Proactive approach to gearbox repairs

Reg Tucker, US Editor, Renewable Energy Focus

The trend toward larger wind turbines and the growth in off-shore wind farms creates new maintenance challenges. Nonetheless, gearbox makers and overhaul service companies are adapting to meet demand.

For wind turbine manufacturers, it’s no longer enough to supply quality wind turbine gearboxes. These days, there’s much more emphasis on the “service” aspect — meaning suppliers and gearbox overhaul service providers are taking a more proactive approach in serving their clients’ maintenance needs. These services range from providing real-time systems “monitoring” to anticipate when turbines might require servicing before they break down, to actually building in periodic maintenance schedules to avoid costly downtimes that often come with catastrophic failures.

This strategy is becoming increasingly important when it comes to off-shore wind farms, where operators share horrors stories of having to wait for months on end to receive replacement parts. To address this issue, gearbox overhaul companies are getting more sophisticated in their approach. “We’re beginning to add new things such as condition monitoring and vibration analysis, which allows us to monitor the customers’ equipment remotely,” said Dave Morgan, UK business manager, ZF Wind Services, UK. “This is especially critical with off-shore installations, where you could be waiting a few months if the gearbox goes down.”

Remote condition monitoring lets service companies track the status of key drive train elements, gauging attributes such as wind speeds, shaft speeds, bearing temperatures, power output and other critical parameters. Some advanced monitoring systems even boast the capability of detecting cracks in gear teeth! (REF, Sept/Oct 2013 edition).

“With our ability to do conditioning monitoring, we can make predictions on when to remove gear boxes, and we’re working with our customers to devise planned maintenance schedules to figure out the best time to do that,” Morgan explained. For example, on off-shore wind farm systems that entail, say, 30 turbines, ZF Services may advise proactively overhauling 5-6 turbines per year. “This represents a considerable cost savings compared to running the turbines until they fail, then ordering the parts and scheduling a trip out to the installation site.”

In markets such as the UK, where off-shore wind farms are commonplace, this can be particularly challenging. Not only has there been a proliferation of off-shore wind farms, but, as Morgan notes, there has been a drive to increase the size of the turbines and rotor diameters to increase overall yields. (Hence the popularity of 6MW and 8MW turbines.) Morgan is also seeing more “floating” systems crop up, which pose their own unique maintenance challenges.

“We’re moving more into the off-shore shore field, although they’re not easy to get to,” Morgan explained. “While they are built to last a long time, we’re also looking at doing things such as taking components of the gearbox apart in sections up the tower, thereby savings time and costs. We’re also doing endoscope inspections on an annual basis.”

View this article in its entirety in the January/February issue of Renewable Energy Focus magazine. Subscribe online today to receive your issue!



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14 February 2014


14 February 2014

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