Process Underload Fault (Torque)

What does ULF mean?

A torque underload detected fault. This indicates that the motor is operating with significantly less load than expected, potentially pointing to a mechanical failure (e.g., broken belt, pump cavitation) or a material flow issue. While not immediately damaging, it signals an abnormal process condition.

• Loss of mechanical load on the motor (e.g., broken belt, coupling failure, pump cavitation, fan blade damage).
• Underload detection threshold (e.g., Parameter P1-25) set too high or delay time (P1-26) too short.
• Incorrect motor parameters programmed into the drive, leading to an inaccurate torque estimate.
• Sensor failure or poor calibration if external torque/load feedback is used.

Click steps to track your progress.

1. 1

   1. Inspect the mechanical connection between the motor and the driven equipment for belts, couplings, or gears.

2. 2

   2. Monitor the drive's output current (e.g., display parameter d0-02) or estimated torque to assess actual load.

3. 3

   3. Adjust the underload threshold parameter (e.g., P1-25) to a level appropriate for the application's normal minimum load.

4. 4

   4. Verify the underload delay time parameter (e.g., P1-26) is long enough to ride through normal load fluctuations.

5. 5

   5. Confirm motor nameplate data (P0-01 to P0-10) is correctly entered, as this affects torque estimation accuracy.