250A Series - 3-Phase Voltage/Phase Monitor

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Disclaimer Notice

Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, automotive, military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse. "Littelfuse" includes Littelfuse, Inc., and all of its affiliate entities.

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)HumidityInput AC Line Frequency (Hz)Maximum Input PowerOutput Load Rating (VA)Overvoltage Reset Voltage (%)Overvoltage Trip Voltage (%)Restart Delay RangeStorage Temperature (F/C)Trip Delay RangeStockCompare
250A190 - 480 VacDPDT - 2 Form CTorque: 7 in-lbs; Wire Size: 12 - 18 AWG#8 screws2.93 H x 5.27 W x 2.95 D in. (94.4 x 133.9 x 74.9 mm)0 LbUp to 95% non-condensing per IEC 68-2-350 / 60 (50 will increase all delay timers by 20%)5Pilot Duty: 480 VA @ 240 Vac B300; General Purpose: 10 A @ 240 Vac107%110%Manual; 2 - 300 s adjustableUnder/Over Voltage: 4 s; Unbalance/Phase faults: 2 sCheck
250-100-MET95 - 120 VacDPDT - 2 Form CTorque: 7 in-lbs; Wire Size: 12 - 18AWG solid or stranded#8 screws2.93 H x 5.27 W x 2.95 D in. (94.4 x 133.9 x 74.9 mm)0 KgUp to 95% non-condensing per IEC 68-2-350 / 60 (50 will increase all delay timers by 20%)5Pilot Duty: 480 VA @ 240 Vac; General Purpose: 10 A @ 240 VacManual; 2 - 300 s adjustable-40° to 80°C (-40° to 176°F)Under/Over Voltage: 4 s; Unbalance/Phase faults: 2 sCheck
250A-MET190 - 480 VacDPDT - 2 Form CTorque: 7 in-lbs; Wire Size: 12 - 18 AWG#8 screws2.93 H x 5.27 W x 2.95 D in. (94.4 x 133.9 x 74.9 mm)0 KgUp to 95% non-condensing per IEC 68-2-350 / 60 (50 will increase all delay timers by 20%)5Pilot Duty: 480 VA @ 240 Vac B300; General Purpose: 10 A @ 240 VacManual; 2 - 300 s adjustableUnder/Over Voltage: 4 s; Unbalance/Phase faults: 2 sCheck
250600500 - 600 VacDPDT - 2 Form CTorque: 7 in-lbs; Wire Size: 12 - 18AWG solid or stranded#8 screws2.93 H x 5.27 W x 2.95 D in. (94.4 x 133.9 x 74.9 mm)0 KgUp to 95% non-condensing per IEC 68-2-350 / 60 (50 will increase all delay timers by 20%)5Pilot Duty: 480 VA @ 240 Vac; General Purpose: 10 A @ 240 Vac107%110%Manual; 2 - 300 s adjustable-40° to 80°C (-40° to 176°F)Under/Over Voltage: 4 s; Unbalance/Phase faults: 2 sCheck
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