What is a transformer differential protection

Explain the differential protection in a transformer

Differential protection is unit-type protection for a specified zone or piece of equipment. It is based on the fact that it is only in the case of faults internal to the zone that the differential current (difference between input and output currents) will be high. Differential means the difference of input and output currents of a power object like power transformers, generators, or short transmission lines.If the difference of both currents to the relay is zero, it means that no leakage of current in the protected object exists and it is behaving normally.On a ground or phase faults, the balance of both currents is disturbed and different current flows in the operating coil of the differential relay and it operates to clear the fault.

Monitors the transformer protection zone and sends a trip signal as a consequence of transformer internal faults.