60/70/80 Amp Thermal Overload Relay, 220V, 3-Phase

A thermal relay is an electrical device used for overload protection in electric circuits. Its primary function is to safeguard motors and other electrical equipment from damage due to prolonged overcurrent conditions, such as excessive heat generated by high current flow.

Key Functions of a Thermal Relay:

1. Overload Protection:

   • The relay detects excessive current in the circuit that could overheat the motor or connected equipment.
   • If the current exceeds the set threshold for a prolonged period, the relay disconnects the circuit to prevent damage.

2. Temperature Monitoring:

   • It operates based on the heat generated by the current. The relay contains a bimetallic strip or heating elements that bend or deform as they heat up due to overcurrent.
   • The deformation triggers a trip mechanism, cutting off the power supply.

3. Automatic Reset or Manual Reset:

   • Some thermal relays are designed to automatically reset after cooling down, while others require manual resetting after a fault.

4. Customization and Sensitivity:

   • The relay settings can be adjusted to match the motor's rated current, ensuring precise protection without unnecessary trips.

5. Coordination with Other Components:

   • Thermal relays are often used in conjunction with contactors and other protective devices in motor starter circuits to provide a comprehensive protection system.

Applications:

• Motor protection in industrial machinery.
• Protecting pumps, compressors, and fans.
• Safeguarding electrical heaters or transformers from overheating.

By providing reliable and simple overload protection, thermal relays play a critical role in ensuring the safety and longevity of electrical systems.