The 102A is a 3-phase, auto-ranging, dual range voltage monitor that protects 190 to 400 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 VAC and 400 VAC range. A unique microcontroller based voltage and phase sensing circuit constantly monitors the 3-phase voltages to detect harmful power line conditions. When a harmful condition is detected, the output relay is deactivated after a specified trip delay. The output relay reactivates after power line conditions return to acceptable levels. The model 102A includes advanced single LED diagnostics. Five different light patterns distinguish between faults and normal conditions.