Difference between a Contactor and a Relay

A contractor is an electromagnetic device which is used to make or break of an electrical circuit. there is two type of contractor.

power contactor.
auxiliary contactor.

Power contactor is used in power circuit like switch on/off of a motor capacitor. while auxiliary contactor is used to switch on or off of a control circuit. a power contactor have 3 main contacts while an auxiliary contactor has many contacts like 1no+1nc 2no+2nc ect..power contactor is generally used where we required to make and break a large current carrying circuit.

The Relay is similar to an auxiliary contactor which is used in general control circuit, especially in plc for as a digital input feedback or as a digital output to switch on or off an electrical contractor. we can also be used as a relay in place of an auxiliary contactor. relays are always used in a low current carrying circuits. it comes with a rating of 5–20 amps. while a power contactor generally comes with from 9 amps to 600 amps

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