The ATC Diversified Electronics GFD Series is intended for the use on ungrounded systems to detect and indicate the phase of the first ground fault condition. This enables corrective action to avoid the potential hazards resulting from a second ground fault.Operation:With nominal 3 phase line voltage applied, a flashing NORMAL green LED gives indication of a non-fault condition and integrity of the wire connection to the corresponding phase.A flashing red LED gives positive FAULT indication of either a phase-to-ground fault, or a lost connection to the corresponding phase.NOTE: Distributed capacitance to ground or equally loaded phases to ground will de-sensitize detection and will require lower phase-to-ground resistance to produce a FAULT indication.