Schaeffler North America


Technical Product Information | 2011-04
Current-Insulating Bearings
Rolling bearings for prevention of damage due to current passage



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 urrentinsulated bearings.