Re: Inductance calculations

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Original poster: "Godfrey Loudner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <ggreen-at-gwtc-dot-net>

Hello Antonio

If its conveniant, can you please make a posting of the formula
used in the Maxwell method for the primary inductance. I've
upgraded my adobi, so the computer will translate now. I'm going
to have to order Maxwell's books from Dover press.

Godfrey Loudner

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, March 12, 2003 7:12 PM
Subject: Inductance calculations


 > 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
 >
 >