Yamaha
Overload / Voltage Sag Under Motor Starting
Generator starts and runs but shuts down when large loads (e.g., HVAC) start, without logging a specific code.
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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.
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Possible Causes
Generator undersized for load, Weak AVR response, Loose connections causing voltage drop, Failing alternator windings
How to Fix / Troubleshooting
Safety first: Isolate the generator from the building via the transfer switch before changing wiring or loads.
- Assess load: Add up the running and starting kW of major loads (HVAC, pumps, etc.) and compare to the generator's rating. Consider using soft-start kits on large motors.
- Check connections: Tighten all power lugs at the generator, transfer switch, and main panel to reduce voltage drop.
- Monitor voltage: With a meter, observe voltage during motor start. If it drops excessively, consult a Yamaha technician about AVR performance or alternator condition.
- Load management: Reconfigure circuits on the ATS to stagger motor starts or remove non-essential loads.
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Repair Difficulty
Medium
3/5
Required Part
Automatic Voltage Regulator (AVR)
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