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How does an undervoltage accessory trip a circuit breaker?

Issue:
How does a UVR undervoltage work?

Product Line:
Circuit Breakers

Resolution:
An undervoltage trip device is an optional accessory in a circuit breaker that mechanically trips the breaker when voltage to the terminals drops below a threshold level. It is a coil and plunger. When voltage is supplied, the coil is activated and retracts the plunger. When that voltage is removed, the plunger is no longer held in, and pushes on a lever in the breaker that trips it.

he power for the undervoltage trip does not come from within the breaker, so it must be supplied from an external source. Some circuit breakers allow field installation of a undervoltage trip kit, while others require factory installation when the breaker is ordered. Check the specific breaker type for available ac and dc voltage ratings and for the method of installation.