A contactor is an electromechanical control device that used to make or break the connection between the load and power supply. The use of a contactor is similar to the relay. But the device used for higher current carrying application is known as a contactor and the device used for lower current applications is known as Relay.
A contactor has several contacts as per the application and load. Generally, these contacts are normally open (NO) contact. And hence the load is shut off when the coil of the contactor is de-energized. But the contactor can design for both normally open and normally close applications. The most common application of contactor is in the starter that used to turn ON and OFF the equipment like motor, transformer, etc.
Working of Contactor
An electromagnetic field produced when the electromagnetic coil is energized. As we have seen in the construction, the moving contact of the contactor is connected with the armature (metallic rod) of an electromagnet.
When an electromagnetic field produced, the armature experiences the force and pulls towards the fixed contact. The force produced by the coil is more than the force of the spring. Both contacts remain in this position until the coil is not de-energized.
Once the coil is de-energized, the electromagnetic force is zero and the armature pulls back due to the force of spring. And return in the normal condition (OFF position). The contactors are designed for the rapid ON-OFF operation.
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