Fagor alarm E003: Power bus voltage drops when torque is demanded

What it means

With the drive producing torque, the common DC bus collapses, which points to a missing or weak mains phase feeding the power supply or a defective drive module dragging the bus down. The manual instructs checking the condition of the three-phase lines and all drives on the bus, then restarting the system.

Likely causes

• one mains phase missing or a loose L1/L2/L3 terminal at the power supply
• another drive module on the power bus failing internally and loading the bus
• undersized or high-impedance supply line dropping under peak current
• poor bus bar contact between modules

Replacement parts

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

• AXD/SPD drive module (rating per machine list)

  drive · Common cause

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• XPS/RPS power supply module (rating per machine list)

  power-supply · Check if others ruled out

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