Electromechanical Switch or Relay – Construction, Advantages | New Note [2024]

In this note, we are going to know about an Electromechanical Switch or Relay Switch. About its construction and advantages as well. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.

Author Name: Arun Paul.

What is an Electromechanical Switch?

It is a mechanical Switch is operated electrically to turn ON or OFF current in an electrical circuit.

Construction of Electro-mechanical Switch

The electromechanical switch, often known as a relay, is an upgraded version of a simple mechanical switch. Below figure depicts the schematic representation of a standard relay. It comprises of a lever L with an armature A and a solenoid C. The spring pulls the lever upwards, while the solenoid, when activated, pulls it downwards. The solenoid circuit is configured so that when switch S is closed, the downward pull of the solenoid exceeds the upward pull of the spring.

Working of Electromechanical Switch

When the switch S is closed, the lever is pulled down, and the armature A closes relay contacts 1 and 2. This turns on the current in the circuit. When switch S is opened, the solenoid is de-energized, and the spring pushes the lever, causing armature A to rise. As a result, the relay contacts 1 and 2 are opened, and current flow in the circuit is terminated. In this sense, a relay functions as a switch.

Advantages of Electro-mechanical Switch

Here are some advantages of this type of switch –

1. The relay or electromechanical switch takes a little amount of power to operate. This allows you to regulate a huge power in the load with a modest power to the relay circuit. Thus, a relay functions as a power amplifier, combining control and power amplification.
2. The switch in the relay coil has a low current as compared to the load current. This allows for the use of a smaller switch in the relay coil circuit.
3. The operator can turn on or off electricity to a load from a distance. This is a significant advantage when handling high voltages.
4. There is no risk of sparking since the relay coil switch, which carries a modest current, turns the power on or off.