Page 6 of catalogue Bearing Technology for Wind Turbines of Schaeffler Technologies GmbH & Co. KG

Bearing

Technology

Longer service life by current insulation

A generator operating in the nacelle of a wind turbine is subjected to significantly greater vibration loads than its counterpart on the ground. This additional permanent load has a negative influence on the cages and places a strain on the lubricant. In the design of bearings for a generator, it is not only the speed, size and design that play an important role. Particular attention must be paid to the lubrication and protection against possible current passage. The bearing arrangement of a generator generally contains two Deep groove ball bearings or one deep groove ball bearing and one cylindrical roller bearing. Current insulation of generator bearings The passage of current in a wind turbine generator can cause serious damage to the raceways of bearing rings in the form of melt craters and false brinelling, leading to enormous repair costs. It is therefore to take precautions at the planning stage to prevent such damage and failures, thereby helping to save costs. In many cases, it is sufficient to fit currentinsulated bearings. Current-insulated bearings are available with coated rolling bearing rings and as hybrid bearings with ceramic rolling elements. The current-insulating, highly wear-resistant layer consists of oxide ceramic and offers protection against a puncture voltage of up to 1 000 volts, even in a damp environment. Hybrid bearings with ceramic rolling elements allow even higher values. In addition, hybrid bearings give longer grease operating life. They are suitable for high speeds and have good emergency running characteristics. The use of these variants is based on the customer requirements. Conventional bearings can be replaced by current-insulated bearings at any time since the external dimensions are identical.

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