At 3 p.m., technicians working on a wind farm observed smoke rising from a wind turbine nacelle. They alerted the operator, which shut down the entire farm. The electricity network administrator shut off the HV network. Smoke was visible and debris fell at the foot of the wind turbine. Firefighters extinguished bush fires that had broken out on the ground. The smoke dissipated on its own within 15 minutes. At 5 p.m., the wind farm was started back up except for the affected wind turbine. The operator has set up a guarding system. It inspected all the blades visually. No damage was observed.

Burning residue that fell to the ground caused damage to 20m² of vegetation at the foot of the wind turbine. The main internal damage was to the generator in the nacelle, which required repair. The wind turbine remained shut down for 7 weeks, causing operating losses.

Smoke was discharged due to heating of protective parts (varnish, Perspex housing, rubber body) of the wind turbine’s generator. When restarting the turbine, a burning rubber gasket between the generator housing and stator windings caused the protective housing to heat up. After analysis, the operator observed that the specifications of the gasket, which is used to route air flow to the generator, were non-compliant. The gasket’s characteristics combined with the localised poor generator insulation caused the gasket to catch fire.

In addition, the wind turbine’s smoke detector detected a fault that was not transmitted to the control centre, because a higher priority alarm (ground fault) had been detected earlier. This initial electrical fault caused the turbine to be shut down before smoke was discharged. This discharge was detected by technicians working on another wind turbine.

The soot around the generator was cleaned with dry ice over the following days. The operator corrected the smoke detector fault and updated the alarm management software on all the turbines. The generator’s insulation was bolstered. It also planned to replace all the rubber gaskets with silicone gaskets with the required specifications.

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