Re: Mutual Inductance & K Factor

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Malcolm, John -

ETesla6 is the best program to date for a pre-determined frequency with
topload by which we can
determine effective top C because it pulls in the walls and ceilings.
Measurements run against ETesla6
confirmed it's accuracy to me. My top C measurements varied a wider range
than 15 - 25% and can easily
be confirmed by any coiler who takes Fres measurements while changing top
load dimentions, terminal
heights, terminal to ground heights, etc. Modeling with ETesla6 will also
show a large variation.

If empirical data is where the 15 - 25% values were derived, then I suspect
this data-set of coils just
happened to fall within that range and probably from a commonality of coil,
toroid, and terminal height
ratios. I do agree that about 20% appears common. The only problem I have
with a "standard reduction" is
that the value used can be way off on many coils. If ETesla6 is used, a
standard reduction is no longer
needed. The real trick is to pull this function into design programs. We
have all the parts (electrical
and physical). It's just a matter of sitting down and getting it done.

Take care,
Bart



Tesla list wrote:

> Original poster: "Malcolm Watts by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
>
> Hi John,
>
> On 21 Mar 2002, at 16:38, Tesla list wrote:
>
> > Original poster: "John H. Couture by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
> >
> >
> > Bart -
> >
> > Thank you for the explanation regarding ETesla6. I should have realized
that
> > this was a possibility because ETesla6 does this so well. This goes back to
> > the time I pointed out on the List that after the TC is built and
tested the
> > JHCTES Ver 3.3 program can be used to find the true capacitance of the
> > toroid when placed on the secondary .
> >
> > When the toroid is placed on the secondary the toroid capacitance is
reduced
> > an indeterminate amount. Etesla6 estimates an operating frequency so the
> > toroid capacitance can be estimated very closely before the coil is built.
> > The actual value can be found with JHCTES Ver 3.3 or Java9.1 by
reducing the
> > toroid capacitance value until the program operating frequency agrees with
> > the actual test operating frequency.
> >
> > The toroid capacitance reduction has been discussed in the past on the
List.
> > My own limited tests indicated the reduction to be about 15 to 25%. Because
> > the only way to find the true toroid capacitance on the secondary is by
> > tests all coilers will have to wait until enough tests are made. The
> > programs can then be updated to give more accurate outputs.
>
> "Indeterminate amount?" I refuse to believe that a well behaved
> result cannot come from some correct modelling and applied physics.
> As for the 15-25% figure, that might be ballpark for a lot of systems
> but as I have found, the actual figure can be almost 100% if the
> terminal has a considerably smaller diameter than the coil. That is
> not to say it is useful or practical to do this but it is an
> illustration of the degree of variation that can be obtained.
>
> Regards,
> Malcolm