Harmful effects of moisture on wind turbine gearboxes

Moisture in lubricating oil is a major factor leading to failure of wind turbines. Researchers have found that when the moisture content in wind power gear oil reaches 1000ppm, the life of the bearing will be reduced by 70%. According to the research of the American Renewable Energy Laboratory, the failure of the gearbox starts from the bearing. Once the bearing starts to fail, other gears and other components will also have problems.

Therefore, in order to make the service life of the wind power gearbox reach 20 years, the moisture in the wind power gear oil must be strictly controlled. The standard of the American Gearbox Manufacturers Association stipulates that the moisture content of wind power gear oil should be below 500ppm. However, the latest research shows that in order to improve the service life of the bearing, the moisture should be controlled below 150ppm, so that the service life of the bearing will be increased by 2 to 3 times.

  1. Where does the moisture in the gearbox come from?

When the fan is in operation, the working temperature of the gearbox will be as high as 95°C, and when it is shut down, the gearbox will gradually cool down to produce a “breathing” effect, resulting in the absorption of moisture and humidity from the air.

  1. What are the forms of moisture in wind power gear oil?

(1) Dissolved water (2) Emulsified water (3) Free water.

Usually we find that the state of the oil is transparent, and when it is not turbid, the water exists in the state of dissolved water. When the dissolved water reaches saturation, the oil will appear turbid, sometimes even emulsified, and the water at this time is called emulsified water. When the water in the emulsified oil continues to increase, the oil and water will separate, and the water at this time is called free water.

  1. What are the hazards of moisture in wind power gear oil?

(1) Accelerate the failure of the antioxidant, thereby accelerating the oxidation reaction of the oil and increasing the acid value of the lubricating oil. At the same time, the resulting gelatinous polymers can clog filter equipment, form sludge, etc.

(2) Due to the low viscosity and incompressibility of water, the bearing capacity of lubricating oil will be reduced, so that under high load, high pressure will turn water into superheated steam, and superheated steam will make oil leave the friction surface, resulting in wear of friction surface.

(3) Accelerating the hydrolysis of oil products, especially for ester lubricating oils, will lead to the formation of corresponding alcohols and acids, increasing the acid value of lubricating oils.

(4) Make the additives in the lubricating oil ineffective, thereby causing the function of the lubricating oil to decline and increasing friction and wear.

(5) It reacts with certain additives to form gels, and these gels agglomerate to form sludge to block filter equipment.

(6) The surface tension is reduced, making it easier for air to enter the oil, increasing the foam in the lubricating oil.

Moisture is one of the key factors affecting the life of the gearbox. Wind field technicians attach great importance to the moisture index of the gearbox lubricating oil. Yateks has a specially developed wind power sensor, which can strengthen the daily monitoring of moisture and strictly control moisture Content, to ensure the continuous and smooth operation of the fan.

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