP - RESTARTING

THE FOLLOWING SEQUENCE OF ACTIONS THE FOLLOWING SEQUENCE OF ACTIONS MUST BE FOLLOWEDMUST BE FOLLOWED

• RESET STEAM TURBINE RESET STEAM TURBINE • RESET BOTH CLASS B TRIP RELAYSRESET BOTH CLASS B TRIP RELAYS• SYNCHRONISE UNING GCBSYNCHRONISE UNING GCB

Note: Reset trip relays only when Note: Reset trip relays only when starting to rollstarting to roll

CLASS C TRIP - ACTIONSCLASS C TRIP - ACTIONS

• Ensure unit has come on HOUSE Ensure unit has come on HOUSE LOAD and stabilizedLOAD and stabilized

• Ensure availability of DG setEnsure availability of DG set

• Inform Electrical MaintenanceInform Electrical Maintenance

CLASS C - RESTARTINGCLASS C - RESTARTING

THE FOLLOWING SEQUENCE OF THE FOLLOWING SEQUENCE OF ACTIONS MUST BE FOLLOWEDACTIONS MUST BE FOLLOWED

• Energise 400KV switchyardEnergise 400KV switchyard

• After getting concurrence from After getting concurrence from SRLDC synchronise the unit using SRLDC synchronise the unit using 400KV breakers 400KV breakers

STARTUP/TRIPPING RELAY-STARTUP/TRIPPING RELAY-RESETTINGRESETTING

• Just before rolling only, reset the trip Just before rolling only, reset the trip relaysrelays

• After excitation, in case any of the After excitation, in case any of the fuse fail relays/50GDM flag has fallen fuse fail relays/50GDM flag has fallen reset themreset them

• After synchronisation, see that no After synchronisation, see that no relays have acted. relays have acted.

• If the Low forward power relay LED If the Low forward power relay LED has come, it should be reset.has come, it should be reset.

THANKYOUTHANKYOU

QUESTIONS QUESTIONS

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