Motor Underload Protection

What does UL6 mean?

The motor has been operating under an underload condition, where the current drawn is significantly lower than expected for the commanded speed. This can indicate a broken belt, pump cavitation, or loss of load.

Click steps to track your progress.

1. 1

   Inspect the driven equipment (e.g., pump, fan, conveyor) for mechanical faults such as broken belts, uncoupled loads, blockages, or loss of process material, ensuring the motor has proper mechanical connection and resistance.

2. 2

   Verify the motor nameplate data (rated current, voltage, frequency, RPM) programmed in the Yaskawa P1000 drive parameters (e.g., L3-01 to L3-10, Pn002 to Pn005) against the actual motor specifications.

3. 3

   Inspect all motor power cable connections (U, V, W) at the drive output terminals and the motor terminal box for looseness, corrosion, or damage.

4. 4

   Measure the actual motor phase currents (U, V, W) with a clamp-on ammeter during operation and compare these readings to the current displayed on the drive HMI to confirm true motor current.