Power Monitoring and Protection


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MotorSaver™ Three-Phase Voltage Monitor 201A

MotorSaver™ Three-Phase Voltage Monitor


The MotorSaver™ 201A three phase voltage monitor is an autoranging plug-in voltage monitor designed to protect three phase motors regardless of size. It is used on a 190-480 volt AC 50/60 Hz three phase motor to prevent damage caused by single phasing, low voltage, phase reversal, or voltage unbalance. To detect harmful power line conditions in building automation systems, BAS, the unique microprocessor-based voltage and phase sensing circuit constantly monitors the three phase voltages. When a harmful condition is detected in a three phase motor, the output relay is deactivated after a fixed trip-delay time period. The output relay reactivates after three phase power conditions return to an acceptable level for a fixed restart delay time. The trip delay prevents nuisance tripping due to rapidly fluctuating power line conditions.


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QtyModelDescriptionIn StockList PriceInternet Price
201A 3PH VOLT MONITOR 190-480V SPDTIn Stock223.00124.88


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  • Protection of three-phase motors against single phasing, low voltage, phase reversal, and voltage unbalance
  • DIN rail- or surface-mounted socket
  • UL and ULC listed, CE certified
  • Bicolor LED indication of normal and fault conditions
  • Single-phase condition detection regardless of regenerated voltages

Supply Voltage:190-480 VAC

Supply Watts:5W

Frequency:50* or 60 Hz

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

Transient Protection:2500V for 10 ms

Low Voltage Trip:90% of setpoint

Low Voltage Reset:93% of setpoint

Reset Delay Time after Fault:2 seconds

Reset Delay Time after Power Loss:2 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%

Dimensions:2.4"W x 1.8"D x 4.1"H (6.0 x 4.4 x 10.4 cm)

Mounting:OT08PC base

Weight:0.56 lb (0.25 Kg)

Approvals:UL File #E68520, CE

Warranty:5 years