Why is the relay called "automatic switch" with small control and big control

Update:2020/12/04

Why is the relay called "automatic switch" with small control and big control

The relay is an electrical control device, made based on the principle of electromagnetic induction, and is an "automatic switch" that uses a small current to control a large current. It is widely used in remote control, telemetry, communication, automatic control, mechatronics and power electronic equipment. It is one of the most important control components.


The core of the latching relay manufacturers  is an electromagnet. Under the action of current, the electromagnet attracts the armature to drive the switch connected to it to open or close, thereby controlling the on and off of another circuit.

There are multiple classification methods for relays:
1. According to the working principle or structural characteristics of the relay, it can be divided into: electromagnetic relay, solid state relay, temperature relay, reed relay, time relay, high frequency relay, polarized relay, etc.
2. According to the classification of the external dimensions of the relay, it can be divided into: micro relay, ultra-small micro relay, and small micro relay.
3. According to the relay load classification, it can be divided into: micro power relay, weak power relay, medium power relay, and high power relay.
4. According to the protection characteristics of relays, it can be divided into: sealed relays, enclosed relays, and open relays.
5. According to the relay, it can be classified according to the principle of action, which can be divided into: electromagnetic type, induction type, rectifier type, electronic type, digital type, etc.
6. According to the physical quantity of the reaction, it can be classified into: current relay, voltage relay, power direction relay, impedance relay, frequency relay, gas (gas) relay.
7. Relays can be classified according to the role they play in the protection circuit, which can be divided into: starting relays, measuring relays, time relays, intermediate relays, signal relays, outlet relays, etc.

The role of the relay
As a control element, the relay plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit.
Symbol of the relay
Because the relay is composed of two parts: a coil and a contact group, the graphical symbols of the relay in the circuit diagram also include two parts: a long box represents the coil; a group of contact symbols represents the contact combination.

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