RE: TC efficiency, was Math help...

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

Original poster: "John H. Couture by way of Terry Fritz <twftesla-at-qwest-dot-net>" <couturejh-at-worldnet.att-dot-net>


Bart -

You are correct I was refering to the "overall efficiency" of a Tesla coil.
Refer to my post to John F.

I don't understand what you mean by "spark gap losses may offset any
efficiency gain". The losses determine the amount of the efficiency.

Don't confuse power with energy. The the spark length vs input power
equation is a power equation. The input power for a foot of spark can be
considered an energy equation regardless of the amount of input power.

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.

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

I agree we have a lot to learn about Tesla coils before we can design them
with a minimum of guestimating.

John Couture

---------------------------------


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, July 15, 2001 4:40 PM
To: tesla-at-pupman-dot-com
Subject: Re: TC efficiency, was Math help...


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

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>
>
> John F -
>
> A well known characteristic of Tesla coils is that the watts per foot of
> spark increases as the TC gets larger. This means losses increase and
> efficiency decreases as the TC is made larger. The range is about 200
watts
> per foot of spark for small coils to 2000 watts for large coils. This is
> based on measurements that  coilers make every day. Have you made
> measurements that would indicate the contrary?
>
> John Couture

This may be true in "overall" efficiency. I disagree with that this is a
"well known characteristic" but we
have discussed this over and over again on the list. Maybe well understood
by only a select few (I don't put
myself into that catagory). There are areas in larger systems that may be
more efficient and areas less
efficient. Although the transformer should be more efficient, the sparkgap
losses probably offset any
efficiency gain. This offset may be large or small based on gap designs,
low to high inductive primary's,
coupling, etc..

How much data is there really where losses are quantified across "main
components" on big systems or small?
Sure, there may be a few, but is there enough data on coils where we can
make statements about large coils
power per foot of spark increasing with coil size and relate "that" to
large coils are more or less efficient?
I would say yes, "if" we include that "typically" this occurs on larger
systems because, with larger coils
comes larger current feeds, enabling larger systems to simply add another
megawatt to achieve longer
sparklengths without consideration to efficiency in the design.

However, if we build and test a small and large system designed for peak
efficiency in every possible
aspect.... well, I don't think we have that information and couldn't make a
definitive statement (although we
could easily theorize).

Take care,
Bart