250A Series - 3-Phase Voltage/Phase Monitor

Littelfuse Voltage Monitoring Relays
The 250A is a 3-phase, auto-ranging, dual-range voltage monitor that protects 190-480VAC, 50*/60Hz motors regardless of size from low and high voltage, unbalance/single-phase, and reverse-phase. The product provides a user selectable nominal voltage setpoint and the voltage monitor automatically selects between the 200V and 400V range. The 250A also features adjustable or manual restart delay.


This unique microcontroller-based voltage and phase-sensing device constantly monitors the 3-phase voltages to detect harmful power line conditions. When a harmful condition is detected, the Littelfuse’s output relay is deactivated after a specified trip delay. The output relay reactivates after power line conditions return to acceptable levels. The Model 250A includes advanced single LED diagnostics. Five different light patterns distinguish between faults and normal conditions.

Access specifications, certifications, check availability and order parts below

Catalog #Input
Voltage (V)
Output
Form
Termination TypeMounting MethodDimensionsWeight (lbs/g)Compare
250A190 to 480VACDPDT - 2 Form CTorque: 7in-lbs; Wire: 12-18AWG#8 screws2.93 in H x 5.27 in W x 2.95 in D (94.4 x 133.9 x 74.9 mm)1.02 lb. (16.3 oz. 462.7 g)
250-100-MET95 to 120VACDPDT - 2 Form CTorque: 7in-lbs; Wire: 12-18AWG solid or stranded#8 screws2.93 in H x 5.27 in W x 2.95 in D (94.4 x 133.9 x 74.9 mm)1.02 lb. (16.3 oz. 462.7 g)
250A-MET190 to 480VACDPDT - 2 Form CTorque: 7in-lbs; Wire: 12-18AWG#8 screws2.93 in H x 5.27 in W x 2.95 in D (94.4 x 133.9 x 74.9 mm)1.02 lb. (16.3 oz. 462.7 g)
250600500 to 600VACDPDT - 2 Form CTorque: 7in-lbs; Wire: 12-18AWG solid or stranded#8 screws2.93 in H x 5.27 in W x 2.95 in D (94.4 x 133.9 x 74.9 mm)1.02 lb. (16.3 oz. 462.7 g)