Motor trips the thermal overload relay – how to find the root cause

What does the thermal overload relay do?

The thermal relay protects the motor from prolonged overload.

Potential causes

• Excessive mechanical load.
• Phase loss.
• Incorrect thermal setting.
• Worn bearings.
• Voltage issues.

Correct diagnosis

We measure the current in each phase and compare it with the rated current on the nameplate. We also check the mechanical load.