Re: [femm] Plots of Je

["Robert Macy" <macy@xxxxxxxxxxxxxx>]

Here is more on my problems plotting Je....

*IF* the conductor has zero conductivity (as in a wire bundle), then the
plots of Je and Js+J_eddy all make sense whether the current is defined by
Js in the materials section or whether it is defined as a total current in
the circuit section.

*IF* the conductor has nonzero conductivity (as in a solid wire) *and* the
current is defined by total current in the circuit section, the answers all
make sense with the plot of Js+J_eddy being appropriate. However, Je by
itself goes way wonky inside the conductor. Outside the conductor where
there is no source current flowing the plots are still correct. Conclusion:
Only use Js+J_eddy.

*IF* the conductor has nonzero conductivity (as in a solid wire) *and* the
current is attempted to be defined as Jsource in the materials section, then
the analysis really shifts the value of the source current and the results
are useless. Can't remember about the plots, but the errors make them
worthless. Conclusion: Always use circuits to define current in a solid
wire.



Did I misuse the femm program without knowing it? Is a Jsource for
conductive wires just incorrect?

- Robert -



----- Original Message -----
From: robert Macy
To: femm@xxxxxxxxxxxxxxx
Sent: Tuesday, July 08, 2003 8:17 PM
Subject: [femm] Plots of Je


I'm having difficulty interpreting the significance of
plotting eddy currents.

I'm plotting eddy currents both in the magnetic material
and in the conductor's area.

In the magnetic material where there is no circuit current
if I plot Je or Js+J_eddy, the plots are identical and look
as expected.

In the conductor area if I plot Js+J_eddy, the plots look
as expected. But when I plot Je by itself, I get
outlandish values.

If I plot from the magnetic area into the conductor area
using only Je, I get identical values to earlier plots
until the line gets to the conductor, suddenly everything
goes wonky - making no sense.

Right now the safe thing to do is to simply only use
Js+J_eddy for all locations, plot to file, then manually
remove Js in Excel to see what Je looks like.

Am I doing something wrong here?

There is no mention of eddy currents in the manual.

- Robert -