Difference between a contactor and a relay?

Contactors and Relays perform the same task of switching a circuit. If you see from the application point of view, you would have seen contactors placed in control panels of industrial motors or other heavy loads. Whereas, relays are used in low voltage applications such as switching a LED or tube-light or even actuating a circuit breaker .

Both are electromagnetic switches and operate under similar principles. The difference comes if we see from the application perspective. Contactors are used for high voltage switching purposes whereas relays are used for low voltage switching.

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A Contactor is a electromagnetic device which is used to make or break of any electrical circuit. there are two type of Contactor.

  • 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 a auxiliary contactor have many contacts like 1NO+1NC, 2NO+2NC ect….Power contactor is generally used where we reuired to make and break a large current carring circuit.

A Relay is similar to a Auxiliary contactor,which is used in generally control circuit,specially in PLC for as a Digital input( feedback) or as a Digital out put to Switch on or off a electrical Contactor. we can also used a relay in place of a auxiliary contactor. relays are always used in a low current carring circuits. it comes with a rating from 5–20 Amps. while a power contactor generally comes with from 9 Amps to 600 Amps…

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