Failure in Output Stage (IGBT Desaturation)

What does Desat mean?

This fault indicates a desaturation of IGBTs in the output stage, signaling a hard short circuit between phases or phase to earth, or an earth fault. It can also be related to the brake IGBT (up to SX-D4037). If left unresolved, it can lead to severe damage to the drive's power components and connected motor, requiring costly repairs.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Check for water, moisture, or condensation in the motor housing and cable connections.

2. 4

   Verify that the rating plate data of the motor is correctly entered into the VSD parameters.

3. 5

   Inspect the brake resistor, brake IGBT, and their associated wiring for damage or malfunction. For larger units (size G and up), ensure PEB cables to the motor are correctly ordered in parallel connections.