Brake chopper defective

What does F4.2 mean?

The output stage of the brake chopper component is defective. This critical failure prevents the drive from effectively dissipating regenerative energy during deceleration, potentially leading to DC bus overvoltage faults and irreversible damage to the drive.

• Complete failure of the brake chopper IGBT (e.g., open circuit, internal short, or gate-emitter short).
• Failure of the gate driver circuit specifically for the brake chopper IGBT, preventing proper switching.
• Damaged or unreliable control signal path from the drive's main board to the brake chopper circuit.
• Prolonged overcurrents or thermal stress leading to component degradation within the chopper module.
• Incorrectly wired external braking resistor causing damage to the chopper output stage.

Click steps to track your progress.

1. 1

   Disconnect main power. Visually inspect the brake chopper module (if external or modular) and its internal components for signs of burning or damage.

2. 2

   With the braking resistor disconnected, measure the resistance across the brake chopper terminals on the drive (e.g., X20/X21) to check for internal shorts or open circuits (after DC bus discharge).

3. 3

   Check the internal diagnostic codes (e.g., Parameter P8-01) for specific sub-faults related to the brake chopper or power module.

4. 4

   Verify the integrity of the control signals sent to the brake chopper (if accessible for testing) using an oscilloscope during a commanded deceleration.

5. 5

   If the brake chopper is an integral part of the drive's power module, consider replacing the entire power module or the complete drive unit.