In fact, the relay is the "automatic switch" used in our daily life to control the current. It is an electrical control device. When the change of the input quantity meets the specified requirements, it is an electrical appliance that makes the controlled quantity have a predetermined step change in the electrical output circuit. The relay has an interactive relationship between the control system and the controlled system. Because it plays the role of automatic adjustment, safety protection and conversion circuit in the circuit, it is usually used in the automatic control circuit.
There are many kinds of relays. The following are classified according to the working principle or structural characteristics of relays:
1. Tongue spring relay: it is a kind of relay which can open, close or change the circuit by using the tongue spring action which is sealed in the tube and has double functions of electric shock spring and armature magnetic circuit
2. High frequency relay: it is used to switch high frequency and radio frequency lines with minimum loss.
3. Polarized relay: a relay operated by the combined action of polarized magnetic field and magnetic field generated by control current through control coil. The action direction of the relay depends on the direction of the current flowing in the control coil.
4. Electromagnetic relay: an electrical relay that works by using the suction force between the electromagnet core and the armature generated by the circuit in the input circuit.
5. Time relay: when the input signal is added or removed, the output part needs to delay or limit the specified time to close or disconnect the controlled line relay.
6. Solid state relay: it refers to a relay whose input and output are isolated when electronic components perform their functions without mechanical moving components.
7. Temperature relay: when the outside temperature reaches the given value, it acts.
8. Other types of relays: such as optical relay, acoustic relay, thermal relay, instrument relay, Hall effect relay, differential relay, etc.
The above detailed introduction of relay classification will help us to know more about relay related knowledge and help us to choose and use relay in the future.