What is the electromagnetic relay? What is its structure and applications?

The use of protective electrical equipment, troubleshooting in electrical systems is extremely important. So what is the electromagnetic relay? What is its structure? This article will help us understand more about electromagnetic relays.

What is the electromagnetic relay

The relay is an automatic electrical device that outputs the jump signal when the input signal reaches the specified values.

In another aspect, Relay is an electrical device used to close, protect and cut the control circuit.

Electromagnetic relays are one of the most important equipment in automation equipment used in the electrical industry. The relay is responsible for protecting the electrical system elements in abnormal working conditions by isolating incidents through switchgear.

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The structure of an electromagnetic relay 

Electromagnetic relays have nine parts: magnetic circuit, coil, contact, shell.

Magnetic circuits are made of two-part ferromagnetic materials. The static section and dynamic part is U-shaped steel plate. The dynamic part connecting a mechanical link with dynamic contact.

Block diagram of electromagnetic relay

Classification of electromagnetic relays

• According to the suction coil: 1-way suction coil and alternating suction coil.

• According to the current through the contact: 1-way relay, alternating relay.

• According to the number of contact pairs: 2 pairs of contacts, 3 pairs of contacts, …

• According to the pin structure: round pin, flat pin.

• According to the relay socket: round socket, square socket.

Operation principle of the electromagnetic relay

The electromagnetic relays operate on the principle of electromagnets, often used to close circuits with small capacities and large switching frequencies.

When there is an electric current flowing through the coil, it will generate an electromagnetic attraction that draws the dynamic plate toward the core. The electromagnetic attraction has a directly proportional to the square of the current and is inversely proportional to the distance of the magnetic circuit gap. When the current in the coil is smaller than the impact current, the electromagnetic attraction is greater than the spring pulling force. The dynamic plate is pulled towards the side to make the circuit gap smaller. That is, sucking towards the static part. When the circuit gap is small, the higher the suction force, the dynamic sheet is drawn to the static part and the dynamic contact will close to the static contact.

The applications of an electromagnetic relay

Widely used in industries and living by automation features.
Monitoring of industrial safety systems. Or be used to disconnect power to ensure safety.

Source: vandientu.org


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