Error CodewarningPower Supply
F30021 Power Unit DC Link Overvoltage
In system: Siemens S120 Error Codes
DC link voltage exceeded the configured protection threshold.
Technical Details
Fault ClassPower Supply
Default ReactionOperation limited until condition clears
AcknowledgeAfter root cause correction and verification
Drive ObjectSiemens S120 Error Codes
Possible Causes
1Insufficient braking resistor
HIGH likelihoodValidate this cause with diagnostic values and wiring/mechanical inspection before replacing parts.
2Aggressive deceleration ramps
MEDIUM likelihoodValidate this cause with diagnostic values and wiring/mechanical inspection before replacing parts.
Step-by-Step Solution
1
Action 1
Check braking resistor sizing
Details
- Record measured values before and after this action
2
Action 2
Increase deceleration time
Details
- Record measured values before and after this action
Diagnostic Parameters
| Parameter | Description | Value/Unit |
|---|---|---|
| r0056 | DC link voltage | Vdc |
| r0949 | Fault value | Code-specific |
Prevention Tips
Record baseline operating values after commissioning and compare during maintenance.
Review wiring torque, grounding, and cabinet conditions during planned shutdown.
Apply parameter change control to reduce repeat faults after service activities.
Frequently Asked Questions
Structured fault troubleshooting workflow for maintenance teams