what is diffential relay? testing proceure?and
transformer reach Over load thet time differencilal relay
operate or not ?

Answer Posted / g.govarthinam

Dear friends
1.Diff relay compares two currents entering and leaving the
protected equipment or zone in respect of current
maagnitude and phase angle, and if there is any unbalance
or spill current found, that current will flow through the
operating coil of the relay and give trip pulse to the
Circuit breaker to isolate the supply to the transformer.
2.Please note that,Diff relay will operate only for
internal fault of the protected equipment(for
example,winding fault in transformer) and it should not
trip for over load of transformer and any external fault.

please feel free to ask further doubts in this topic.
regards
gova

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