Fagor alarm 4140: ERROR 311: Short-circuit at the Low Side of the IGBT

What it means

Short-circuit detected on the low-side IGBT of the output bridge. Immediate PWM cutoff (category 0 stop) plus the CNC emergency sequence on all channels. Service/replacement of the drive is required; do not repeatedly reset onto a shorted bridge.

Likely causes

• Shorted low-side IGBT
• Gate-driver failure causing shoot-through
• Motor/cable short damaging the bridge leg

Replacement parts

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

• DDS / AXD / SPD drive (inverter stage)

  drive · Common cause

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