The GFR4D20030 from Altech is DIN rail mount ground fault relay (with overload protection) GFR series with 3 pole + N, D trip characteristic and 30mA ground fault sensitivity level. This circuit breaker has 20A current rating, 480Y/277VAC voltage rating and 50/60Hz rated frequency. Designed to provide protection against overloads and AC ground faults (residual current faults) as well as pulsating DC ground faults. Short circuit withstand rating is 10kA.