Brake chopper short-circuited

What does 27 mean?

The internal brake transistor (chopper) within the drive, which is responsible for switching the brake resistor, has short-circuited. This renders the regenerative brake function inoperative and can cause immediate faults or damage if the drive attempts to use it.

• Failure of the IGBT (Insulated Gate Bipolar Transistor) within the brake chopper circuit due to overcurrent or overvoltage stress.
• Contamination or foreign material bridging terminals on the power board, creating a short path for the brake chopper.
• Aging and degradation of semiconductor components leading to internal breakdown of the chopper circuit.
• Repeated high-energy braking events exceeding the chopper's continuous power dissipation rating.

Click steps to track your progress.

1. 1

   Safely disconnect all incoming power to the drive and wait for DC bus discharge (verify 0VDC at DC+ / DC- terminals).

2. 2

   Measure resistance between the drive's DC+ terminal and the B1/B2 brake terminals; a reading near 0 Ohms indicates a short circuit.

3. 3

   Visually inspect the drive's power board for signs of damage, burning, or conductive debris near the brake chopper components.

4. 4

   If an internal short is confirmed by measurements, replace the entire drive as the brake chopper is an integrated component.

5. 5

   Before applying power to a new drive, verify the external brake resistor's impedance matches the drive's specifications.