Re: Wire Length (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sun, 24 Dec 2006 09:29:03 -0800
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Wire Length (fwd)

Hi Paul,

Interesting. Something you can do is also experiment with larger 
sphere's and distance. I'm not locked into any particular sphere size. 
Regarding breakdown: A year or so ago, my closewound flat coil burned 
the outer 3 or 4 windings (rim grounded).

Take care,
Bart

Tesla list wrote:

>Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>
>
>
>
>---------- Forwarded message ----------
>Date: Sun, 24 Dec 2006 06:13:05 GMT
>From: Paul Nicholson <paul@xxxxxxxxxxxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Re: Wire Length (fwd)
>
>Bart, All,
>
>There doesn't seem to be a coding error involved with this Cint
>problem.  Removing the interpolation (ie running the internal
>capacitance extraction at the same resolution - 91 segments - as
>the network model) doesn't help.   What does make a difference,
>and accounts for the discrepancy between the two programs,
>is the precise manner in which the disc of the secondary is
>segmented within the model, especially in the region near the
>grounded rim where dQ/dx and dI/dx are very high.
>
>It's a matter of taking the approximately smooth and continuous
>charge distribution across the disc and representing it by
>a matrix of finite size.  That means chopping the disc into
>a set of concentric rings and we have some free choice over
>where to set the boundaries between the rings.   Normally,
>with a large enough number of rings, variation in the placement
>of ring boundaries doesn't make much difference to the final
>results, and that gives us confidence that the model is stable
>and reliable.    Difficulties usually only arise when looking
>at the overtones (in which the in-coil wavelength spans fewer
>segments so is more sensitive to segmentation, especially at
>the ends).
>
>For some reason, in the rim-grounded flat coil, there's a
>lot going on in the outer few turns and this is stressing
>the model.  With various slight changes in segmentation, I can
>vary Fres from 460kHz to 500kHz, which is not much good at all.
>The only prediction then is 480kHz +/-5%.
>
>I'll try to put in the primary and center load.  Perhaps that
>will settle things down in the model... one wonders if the
>electrical stresses in the coil will appear in the same place,
>perhaps for the same reason.
>
>When rim-grounded flat coils fail, do they fail in the outer
>few turns?
>
>--
>Paul Nicholson
>--
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