Electromagnetic relay is one of the earliest and most widely used relays. Electromagnetic relay is usually composed of iron core, electromagnetic coil, armature, return spring, contact, bracket and pin.

The working principle of Electromagnetic relay is not simple. Mainly using the principle of electromagnetic induction. When a current is applied to the coil, the coil generates a magnetic field, and the iron core under the coil is magnetized to generate a magnetic force. Therefore, the armature is attracted to the iron core under the action of electromagnetic attraction. At this time, the armature drives the support rod to push the leaf spring open, thereby disconnecting the two normally closed contacts. When the current of the relay coil is disconnected, the iron core is demagnetized, the armature returns to the initial state under the action of the leaf spring, and the contact is closed again.