The mechanical device that physically moves the heavy contacts inside switchgear or a circuit breaker. Actuators rely on stored energy from charged springs, compressed air, or magnetic coils to open or close the contacts with enough speed to extinguish electrical arcs.
Heard on the job
The breaker failed to close because the spring charging motor on the actuator burned out.
Related terms
Circuit breaker
A mechanical switching device capable of making, carrying and breaking currents under normal and fault conditions.
Switchgear
Assemblies of breakers, switches, fuses, busbars and enclosures that control and protect power circuits.
Contactor
An electrically controlled switch used for switching an electrical power circuit.