Re: TC efficiency, was Math help...

["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 John C.,

Tesla list wrote:

> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <couturejh-at-worldnet.att-dot-net>
>
> Bart -
>
> I don't understand what you mean by "spark gap losses may offset any
> efficiency gain". The losses determine the amount of the efficiency.

Simply, if higher efficiency is achieved with a robust (low loss)
transformer, the current availability allows
larger cap values (for charge time domain) and increased bang size
consequentally (this is typical for coils).
Because of that, gap losses may increase due to larger bangs, thus
offsetting a low loss transformer. This
statement only assumes gap losses increase with bang size when in fact,
maybe it doesn't (I'm assuming here
and may be wrong - probably depends upon design).

> The input power for a foot of spark always is larger for larger coils
> compared to small coils. This is an indication that larger Tesla coils are
> less efficient than small coils. I think Tesla mentioned this in the CS
> Notes. The reason is that large coils have much heigher voltages than small
> coils and this increases the corona, etc, losses per unit of output/input.

hmm.., I don't think this is always true. My current 8.5"diam. coil will
acheive higher voltages than my
previous 12.75" diam. coil by approx. 100kV (same bang size). The question
will be if the smaller coil can
tollerate the same bang size as the larger (I think it will, but we shall see).

> Note that coupling is not involved with efficiency, only with the
> Coefficient of Leakage which is an interesting magnetic circuit limitation
> for Tesla coils.

Coils always complete energy transfer, but the time in which that is done
vary's. Mutual inductance is
involved here (as well as the gap and the spark criteria). Because of that,
there are losses involved and
efficiency is affected. That's all I meant by using coupling in the
statement. That's at least my
understanding at this time.

Take care,
Bart