Thermal relay or Thermal Overload Relay is an electromechanical protection device used to safeguard electric motors from overloading and drawing excessive input current. It operates based on the thermal effect principle of current, which means that it uses the heat generated by the current to detect overloads. When an overload occurs, the thermal relay cuts off the motor circuit, providing overload protection for the motor.

The thermal relay typically consists of a bimetallic strip, which is heated by the current passing through it. Due to the difference in expansion coefficients of the metals in the bimetal, the strip bends as it heats up, causing the relay contacts to open or close. This mechanism allows the thermal relay to switch a magnetic contactor, protecting the motor from overload.

Thermal relays are often combined with magnetic contactors because they cannot switch the main circuit directly and are widely used in industrial automation and motor control systems for their reliable protection against electrical anomalies like overvoltage and phase failure.

Changan Electric offers you thermal overload relays with trip class 10 (trip class means that at 600% (6 times) of the maximum thermal current rating (or 600% of the actual dial setting for adjustable overload), class 10 will trip in 10 seconds or less), welcome to consult and order our products.