The Wind Turbine
- Measures the wind speed and
transmits wind speed data to the controller.
- Most turbines have either two or
three blades. Wind blowing over the blades causes the blades to "lift"
- A disc brake, which can be applied
mechanically, electrically, or hydraulically to stop the rotor in
- The controller starts up the
machine at wind speeds of about 8 to 16 miles per hour (mph) and shuts
off the machine at about 55 mph. Turbines do not operate at wind speeds
above about 55 mph because they might be damaged by the high winds.
- Gears connect the low-speed shaft
to the high-speed shaft and increase the rotational speeds from about
30 to 60 rotations per minute (rpm) to about 1000 to 1800 rpm, the
rotational speed required by most generators to produce electricity.
The gear box is a costly (and heavy) part of the wind turbine and
engineers are exploring "direct-drive" generators that operate at lower
rotational speeds and don't need gear boxes.
- Usually an off-the-shelf induction
generator that produces 60-cycle AC electricity.
- Drives the generator.
- The rotor turns the low-speed shaft
at about 30 to 60 rotations per minute.
- The nacelle sits atop the tower and
contains the gear box, low- and high-speed shafts, generator,
controller, and brake. Some nacelles are large enough for a helicopter
to land on.
- Blades are turned, or pitched, out
of the wind to control the rotor speed and keep the rotor from turning
in winds that are too high or too low to produce electricity.
- The blades and the hub together are
called the rotor.
- Towers are made from tubular steel
(shown here), concrete, or steel lattice. Because wind speed increases
with height, taller towers enable turbines to capture more energy and
generate more electricity.
- This is an "upwind" turbine,
so-called because it operates facing into the wind. Other turbines are
designed to run "downwind," facing away from the wind.
- Measures wind direction and
communicates with the yaw drive to orient the turbine properly with
respect to the wind.
- Upwind turbines face into the wind;
the yaw drive is used to keep the rotor facing into the wind as the
wind direction changes. Downwind turbines don't require a yaw drive,
the wind blows the rotor downwind.
- Powers the yaw drive.
From U.S. Department of Energy - Energy Efficiency and
Renewable Energy Wind and Hydropower Technologies Program