Re: Primary Heating

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

Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Peter.Lawrence-at-Sun-dot-com>


Are you suggesting that the current flow in a thick primary conductor is not
uniform across the cross section of the conductor, and that this non-uniformity
would be different for inner turns verses outer turns? Wouldn't this have to be
something other than skin effect since inner and outer are both operating at
the same frequency? Are you suggesting that the inner facing surface of a 
spiral has different magnetic coupling hence voltage and current than the
outer facing surface of the same portion of that spiral conductor, since it is
geometrically closer to the center.

-Peter Lawrence.


>Original poster: "Paul Nicholson by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
<paul-at-abelian.demon.co.uk>
>
>Hi All,
>
>David Rieben wrote:
>> I definitely have a good, solid low resistance ground connection
>> fron the inner primary turn
>
>Fair enough - had to be eliminated.
>
>Bert wrote:
>> Perhaps "current bunching" on the innermost turns (due to proximity
>> effect?) so that these turns develop higher Joule heating? 
>
>Well that sounds like the next best explanation.  I suppose I'm going
>to have to write that program to plot the magnetic field. As a quick
>look we can use acmi to show the distribution of self-induction
>across the primary.  If this is divided by the area of each turn,
>we end up with a set of numbers proportional to the B field strength
>in the region of each turn [*]. Eg for a 12 turn primary, 5" inner, 
>12" outer, see
> http://www.abelian.demon.co.uk/tmp/flat-pri-B.gif
>
>Is that enough of a concentration in the center?  If the inner field
>were say 5 times the outer field, does that mean the proximity loss
>is 5 times higher in the inner turns?  It would only make a difference
>to the heating of the inner turns if the proximity loss was 
>significant (equal or greater than) compared with the straight line
>AC resistance (ordinary skin-effect) loss.  I've no idea how to work
>that out.
>
>rheidlebaugh wrote:
>> MY 4 PARRALEL DOUBLE STRAPED WITH 1" WIDE STRAPS 30 KV CAPACITORS
>> ONLY PRODUCE SLOW CURRENT INPUT OF A SIGN WAVE WHEN MY SG FIRES.
>
>Caps key stuck?  You seem very sure that your primary fails to obey
>elementary circuit theory.  I wonder why?  Hmm, on second thoughts,
>perhaps I'd better not ask.
>
>[*] I've just thought, dividing by the area enclosed by each turn
>just gives the average field within the given turn, so the actual
>difference between inner and outer parts of the field may be a lot
>higher than shown in the graph.  I'll just have find time to do
>that program.
>--
>Paul Nicholson
>--
>
>
>