A transformer circuit breaker is equipped with 500/5 A C.T.s connected to a induction typeover current relay. The relays have 125% plug setting and 0.4 time setting. If a 3- o faultcurrent of 7500 A flows from C.T. and relays follow characterstics given by below table at(TMS = 1), then operating time of the relay will bePSMOperating time(sec.)4 812165 3 2.8 2.2

Given- A transformer circuit breaker- 500/5A C.T.s 125% plug setting and 0.4 time setting, 3-ϕ fault…

A transformer circuit breaker is equipped with 500/5 A C.T.s connected to a induction type over current relay. The relays have 125% plug setting and 0.4 time setting. If a 3-fault current of 7500 A flows from C.T. and relays follow characterstics given by below table at (TMS = 1), then operating time of the relay will be PSM 48 12 16 Operating time(sec.) 5 3 2.8 2.2

A transformer circuit breaker is equipped with 500/5 A C.T.s connected to a induction type over current relay. The relays have 125% plug setting and 0.4 time setting. If a 3-fault current of 7500 A flows from C.T. and relays follow characterstics given by below table at (TMS = 1), then operating time of the relay will be PSM 48 12 16 Operating time(sec.) 5 3 2.8 2.2

Electric Motor Control

10th Edition

ISBN:9781133702818

Author:Herman

Publisher:Herman

Chapter14: Phase Failure Relays

Section: Chapter Questions

Problem 1SQ: What is the purpose of phase failure relays?

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