Scope of this technical record
DC bus overvoltage trips that appear during deceleration, stopping, lowering or other regenerative machine states.
DC-link and braking hardware can remain hazardous and hot after shutdown. Work must follow qualified isolation and rated braking-component procedure.
The useful interpretation
A deceleration overvoltage usually means the motor is returning energy into the DC link faster than the drive can absorb, dissipate or return it. That makes the fault a system-energy problem before it is a board-replacement problem.
The route starts with machine timing and parameter configuration: stop mode, ramp-down time, overvoltage stall/control, braking enable and load direction. Then it moves to brake resistor wiring, chopper hardware, DC-bus feedback and common-DC-bus interaction.
Evidence map
If lengthening the ramp removes the trip, braking capacity or machine inertia is implicated. If the trip remains with gentle ramps, suspect bus feedback, incoming supply condition or system-level DC-link interaction. If braking hardware is fitted but never heats or shows no switching evidence, chopper/resistor routing becomes the priority.
Overvoltage during deceleration route
| Evidence | Likely boundary | Next step |
|---|---|---|
| Trip only on fast stop | Ramp/load inertia | Review decel time and stop mode |
| Brake resistor fitted but no effect | Chopper/resistor path | Check wiring, resistance and enable |
| Trip on lowering or unwinding | Regenerative load | Review braking or regenerative front end |
| Common DC bus present | System energy exchange | Check other drives returning energy |
| Measured bus disagrees with panel | Bus feedback | Inspect sensing path |
Field record checklist
- Fault timing during decel/stop/lowering
- Ramp-down and stop-mode settings
- Brake resistor value and wiring
- Internal or external braking unit status
- Common DC bus or regenerative unit presence
- Measured bus evidence if qualified
Technical basis and reference documents
This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.
Linked workflow for DC-link overvoltage triage.
Diagnostic workflow
Drive trips on DC bus overvoltage when stopping, lowering, braking or reducing speed.
Drive reports undervoltage/precharge fault, blows input fuses or shows no-display symptoms with uncertain DC-link charging.