Lubrication can have a big impact on the safety of wind turbine operations by reducing operational safety risk at an operation during equipment servicing and maintenance, says oil company ExxonMobil Europe, Africa and Middle East SHC brand adviser Rainer Lange.

He explains that, inspecting equipment to determine if any additional servicing is required before filing components with new oil during a routine oil change, which can be a fairly straightforward process for ground-based equipment, becomes much more complex for wind turbine equipment as maintenance teams must ascend the tower, at times to elevations as high as 121.92 m.

This is not easily achieved, which is why one of the most effective opportunities to enhance the safety of a wind turbine operation is by reducing human-machine interaction (HMI), or the frequency of maintenance personnel’s interaction with wind turbine equipment.

Reducing HMI requires having a robust lubrication programme that prevents unnecessary downtime and extends the service intervals of wind turbine equipment.

ExxonMobil Fuels & Lubricants senior lubrication engineer Brad Pricket has published his findings on the optimisation of lubrication programmes generally used to drive productivity, documenting how they can also enhance the safety of an operation.

Pricket’s key guidelines to optimising the lubrication programme and enhancing the safety of the operation starts with the use of high-performance, synthetic lubricants, as the success of any wind turbine operation depends on using the right lubricants.

He notes that wind turbine components operate under severe conditions – including heavy loads, and vibration and varying speeds. To ensure the best possible equipment protection, high-performance and synthetic lubricants can be specifically formulated to perform in these conditions.

Some important lubricant properties include viscosity, viscosity index and oxidation stability.

Pricket says viscosity is the most important characteristic of an oil, particularly for wind turbine lubricants. “A lubricant’s viscosity indicates its resistance to flow – or the thickness of the film layer it produces to prevent contact between surface metals.”

He notes that a lubricant’s viscosity index measures the change in that lubricant’s viscosity owing to alterations in temperature. “Synthetic lubricants possess better viscosity indexes than their mineral-based counterparts, meaning their viscosity remains more stable and continues to function properly when exposed to extreme ranges of hot and cold temperatures.”

Meanwhile, oxidation stability measures a lubricant’s ability to withstand oxidation. Pricket notes that oxidation typically creates sludge and results in component wear and corrosion, and the rate of oxidation is dependent on both the rise in temperature and the amount of contaminants in a system. Synthetic oils include additives that can reduce deposit formation caused by oxidation, which extends oil life and slows down component degradation.

Health Monitoring
Pricket suggests that the second key guideline is to proactively monitor the health of equipment. “There is no better way to monitor the health of your equipment than through used oil analysis. This service helps you better understand how your equipment is performing and identify potential pain points.”

Operators armed with such information can then tailor their maintenance programme to get more out of their equipment and prevent unplanned downtime.

Pricket states that advanced oil analysis platforms can provide even more helpful insights, by identifying high-level trends not typically seen when viewing individual sample reports, as well as providing documentation to validate used oil analysis results.

Moreover, he states that the lubricant supplier can help clients make the right decisions to ensure that the programme works, leveraging decades of experience working with equipment builders and developing new technologies to identify the best solutions to fit the needs of specific equipment.

Improper storage and handling of lubricants is another important consideration, as it can significantly reduce a lubricant’s effectiveness and even turn safe lubricants into potentially hazardous waste. Optimising a lubrication programme is typically used to drive productivity, it can also meaningfully enhance the safety of an operation.

ExxonMobil South Africa has introduced Mobil SHC Grease 102 WT, a synthetic wind turbine grease that can protect pitch, yaw and generator bearings from extreme temperature conditions as high as 120 ºC to as low as –50 ºC.

“Extreme cold temperatures commonly occur in many places that also have high wind energy potential. In places like northern Asia, Scandinavia, the northern US and Canada, high wind conditions make protecting wind turbine equipment challenging,” says Lange.

He concludes by noting that, with Mobil SHC Grease 102 WT, operators can keep turbines running in these extreme conditions, helping them decrease downtime and reduce maintenance costs.”