What is a shunt-trip breaker?

It works just like a normal circuit breaker with one additional function. A shunt-trip breaker also has a built-in magnetic coil that can be energized externally to trip the breaker. For instance, fire sprinklers are sometimes required in the top of elevator shafts in case of a fire in the shaft. If the sprinklers were to spray water on the electric controls in the elevator cab, people could be hurt or killed, either from electrocution or from the elevator malfunctioning. In these cases, a shunt-trip breaker is installed in the circuit feeding the elevator controls, and the fire alarm system sends a trip signal if it detects waterflow from the sprinkler system. This trips the breaker and removes power from the elevator cab. Once tripped, shunt-trip breakers require a person to manually reset them.