In simple terms, the wind blows the rotor blades, which turns a shaft in a generator to make electricity.
The tower is bolted into a platform. The nacelle is attached to the top of the tower. The nacelle contains the rotor gearbox and generator. Attached to one end of the nacelle is the rotor hub, to which the three blades are attached.
An industrial wind turbine is constructed to supply the electric grid.
To produce alternating current in phase with the grid, the rotor shaft has to turn at a set rate. Innovative designs allow a small amount of brief variance.
The blades can be pitched to adjust how they respond to the wind. This is called pitch control and is done with a motor at the base of each blade.
Yaw control motors at the base of the nacelle turn the nacelle so that the blades are facing into the wind.
Except for line loss between the wind turbine and the substation where it connects to the grid, the power used by wind turbines themselves has not been documented publicly.
Without power from the grid, wind turbines can not function. When there is a blackout, the wind turbines go out, too.
Every wind turbine design has a cut-in wind speed, a rated wind speed, and a cut-out wind speed.
At the cut-in wind speed, the blades start to turn and a trickle of electricity starts to be produced. Around cut-in, the generator may be used as a motor to help the wind overcome inertia and start the blades turning.
The cut-in speed is typically 7 to 9 mph.
At the rated wind speed, the turbine is able to generate electricity at its maximum, or rated, capacity.
The rated speed is usually in the range of 25 to 35 mph.
At the cut-out wind speed, the turbine shuts down to avoid damage. The pitch controllers feather the blades to let the wind flow past them and the rotor hub is braked. The wind usually has to return to a much lower speed, called the cut-back-in wind speed, for a certain amount of time before the turbine will restart.
The cut-out speed is generally around 55 mph. The cut-back-in speed is around 45 mph.
© National Wind Watch, Inc.