F10
Siemens
High Generator Output Voltage
Generator shuts down or refuses to transfer; controller shows F10 High AC Voltage.
Advertisements
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Advertisements
Possible Causes
AVR voltage sense failure, Incorrect AVR adjustment, Loose or broken voltage sensing leads, Defective AVR
How to Fix / Troubleshooting
Safety first: High voltage can damage connected equipment. Keep the generator output breaker open and ATS in the normal (utility) position until the issue is resolved.
- Confirm voltage: With the generator running unloaded, measure output voltage with a true-RMS multimeter. If significantly above nameplate (e.g., >10% high), shut down the unit.
- Inspect sensing leads: Trace the small-gauge sensing wires from the alternator output to the AVR and controller. Tighten any loose terminals and repair damaged insulation. Incorrect sensing can cause the AVR to over-excite the alternator.
- Check AVR adjustment: Many Siemens AVRs have a voltage adjustment potentiometer. With the generator running and no load, carefully adjust the pot to bring voltage within specification. Make only small adjustments and recheck.
- Replace AVR if unstable: If voltage fluctuates widely or remains high despite correct sensing and adjustment, replace the AVR with the correct Siemens part.
- Retest under load: After repair, run the generator under moderate load and verify stable voltage before allowing automatic transfer.
Advertisements
Repair Difficulty
Hard
4/5
Required Part
Automatic Voltage Regulator (AVR)
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements