Siemens alarm F30045: Power unit: Supply undervoltage
SINAMICS S120 drive fault · SINAMICS S120
What it means
An internal voltage monitor signalled undervoltage on the module's own electronics supply - distinct from the external 24 V rail monitored by F30040. After checking the supply and performing a POWER ON, a module that keeps reporting this fault should be replaced.
Likely causes
- electronics supply voltage sag under load
- internal DC/DC converter degradation in the module
- supply wiring/contact resistance too high
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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6SL3121-… / 6SL3310-… matching power unit
motor-module · Common cause
Need the part urgently?
Send us alarm F30045 with your machine details — typical RFQ turnaround is 24–48h.