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Forum Index : Windmills : 21 phase F&P
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| KiwiJohn Guru  Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Explanation of 3 phase here. Delta with our 44 magnet rotor will be a little more complex and I would need to think about how to describe the connections to you, but it might no come to that. Those voltages in my graphs are at quite low RPM, I suggest we wont be able to choose the appropriate configuration until we get to give it a spin with the 44 magnet rotor. Then we will know more about the voltages etc. If it works as my graphs show I think you will have plenty of volts with just the star. Regarding eddy current, you mean when you put the metal band on? No, that will not be subjected to variations in magnetic field so no eddy currents will be induced. Remember with the multiple neos that you can only add magnets until the stator gets magnetically saturated and from then on there is no improvement though I guess it does get harder to turn. Hang in there... |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Ok. I didn't reply when I first saw this because I was really tired and thought I'd mis-read it. I've read it again now, and I still can't make sense of this. How does wiring in delta give 30% more voltage out than wiring in star? *puzzled* |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
You are quite right Ross and obviously my brain had been operating in the red-zone for too long. 
Please disregard my [quote]You can use these three phases in any of the usual ways, connect in star for about 9 volts** or delta for a bit over 12 volts** [/quote] I am now so confused I can hardly rememebr which is which. |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
OK, back to take another look at this.. The voltage curves I showed indicate we can expect about 9 volts at the RPM where the generator is producing 1 volt per coil. This is the voltage that we can expect connecting between the central star connector and one of the phases. Connecting between two of the phases would give something a little over 15 volts. Connecting in a full star configuration, for example using two bridges and not using the central star connection, would give the same 15 volts or so but at a higher current. Re arranging the coils to delta configuration would give more current still but the voltage would be only 9 volts or so. I hope I got it right that time! 
Star is really easy in the standard stator and in the modified form I suggest for the 44 magnet machine. Delta is also easy to arrange in the standard stator but a bit more complicated in the 44 magnet scheme. |
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Highlander Senior Member  Joined: 03/10/2006 Location: AustraliaPosts: 266 |
I had a old time blacksmith bend me the metal ring, I'll buy glue and fit on Sat,(and let dry) maybe results by Sun. Then I'll ask more about wiring but lets see how cogg goes first.   Central Victorian highlands |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
You are right on there Highlander, we do need to check the cogging before getting too excited. |
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| Highlander Senior Member Joined: 03/10/2006 Location: AustraliaPosts: 266 |
Hey John I haven't forgotten, I glued the ring on a rotor,let it dry and picked out the ferrites but found the laminations inside were all rusty. Rust only grows and will effect gap spacing and eventually cause the magnets to hit the stator. I tried three rotors and finally found one that wasn't too rusty. I have to grind and rebind the join, so a couple more days yet. Central Victorian highlands |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
I guess you can allways reposition the magnets if the 44 magnet format turns to custard? With that ring on you will not have any fear of over-revving it! 
I look forward to learning how the cogging feels with the 44 magnets. I see new discussions opening about the new F&Ps with very low cogging so I hope we are not too late with all this effort of yours! |
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| Highlander Senior Member Joined: 03/10/2006 Location: AustraliaPosts: 266 |
Custard 
I got impatient and figured the locktite 406 would dry quickly, anyway 44 magnet rotor is finished. Running cogg was pretty good 250ml But start cogg was terrible I stopped measuring when it got to 2 litres. Oh well worth a go, boo hoo. 
NEXT!!! hmmmmmmmmm Central Victorian highlands |
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| Highlander Senior Member Joined: 03/10/2006 Location: AustraliaPosts: 266 |
BTW here's the 3mm ring 
I wonder if this effected the results? Central Victorian highlands |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Scheesh, I never expected starting cog to be that bad! Another idea to go in the bin I suppose. The ring might have strengthened the magnetic field a little but I dont see how it could have increased starting cogg without also increasing running cog. Did you try turning it with the leads shorted? Hard to turn when shorted indicates a good generator. |
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| Highlander Senior Member Joined: 03/10/2006 Location: AustraliaPosts: 266 |
I just have a stock stator with no mods yet. Yep very hard to turn shorted, but not as hard a the 7 shorted. Boo hoo, no hard feelings mate, it was worth a go.
I wonder what would happen if you use less magnets than there are poles? say 36, I know power would be down, but would it work? Central Victorian highlands |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
I am sure there would be output with any even number of magnets although as the number get less so will the output. |
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