High Voltage Wind Gen Brake Sw. [RE-wrenches]

[Matt Tritt]

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Jeremy,

As far as I know, there is no actual requirement for a brake switch. 
However, one consequence of simply disconnecting any wind turbine with a 
fixed-pitch rotor from a load , (like SWWP, Bergey, etc.) will be that 
the machine can "run away", and sometimes even go ka-blooey. The only 
thing that will cause these machines to yaw out of the wind is when the 
wind speed is great enough for the yaw to commence, and not the actual 
RPM of the machine. When the wind is below that threshold speed, there 
is nothing to prevent the rotor from over-speeding except a connection 
to some kind of load or short-circuit, but a direct short of the 
windings will often not be able to stop the rotor in a high enough wind. 
Machines that control their rotor speed by variable-pitch of the rotor 
blades through mechanical means (centrifugal force) will only reach a 
certain (non-destructive) speed, usually slightly higher than the rated 
output of the alternator, regardless of the presence of a load. Because 
of this, fusing the output of a variable-pitch turbine does not expose 
the machine to potentially destructive forces should the fuse blow.

A complicated answer to a simple question! ;-)

Matt T

Jeremy Rodriguez wrote:

>Wrenches, 
>Has anyone had to install a Break Switch/Disconnect for a Grid tied wind 
>turbine. I have a need for one on a Whisper Link 1kw system. I do not 
>want a fused unit and it needs to be rated for 400vdc.  Southwest 
>Windpower tells me that they have a brake switch for there 3kw battery 
>based machine but no such thing for the grid tie machine!
>Is this a code requirement or an inspector's requirement?
>
>Thanks in advance
>
>Jeremy
>All Solar
>Colorado 
>
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