Relays for Protection against 50 MVA 132/33 kV Transformer

Sl. No.Type of RelayRelay NameAppearanceANSI CodePurpose
1.Numerical RelayTrafo. Differential Protection Relay87For protection against phase-to-phase fault and phase to earth faults
2.Numerical RelayOver Current & Earth Fault Protn. Relay51For protection of transformers from over current and earth faults
3.Circulating Current E/F Diffn. Protn. Relay64
4.LBB Protn. Relay50LBBTo isolate the fault in case the circuit breaker is failed to trip
5.LBB Trip Relay96Operate for the fault clearance of a system by tripping other circuit breakers when the related circuit breaker fail to operate
6.Master Trip Relay86A collection of all tripping circuits. If the fault detected by any of the protn. relay, means at the same time the protection relay trips the associated circuit breaker, through the mater tripping relay circuits. The master trip relay’s output is wired to the circuit breaker trip Coil.
7.Supervision RelayDC Supvn. Relay.80DCTo supervise DC supply of the trip circuit of the breaker and gives an alarm if trip coil DC supply is failed.
8.Supervision RelayMaster Trip Supvn. Relay 95/86
9.Supervision RelayTrip Ckt. Supvn. Relay 1195
10.Supervision RelayTrip Ckt. Supvn. Relay 2295
11.Supervision RelayHigh Speed Tripping Supvn. Relay95/96
12.Auxiliary RelayAux. Relay for 8630
13.Auxiliary RelayAux. Relay for CB Discripency30
14.Auxiliary RelayAux. Relay for REF Protn.30
15.Auxiliary RelayAux. Relay for CB Trouble52X1, 52X2, 52X3, 52X4
16.Trafo. Aux. Relays for Alarma. Buchholz Alarm
b. Winding Temp. Alarm
c. Oil Temp. Alarm
d. MOG Alarm
e. LV Winding Temp. Alarm
17.Trafo. Aux. Relays for Tripa. OLTC Buchholz Trip
b. LV Winding Temp. Trip
c. HV Winding Temp. Trip
d. Oil Temp. Trip
e. Buchholz Trip
f. DT MOG Trip
g. PRD Trip

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