Power Monitoring and Protection


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MotorSaver™ Three-Phase Voltage Monitor 250A

MotorSaver™ Three-Phase Voltage Monitor


The MotorSaver™ 250A three phase voltage monitor is an autoranging 3 phase voltage monitor designed to protect three phase motors regardless of size. It is used on a 190-480 volt AC, 50/60 Hz 3 phase motor to prevent damage caused by single phasing, low voltage, phase reversal, voltage unbalance, and high voltage. Added features include DPDT contacts and an adjustable restart time-delay setting. The unique microprocessor-based voltage and phase-sensing circuit constantly monitors the three phase voltages to detect harmful power line conditions. When a harmful condition is detected in a HVAC, industrial or BAS application, the three phase voltage monitor's output relays are deactivated after a fixed trip-delay time period. The output relay reactivates after power line conditions return to an acceptable level for an adjustable restart delay time. The trip and reset delays prevent nuisance tripping due to rapidly fluctuating power line conditions.


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QtyModelDescriptionIn StockList PriceInternet Price
250A 3PH VOLT MONITOR 190-480V DPDT In Stock381.53305.22


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  • Protection of three-phase motors from single phasing, low-voltage, phase reversal, voltage unbalance, and high voltage
  • Adjustable restart delay
  • DPDT contacts
  • UL and cUL listed
  • Bicolor LED indication of normal and fault conditions
  • Detection of single-phase conditions regardless of regenerated voltages

Supply Voltage:190 to 480 VAC

Supply Watts:5W

Frequency:50* or 60 Hz

 :* 50 Hz will increase all delay times by 20%

Contact Rating:DPDT, pilot duty 480 VA @ 240 VAC General-purpose 10A @ 240 VAC

Transient Protection:IEC 1000-4-5

Low Voltage Trip:90% of setpoint

Low Voltage Reset:93% of setpoint

Reset Delay Time after Fault:Manual or 2-300 seconds

Reset Delay Time after Power Loss:Manual or 2-300 seconds

Trip Delay Time High Voltage:4 seconds

Trip Delay Time Low Voltage:4 seconds

Trip Delay Time Phase Fault:2 seconds

Trip Delay Time Unbalance:2 seconds

Voltage Unbalance Reset:4.5%

Voltage Unbalance Trip:6%

Operating Temperature:-40° to 158°F (-40° to 70°C)

Dimensions:5.25"W x 2.9"H x 2.92"D (13.3 x 7.4 x 7.4 cm)


Weight:0.88 lb (0.4 Kg)

Approvals:UL File #E68520

Warranty:5 years


Download Additional Data

document   250A Catalog Page
document   201A Installation Instructions