Siemens alarm A30031: Power unit: Hardware current limiting in phase U
SINAMICS S120 drive warning · SINAMICS S120
What it means
The hardware current limiter for phase U responded and inhibited pulsing in that phase for one pulse period. Individual events are tolerated, but repetition escalates to fault F30017. The identical warnings A30032/A30033 cover phases V and W. Treat frequent occurrences as evidence of motor, cable or output-stage trouble.
Likely causes
- transient motor overloads (crash, stick-slip)
- motor cable faults or excessive length
- controller gains too aggressive
- weakening output-stage semiconductors
Triage note: Counterpart phases: A30032 (V), A30033 (W); escalation limit leads to F30017.
Need the part urgently?
Send us alarm A30031 with your machine details — typical RFQ turnaround is 24–48h.