Undertorque Detection 1

What does UL3 mean?

The drive detected that its output current was continuously below the threshold set in L6-02 for longer than the time specified in L6-03, when L6-01 was configured for undertorque detection. This fault indicates that the connected motor is operating under an unexpectedly low load, potentially due to a mechanical issue or process change.

• Mechanical decoupling of the motor from its load (e.g., broken belt, coupling failure, pump running dry).
• Process material flow stoppage (e.g., conveyor belt empty, fan damper fully closed).
• Undertorque detection level (L6-02) set too high, triggering even under normal light load conditions.
• Undertorque detection delay time (L6-03) set too short, causing nuisance trips during transient low current.
• Drive's internal current measurement inaccuracy or drift.

Click steps to track your progress.

1. 1

   1. Visually inspect the mechanical coupling between the motor and its load (e.g., belt tension, coupling integrity).

2. 2

   2. Confirm the process being driven by the motor is operating normally and not in a no-load or extremely light-load condition.

3. 3

   3. Use a clamp-on ammeter to measure the actual motor output current during normal light-load operation and compare it to the L6-02 setting.

4. 4

   4. Adjust parameter L6-02 (Undertorque Detection Level 1) to a lower, more appropriate current threshold that reflects actual light-load operation.

5. 5

   5. Increase parameter L6-03 (Undertorque Detection Time 1) to allow for temporary low current conditions without tripping the fault.