why we are using DC supply for all protection relays, why
cant we use AC supply..???



why we are using DC supply for all protection relays, why cant we use AC supply..???..

Answer / n k singh

We can use AC also but additional shading ring must be
provided which gives sufficient phase displaced flux for
relay to be continuously on in negative half cycle of AC
supply also. In case of DC the flux is unipolar hence relay
will be on if DC is available.

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