There are many classification methods for relays, which can be classified by working principle, external dimensions, protection features, contact load, product application, etc.

I. Classified by working principle

one Electromagnetic relay

A relay that generates a predetermined response due to the relative motion of mechanical components under the action of current in the input circuit.

It includes DC electromagnetic relays, AC electromagnetic relays, relays, polarized relays, reed relays and energy-saving power relays.

(1) DC electromagnetic relay: An electromagnetic relay in which the control current in the input circuit is DC.

(2) AC electromagnetic relay: An electromagnetic relay whose control current in the input circuit is alternating current.

(3) Relay: By introducing the magnetic steel into the magnetic circuit, after the relay coil is de-energized, the armature of the relay can still remain in the state when the coil is energized, thus having two stable states.

(4) Polarized relay: A type of DC relay whose state change depends on the polarity of the input excitation quantity.

(5) Reed relay: A relay that uses the action of a reed sealed in a tube, which has the dual functions of a contact reed and an armature magnetic circuit, to open, close or switch circuits.

(6) Energy-saving power relay: An electromagnetic relay with alternating current as the control current in the input circuit, but it has a large current (generally 30-100A), small size, and energy-saving function.

A relay in which the input and output functions are accomplished by electronic components without mechanical moving parts.

When an input signal is applied or removed, the output part needs to delay or limit the time to the specified time before closing or opening the relay of its controlled circuit. 4. Temperature relay

A relay that operates when the external temperature reaches the specified value.

When the speed of the wind reaches a certain value, the controlled circuit will be connected or disconnected.

When the acceleration of a moving object reaches the specified value, the controlled circuit will be connected or disconnected.

Such as optical relays, acoustic relays, thermal relays, etc.

Ii. Classified by external dimensions

Name definition

A micro relay is a relay with the longest side dimension not exceeding 10mm

Ultra-small relays are relays with the longest side dimension greater than 10mm but not greater than 25mm

A small relay with the longest side dimension greater than 25mm but not greater than 50mm

Iii. Classified by contact load

Name definition

A low-power relay is a relay with a capacity of less than 0.2A.

Low-power relay: A relay with a power range of 0.2 to 2A.

Medium-power relays: relays with a power range of 2 to 10A.

High-power relays of 10A or above.

Energy-saving power relays: relays ranging from 20A to 100A

Iv. Classification by protective features

Name definition

Sealed relays are relays that use welding or other methods to seal contacts, coils, etc. within a metal cover, and they have a relatively low leakage rate

Plastic-encapsulated relays are relays with a relatively high leakage rate. They use sealing glue to enclose the contacts, coils, etc. within a plastic cover

A dust cover relay is a type of relay that uses a cover to enclose and protect its contacts, coils, etc

An open relay is a relay that does not use a protective cover to protect its contacts, coils, etc

V. By Purpose

Name definition

Communication relays (including high-frequency relays) : The contact load range of this type of relay is from low level to medium current, and the requirements for environmental usage conditions are not high.

The relays used in machine tools have large contact load power and long service life.

Relays for household appliances: Relays used in household appliances are required to have good safety performance.

Automotive relays are relays used in automobiles. This type of relay has a large load switching power and high impact and vibration resistance.