Re: Inductance calculations

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

Original poster: "Barton B. Anderson by way of Terry Fritz <teslalist-at-qwest-dot-net>" <classictesla-at-netzero-dot-com>

Hi Antonio,

I ran Inca v1.0e- 11/3/2003 and obtained the following primary inductance 
in question:

n1= 5.00; h1= 0.20; r11= 0.50; r12= 0.50; b1= 0.00 (wd doesn't print to 
screen, but was 0.002)
Primary inductance L1:    0.0379600169 mH

FanTC (detail 3)
r1=.5, r2=.5, h1=0, h2=.2, t=5, wd=.002
Primary Inductance (L1): 39.37069 uH

Also checked JavaTC (for reference with the upcoming version).
r1=.5, r2=.5, h1=0, h2=.2, t=5, wd=.002
Primary Inductance (L1): 39.319 uH

All looks good. For 46uH, I'd would guess an input error.

Take care,
Bart

Tesla list wrote:

>Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
>
>Hi:
>
>I have implemented in my Inca program some routines for inductance
>and mutual inductance calculations using elliptic functions in the
>solution. The method is essentially the same outlined in Grover's
>book, and exactly as described by Maxwell.
>I left all the approximate formulas and numerical solutions using
>true spirals available too for comparison.
>The approximations that are still incorporated in the calculations
>are that the turns are closed circles, the radius of curvature of
>the circles is much larger than the radiuses of the wires, and that
>the current flows uniformly distributed in the wires. The "exact"
>formulas assume integer number of turns (for awhile).
>
>The results for mutual inductances seem perfect, and the results
>for inductances of long coils too. For some coils, however, the
>inductances differ considerably from the results obtained with
>Acmi or Fantc (or even Wheeler). A typical case (the worst that
>I have found) is the example of two helical coils in Fantc.
>The primary has:
>turns= 5;
>height= 0.20 m;
>radius= 0.50 m;
>wire diameter= 0.002 m
>Inca obtains 46 uH, while Wheller, Acmi, and Fantc give 38-39 uH.
>
>Inductance calculations by Maxwell's method are quite badly
>conditioned numerically, but I don't so great discrepancy with
>other geometries.
>
>Could someone verify?
>The program is in http://www.coe.ufrj.br/~acmq/programs
>
>Antonio Carlos M. de Queiroz
>
>
>
>