Winding 6 in hand coils.

[Murlin]

I had a question on winding coils.

I have noticed that when you guys wind your coils, you twist the wires together when using multiple, in hand windings.

It seems to me that leaving the wires untwisted would allow for more copper and less air gaps.

Does it matter that you twist the wires together or not when winding the coils?

Thanks for your time....

Murlin

[Flux]

I haven't seen anyone do that for conventional coils.

I have suggested it for the windings of high frequency inductors for converters.

Twisting the wire would effectively be the same as a transposition on large multi strand sections for transformers and monster alternators and would properly equalise the volt drop per strand but should not be needed for small coils of machines used here.

With 6 in hand you are pushing your luck somewhat and I would suggest that when you interconnect your coils you change the relative position of the strands as you progress through the winding. Don't join all the strands at each coil junction.

Flux

[Murlin]

Thanks Flux...Gotcha, mix up the order as you wind the coils around.

Do you reccomend joining the coil 3+3 or 2+2+2.

Murlin

[Ungrounded Lightning Rod]

I have suggested [twisting the n-in-hand conductors] for the windings of high frequency inductors for converters.

Braid them.  For more than three-in-hand: braid braids.  That makes the conductors spend equal amounts of run inside and outside the bundle, evening out skin effect.

Poor man's "litz wire".

(My brother was working for a company building an induction stove "burner" for NASA, decades ago.  It used such a braid-of-braids-of-braids wire, machine-braided to exactly equalize the skin effect, for building something in the neighborhood of number 30 into something in the neighborhood of single-ought, of which they made a two-turn coil.)

[SamoaPower]

Murlin,

I think your're looking at two issues here. One is removing generated heat from the interior of the coil and the other is the possibility of circulating currents in the multiple strands.

To avoid dead air pockets within the coil, it would be best if you could use a single turn per layer. With 6 in-hand this could be reasonable. Avoiding winding crossovers is the point. Also, bonding the coil together with a heat-conducting agent will help. See:

http://www.fieldlines.com/story/2006/10/21/61110/798

I'm still not sure that circulating currents are a significant issue for strands of the same exact length. Certainly, Flux's suggestion of transposing coil interconnections should minimize the problem if it exists to a substantial degree. For further discussion on this see:

http://www.fieldlines.com/story/2006/12/15/16162/136

Another suggestion is that you avoid casting the stator in resin. Casting is a real mistake for higher power machines even though it's often done.

[willib]

Hi Samoa , how is that machine comming along?

i hope your gonna do a posting on it soon?

[Murlin]

Thanks Sammo...I was a little confused about what Flux was talking about, but I think I understand now.

Very nice coil winder.

I envy the time you have put in on your project and wish I had been given a little more time to invest last year.  I will have a lot more time this summer. It is going to be fun.  I think you might like the way the variable works on the machine I am building.  It turned out a little different than the pics I have up.

I have also been thinking about machining a stator board well.

Thanks for the like for the material to use.