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“What are some of the most common issues in lubricating wind turbines?”
In many cases, the same types of lubrication issues occur in wind turbines that arise in similar equipment across all types of industrial environments. However, there are exceptions. Wind turbines often operate in harsh environments with extreme temperatures, challenging weather conditions and intermittent maintenance. These extreme environments demand specific gear oils that can lubricate at high or low temperatures and handle the variety of operating speeds.
Keep in mind that with wind turbines, the entire nacelle, rotor hub and rotor blades all move and have a point of rotation to control the positional direction and pitch as well as regulate speed. Whenever possible, the bearings at these points should be greased with a centralized system, but many require manual regreasing. In either case, the lack of routine inspections or regreasing can lead to progressing failure modes.
In addition, the bearings frequently are heavily contaminated from environmental dust, dirt or moisture. These inherent issues coupled with slower speeds and minimal condition monitoring are a recipe for expensive failures. In these applications, several predictive maintenance technologies may be utilized, including grease analysis.
Maintenance on other critical components in the nacelle, such as the gearbox and generator, will face the same operational oddities and environmental extremes. These components require more attention, as well as specialized lubricants, to deal with the extremes and to catch early signs of failure. The gearboxes have been known to experience premature wear or oil foaming when the right oil isn’t selected or when the drain intervals are too far apart. Taking proactive measures, such as routine inspections and oil sampling, can help avoid these failure progressions.
Since access to the nacelle during operation typically is not recommended, make an effort to collect an oil sample within 10-15 minutes after the system has been stopped and the oil is still considered “hot.” This will enable you to obtain a representative sample.
Finally, the reliability of all lubricated components on a wind turbine should be a concern, regardless of the turbine’s design. Despite their unique operational and environmental conditions, wind turbines are at risk of experiencing the same issues found on other industrial systems. These include grease cross-contamination, lack of contamination control measures and insufficient attention to normal lubricant degradation. All of these issues can be addressed with lubrication best practices.