Wind for electricity generation
Practical Action
Tail Vane
There is often a tail vane which keeps the rotor orientated into the wind. Most small-scale
wind-machines have a tail vane which is designed for automatic furling, pivoting the blades
out of the wind on its yaw bearing at high wind speeds – over 15m/s - in order to prevent
damage to the turbine. There are several mechanisms that can be used which depend on
gravity or on springs that counter the force of the wind.
Larger machines have pitch-controlled blades: the angle at which the blades meet the wind is
controlled. This will achieve the same function.
Tower
The tower is of low solidity (thin), to minimise wind interference. Towers are often guyed for
extra support. For small towers, guy cables can be anchored with a piece of scaffold or pipe
which has been driven into the ground.
Auxiliary system
Charge controller / regulator
The function of the charge controller is to prevent damage to the batteries. If the batteries are
fully charged then the charging current is diverted. The controller then diverts the excess
charge to the dump load. Different types of battery require different types or charge controller
settings.
Fuse boxes & circuit breakers
To protect the appliances from high currents, fuses or circuit brakes should be installed into
the system. Such safety features are important for all electrical systems.
Dump resistor
In the simplest systems, the dump load is consumed by directing the excess current to a set of
light bulbs or a heating element which can heat air or a tank of water.
Inverter
The inverter is used if the appliances are designed for alternating current.
Battery
Deep-charge batteries specifically designed for renewable energy systems do exist. However,
they are expensive and only available in certain locations. Car batteries are often used instead,
therefore. A battery can be damaged if excessively discharged, so a low-voltage disconnect
device is often used to protect it.
More information on battery use and maintenance is in the Practical Acton Technical Brief:
Batteries.
Installation
Small-scale wind turbines can be installed without heavy lifting equipment. The tower is
pivoted at its base so it can be winched up with the aid of a lifting pole.
5