Siemens alarm A30502: Power unit: DC link overvoltage
SINAMICS S120 drive warning · SINAMICS S120
What it means
The power unit measured DC-link overvoltage during pulse inhibit, i.e. while the output stage was off yet the bus kept charging - pointing at the supply side rather than regenerating drives. The alarm value carries the bus voltage in 100 mV/bit (compare r0070). Persistent occurrence precedes hard faults and stresses the DC-link capacitors.
Likely causes
- device supply voltage above the p0210 setting
- line reactor incorrectly dimensioned (too small)
- high line voltage transients on an unstable supply
- misconfigured p0210 relative to actual mains
Triage note: Distinct from fault F30002 (active DC-link overvoltage trip); verify p0210 matches the real line voltage.
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Send us alarm A30502 with your machine details — typical RFQ turnaround is 24–48h.