Scope of this technical record
DC-bus energy-discharge path through bus sensing, brake chopper command, brake transistor, resistor and thermal protection.
Brake resistors and DC-link circuits can remain hot and hazardous. Rating, enclosure and duty cycle must be respected.
Brake chopper route
The brake route links ramp, hardware and duty cycle instead of only saying to increase decel time.
Brake chopper DC-bus discharge image
A braking path is both parameter and hardware
A brake resistor must be correctly rated, connected, enabled and switched by a healthy chopper circuit. If any part of that route is missing, the drive may still run normally and only trip when the motor returns energy during deceleration.
The page links the deceleration overvoltage symptom to resistor wiring, resistor value, thermal contact, chopper transistor and bus voltage feedback instead of only recommending a longer ramp.
Brake-chopper decision table
Use temperature, timing and bus behavior to separate hardware, sizing and feedback issues.
Braking circuit split
| Observation | Likely area | Service action |
|---|---|---|
| Resistor cold after repeated decel trips | Open/disabled brake path | Check wiring, enable, chopper command |
| Resistor overheats | Duty cycle or rating | Review braking energy and thermal contact |
| Chopper shorted | Brake transistor / driver | Inspect before connecting resistor |
| Bus rises despite brake fitted | Sizing or chopper failure | Separate resistor rating from switching failure |
| Bus feedback abnormal | Sensing path | Check divider and control feedback |
Field record checklist
- Load and decel event
- Brake resistor value/rating
- Wiring and thermal contact
- Parameter enable status
- Chopper transistor evidence
- Bus feedback evidence
Technical basis and reference documents
This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.
Workflow for brake and regeneration evidence.
Turn this record into a qualified service request
A repair decision is much more reliable when the request includes the exact identity of the drive, the first fault evidence and the machine condition when the symptom appeared.
- Complete drive type code / MLFB or nameplate model
- Fault code, fault value and first event before reset
- When the event appears: power-up, enable, ramp, run, decel or stop
- Motor/cable connected or isolated during the symptom
- Visible board, option-card, module and connector identifiers
- Previous repair history, replacement parts and repeat-failure pattern