ATC SLU100ASD Universal Phase Monitoring Relay

The ATC Diversified Electronics SLU-100-ASD Universal Phase Monitor/Relay is a DIN-rail mounted protection relay for 3‑phase power systems that detects phase faults and voltage imbalances and signals an external control circuit via its relay output. It supports both Delta and Wye configurations, and in Wye systems neutral is not required. The unit is UL-listed under UL file E55826, validating its use in industrial panels. The SLU-100-ASD belongs to the SLU‑100 series, a universal phase monitor designed to guard motors and other equipment against single‑phasing and unbalance. It provides adjustable monitoring thresholds for the supply voltage, adjustable voltage imbalance percentage, and an adjustable time delay to avoid nuisance trips. It uses auto‑ranging to operate across a wide AC voltage range with 50/60 Hz supplies, including voltages up to about 550 V AC in applicable configurations. The ASD variant is designed for DIN‑rail mounting; a separate ASA variant exists for panel‑mount applications (SLU‑100‑ASA). In typical installations, this relay serves as a single, configurable protection device that can trigger alarms or interlocks when abnormal voltage conditions are detected, helping prevent premature equipment failure in both Delta and Wye networks.