Overload Relay

About Overload Relay

Overload relays protect electric motors against overpowering. It prevents motor overload using a motor starting switch. Overload switches monitor motor circuit current and break it if it exceeds a set limit for a specified duration. This prevents motor overheating.

Many overload switches exist, including:

• Bimetallic Overload Relays: These relays measure motor circuit current with a bimetallic strip. When the current exceeds a particular limit, the bimetallic strip warms and bends, tripping the relay.
• Thermal Overload Relays: Thermal elements measure motor circuit current. The switch trips when the heating element warms up.
• Electronic Overload Relays: Electronic wiring measures motor circuit current. Electrical circuits trigger the relay at a particular current.

Overload relays and contactors are usually used to start a motor. The overload circuit protects the motor from excessive current, while the contactor controls motor power.

The contactor closes when the motor starts, powering the machine. 

The overflow switch cuts the motor circuit if the current exceeds a particular limit for a specified time. This disables the motor's control circuit and contactor, cutting power.

After fixing the overload, the overload switch may be reset and the motor restarted. However, overload relays that are often tripped and reset might harm the motor and limit its mechanical life.

Overload switches protect motor control circuits against overpowering. Each type of overload switch has benefits and downsides. For the correct overload relay, consider the motor's demands and purpose.

Frequently Asked Questions

1. What are Overload relays?

Ans: Overload relays and check circuit current to safeguard motors. The overload relay trips if the current reaches a specific limit over a certain duration, disconnecting the motor control circuit and de-energizing the contactor.

2. Explain overload relays.

 Ans: Overload relays trip when circuit current reaches a particular limit. An auxiliary contact disrupts the motor control circuit, reducing motor power.

3. What are overload relay types?

Ans: Bimetallic, eutectic, and electronic overload relays exist. Electronic overload relays detect current electronically and are heaterless, reducing costs.

4. How do I choose an overload relay? 

Ans: Be cautious. Repetitive tripping and resetting might destroy the relay and motor. Ensure the overload relay's current rating, trip class, and other specs match the motor.