Electromechanical Relays: Working Principle

Electromechanical Relays: Working Principle

What is Electromechanical relays?

Electromechanical relays are switching devices that use a combination of mechanical and electrical principles to operate. They consist of a coil, which when energized, creates a magnetic field that pulls an armature towards it, causing the contacts to close or open.

These contacts can be used to switch electrical circuits on or off, making electromechanical relays an important component in many electrical systems. They were widely used in the past, but have now largely been replaced by solid-state relays in most applications.

Related: HANDBOOK FOR PROTECTION ENGINEERS

Working Principle of Electromechanical relays

• An electromechanical relay is an electrical switch that uses an electromagnet to mechanically switch electrical contacts.
• The relay consists of two circuits: the control circuit and the load circuit. The control circuit is the one that activates the relay, while the load circuit is the one that is switched on or off by the relay.
• The control circuit consists of a coil of wire wrapped around an iron core. When a current is passed through the coil, it creates a magnetic field that attracts a piece of iron called an armature.
• The armature is attached to a set of contacts that are normally open. When the armature is attracted to the core, it closes the contacts, completing the load circuit.
• The control circuit can be activated by a variety of means, such as a switch or another relay.
• Once the control circuit is activated and the contacts are closed, the load circuit is energized, allowing current to flow through the load.
• When the control circuit is de-energized, the magnetic field disappears, and the armature returns to its original position, opening the contacts and interrupting the flow of current in the load circuit.
• Electromechanical relays are commonly used in a wide range of applications, such as industrial controls, automation, and power systems.
• One of the advantages of electromechanical relays is their simplicity, reliability, and durability.
• However, they have some limitations, such as their relatively slow response time compared to solid-state relays, and their susceptibility to mechanical wear and tear over time.