Formulas and calculators > Coil winding

Question for Flux and Otrhers too!

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freejuice:
Hi,

 Sometime ago you folks were helping as I was building my 12 volt windturbine...and helping to explain many things to me, including what my volt meter was telling me. During the course of the conversation, Flux mentioned a stator for a 10 ft, 12 volt machine using (if not mistaken) 14ga wire, 4 strands with 17 turns. ( standard 9 coil,3 phase, star wiring)

What is the advantage to using the 4 strands.... is it to push more current?

How would this affect my cut in speed....would the mill hit battery charging sooner /later or no change at all?

 Thanks,

 Gavin

opo:
Ussing 4 strads is the same as useing 4x thicker wire, which btw is harder to wound. And yes, it means more current at the same voltage. Number of turns determine voltage.

wpowokal:
opo me thinks you just contradicted yourself.
allan

Flux:
I can't remember that far back but 10ft 12v machine will have few turns and will need very thick wire. It is tricky to wind with all coils in series per phase and star connected.
There is a maximum thickness of wire that you can use because of eddy currents ( the thicker wires are probably very difficult to wind physically in any case) so you are forced to use several strands of a manageable size wire in parallel.
The multiple strands carry the same current as the equivalent thicker wire. The current you get depends on the power you put in from the prop. The number of turns determines your voltage and cut in speed and the thickness of wire determines what current it can carry without burning out.
For multiple strands in hand, turns are the number of times the bundle is wound round the former, not the total number of actual wire turns. If a single wire coil had 40 turns, 4 in hand would end up with 10 turns. The number of turns in hand only affects the number of real turns. Just think of it as using fewer turns of thicker wire.
Using multiple strands in hand is just a trick that lets you make low turn number coils of large cross sectional area, there is nothing magic about it and as long as you think in terms of the single wire equivalent you will see that the voltage and current issues are not influenced by it.
The only other way to deal with a low voltage high current machine is to use parallel coils and this invariably results in eddy currents circulating and may cause start up trouble so you end up splitting the parallel sections with separate rectifiers. You can do multiple star windings or you can rectify each coil separately as a Jerry connection. The snag is that you need the rectifiers up on the machine or you have to bring many wires down the tower.
10ft 12v can be done as a single 3 phase star with the multiple strands in hand but even bigger 12vmachines would probably have to have the rectifiers up the tower.
Flux

freejuice:
Hi Flux and Everyone,

 You guys are the greatest! :o)

 Thanks for the info, I have  just over a half of spool of 14ga wire and was thinking of making a good 12 volt stator.

 I have modified my rotors somewhat in regards to the trailer hub bearing. Instead of mounting the hub to the inside of the first rotor I have mounted it to the back of the rotor, which allows me to make a stator with a much smaller inside hole diameter...when wiring things up in stator, it can get crowded with wiring and connections very fast in this area, so it frees up more room to work with... everything else mechanical is following the Dan's recipe... hopefully it will not change the wind tracking characteristics too much.

 All the best,

 Gavin

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