Technical Specifications / Parameters Parameter Specification Manufacturer Order Code 1SVR011700R0000 Product Family / Series ABB CM-E Series (Ground Fault & Earth Monitoring Relays) Device Type Neutral Grounding Resistor (NGR) Monitor / Broken Resistor Detector Monitored System Type Primarily for Resistance-Grounded AC systems (High-Resistance Grounding - HRG, or Low-Resistance Grounding - LRG). Monitoring Principle Continuously injects a small, safe DC or low-frequency AC test current through the NGR and neutral point, measuring the resulting voltage or impedance to calculate and monitor the actual resistance value. Monitoring Functions • Resistor Failure Detection (Open Circuit / Broken Resistor) • Resistor Short-Circuit Detection • Resistance Value Deviation Alarm (High/Low Thresholds) • Ground Connection Continuity Monitoring Input Voltage (Supply) Typically 24-240V AC/DC (wide-range, for relay logic power). Auxiliary Supply for Monitoring Circuit May have a separate, isolated low-voltage DC source for the injection/monitoring circuit. Output Relays Typically 2 or more changeover (CO) contacts for: • Alarm (Warning for deviation) • Trip (for critical failure like open circuit) Resistance Measurement Range Designed to match common NGR values (e.g., from a few ohms to several kilohms). Specific range depends on the model variant. Setpoints Adjustable thresholds for: • High Resistance Alarm/Trip (detects open circuit or increased resistance) • Low Resistance Alarm/Trip (detects shorted turns or decreased resistance) Status Indication LEDs for Power, Alarm, Trip, and System Healthy. Mounting DIN Rail Mounting (35mm). Communication Basic models have relay outputs only; advanced variants may include Modbus RTU or other communication protocols. Standards & Approvals IEC/EN 60255, UL 508, CE. Key Application Protection of motors, generators, transformers, and cables in: • Industrial plant power distribution (e.g., mining, oil & gas, manufacturing) • Marine electrical systems • Data center power systems • Any critical system employing resistance grounding for fault current limitation and service continuity.