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Forum Index : Windmills : How many phases?
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arpolis Newbie  Joined: 04/08/2010 Location: United StatesPosts: 26 |
Hello again. My question here is if you have an altinator built with one, two, three, four..... electrical phases. Does any combination have benifits or drawbacks? I just read on another post; "and for the life of me can't remember where it is", that if you have only one phase from a windmill it tends to shake itself apart. Is this true? Sounds weird but befor I figure up the pole combination on a project of mine I would like to figure this out. Any comments always welcomed. Will it work? Well lick your fingers and touch the two leeds. PZZZZZZZT |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Arpolis The effect is much like the comparison from a single cylinder engine to a v8 engine of the same capacity, one large power pulse causes torsional variations in the rotational speed of the device, whereas a v8 has eight smaller pulses so the torsion vibration is reduced by eight, and runs smoother. A single phase alternator will work OK but needs more rotational mass to act as a flywheel to smooth out the torsional vibrations {power pulses| I have used up to 12 phases on experimental design, but for a good compromise a three phase is very good, because it is a standard, and components are readily available at a reasonable price. All the best Bob Foolin Around |
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niall1 Senior Member  Joined: 20/11/2008 Location: IrelandPosts: 331 |
hi Arpolis i think i made the comment on single phase alts " shaking " too much...it was a bit vague looking back at it so heres another stab at it... with single phase the torque effect on the stator is is kind off on/off ...theres a pulse and then a dead spot as the alt mags rotate ..kind of all or nothing ..this i think sets up a lower frequency vibration in the stator which then transfers itself to the whole machine right down the tower , any screws ,nuts ,bolts and electrical connections will see this as well ...nuts and vibration dont go well together with multi phase the vibration (or torque)is kind off spread out across the phases (no dead spots) so the alt has more off a constant lower drag feel...not a notchy big one ..i think...  niall |
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| arklan Newbie Joined: 18/08/2010 Location: AustraliaPosts: 29 |
army crossing a bridge, they have to break their steps or else theyll shake the bridge |
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| niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331 |
much better explanation.....  niall |
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| arpolis Newbie Joined: 04/08/2010 Location: United StatesPosts: 26 |
Didn't they try that on mythbusters and not be able to re-produce that affect? Lol Ty all for the explinations. It seems to make sens now. Will it work? Well lick your fingers and touch the two leeds. PZZZZZZZT |
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| arpolis Newbie Joined: 04/08/2010 Location: United StatesPosts: 26 |
Didn't they try that on mythbusters and not be able to re-produce that affect? Lol Ty all for the explinations. It seems to make sens now. Will it work? Well lick your fingers and touch the two leeds. PZZZZZZZT |
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| niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331 |
erm... earlier i said .."i think i made the comment on single phase alts " shaking " too much" that should have read " some off the comments "....it was to do with some off Macs older posts Arpolis i suppose in truth i am stuck with a soft spot for a single phase alt...even with all its misgivings...there certainly not complicated and do have a purpose as a good learning tool ...kind off ...think 1 phase ..then think about ways of multiplying the physical format ..add in the star/delta wiring that goes along with it.... ultimately........ it does seem to be the way to go niall |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
[Quote=niall1]I suppose in truth i am stuck with a soft spot for a single phase alt...even with all its misgivings... I'm with you there. Oztules (rip*) schooled me to the point I thought I'd never even look at another single-phase or iron-cored unit as long as I lived, but damned if I'm not building one right now. That magnetite-filled resin core project I tossed up a post on is going to turn into a set of three cores, each one 1/18th out of phase with the other. All that really means is there are 6 magnets (was using 8 but changed to 6) and 6 coils per magnetite-filled core; 3 cores. One phase would likely cog like a boat's anchor, but the way I'm building it, as 6 magnets on one core are opposite their individual coils, there are 6 more magnets on another core just arriving and 6 more magnets on a third core just leaving their coils (18 magnet stacks; 3 magnetite-filled cores). I know there will be lots of internal friction due to all the magnetic 'holding power' but I'm in hopes the thing will not cog. Each "phase" (read that 'individual core'), is going to be individually rectified, tied in star and sent down the tower. To top it off, this build will use a single-bladed turbine. I think (haven't finished the hub yet) I figured out how to swing a single blade and make it yaw without bouncing -- we'll see. *John Tulloch didn't pass away from life, just this board. He's alive and well; we email often. 
. . . . . Mac 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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