Voltage warning low

What does 6 mean?

The DC bus voltage (VDC) has dropped below the 'Voltage warning low' limit. The motor continues to operate, but if the VDC remains low for 2-25 seconds, the inverter will trip with an Alarm 8 (Undervoltage). This can be caused by an insufficient supply voltage or an unstable power source.

• Low incoming AC line voltage (L1, L2, L3) falling below the drive's minimum operating threshold.
• Temporary voltage sag or brownout condition on the utility power supply due to heavy load demands elsewhere on the grid.
• High current draw by the motor exceeding the supply capability, causing voltage drop across the input inductance.
• Loose or high-resistance connection in the incoming AC power path (L1, L2, L3) to the drive.

Click steps to track your progress.

1. 1

   1. Measure the incoming AC line voltage (phase-to-phase) at terminals R, S, T and compare to the drive's rated input voltage; report any sustained undervoltage to facility maintenance.

2. 2

   2. Power down the drive, then inspect and re-torque all incoming power connections (R, S, T) for looseness or corrosion.

3. 3

   3. Check for any transient voltage sags on the input power by monitoring with a power quality analyzer during operation.

4. 4

   4. Verify that the motor load is not excessive or causing instantaneous overcurrent, leading to bus voltage sag.

5. 5

   5. Review parameter P1-29 (Low Voltage Warning) to ensure it is appropriately set relative to the expected minimum supply voltage.