Thermal relay

 The function of thermal relay:

A thermal relay is a protective device used in electrical systems to protect motors and other equipment from overheating due to excessive current. It operates based on the heat generated by the current passing through it. Here’s how it functions:

1. Heating Element:

 The thermal relay has a heating element that heats up when current flows through it. The amount of heat generated is proportional to the current.

2. Bimetallic Strip:

 Attached to the heating element is a bimetallic strip made of two metals with different coefficients of thermal expansion. When heated, the strip bends because one metal expands more than the other.

3. Trigger Mechanism:

 As the bimetallic strip bends, it eventually reaches a point where it triggers a mechanism that opens the relay contacts. This breaks the circuit, stopping the current flow and protecting the equipment.

4. Resetting:

 After the relay trips and cools down, the bimetallic strip returns to its original shape. Some thermal relays reset automatically, while others need to be manually reset.

5. Adjustable Settings:

Many thermal relays have adjustable settings to tailor the trip point to the specific requirements of the system being protected.

Thermal relays are widely used because they are simple, reliable, and provide effective protection against overload conditions.