GFR-3 Ground Relay is factory calibrated to operate with the model of sensor identified on the nameplate. The front panel has controls knobs for both the ground fault Trip sensitivity and the Time delay setting. Test and No Trip pushbuttons are also provided. When ground fault occurs, the Sensor creates a signal that will trip the GFR-3 relay. DPDT output contacts are provided to operate the breaker trip coil and/or the annunciator. After the fault has been cleared, the GFR-3 will reset automatically (non-latching option) or, with the mechanically latching option, it has to be manually reset. The electrically latched version of the GFR-3 requires that the power supply be shut off to reset the relay. The GFR-3 features definite time/current characteristics (see diagram below).