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Forum Index : Windmills : Shutting down a turbine
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| RossW Guru  Joined: 25/02/2006 Location: AustraliaPosts: 495 |
A general question.... If you're using your turbine to charge batteries and the batteries now reach full charge, the conventional practice is to dump windgen output to a load. This means the turbine doesn't overspeed, sure... but it's still making a fair bit of noise, all that heat has to be dissipated. In the situation where you no longer need the output, or can no longer use the output for something useful, would it be better to shut the thing right down (load it more and more until it stops, then keep it shorted)? This would not only reduce noise, it would also reduce the heat one would need to dissipate. If/when the batteries needed a top-up, the load could be removed to allow the machine to crank back up again. Is there a flaw with this idea? Sure, the current while slowing the machine down would be high... but would it actually harm anything? And while the batteries are "topping off" you would want to keep some current flowing but perhaps not the whole lot... Am I just adding complexity for no real gain? |
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| adelaide Regular Member  Joined: 24/03/2006 Location: AustraliaPosts: 46 |
hi i do simular thing when hi volt reached i lach a relay that pulls relays in on windmills to short the 3 phases befor the rectafiers. turns on green light and can be reset when im home , outher dump still cuts in out on soler is basic and can be inproved later help to make progres or radio and vitamin b |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I think a dummy load is used because it keeps the windmill turning at reasonable speed, so when it switches back to the charging the windmill is already up to speed. But it could be a good idea to slow it right down by placing a dead short across the alternator. The dummy load is a little more gentle on the alternator, a dead short will give the poor old relay a hard time. I know when I short out my windmill I get a bit of a fireworks display. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Yes, sounds reasonable. My thoughts were to PWM a powerFET.... while monitoring the temperature on its heatsink. As the machine runs more slowly, the power output is less, so the brakes can go on harder etc. It's really just that first bit thats hardest I think. |
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Chris Senior Member  Joined: 12/09/2005 Location: AustraliaPosts: 146 |
Your windings would get pretty hot dead shorted though wouldnt they? You might damage them? Or melt the plastic hub over time maybe? |
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| adelaide Regular Member Joined: 24/03/2006 Location: AustraliaPosts: 46 |
it may get hot on some alts but never had prob with heat on a f/p yet seems like they have exelent coooling ,and i have 5 that i use the eletric breaks on alot ,but in my opinion i dont think the eletric breaks are quite good enuff for storms if u have talky prop so am loooking at alot better idear pulling the tail around .cos have had the blades over come the eletric breaks befor on singls and double alt w mills help to make progres or radio and vitamin b |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yeah I've had a windmill in a storm run up to speed even though it was shorted out. Not much you can do but hope it keeps its cool, there must be several hundred watts in heat generated in the windings. Like you say adeliade, the windings seam to be able to handle it ok. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Chris Senior Member Joined: 12/09/2005 Location: AustraliaPosts: 146 |
Why not use a small servo to activate a disk brake or something like that? Mountain bike disc brakes weigh nothing... They are pretty powerfull too... |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Where this all started was on a commercially constructed, fabricated and supplied gen, complete. Pulling it apart to add things like brakes etc is at best "impractical".... given things like warranty etc, but there is also (on mine anyway) no room to do it. The space from the front of the machine to the hub is virtually nothing, and I can't get to the back of the shaft. And please, don't suggest a lump of inch steel rod on a solenoid that fires forward between the blades to lock it! |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Darn it all, I was going to suggest a lump of inch steel rod on a solenoid.
The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Try this -it worked for me . I rigged the disc brake caliper with a fishing line down the tower-pulled it to stop the mill --chatters a bit when pulled on at first but once th emill slows it stops it . I'd go for a motorcycle one next time- a bit beefier-- Bruce Bushboy |
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| Chris Senior Member Joined: 12/09/2005 Location: AustraliaPosts: 146 |
Rossw: Thats fair enough thats its hard to add it to a already built system. But on a system that your building, it wouldnt be too difficult to implement the disc brake system. With the F&P system, like glenns and most others. There seems to be alot of shaft room between the prop and the stator. You could fit it there. Where would you get the idea of inch rods of steel between the blades to stop it...  |
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