Working of relay

It is working on the principle of electromagnetic attraction. The relay circuit senses the fault current and energizes the electromagnetic field, and it produces the temporary magnetic field.

This magnetic field moves the relay armature for opening and closing the connections. The one contact is in a small power relay and the high power relay has two contacts for opening the switch.

The inner section of the relay is shown in the figure. It is wound by a control coil by an iron core. It is given power supply to the coil through the contacts of the load and the control switch. The current flowing through the coil produces the magnetic field around it.

In this magnetic field the upper arm of the magnet attracts the lower arm. The circuit makes the current flow through the load. The contact is already closed and moves oppositely to open the contacts.