14
You
1.8 m
24 m
Residential scale
12 m
W
ater pumper
80 m
Utility scale
Scale of wind machines
A wind turbine that could power your whole house is still considered
“small.” This wind turbine might have a rotor diameter of 7 m and could
produce 10 kW (10,000 watts) in a 25 mph wind.
A typical “large” or utility scale wind turbine has a rotor diameter of
80 m and stands on a tower 80–100 m tall. This wind turbine could
produce 1.5 MW (1,500,000 watts)—enough electricity for about 400
American homes in a 30 mph wind.
Utility scale turbines are getting bigger and bigger. Some turbines today
can produce over 5 MW and have a rotor diameter of 126 meters!
Energy transformations
Wind turbines transform the kinetic energy of the wind into electricity.
The force of the wind on the blades causes them to move. Blades are
usually shaped like airfoils, using lift to spin the blades faster than the
wind.
The blades and the hub together are called the rotor. The blades on
large utility scale turbines change their pitch to react to wind speed. The
red blades on your MINI have a fixed pitch, more similar to a residential
scale turbine. With the crimping hub, you can manually change pitch.
As the rotor turns, it spins a drive shaft which is connected to a generator.
The spinning generator converts mechanical (rotational) energy into the
electrical energy we use every day. Many large wind turbines often have
a gearbox between the rotor and the generator, so that the generator
can spin much faster than the blades are spinning.
Generators on large grid-connected turbines spin at 1200 to 1800
revolutions per minute (RPM). On the smaller, residential turbines, the rotor
and the generator spin at the same speed, anywhere from 0–500 RPM
since there is no gearbox.
Your MINI does not have a gear box and is considered a “direct drive”
device. That means you have to get the blades spinning very fast to
create usable power. Large turbine manufacturers have started to make
turbines without gearboxes, but to do this they need generators with lots
of heavy magnets and wire. This makes the tower designers job much
more difficult.
At KidWind we have other kits which let you experiment with
gearboxes and winding your own generators. Check them out
in the at www.KidWind.org.
OTHER KIDWIND KITS
The airfoil shape of most wind turbine blades uses
lift to increase rotor speed.
Lift
Summary of Contents for MINI Wind Turbine
Page 1: ...MINI Wind Turbine Instruction Manual...
Page 13: ...15...
