Motor Starter

A motor starter is a device that’s used to start an electric motor. It consists of a contactor and an overload relay. A contactor is a heavy duty magnetically actuated switch that connects the motor to the line. The overload relay senses the current drawn by the motor and opens a switch to shut the motor down if the current is excessive. The magnetic coil that closes the contactor is wired to the machine’s control circuit.
Motor starters are seen most on motors 3 hp and larger, or smaller motors that need to be remotely controlled. Smaller compressor motors may have temperature switches built in to their windings to shut down the motor if it becomes overloaded. These motors are stopped and started directly by the pressure switch. Starting larger motors directly with the pressure switch is not a good idea. The pressure switch contact points are not capable of carrying the high starting current and will quickly burn out. Motor starters are sized by the current they have to carry. They are also rated by horsepower and voltage. Contact us for sizing assistance and a price quote.