SIGMA 3 GROUND FAULT & MONITORING RELAY is a product that can protect industrial and commercial electrical equipment and the people who operate them. This equipment uses high-resistance grounding systems and optical arc mitigation technology to reduce electrical hazards, such as arc flash and ground faults.
The SIGMA 3 Ground Fault & Monitoring Relay combines a ground‑fault relay with a neutral‑grounding resistor (NGR) monitor. It measures NGR current, neutral‑to‑ground voltage, and NGR resistance, and provides LED indicators and relay outputs when abnormal conditions are detected. The manual covers system components, dip‑switch settings for trip level and time, pulsing techniques for fault location, and integration with the SIGMA 3‑TDM touchscreen display.
Installation, commissioning, MODBUS communication, and detailed technical specifications are included, along with dimensional drawings and part numbers. The document also explains LED behavior, manual reset procedures, and safety features such as fail‑safe and shunt‑trip modes.
| Control Power | 110‑240 VAC/DC 50/60 Hz |
|---|---|
| Meter Output | 0‑1 mA DC (0‑100 % of Let‑through Current Setting) |
| Temperature Range (Operating) | -40 °C to +60 °C |
The ground fault trip level is DIP‑switch selectable as a percentage of the NGR let‑through current setting (5 %‑50 %).
The red GND FAULT LED turns on when the SIGMA 3 detects and qualifies a ground fault.
Perform a manual reset; the fault LEDs flash for two seconds and then the relay returns to normal operation.