Power Bridge Fault (Adv. Code 0,1,2)

What does 27 mean?

The drive has detected a failure in its output power devices, such as IGBTs or diodes within the power bridge. This critical fault can lead to uncontrolled motor operation, damage to the motor, or complete drive failure. It may also indicate a problem with the input power section.

• IGBT short-circuit or gate drive failure within the drive's output power stage (Advanced Code 0).
• Motor cable insulation breakdown, causing a phase-to-phase or phase-to-ground short circuit at the drive output.
• Excessive current transients due to drive output connected to high capacitance loads or improper motor sizing for the application.
• Loose power connections on drive output terminals U, V, W leading to arcing and localized overheating.

Click steps to track your progress.

1. 1

   1. Power off the drive. Disconnect motor from drive output terminals U, V, W. Measure resistance between each output terminal to ground, and between each output terminal pair, expecting open circuit readings (Megaohm range).

2. 2

   2. Perform an insulation resistance test on the motor windings and cable using a 1000V megohmmeter, verifying readings above 100 Megaohms to ground and between phases.

3. 3

   3. With power off, visually inspect drive output terminals and internal bus bars for signs of arcing, discoloration, or loose connections.

4. 4

   4. Verify input power quality using an oscilloscope to detect voltage spikes exceeding the drive's maximum input voltage rating.

5. 5

   5. If the fault persists after disconnecting the motor, the drive power stage is confirmed faulty and requires replacement.