(1) Structure: The main components of the electromagnetic relay are electromagnet A, armature B, spring C, moving contact D, and static contact E. (as shown in the figure)

(2) The working circuit can be divided into two parts: a low-voltage control circuit and a high-voltage working circuit. The low-voltage control circuit includes an electromagnetic relay coil (electromagnet A), a low-voltage power supply E1, and a switch S; the high-voltage working circuit includes a high-voltage power supply E2, a motor M, an electromagnetic Contacts D and E of the relay.
(3) Working principle - close the switch S in the low-voltage control circuit, and the current passes through the coil of the electromagnet A to generate a magnetic field, thereby attracting the armature B, making the moving and static contacts D and E contact, the working circuit is closed, and the motor works ; When the low-voltage switch S is disconnected, the current in the coil disappears, and the armature B, under the action of the spring C, disconnects the moving and static contacts D and E, the working circuit is disconnected, and the motor stops working.