AC Overcurrent & Undercurrent Sensing Relays CAH, COH & CUH Series
The CxH Series is an AC current sensing relay that is available in three versions:
CAH Series--can detect either an overcurrent or undercurrent fault (selectable);
COH Series--overcurrent only; and CUH Series--undercurrent only. The currentcarrying
wire is run through the built-in 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 (tS) 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 (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.
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