The 201A is a 3-ph, auto-ranging, dual-range voltage monitor that protects 190 to 480 VAC, 50/60 Hz motors regardless of size. The product provides A user selectable nominal voltage set point and the voltage monitor automatically selects between the 200 V and 400 V range. The 201A includes advanced single led diagnostics, where color and different light patterns distinguish between faults and normal conditions. This unique microcontroller-based voltage and phase-sensing device constantly monitors the 3-ph voltages to detect harmful power line conditions. When a harmful condition is detected, the 201A's output relay is deactivated after a specified trip delay. The output relay reactivates after power line conditions return to acceptable levels.