Windy Nation Windtura 750 Wind Turbine Generator - Manual (Page 15)

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If the Windtura 750 is used to charge a 12 or 24 volt battery bank, there must be a
device in place to prevent the battery bank from being overcharged by the Windtura 750.
Additionally, this device must keep the Windtura 750 under an electrical load while the
Windtura 750 is not charging the battery bank. To accomplish both these tasks, a device called
a diversion load (or dump load) charge controller is used. In the most simple terms, a diversion
load charge controller is a voltage monitoring device. The diversion load charge controller
monitors the voltage of the battery bank. When the voltage of the battery bank reaches a level
that indicates the battery bank is fully charged, the diversion load charge controller disconnects
the Windtura 750 from the battery bank. Because the Windtura 750 must stay under an
electrical load to operate safely, the diversion load charge controller connects the Windtura
750 to a diversion load. Generally, large wire wound resistors or heating elements are used as
the diversion loads. Once the battery bank’s voltage level drops from a fully charged level, the
charge controller senses this and switches the Windtura 750 back to charging the battery bank.
Overspeed protection in high winds:
All wind turbines need to be capable of protecting themselves in high wind conditions
(typically greater than 30-35 mph). If a wind turbine has no method of protection in high winds,
catastrophic failures can occur: (1) The blades will begin to spin too fast and will be under very
high stress, strain and tension forces. This could lead to the blades cracking or breaking.
Additionally, the noise from the blades will be very loud in high winds. (2) The wind turbine’s
generator will begin to rotate at very high rpms and the current (amps) produced by the
generator might produce too much heat for the generator to handle. The intense heat will
overheat the generator and it will break.
The Windtura 750 uses a high wind protection method called furling. The tail assembly
of the Windtura 750 is attached to the yaw mount on a pivot bar angled at 20 degrees. The
pivot bar allows the generator and yaw mount to rotate away from the wind. At a wind speed
of approximately 30 mph, the rotational inertia of the blades begins to turn the blades and
generator “out of the wind”. As the wind speed increases, the Windtura 750 will continue to
turn “out of the wind” to almost 90 degrees. By turning “out of the wind”, the blades no longer
capture all of the wind’s kinetic energy and, therefore, the Windtura 750 is capable of
protecting itself in high winds. Because the tail assembly is mounted on a 20 degree pivot bar
and is free to rotate, the tail assembly does not move and stays “in the wind”. When the wind
speed lowers to 28-30 mph, the Windtura 750 unfurls and the blades and generator face the
wind again.
Because the Windtura 750’s furling mechanism is based on an angled tail boom, it is
very important that the tower is installed vertically. Use a level to confirm that your tower is
mounted vertically. If it is not, you will have to adjust the tower until it is vertical. A tower that
is not mounted vertically can cause the Windtura 750 to furl at an undesignated wind speed.