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Instantaneous Earth Fault Relay (EFR) can be employed with various earth fault protective
schemes, which are explained in brief with figures. The magnitude of the earth fault current depends on the fault impedance and invariably the fault impedance for earth fault is higher than that for phase faults, hence the earth fault current is low compared to the phase fault currents. The fault impedance depends on the system parameter and also on type of earthing. The neutral may be solidly grounded, grounded through resistance or reactance.