CUH Series


  • Detects Undercurrent only
  • Monitors single phase AC current
  • Three separate adjustable Fault Trip Current ranges covering 0.5 - 50 amperes
  • Built-in toroidal through-hole current transformer allows easy access & multiple loops for increased sensitivity
  • Adjustable time delay on fault trip
  • LED indicates fault condition
  • 10A SPDT output contacts
  • Encapsulated for protection in harsh environments
Enclosure Style Encapsulated 2.5" x 3.5" enclosure with dual screw mounting
Contact Rating
  • SPDT
  • 10 Amperes @ 240VAC, General Purpose; 8 Amperes @ 28VDC, Resistive; 1/4HP @ 120/240VAC; B300
Approvals c-ur-us.jpgCE_Logo.gifUL File #E109466
Technical Documentation


The CUH Series is an AC current sensing relay that can detect undercurrent only. The current-carrying wire is run through the built-in toroidal current transformer and can be looped multiple times for greater sensitivity. These relays include user-adjustable settings for Fault Trip Current & Time Delay on Fault Trip as well as an LED to indicate fault condition. The encapsulated construction offers protection in harsh environments. Applications such as monitoring for locked rotor or load loss condition, open heater or lamp, and process control are perfect for these products.

Undercurrent Sensing

After input voltage is applied & the sensing delay on power-up (ts) is completed, the unit will begin sensing for a fault condition. A fault will occur when the monitored AC current (I) goes below the Fault Trip Current setting & remains below the Reset level for a period longer than the adjustable time delay period (t). The LED will turn ON immediately and the relay will energize after the time delay on pick-up (t) is completed. The relay will de-energize & the LED will turn OFF when the monitored AC current goes above the Reset level.

Undercurrent Sensing Relays

Macromatic's Current Sensing Relays Knowledge Base contains general and technical industry articles to help you learn more about Current Sensing Relays.

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