In transformer (Tx) protection, Normal Earth Fault or Ground Fault Relay to protect Tx from ground fault at feeder side, REF (restricted earth fault) relay to protect Tx from ground fault between CT neutral and CT phase (REF is more sensitive than Differential Relay to protect winding of Tx (internal fault) from ground fault close to neutral), Standby Earth Fault to protect Neutral Grounding of Tx from ground fault at feeder.
