Here's a look inside a turbine designed to produce about 1.5 megawatts of electricity. Blades rotate at 18 to 30 revolutions per minute. As wind speeds change, a mechanism changes the pitch, or angle, of the blades to control rotation speed. This is also used in combination with the brake inside the turbine to stop the rotor.
Electricity runs down the tower through cables.
GEAR BOX Steps up the rotation rate to about 1,500 r.p.m. for the generator. To combat power losses along the grid, a transformer steps up the voltage to 10,000 to 30,000 volts. When wind speed reaches 10 knots, an electronic controller starts the turbine. If wind speed exceeds 50 knots, the controller engages a hydraulic brake system. A yaw drive can turn the turbine a few degrees to catch the wind.