Arc flash fire destroys wind turbine nacelle at Maine university campus

A 600 kilowatt wind turbine on the campus of the University of Maine at Presque Isle caught fire on the night of 1 April 2018. The fire broke out in the nacelle, which houses the generator and other key mechanical components, and was attributed by Vestas, the company contracted to maintain the turbine, to an arc flash, a type of electrical explosion. The fire burned out on its own. Parts of the campus lost power for several hours that night. No injuries were reported and no other structures were damaged. According to Vestas the turbine was up to date on maintenance, but the root cause of the arc flash remained unknown. Vestas technicians declared the nacelle a total loss, while the tower and foundation were assessed as reusable, and a 300 tonne crane was brought in to remove the nacelle. The turbine was installed in 2009 at a cost of 2 million dollars. The university submitted an insurance claim and began reviewing options including replacing the turbine or moving to other renewable technologies such as solar.

An arc flash in the nacelle led to an electrical fire. The root cause of the arc flash was not established, and the turbine was reported to be up to date on maintenance.

1. An electrical arc flash can cause total loss of a turbine nacelle even where maintenance is up to date, so electrical fault detection and arc mitigation deserve attention alongside mechanical inspection.
2. Where a root cause cannot be established, operators should record the open finding and review similar electrical assemblies across the fleet rather than close the investigation.
3. A single turbine fire can interrupt supply to the host site, so owners of behind-the-meter generation should understand what loads depend on the asset.
4. Insurance cover and a replacement strategy should be planned in advance, because major components such as nacelles can be written off in a single event.

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