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About the Gearbox Reliability Collaborative

Premature gearbox failures have a significant impact on the cost of wind farm operations. In 2007, NREL initiated the Gearbox Reliability Collaborative (GRC). The project combines field testing, dynamometer testing, analysis, modeling, condition monitoring, development of a failure database, and operations and maintenance research in a multi-pronged approach to determine why wind turbine gearboxes do not always achieve their expected design life—the time period that manufacturers expect them to last.

The collaborative of manufacturers, owners, operators, researchers, and consultants focuses on gearbox modeling and testing and the development of a gearbox failure database. Collaborative members also investigate gearbox condition monitoring techniques. Data gained from the GRC will enable designers, developers, and manufacturers to improve gearbox designs and testing standards and create more robust modeling tools.

GRC project essentials include the development of two heavily instrumented representative gearboxes—one older gearbox representing existing design practices and one newer gearbox incorporating the latest design practices and lessons learned from previous GRC testing. Knowledge gained from the field and dynamometer tests conducted on these gearboxes builds an understanding of how the selected loads and events translate into bearing and gear response. The GRC evaluates the current wind turbine gearbox gear and bearing analytical tools and models, develops new tools and models, and recommends improvements to design and certification standards. In addition, the GRC investigates condition monitoring methods to improve turbine availability. Development of the failure database provides the means for multiple partners to document root cause analyses in a tool that identifies key failure trends. Once identified, the trends allow researchers to focus on the solution to gearbox challenges and the research provides a method to measure improvements.

NREL and its GRC partners have been able to identify shortcomings in the design, testing, and operation of wind turbines that contribute to reduced gearbox reliability. In contrast to private investigations of these problems, GRC findings are quickly shared among GRC participants, including many wind turbine manufacturers and equipment suppliers. Ultimately, the findings are made public for use throughout the wind industry. This knowledge is already resulting in increased gearbox reliability and an overall reduction in the cost of wind energy, and continues to be used to achieve even better performance.