CAH Series

Operation:

The CAH Series is an AC current sensing relay that can detect either an overcurrent or undercurrent fault (selectable). 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.

Overcurrent Sensing

After input voltage is applied & the sensing delay on power-up (t_s) is completed, the unit will begin sensing for a fault condition. A fault will occur when the monitored AC current (I) goes above the Fault Trip Current setting & remains above 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 below the Reset level.

Undercurrent Sensing

After input voltage is applied & the sensing delay on power-up (t_s) 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.

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