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Forum Index : Windmills : new 36 pole stator
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| brucedownunder2 Guru  Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Well,the new 36 pole stator has arrived by courier. a couple of surprises !! 1. it's wound with the .6 wire(fine wire), which has a coil resistance of 15 Ohms. Each 12 poles of the 3 phases would in series. 2. The pole "ends" are "domed' as the earlier diy attempts to reduce cogging. So maybe this is a further non-cogging refinement by F&P. So, what do u think about re-configuring the wiring?.. I'll set it up stock standard with the new rotor and see what I get turning it by hand and then into a 12 V battery. I sort of expect lower o/p than we have been getting in the past with the "cogging" type matched with a modified Neo magnet rotor. Bruce Bushboy |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
Its all up to you Bruce. You need to set it up in a jig and crank it over so you can see how much cogging it has compared to a normal 3 phase 42 pole stator, and a 7 phase stator. And you would have to spin by hand to see what sort of volts you can get from it in standard trim, though I would expect close the the same figures we had from the old stators. Then try a few wiring combinations. All new ground here, your on your own bruce 
Any chance of a photo? Glenn 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 |
Well, just set it up on the bench --- get around 150v plus out of it just by spinning it by hand --absolutely no cogging at all.thing nearly free wheels at very low rpm But.................. connect a battery to it -either 12v or 24v and whammo, can hardly turn it------soooo, it looks like I'm in for a re-configuration of the pole windings Would like some assistance , as @ $112 I'd like to make the almost right re-config. lol. Never had so much fun since our Tom left his balls on the barbwire bruce Bushboy |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
You need to find out how many volts one coil makes at a certain rpm. Set up your lathe and spin the hub at whatever your windmill runs at, say for example 300 RPM. Then measure the output voltage from the star center to one phase connection. Be carefull, those volts could kill you. Then divide the result by 12 ( 12 poles per phase ). That will give you a voltage per pole, a good starting point. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Bruce, how about giving it a try with a transformer on one phase? (Yeah yeah, I know no one on this site likes transformers!  ) |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
Once you get the voltage per pole, multiply that by 1.73 to convert to 3 phase output levels. So if each coil made 10 volts, and you wanted to charge 24 volts, well 10 * 1.73 = 17.3 volts, not enough, so 2 coils in series = 20 volts * 1.73 = 34.6 volts, yipee! But you need the voltage per coil per RPM first. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
The problems with transformers is they are usually designed for 50 Hz, where the F&P could run from say 43Hz at 100 RPM to 216Hz at 500 RPM. They will work but loose efficiency above 150RPM on a F&P. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Maybe so but a transformer provides an easy means of gauging what output might be practical at lower voltages. Safer too especially if you are going to drive the F&P on a lathe or somesuch. |
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kenputer Newbie  Joined: 02/05/2006 Location: CanadaPosts: 30 |
I recieved a new 36 pole stator today to go with the new rotor from late last year :-) Do I just divide up into six groups and rewire like the 42 pole for charging 12 volt? Thanks Ken As good as you are and as bad as I am,I'm as good as you are as bad as I am! |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
Hi Ken Dont know, the new 36 pole stators and recofiguring them is all uncharted waters. But yes the standard SP rewire should work fine for 12V. Sorry cant give you a yes no answer on this one. Glenn 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 |
Posted: 03 January 2007 at 7:29am | IP Logged ------------------------------------------------------------ -------------------- Yes, Glenn,I've done the electrical test on the new 36 pole Stator. Have to retake the pic's ,as my flash was turned off,and this Old Fella had to read 5 pages of instructions to get the bloody thing turned on again,lol. 1 Phase across the star point produces 244-250 v ac at 574-600 rpm. calculating this ,I end up with 38v ac approx.before the rectifiers. This makes me think I will re-configure the Stator into a 3phase 4 pole unit. What do you think ?. Also ,I'm heading towards a dual set-up with ,like you say, different wired Stators, 1 of the 3 phase and 1 of the 7 phase ,seperate rectifiers up at the platform ,then 2 wire dc feed to the workshop control panel. Anybody that wants to do this should consider Trev's extended s/s shaft (extended milled spline for the dual rotor) , and his cast extended bearing holder . The only thing I'm worried about is the strength of the s/s shaft being directly connected to any 3 bladed mill of more than ,say, 11 feet diameter. Mine is up now and is spinning slowly even in no apparent wind. So, direct drive looks like the only way ,unless you are going over ,say,12 feet ,then the belt drive may be successful. Sorry to be so long winded,haha. Bruce __________________  Bushboy |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Bruce, I suggest to get a useful voltage reading you would need to connect some load, did you do that or did you measure open circuit voltage? |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
hi Kiwijohn, Thanks for that ,I didn't have a load connected ,but maybe I could install another stator and rotor on the other side of the shaft and see what happens . I could short out 1 phase ,this should give it a load. (I just edited a previous post to show the testbed,smallish drive motor ,but does the trick for evaluation ). I don't think Glenn has suggested in the past to apply a load,this was with the old re-configured stators and they seem to have come out fairly well. Bruce Bushboy |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Hi Bruce, I feel shorting out is a bit severe. If I recall the lessons of long ago the maximum power transfer will occur when the source and the load have the same impedance.** If we ignore the niceities of 'impedance' versus 'resistance' I think a suitable test load would be a resistance about the same, maybe a bit less than the resistance of the phase you are testing (15 Ohms?). If you have another stator you could just lie that on the bench and connect as a 'load', I think that would be an ideal load having the same resistance and even impedance as the one being tested. Measure amps and volts at various revs. Would someone please correct this if I am wrong! ** It may be convenient to think of this load matching as being similar to loading a mechanical power source. Put too much load on an engine, for example, and it will not be able to turn fast enough to develope any useful power but put too little load on and the engine just revvs and still does nothing useful. A short circuit is like too much load, a high resistance or open circuit is like having no load on the engine. |
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Megawatt Man Senior Member  Joined: 03/05/2006 Location: AustraliaPosts: 119 |
G'day KiwiJohn, no you are right on both counts. Megawatt Man |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Thanks. I have some 0.5mm resistance wire from an old clothes dryer. 1 metre has a resistance of about 4 Ohms, originally coiled in the familiar shape I stretched it out straight to do the measurement. |
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| Megawatt Man Senior Member Joined: 03/05/2006 Location: AustraliaPosts: 119 |
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| Megawatt Man Senior Member Joined: 03/05/2006 Location: AustraliaPosts: 119 |
G'day KiwiJohn, a slight amanedmant to a compliment I paid you the other day. The maximum power transfer froman alternator occurs when the magnitude of total resistive load equals the magnitude of the machine's inductive reactance. THat's another rerason why I want to know more about the fundamentals of these machines, such as the saturation flux, the reactance etc. If you have a set of maths equations to start with, you can predict and recommemnd and hopefully save a lot of blokes a lot of time! Megawatt Man |
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| Megawatt Man Senior Member Joined: 03/05/2006 Location: AustraliaPosts: 119 |
I wish I could type! Megawatt Man |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
[quote]G'day KiwiJohn, a slight amanedmant to a compliment I paid you the other day. The maximum power transfer froman alternator occurs when the magnitude of total resistive load equals the magnitude of the machine's inductive reactance. [/quote] OK, I think I understand. So if there is an inductive load capacitance should be added to bring the load's inductive reactance into phase with the source? But a battery under charge is pretty much resistive. I am a bit suprised though if the resistance of the machine's coils is not part of the picture. I agree entirely, a few calculations could save an awful lot of cut and try, I gave it a bit of a go but its really beyond me!  |
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