A257B 3-Phase Power Monitor

480VAC, 60Hz, 3.7W, Adjustment Range: 380-480VAC, Automatic Reset

The Time Mark A257B monitors 3 phase power lines for faulty conditions. When the A257B is properly adjusted it'll detect phase loss on a loaded motor in the presence of regenerated voltage.

A neutral connection is not needed with the A257B and it can be used with Delta and Wye systems. The A257B can be adjusted to meet existing conditions.

"Trip" and "Norm" indicators are located on the top


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  • Nominal AC Voltage: 480VAC
  • Frequency (Hz): 60
  • Reset: Automatic
  • Stock Level: In Stock