Generator produces a whining or humming noise from the alternator area under load.

Safety: Keep clear of rotating parts. Shut down and isolate generator before physical inspection.

• Listen and localise: Use a mechanic's stethoscope or similar tool to confirm the noise originates from the alternator bearings.
• Check mounting: Tighten alternator mounting bolts and inspect for movement on the base frame.
• Load type: Identify large non-linear loads (e.g., VFDs, UPS) that may cause electrical noise. Consider adding filters or derating.
• Bearing replacement: If bearing noise is confirmed, schedule alternator removal and bearing replacement by a specialist to prevent catastrophic failure.