Output Short-Circuit or IGBT Fault

What does SC mean?

A short-circuit or ground fault is detected on the drive output side, which could be due to motor insulation damage, a shorted motor cable, or a hardware fault within the drive's output transistors (IGBTs). If unresolved, this fault can lead to significant damage to the drive's internal circuitry.

• Motor winding insulation breakdown causing a phase-to-phase or phase-to-ground short circuit.
• Physical damage or insulation failure in the motor output cables (U, V, W) leading to a short.
• Internal insulated-gate bipolar transistor (IGBT) module failure within the drive's output stage.
• Water ingress into the motor terminal box or drive output terminals causing a conductive path.

Click steps to track your progress.

1. 1

   1. Disconnect all motor leads (U, V, W) from the drive output terminals.

2. 2

   2. Measure the insulation resistance of each motor winding to ground and phase-to-phase using a megohmmeter (e.g., 500VDC or 1000VDC test voltage).

3. 3

   3. Visually inspect motor cables for signs of damage, chafing, or exposed conductors along their entire length.

4. 4

   4. With power removed, measure the resistance between the drive output terminals (U, V, W); a short indicates internal IGBT failure.

5. 5

   5. If the motor and cables test good, disconnect any brake or encoder wiring from the motor and re-test motor insulation.

6. 6

   6. If the fault persists after disconnecting motor and cables, replace the drive unit.