Schneider Electric RH99M Vigirex Ground Fault Relay

Schneider Electric Vigirex RH99M Ground-Fault Relay is a residual-current monitor that, when used with an external toroid sensor, continuously measures leakage current to ground in a distribution or feeder circuit and trips the connected protective device when leakage exceeds the programmed setting. The RH99M family covers earth-leakage sensitivities from 30 mA up to 30 A, with fixed settings from 30 mA to 1 A and adjustable settings up to 30 A in available configurations, offering precise protection for both sensitive and higher-leakage applications. It is offered in multiple supply variants, including common 220–240 VAC 50/60 Hz models and AC/DC options such as 12/24 VAC or 12/48 VDC, to suit a wide range of control-supply environments. The relay is designed for DIN-rail mounting and relies on a separate current transformer (toriod) to sense residual current; front LEDs provide status indications, and the unit self-validates its power, sensor link, and internal electronics. Outputs can trip a circuit breaker or feed a remote alarm, with many versions supporting automatic reset after fault clearance. As part of the Vigirex system, RH99M installations are intended to protect feeders and panels up to substantial current levels when paired with the appropriate sensor (the system supports protection up to about 3200 A with the correct toroid). Typical applications include protection of distribution boards, motor-control centers, and industrial panels where early ground-fault detection helps prevent equipment damage and safety risks.