Shunt Trip Breaker

A shunt-trip breaker, in addition to the internal instantaneous overcurrent and time-overcurrent protective functions, has an externally powered solenoid that will trip the breaker when energized. This is normally tied to a safety interlock system that will shut power off to the affected equipment when, for example, a protective cover is opened or removed. A limit switch or other similar device will be used to detect if the cover is in place or not. It is held open by the cover. If the switch closes, the breaker is tripped and the machine is rendered electrically safe.