Investigation sequence
Capture exact evidence
Record type code, voltage class, fault code, whether the fault appears at power-up or during run, and any prior repairs.
Prove input supply
Measure or document three-phase supply at the drive input terminals and inspect input fuses/contactors.
Route to DC-link boundary
If supply is present, evaluate rectifier, precharge and DC-link charging evidence under qualified procedure.
Separate line converter context
For LINE CONV or cabinet arrangements, confirm whether the panel is referencing a line-side unit rather than the motor-side inverter.
Decide repair route
If evidence points to rectifier/precharge/DC-link hardware, collect board and module identifiers before parts or repair quotation.
Stop conditions
- Unknown voltage class
- DC bus not verified discharged
- Blown fuse repeats after replacement
- Evidence suggests cabinet line-converter arrangement beyond standard drive scope
Linked records
The intermediate DC circuit voltage is not sufficient for normal operation. The first boundary is incoming supply, input fuses, rectifier/precharge path and DC-link condition rather than keypad or motor replacement.
The indication belongs to the line converter or input-side conversion boundary. On larger ABB systems this may require distinguishing the motor-side control panel context from the line-side converter control context.
Maps incoming three-phase supply through fuses/contactors, rectifier/precharge and the intermediate DC circuit for DC UNDERVOLT and LINE CONV investigations.