UOA Series Single Phase Under Voltage Monitoring Relay

The UOA Series Single Phase Under Voltage Monitoring Relay from the ATC Diversified Electronics division of Marsh Bellofram is a family of single phase voltage monitoring relays, designed to ensure the cost-effective reliable protection of critical equipment that is required to continuously operate above a certain voltage minimum, with the ability to monitor voltage levels up to 240 VAC.  Design of the UOA series ensures that when operating voltage is applied above the preset pick-up voltage, the internal relay will energize. When the voltage falls below the preset drop-out voltage for a period longer than the release delay, the output relay will de-energize. When line conditions return above the preset pick-up voltage, the UOA Series automatically resets and the internal relay energizes. The hysteresis integral to each series unit provides a differential between pick-up and drop-out trip points.



  • Monitoring capabilities up to 240 VAC
  • Single phase under voltage monitoring relay
  • Adjustment for voltage trip point (plug-in style only)
  • Plug-in or surface mount enclosure


  • Pump and motor monitoring
  • Conveyor belt chain breakage protection
  • Protection from idle running of a submersible pump
  • Light bulb burnout detection
  • Battery voltage/power supply verifications
  • Communication base control power supply monitoring