Contactor is an electro magnetic device whose working principle utilizes the theory that an electric current flowing in a copper will produce a magnetic field. Usually contactors are used for 3 phase electrical systems. Not all contactors have normally open and normally close. There are only R-S-Ts without NC and NO.
Contactor Application
One example of contactor application is used to start a motor, usually also used for starting star delta. Contactors are combined with thermal overload to prevent excessive electric current. The use of thermal overload is needed because the contactor does not have the ability to detect overcurrent.
