which protection system is used for earth fault in power transformer?

The protection system commonly used for earth fault detection in power transformers is the Earth Fault Relay (EFR). This system monitors the current flowing to the ground and detects any imbalances caused by insulation failures or faults. When an earth fault occurs, the relay activates, triggering alarms and disconnecting the transformer from the power supply to prevent damage and ensure safety. Additionally, differential protection can also be employed to enhance fault detection capabilities.