This system is used to protect electrical distribution equipment against damage caused by low magnitude ground currents. GFR-3 operates effectively on both high and low resistance grounded distribution systems.

The sensor, in the event of ground fault, sends a signal to trip the GFR-3 relay. DPDT output contacts are provided to operate breakers, annunciators or other devices. The GFR-3 is an enhanced version of the GFR-2. In addition to the basic ground fault protection mechanism, there is also a built in self-test circuit and adjustable Time delay. The self-test is activated by a TEST push-button, which will trigger the Ground Fault Relay and the breaker. There is also a NO-TRIP push-button, different from the TEST button, designed specifically to test the Ground Fault Relay without tripping the breaker.