IndustrialDriveDataDrive Board & Diagnostic Database
Diagnostic workflow

Siemens MICROMASTER F0003 Supply, Precharge and DC-Bus Workflow

Entry symptom: A MICROMASTER drive reports F0003 undervoltage, resets during start, or loses DC-bus credibility under load.

Safety controls before proceeding
  • Input-side and DC-link checks expose hazardous voltages and must follow lockout and approved measurement procedure.
  • Do not assume the DC link is safe because an undervoltage fault is displayed.

Investigation sequence

1

Measure at the drive terminals

Confirm all input phases and line voltage at the drive, not only upstream of fuses or contactors.

2

Inspect the switching chain

Check isolator, fuse holders, contactor poles, loose terminals and intermittent plant supply before opening the drive.

3

Observe control behaviour

Record whether the keypad and logic stay alive, flicker or reset. Control reset points toward a wider supply/control-power problem.

4

Evaluate precharge and DC-link behaviour

Under qualified procedure, establish whether the bus charges normally, never reaches level, or collapses when the drive is enabled.

5

Escalate only with clean line evidence

If external line evidence is clean, move to precharge resistor/relay/contactor, DC-link capacitors, rectifier and bus-measurement path.

Stop conditions

  • Missing phase
  • Loose or overheated input terminal
  • Unknown DC-link state
  • Visible precharge or capacitor damage

Linked records

F0003
Undervoltage Fault

F0003 indicates the drive has lost a credible DC-bus supply boundary. The evidence route begins outside the drive with phase loss, fuses, contactor poles, loose terminals and supply sag, then moves inward to precharge, DC-link capacitors and measurement circuitry.

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Siemens MICROMASTER Input, Precharge and DC-Bus Supply Path

Separates external supply loss from internal precharge and DC-link failures when a MICROMASTER drive reports F0003 or shows unstable bus charging.

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