Fagor alarm 4080: ERROR 307: Under-voltage of the power bus
CNC 8055 SERCOS drive error (DDS) · Fagor DDS drives
What it means
Software-detected DC bus undervoltage: the bus fell below the permissible minimum for the supply rating. It is a resettable category 1 stop; the CNC still cancels enables, interrupts all programs and activates the external emergency output. Investigate the mains feed and PSU health.
Likely causes
- Mains voltage sag below rated (line <380 V AC class)
- High line impedance under peak current demand
- Blown PSU fuse or loose bus plates
- Missing input phase
Triage note: Also grouped as alarm 4011.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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PS / XPS power supply
power-supply · Common cause
Need the part urgently?
Send us alarm 4080 with your machine details — typical RFQ turnaround is 24–48h.