Statistics Show Bearing Problems Cause the Majority of Wind Turbine Gearbox Failures

September 17, 2015

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In the past, the wind energy industry has been relatively conservative in terms of data sharing, especially with the general public, which has inhibited the research community’s efforts to identify and mitigate the premature failures of wind turbine gearboxes. With support from the U.S. Department of Energy, the National Renewable Energy Laboratory (NREL) started a gearbox reliability data collection effort under the Gearbox Reliability Collaborative to categorize top wind turbine gearbox failure modes, identify possible root causes, and direct future research and development activities to prevent these premature failures. Some of the statistics generated based on this database are made publicly available and this release is an effort to disseminate the database information to a broader audience.

A pie chart showing information of the gearbox reliability database.
According to the latest statistics from the database, the majority of wind turbine gearbox failures (76%) are caused by the bearings. Axial cracks that form on the bearings during high- and intermediate-speed stages are the leading cause for bearing failures and are the focus of a joint research effort by NREL and Argonne National Laboratory to identify the root causes and develop mitigation measures. Gears were identified as the second leading cause of failures (17.1%) followed by other components that account for 6.9% of the failures. Among the other components, lubrication and filtration system problems are dominant.

These statistics are based on 750 confirmable wind turbine gearbox damage records provided by wind plant owners and operators from 2009 through August 2015. The owners and operators participating in this effort represent 34% of the nation’s wind capacity.

The project currently has more than 20 data-sharing partners, including wind turbine and wind turbine gearbox manufacturers and owners/operators, gearbox rebuild shops, and operation and maintenance service providers. The number and variety of partners and the assets they represent, along with inquiries from members of the wind turbine gearbox supply chain, demonstrate the value and need of major wind turbine component data collection and analysis to the industry.