Undervoltage

What does 9 mean?

The DC link voltage has fallen below acceptable limits while the drive is in the Run state. This can be caused by a low supply voltage, a defective internal component, a blown input fuse, or an external charge switch not being closed. A persistent undervoltage can prevent drive operation and indicate a power supply issue.

• Input supply voltage sag or complete loss on one or more phases (L1, L2, L3) at the drive's input terminals.
• Blown fuse(s) in the input power circuit (e.g., F1, F2, F3) to the drive rectifier section.
• Failure of the drive's internal rectifier bridge, preventing proper charging of the DC link capacitors.
• Excessive current draw by the motor or an external short circuit, causing the DC link to collapse.
• Control board fault causing incorrect DC link voltage measurement or reporting.

Click steps to track your progress.

1. 1

   Measure the input line voltages (L1-L2, L2-L3, L3-L1) at the drive's input terminals during operation, ensuring they are within specified tolerance.

2. 2

   Check continuity of all input fuses (e.g., F1, F2, F3) using an ohmmeter, replacing any that show infinite resistance.

3. 3

   Measure the DC link voltage (terminals DC+ and DC-) with a multimeter to confirm it is below the undervoltage threshold (e.g., <340VDC for a 400V drive).

4. 4

   Inspect the input wiring and connections for looseness, corrosion, or damage from the main breaker to the drive terminals.

5. 5

   Verify the drive's nominal input voltage parameter (e.g., P3-10) matches the actual supply voltage.