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Forum Index : Windmills : Overspeed brake for windmills
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marcwolf Senior Member  Joined: 08/06/2009 Location: AustraliaPosts: 119 |
Hi folks. I was reading a few forums (and chatting with others) re the F&P generators. And one of the issues is that using the inertia of a shorted generator to handle overspeed or windy conditions might not work as the holding force could easily be overcome. That set me thinking on how to solve this and I have an idea. Imagine a plastic cloths-peg. The part of the jaws that fit over the washing line is what we are interested in. If you made a simular arrangement so that the 'peg' was large enough for the jaws to open and almost close around the windmill shaft. A small spring wil keep then open enought for the shaft to turn freely. A voltage monitor keeps track of the output voltage. If it exceeds a certain level then a MOSFET is triggered and the output of the generator is pumped though a solenoid which compresses the jaws around the shaft. This in turn slows the shaft until the voltage is below the trigger level - or the shaft can still turn but with a greater resistance. The higher the voltage that is pushed through the solenoid means the more pressure on the shaft to slow it down. This would be excess current anyway as it would be too hight for the invertor to handle so it would have been disconnected at this time. Making this concept would be fairly easy. The pad's in the jaws that would be the brake could be thick leather or similar. The solenoid would need to be custom to handle the current - however as it is just a steel rod within a coil - it would be easy for the handyman to wind their own. The whole system could be made very inexpensively Just an idea.. Dave Coding Coding Coding.. Keep those keyboards coding.. RAW CODE!!!!! |
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| Janne Senior Member Joined: 20/06/2008 Location: FinlandPosts: 121 |
Hi, Using the brake to slow it down(not stop it) will quickly lead to the brake burning out. The brake would need to ba a latching type, in the event of an overspeed situation, it would turn on the brake, and hold the turbine stopped until it is manually reset. I also think that a simple "cloths peg"-type brake will be inadequate for any mill reasonable size.. a small drum or disk brake would be more preferred choise. In my heating windmill, in the event of an overspeed, the mechanical brake is used in combination with overloading the generator to stall the rotor and bring the mill to a stop. The automatic stop needs a manual reset to clear. If at first you don't succeed, try again. My projects |
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| marcwolf Senior Member Joined: 08/06/2009 Location: AustraliaPosts: 119 |
Hi Janne Many thanks for the reply. I don't mind being shot down re idea's. All I can do is think, suggest, and let the more experienced folks show me where I went wrong :> Take Cae Dave Coding Coding Coding.. Keep those keyboards coding.. RAW CODE!!!!! |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
I like simple stuff; the simpler the better. If you recall the windmills of the old West (United States), these were compression wheels, which faced the wind using a tail. When the wind got out of hand, a little jerk on a hanging chain would pull a pin and the hinged tail would flop to one side via a spring mechanism, which in turn pulled the turbine out of the wind flow. Of course, some lucky guy had to climb up the thing and reset the tail when the storm was over, but it worked and it's really low-tech. Just thought I'd throw that into the brew. Whoever coined the phrase, "Simple is best." was my kind of guy! Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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