Model DPR175A Phase Voltage Monitoring Relay (3 Phase)

The Model DPR175A Phase Voltage Monitoring Relay (3 Phase) from the ATC Diversified Electronics division of Marsh Bellofram Corporation is a high-performance voltage and phase monitoring relay designed to protect industrial machinery, motors, and pumps against premature equipment failure caused by unbalanced voltages or single phasing, regardless of any regenerative voltages, on three-phase systems.

The relay monitors phase sequence, under voltage, over voltage and phase loss for three-phase three-wire 230 VAC nominal (170 to 290 VAC supply voltage range) operation and is designed for direct compatibility with most 3 phase 3 wire Wye or Delta Systems.

The Model DPR175A comes standard in a slim, space-saving 17.5 mm DIN housing with a 5 amp SPDT relay output contact configuration. It is easily configured via front knobs for under voltage, over voltage and trip delay. The economical, compact DPR175A voltage/phase monitor is also UL approved and CE certified, making it ideal for use within a variety of OEM equipment, motor and pump protection related applications.



  • Trip time delay of 0.2-10 s
  • LED indication of relay status and power
  • Trip voltage accuracy of ±0.5% F.S.
  • Auto reset on removal of fault condition
  • Front panel knobs for under-voltage, over-voltage, and trip delay
  • Slim, space saving design
  • UL listed, CE certified


  • OEM equipment
  • Motor protection applications
  • Pump protection applications
  • Industrial machinery