Electromagnetic relay principle characteristics
- Nov 03, 2017 -

Electromagnetic relay is the use of electromagnet control circuit breaker on and off.


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


(2) The working circuit can be divided into two parts: the low voltage control circuit and the high voltage working circuit, the low voltage control circuit comprises an electromagnetic relay coil (electromagnet A), a low voltage power supply E and a switch S; the high voltage working circuit comprises a high voltage power supply E, a motor M, Relay contacts D, E section.


(3) Working principle - Close the switch S in the low-voltage control circuit, the current will generate a magnetic field through the coil of the electromagnet A, so as to generate a gravitation to the armature B so that the moving and the static contact D and E contact, the working circuit is closed and the motor works ; When the low-voltage switch S is off, the current in the coil disappears. The armature B under the action of the spring C makes the dynamic and static contacts D and E disengaged, the working circuit is disconnected, and the motor stops working.


As long as the coil ends with a certain voltage, the coil will flow through a certain current, resulting in electromagnetic effect, the armature will be attracted by the electromagnetic force to overcome the return spring tension suction to the core, which led to the armature Moving contact and static contact (normally open contact) pull. When the coil power, the electromagnetic suction will disappear, the armature will be in the spring reaction to return to the original position, the dynamic contact with the original static contact (normally closed contact) release. This pull, release, so as to achieve the conduction in the circuit, cut off the purpose. For the relay's "normally open, normally closed" contacts, you can distinguish between: the relay coil is not energized when the static contact is off, known as the "normally open contact"; is in the state of static contact said For "normally closed contact."