Motor Overload shut-off (electronic overcurrent protection)

What does E.THM mean?

The inverter's electronic overcurrent protection detects motor overheating due to sustained overload or reduced cooling during constant-speed operation. A pre-alarm (TH indication) activates at 85% of the preset overload value. The protective circuit then stops the inverter output when the specified overload value is reached. This internal protection may be insufficient for special motors (e.g., multi-pole motors, multiple motors) which require external thermal relays.

• Motor current exceeds the programmed overload limit (P1-18).
• Excessive mechanical load on the motor causing increased current draw.
• Under-voltage condition affecting motor torque and increasing current.
• Faulty motor winding or bearing leading to increased resistance and current.

Click steps to track your progress.

1. 1

   Measure the actual current draw of the motor during operation and compare it against the motor's nameplate Full Load Amperage (FLA).

2. 2

   Inspect the mechanical load connected to the motor for excessive resistance or binding; reduce the mechanical load if it exceeds the motor's rated capacity.

3. 3

   Check parameter Pr. 71 (Motor Type) and ensure it is correctly configured for a constant-torque motor if applicable to the application.

4. 4

   Verify the motor's cooling fan is clean, unobstructed, and operating effectively to ensure adequate airflow.