Magnetic starter

A magnetic starter is an electromagnetically operated switch which provides a safe method for starting an electric motor with a large load.

Magnetic starters also provide under-voltage and overload protection and an automatic cutoff in the event of a power failure.

[1][2] The overload relay opens a set of contacts that are wired in series with the supply to the contactor feeding the motor.

Motor control contactors can be fitted with short-circuit protection (fuses or circuit breakers), disconnecting means, overload relays and an enclosure to make a combination starter.

Pressing the "stop" button breaks the circuit to the contactor which consequently de-energizes its electromagnet thus cutting current to the motor.