Technical Trends in Wind Turbine Bearings 1

The wind turbine industry offers a variety of turbines configurations with both horizontal and vertical shaft alignments as well as models that do not include a gearbox. In general though the vast majority of industrial scale wind turbines (generally speaking machines that generate more than 500 kW of power) use a three bladed rotor on horizontal shaft connected to a gearbox that drives a generator. Fig. 1 illustrates the nacelle from a typical wind turbine. Inside the nacelle are the mainshaft support bearings, gearbox, induction generator and the yaw drive system. With this mechanism, the energy in the wind used to turn the rotor. This rotation is passed through a gearbox that increases the shaft speed and then passed into a generator where the electricity is produced. With any given wind turbine, the amount of electrical power generated is proportional to the square of the