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wind power- any comments on this statement - Page 16

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Posted by Michael B on December 29, 2009, 12:35 am
 


Perhaps that would be time to short the generator output?



Posted by Curbie on December 29, 2009, 1:32 am
 


Michael,



That will stop the blades from spinning (if it doesn't burn out your
stator in the process), but you still have wind resistance to worry
about (blade furling), even a less efficient sail in high wind can
still be a problem, depends on wind speeds.

Curbie



Posted by Michael B on December 29, 2009, 4:08 am
 

Shorting may have been the wrong word to use, because
it suggests an all-or-nothing thing.
The point is to keep it from having excessive speed and
causing its own self-destruction. So shunting the output to
slow the unit is sensible. Even more sensible, IMO, is to
optimize the unit for low speeds, and operate it at those
speeds, and even if it were to be hit with gusts or really
high winds and turbulence, its actual speed may well not
get up to what a horizontal unit would have in a typical
fashion.
And a VAWT isn't going to get the highest winds anyway,
because it's sitting at the ground.

No need to search for the Holy Grail of the fastest winds,
least gusting, etc. I say go for optimized low speed output,
cheap, readily accessible, etc.  Instead of putting out as
much for the tower as for the generator, it needs to be
rethought. My prototype flap generator cost me $2, and
it took winds over 53 miles an hour, according to my
anemometer. That was with it free-wheeling, no generator
connected. It took it because it didn't have the mass to pull
itself apart. And no tower, it sat on the ground, skateboard
wheels at the ends of conduit sections. Actually, it wasn't
on the ground, but a handy part of my driveway.

Problem is the generator, getting output with low speed. But
those winds are able to push hard when you have 40 sq ft
facing into the wind. You can afford to take some loss by
using some ratio changes. I recently used some bicycle
parts to turn out higher speed to a treadmill motor.



Posted by Josepi on December 29, 2009, 3:37 am
 

Loading or shorting out the turbine is a typical regulating mechanism for
wind turbines, in any case. mechanical furling systems and other means are
usually the failsafe method when the winds are more than the regulating
system can handle.

By looking at the video of it turning I get the impression these units are
self limiting in speed, due to the large fin area travelling across the
ambient air.


Perhaps that would be time to short the generator output?


Jim,

Have you seen one that feathered itself in high winds?
Nope, that's a problem, high wind event protection.

 Curbie



Posted by Michael B on December 20, 2009, 2:36 pm
 

Snow wouldn't interfere with this one.


And a simple sping for the sail could allow it to give with the
pressure of excessive wind speed, cutting the wind to the turbine
by a considerable factor.



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