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.