Re: AWG vs. Diameter

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

It occurs to me that a primary wound with several parallel smaller wires
might actually work better than a "skin effect" equivalent crosssectional
area tube or single wire.  Consider that you were to stack (vertically) a
half dozen AWG 10-14 wires, separated by, say 0.1 inches, and wind the
primary using the "ribbon".  Since the wires are physically separated, the
self inductance (which relates to skin effect) would be reduced (much as
"bundling" does for HV transmission lines).  One could even work out some
sort of "braiding" so that each conductor spends the same amount of time on
the "surface" (essentially what's going on with Litz wire), or stagger the
various spiral layers.

One might also be able to figure out a winding configuration that reduces
the amount of loss on the inner turns: Say the cross section of the whole
primary were thick in the middle and thin at the edges... like a spiral
galaxy viewed edge on.  In the multiconductor scheme outlined above, the
vertical spacing between windings would be greater in the inner turns than
in the outer.

.
>
> Then, as the recent discursion about the inner turns getting hot showed,
we
> have to consider proximity and eddy current effects.  Unfortunately, I
don't
> have an answer there.  I would think the thinner wire would be better, but
I
> don't really know.
>
> In general, people tend to find that the thicker tubing does better than
> thinner wire.  We always attributed that to the differences in skin depth
but
> these new proximity and eddy current factors may matter a lot too.
Primary
> losses can really eat up a coil's performance so this is pretty critical
stuff.
>