The wind passes over the blades creating lift (like an aircraft wing) which causes the rotor to turn. The blades turn a low-speed shaft inside the nacelle. From there, there are two major variations:
a) the shaft is connected to a gearbox which raises the low speed of the rotor shaft to a high speed shaft that drives a generator. Here, the slow rotation speed of the blades is increased to the high speed of generator revolution - usually 1500rpm in Europe and most of Asia to produce 50hz; or 1800 rpm in North America to produce 50hz
b) in 'direct drive' turbines' the rotor shaft is connected directly to the generator, which is generally much larger and more electrically complex.
Electricity from the generator goes to a transformer which converts it to the right voltage for the electricity grid. The electricity is then transmitted via the electricity network.
Posted in: Wind power FAQs