what is the diff. b/w restricted earth fault relay &
standby earthfault relay and where they are used?
Answer Posted / oes
Restricted earth fault (REF) relay is a unit protection
intended for one winding of a transformer (neutral winding)
the input of which is from a neutral bushing CT and in some
applications, balanced by the output of three line CTs in
the Y-winding directly connected to neutral. This provides
accurate sensing of zero-sequence leakage currents for a
fault within its zone of protection, i.e., on the windings.
Whereas, standby EF relay is a back-up overcurrent ground
protection usually connected on the HV side and its main
purpose is to provide local back-up protection in case for
a failure of main protections of the LV feeder/line prots.,
bus prots., and the transf. main protections.
Is This Answer Correct ? | 78 Yes | 28 No |
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