Relays for Protection against 50 MVA 132/33 kV Transformer

2 Comments / Sub-Station Engineering / By Electrical Notebook

Sl. No.	Type of Relay	Relay Name	Appearance	ANSI Code	Purpose
1.	Numerical Relay	Trafo. Differential Protection Relay		87	For protection against phase-to-phase fault and phase to earth faults
2.	Numerical Relay	Over Current & Earth Fault Protn. Relay		51	For protection of transformers from over current and earth faults
3.		Circulating Current E/F Diffn. Protn. Relay		64
4.		LBB Protn. Relay		50LBB	To isolate the fault in case the circuit breaker is failed to trip
5.		LBB Trip Relay		96	Operate for the fault clearance of a system by tripping other circuit breakers when the related circuit breaker fail to operate
6.		Master Trip Relay		86	A 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 Relay	DC Supvn. Relay.		80DC	To supervise DC supply of the trip circuit of the breaker and gives an alarm if trip coil DC supply is failed.
8.	Supervision Relay	Master Trip Supvn. Relay		95/86
9.	Supervision Relay	Trip Ckt. Supvn. Relay 1		195
10.	Supervision Relay	Trip Ckt. Supvn. Relay 2		295
11.	Supervision Relay	High Speed Tripping Supvn. Relay		95/96
12.	Auxiliary Relay	Aux. Relay for 86		30
13.	Auxiliary Relay	Aux. Relay for CB Discripency		30
14.	Auxiliary Relay	Aux. Relay for REF Protn.		30
15.	Auxiliary Relay	Aux. Relay for CB Trouble		52X1, 52X2, 52X3, 52X4
16.	Trafo. Aux. Relays for Alarm	a. Buchholz Alarm b. Winding Temp. Alarm c. Oil Temp. Alarm d. MOG Alarm e. LV Winding Temp. Alarm		30
17.	Trafo. Aux. Relays for Trip	a. 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		30