Wind tower turbines have four main parts: the blades, nacelle, tower and base. Like airplane wings, the blades are designed to optimize lift. Traditional windmill blades are pushed by the wind; the blades of modern wind turbines are dragged by air pressure. Even though the blades spin relatively slowly, they can capture the wind's kinetic energy and transmit it to the turbine generator.
The blades are attached to a rotor that is connected to a pitch system on the nacelle; this system helps control the rotor speed. The nacelle is a bullet-shaped structure that contains a generator and gearbox, which connects the low- and high-speed shafts. In order to produce electricity, the rotors must spin at between 1,000 and 1,800 rpm. The generator within the nacelle produces 60-cycle AC energy.
The nacelle houses many parts, including an emergency brake that can stop the rotors and a controller that manages rotor speed. The anemometer is an instrument that measures wind speeds. It transmits information to the pitch system to reduce speed in dangerous conditions. A wind vane transmits information about wind direction to the yaw drive and yaw motor, which rotates the tower to optimize rotor speed.
The turbine tower, usually constructed from a steel cylinder, connects the nacelle to the base. The base of the tower is usually built from steel-reinforced concrete. In some cases, guy wires support the tower. Towers can be up to 200 feet tall and 10 feet in diameter. The taller the tower, the better able it is to capture wind energy. Towers contain wiring to transmit electricity from the nacelle generator to the base and hold other necessary equipment, such as controls and electrical cables.