Meaning of the indication
The DC bus or input supply is too low or unstable. The first route is line voltage, fuses/contactors, precharge, DC-link capacitors and supply sag evidence.
Checking order
- Measure input voltage at the drive terminals.
- Check fuses, disconnect, contactor poles and loose terminals.
- Compare voltage under plant load changes.
- Record whether the control stays alive or the whole drive drops out.
- Inspect precharge/DC-link evidence only after line evidence is credible.
Suspect areas
Input supplyFuseContactorPrechargeDC-link capacitorDC bus sensing