Siemens alarm F30002: Power unit: DC link voltage overvoltage
SINAMICS S120 drive fault · SINAMICS S120
What it means
DC link exceeded overvoltage threshold (~800-820 V on a 400 V class system); fault value holds trip voltage in 0.1 V.
Likely causes
- regenerated energy with no/undersized braking resistor or chopper failure
- line supply voltage too high
- line phase interrupted during regeneration
- ramp-down time too short for inertia / Vdc-max controller disabled
- aged/degraded DC-link capacitors raising ripple
Triage note: Correlate trip voltage from r0949 with deceleration events; check p1240/p1121 settings before hardware swaps.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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braking resistor/chopper unit per drive sizing
braking resistor or brake chopper · Primary suspect
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6SL3130-… (ALM) / 6SL3210-1SE… (SLM)
Active/Smart Line Module (regulation failure) · Common cause
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DC-link capacitor bank (chassis units G150/S120CM)
DC link capacitors · Check if others ruled out
Need the part urgently?
Send us alarm F30002 with your machine details — typical RFQ turnaround is 24–48h.