Will a transformer Differential Relay act online to line to fault?

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The zone of protection for 2 , 3 or multi windings Transformers differntial relay is decided by the location of CT.s at the respective sides i.e. HV. IV OR LV SIDES . Ideally on any fault within zones of these C.T.s the differential relay should act. However sometimes inadequecy of C.T. s ratings like low burden rating, less knee point voltage or improper biased settings may cause the differential relay to operate even on line faults.

Regards,

J.M.SHAH