Undertorque Detection 1

What does UL3 mean?

The motor current has fallen below the minimum value set for torque detection (L6-02) for longer than the allowable time (L6-03). This indicates either inappropriate parameter settings for the current load conditions or a mechanical fault on the machine side, such as a loss of load or broken coupling.

• Undertorque detection level (L6-02) set too high, exceeding the actual minimum operating current.
• Undertorque detection time (L6-03) set too short, causing nuisance trips from momentary load fluctuations.
• Actual mechanical load significantly reduced or completely absent (e.g., broken belt, coupling failure).
• Incorrect current transformer (CT) ratio set in drive parameters (if external CTs are used).
• Motor parameter auto-tuning (A1-02) results are inaccurate for the connected motor.

Click steps to track your progress.

1. 1

   1. Verify that the undertorque detection level parameter (L6-02) is appropriately set based on the minimum expected load current.

2. 2

   2. Increase the undertorque detection time parameter (L6-03) to prevent nuisance tripping from momentary load fluctuations.

3. 3

   3. Inspect the mechanical system for any disconnections, broken belts, chain failures, or coupling issues in the driven equipment.

4. 4

   4. Monitor the actual motor output current during operation using drive diagnostics (e.g., U1-01) or an external clamp meter and compare to L6-02.

5. 5

   5. Check the drive's motor parameter auto-tuning results (A1-02) for accuracy, especially motor rated current (P1-02).

6. 6

   6. If an external current transformer is used, confirm its ratio is correctly configured in the drive parameters (if applicable).