Undertorque Detection 1

What does UL3 mean?

This fault indicates that the drive's output current dropped below the level set in L6-02 for longer than the time specified in L6-03. This is typically caused by a mechanical issue like a broken pulley belt, or by incorrect load parameters for the application. Continued undertorque can lead to inefficient operation, unnoticed mechanical failures, or unexpected machine stops.

• Mechanical load loss due to a broken belt, sheared coupling, or material feed interruption.
• Pump cavitation or dry running condition, significantly reducing motor load.
• Parameter L6-02 (Undertorque Detection Level 1) set too high for the application's minimum operating current.
• Motor phase loss or severe imbalance causing reduced torque output despite commanded speed.
• Miscalibration or failure of the drive's internal current sensors.

Click steps to track your progress.

1. 1

   Inspect the mechanical connection between the motor and its load for any breaks, slippage, or damage.

2. 2

   Verify the process equipment (e.g., pump, fan) is operating with its intended load and material flow.

3. 3

   Measure the motor's output current on all three phases (U, V, W) and compare it to expected values.

4. 4

   Adjust L6-02 (Undertorque Detection Level 1) to a value just below the normal minimum operating current.

5. 5

   Review L6-03 (Undertorque Detection Delay 1) to ensure it's sufficient to prevent nuisance trips during normal transients.