TL;DR
F004 means the DC bus dropped below the trip threshold. Verify line voltage, P031 (Motor NP Volts), and the input fuses; then power-cycle.
What you might see
- F004
- undervoltage
- drive trips at start
Likely causes
Low or missing supply voltage on one or more phases
Blown input fuse
Wrong P031 motor nameplate voltage parameter
DC bus capacitor degradation
Required tools
- Multimeter
- Fuse puller
- Lockout-tagout kit
Safety first
- Lockout-tagout the upstream disconnect before opening the drive.
- Wait at least 5 minutes after removing power for the DC bus capacitors to discharge.
Procedure
- 1
Measure incoming line voltage at L1, L2, L3 with a multimeter, should match the drive nameplate ±10%.
Warning: Lockout-tagout the disconnect before opening the drive enclosure. - 2
Verify the input fuses are intact.
- 3
Check parameter P031 (Motor NP Volts) matches the motor nameplate.
- 4
Press the STOP / Clear Faults button to acknowledge F004.
- 5
Power-cycle the drive and attempt to start.
- 6
If F004 immediately re-appears, replace the drive, DC bus capacitors may be end-of-life.
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Stop fixing the same fault twice.
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