Contactors
A contactor is an electrically-controlled switch used for switching an electrical power circuit.
A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit, such as a 24-volt coil electromagnet controlling a 230-volt motor switch.
Overload
An overload relay, also referred to as a relay switch, is a device that opens the circuit in the event of an electrical, thermal or power overload. When mounted with a contactor they create a motor starter. Overload relays are normally closed, meaning they only open if they experience an overload.
