Brake chopper

What does F-04 mean?

This fault indicates an issue with the braking resistor circuit, such as excessive regenerative power, an interrupted or short-circuited braking resistor, or incorrect resistor value. It can also be triggered by a defective brake chopper or a ground fault in the circuit. Failure to address this can lead to DC link overvoltage or inadequate braking performance.

• Braking resistor is open circuited or disconnected (e.g., wire break, loose connection to X17/BR terminals).
• Braking resistor has a short circuit, preventing proper energy dissipation and causing excessive current flow.
• Braking resistor is undersized or overheated, causing its internal thermal switch to open and disconnect it.
• Inverter's internal braking chopper circuit has failed (e.g., IGBT short-circuit, control circuit malfunction).
• Excessive regenerative energy exceeding the braking resistor's capacity during deceleration (e.g., P1-09 too short for load).

Click steps to track your progress.

1. 1

   1. Measure the resistance of the braking resistor at terminals X17/BR (expect value within +/-10% of its nameplate rating).

2. 2

   2. Visually inspect the braking resistor for physical damage, discoloration from overheating, or an open thermal switch (if present).

3. 3

   3. Check all wiring connections between the inverter (X17/BR) and the braking resistor for looseness, damage, or corrosion.

4. 4

   4. Monitor the DC link voltage (P0-01) during deceleration to confirm regeneration and chopper activation (voltage should rise and then drop).

5. 5

   5. If the braking resistor is confirmed functional, increase the deceleration ramp time (P1-09) to reduce the instantaneous regenerative power.