CMB Series AC Go/No-Go Current Monitoring Relay

The CMB Series AC Go/No-Go Current Monitoring Relay from the ATC Diversified Electronics division of Marsh Bellofram is designed to detect the presence and level of AC current, ensuring consistent levels for the continuous operation of motors, pumps or other critical industrial machinery. When the monitored current exceeds the trip point for longer than 30 milliseconds, the internal relay energizes. When the monitored current drops below the trip point for longer than 0.5 seconds, the internal relay de-energizes. The delay-on-release is incorporated to prevent nuisance tripping caused by momentary dips in the load line. An external CT may be used to extend the range of the current monitor.



  • Designed to detect presence of AC current
  • Available models from 1-10 amps
  • No physical connection to monitored AC line needed
  • Fixed trip point
  • 8-pin plug-in enclosure


  • Current demand level monitoring
  • Conveyor or motor load jam detection
  • Dull bit or blade detection
  • Remote motor sensing
  • Broken fan belt or chains detection
  • Feed rate to keep two loads at their most efficient point