When the relay works, the electromagnet is energized, and the keeper is drawn down to make D and E contact, and the working circuit is closed. The electromagnet loses its magnetism when it loses power, and the spring pulls the keeper up to cut off the working circuit. Therefore, a relay is a switch that uses an electromagnet to control a working circuit.
The advantages of relay control circuit: control high voltage with low voltage; Remote control; Automatic control.
Relay is a kind of automatic electrical switch that works by electromagnetic induction.
The working principle and characteristics of relay
Relay is an electronic control device, it has a control system (also known as the input loop) and controlled system (also known as the output loop), usually used in automatic control circuit, it is actually a small current to control the larger current of an “automatic switch”. Therefore, it plays the role of automatic adjustment, safety protection and conversion circuit in the circuit.
Electromagnetic relay generally consists of iron core, coil, armature, contact reed and so on. As long as a certain voltage is added to both ends of the coil, a certain current will flow through the coil, resulting in electromagnetic effect, and the armature will overcome the pull force of the return spring under the action of electromagnetic attraction to attract the core, so as to drive the moving contact of the armature and the static contact (normally open contact) suction. When the coil power, electromagnetic suction also disappeared, the armature will return to the original position in the spring reaction force, so that the moving contact and the original static contact (normally closed contact) suction. This suction, release, so as to achieve the purpose of conduction in the circuit, cut off. For “normally open and normally closed” contacts of relays, they can be distinguished in this way: static contacts that are disconnected when the relay coil is not energized are called “normally open contacts”; A static contact in the on state is called a normally closed contact.