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Please recommend wire gauge and # of turns for this setup...


By ezee, Section Wind
Posted on Wed Jun 27, 2007 at 04:05:31 PM MST
Please recommend wire gauge and # of turns for this setup...

My first homebrew turbine is going to be a small (6' - 8'max, three blade) unit.

I am using 3/4" round magnets.  The PMA will be axial, dual rotor, three phase.  The rotors will have 8 magnets per rotor (16 total, dual rotor) and 6 coils.  The specs for the magnets are:

Dimensions: 3/4 inch x 1/8 inch
Br max: 12,100
Bh Max: 35 MGOe

I know (from other posts) that my coils need to be round to maximize the amount of wire that hits the round magnet field lines at 90'.

Other than "round", I don't know how to proceed.  I am a complete newbie.

I know that there is no definate answer without having the actual alternator on a bench to test...but where should I "start" from regarding:

  • coil inside diameter
  • coild ouside diameter
  • coil thickness (e.g. its height when laid flat on its side)
  • wire guage
  • number of turns
  • clock/counter clock
  • etc.
Thanks!
Please recommend wire gauge and # of turns for this setup... | 7 comments (7 topical)

Re: Please recommend wire gauge and # of turns for (3.00 / 0) (#1)
by Flux on Wed Jun 27, 2007 at 10:31:46 AM MST

I haven't looked at this in detail but I don't think your magnets are capable of effectively loading even a 6ft prop.

Flux



Re: Please recommend wire gauge and # of turns for (3.00 / 0) (#2)
by ezee on Wed Jun 27, 2007 at 11:00:22 AM MST

My rotors have to remain small...so I can either use larger magnets, or a smaller prop.

My magnets cant get too much bigger...the rotors have to be the diameter of a CDROM.

[ Parent ]



Re: Please recommend wire gauge and # of turns for (3.00 / 0) (#3)
by Flux on Wed Jun 27, 2007 at 11:26:41 AM MST

With those limitations you are in for lots of problems. You will have trouble finding room for coils and still have space for a hub.

I don't think you are going to manage much more than a 3ft prop ( perhaps 4ft if you keep the speed up).

Flux

[ Parent ]



Re: Please recommend wire gauge and # of turns for (3.00 / 0) (#4)
by dinges on Wed Jun 27, 2007 at 06:01:30 PM MST

Building small generators is an exercise in futility, IMHO.

Anyway, I've built a small axial flux too. More info can be found here:

http://www.anotherpower.com/gallery/album46

Here's the story:

http://www.fieldlines.com/story/2005/11/13/32021/791

I'm not wasting my time on playthings anymore. With the same amount of time and effort you can build the real thing. So why bother (actually, I'm not bothering to build axial fluxes at all anymore, but that's another story)



Re: Please recommend wire gauge and # of turns for (3.00 / 0) (#5)
by luv2weld on Thu Jun 28, 2007 at 07:44:19 AM MST

What happened with the minigen that you ordered??

Let me take your questions in the order you asked them---

coil inside diameter--as you were told in previous postings, the same as your
magnets or smaller

coil outside diameter--depends on the gauge of wire and number of wraps

coil thickness--generally the same thickness as your magnets

wire gauge--depends on what you want to get out of the generator

number of turns--depends on what you want to get out of the generator

etc.---
As you can see, you haven't given enough information for anyone to help you.
I really suggest that you read and reread everything you can find on wind
generators. You said in your initial posting that you had downloaded Hugh's
booklet on PMA's. Read it. Also get Hugh's other books and study them (Windpower
Workshop and/or How to Build a Wind Turbine). At approx. $20 each (US), they
will be the best investment you can make if you are to continue with this
disease/madness of building wind generators. BTW, they are not his only books!

The best path for people just starting this madness is to follow someone
else's plans (step by step) for the first 1 or 2 generators. It really helps
get a better understanding of what is going on and how things interact with
each other. Going off on your own and experimenting is to be applauded---
once you have the basic knowledge and understanding of electricity and
generation.
I'm not trying to "chew you out" or embarrass you. If I have offended you,
that was not my intention. I just think you're trying to move too fast,
and you are not "listening"/understanding what people are telling you.
Russ just told you yesterday--
"Here are some of the factors that go into making a generator with wire and moving magnets.
You want the magnet path to be perpendicular to the wire
You want to avoid cancellation by ensuring that the two "legs" of the coil never see the same magnet pole at the same time
You want to maximize voltage by ensuring that the two legs DO see opposite poles at the same time (one leg seeing a north pole while the other sees a south)
You want as many turns as needed to achieve the desired voltage/rpm.
You want the thickest wire you can fit to minimize resistance.
You want the thickness of the stator (for air core axials) to be as thin as possible to have maximum flux between the rotors.
When you add these to the various shapes of available magnets, you end up with a variety of coil shapes each with its own set of compromises."
Look at the 4th "You Want" from the top. And today you're asking the same question
again.  ????????

Ralph

"The best way to kill time is to work it to death!!"



Re: Please recommend wire gauge and # of turns for (3.00 / 0) (#6)
by dainbramaged on Thu Jun 28, 2007 at 09:22:17 AM MST

Sparweb posted a real good basics. Here is the link---
http://www3.telus.net/faheydumas/Wind_Turbine/Forum/AXIAL_FLUX_HowItWorks.pdf



Re: Please recommend wire gauge and # of turns for (3.00 / 0) (#7)
by ezee on Thu Jun 28, 2007 at 03:50:26 PM MST

Spar-

that is the single most helpful resource I have seen since I have been here.  I am reading it cover to cover now!

THANK YOU

[ Parent ]



Please recommend wire gauge and # of turns for this setup... | 7 comments (7 topical)
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