Fagor alarm 4011: Undervoltage at the power bus (307)

What it means

Drive standard error E307: the software has measured a DC bus voltage below the permissible minimum. It is a resettable error producing a category 1 controlled stop, with the usual CNC shutdown of enables and program. Check the mains side before blaming the drive.

Likely causes

• Mains voltage below rated value (<380 V AC nominal systems)
• Excessive line impedance under high current peaks
• Loose bus plates, blown PSU fuse or missing line phase
• Regenerative power supply module failing under load

Replacement parts

We supply the following units for this alarm — tested, warranty-backed:

• XPS / PS-x regenerative power supply

  power-supply · Common cause

  Request a quote →