2)ABC of contactors

ABC of contactors

Basic Contactor Operation Magnetic contactors operate by utilizing electromagnetic principles. A simple electromagnet can be fashioned by winding a wire around a soft iron core. When a DC voltage is applied to the wire, the iron becomes magnetic. When the DC voltage is removed from the wire, the iron returns to its nonmagnetic state





Fig. Contactor principle




Internal components: There are two circuits involved in the operation of a contactor: the control circuit and the power circuit. The control circuit is connected to the coil of an electromagnet, and the power circuit is connected to the stationary contacts




Fig:Internal components of contactors



Working: When power is supplied to the coil from the control circuit, a magnetic field is produced, magnetizing the electromagnet. The magnetic field attracts the armature to the magnet, which in turn closes the contacts. With the contacts closed, current flows through the power circuit from the line to the load. When current no longer flows through the control circuit, the electromagnet’s coil is de-energized, the magnetic field collapses and the movable contacts open under spring pressure.




Fig:Operation of contactor