uncontrolable gen

[windspeed]

a friend has a 24 v 300 watt pmg "windtalker" brand name,......... not great

the controller has no external dumpload dont know what it does with the power when the batteries are charged (above 30 amps peak in a gale )

would anyone have any simple idea for a switch that would short the thing at at 20 amps or 32 volts

this has no furling

windspeed

[ghurd]

Maybe it shorts itself at ~30V?

G-

[Flux]

Not enough information to give any useful advice.

Firstly would it stop with a shorting switch or would it carry on running and burn out. If it has no furling it may have other methods of self protection or it may just be intended for low winds and it is eventually going to self destruct. 24v 30A is a fair output for a nominal 300W machine, most don't even make their nominal rating in a gale.

If you are sure that it will shut down with a brake switch then you can devise a voltage ( or current) clamp to shut it down. I suspect it may be better to shut down completely in high winds but you could try letting it cycle on and off something like a solar controller ( but shorted rather than open circuited). If the machine itself seems to be able to survive and it is the battery you are worried about then then using a standard diversion controller seems the best way.

There is an Australian controller ( Oakley or Oatley or something) that works in this sort of mode with a braking circuit across the turbine. I have no experience of it and from the look of the circuit diagrams I suspect the components are not adequate for 24v 30A but perhaps you could beef it up.

Flux

[windspeed]

it is a 3 ft rotor I believe it would stop if shorted

the controller that came with it is not up to the job and lets it go mad so I think anautomatic shorting switch is the answer

thanks

windspeed

[Flux]

Small machines up to 3ft often don't have any furling. There is a better survival rate with reduced scale. I should think that you need over 50 mph to produce 30A at 24v so it will not happen very often unless it is on a boat at sea.

You could set a standard diversion controller to work a relay and stop it to give battery protection from excess volts or just use the diversion controller. If you are worried about the alternator then you would need to sense current to shut it down, that probably means building something rather than using a standard device.

Flux

[windspeed]

Flux 50 mph is a calm day on the west coast of Ireland,

would you set a relay to switch as soon as it starts dumping

windspeed

[Ungrounded Lightning Rod]

Are you sure it doesn't furl.  (I found catalog entries for windtalker windmills on the web that seem to claim they furl at "25" (mph?).)

The mill may furl by stalling (allowing the airflow to detach from the blades at high wind speeds when loaded).  As the wind rises to a high level does it go from reasonably quiet to very loud (making "helicopter sounds") over a reasonably narrow range of wind speeds?  That would be a symptom of stall furling.

There are a number of other ways to furl a mill besides folding up the tail to turn it away from the wind.

If the mill is furling properly it will lose torque and won't overspeed in high winds (at least up to some design level).  So all you have to do is protect your batteries against overcharge (say, with a dump load) if the mill doesn't and you're fine.

You might want to contact the manufacturer and ask how and whether it furls, how high a wind it can stand when operating normally, and what to do to protect it in higher winds.

[windspeed]

ULR........I think your right I have not heard it myself but my friend did say it got very noisy in high wind

would the design of the blade control this

thanks again Windspeed

[Flux]

I agree with ULR, it is most likely designed to survive these winds as small machines can be very tough. If you can establish that the alternator can survive this current and you can live with the noise then all you need is a diversion controller.

Several manufacturers have tried this route and found that most people can't live with the noise. The AirX does more or less what you propose and continuously brakes the thing in high winds to maintain a low average speed to keep the noise down. Furling schemes present certain problems on boats where the thing is not always vertical and many small machines rely on intrinsic strength to hold them together.

For land use a furling scheme is very preferable. Even though you will have exceptional winds at times I suspect that a larger machine with furling and a significantly lower maximum output would be a far better all round source of power but it it does the job then it would be worth devising some form of brake controller to tame it but it will be a home build I suspect, I can't think of anything other than that Australian kit that does what you want.

Flux