# RE: Math help...

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

Brent -

This is a good question because it cleary illustrates the differences
between electric and mgnetic circuits. Eddy currents                     are
electric circuit resistive losses. There are no flux losses in magnetic
circuits and no parameters of which I am aware that describe magnetic flux
losses.

John Couture

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

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, July 11, 2001 6:27 AM
To: tesla-at-pupman-dot-com
Subject: Re: Math help...

Original poster: "Brent Turner by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<bturner-at-apc-dot-net>

John -

Then where does the energy used up in eddy current losses in
transformers (magnetic circuits) come from??? When I hook my 5KVa
isolation transformer up and not pull any load on the other side, the
core does still get slightly warm after a while -- heat indicates
energy, in this case a loss.

- brent

Tesla list wrote:
>
> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <couturejh-at-worldnet.att-dot-net>
>
> Bert -
>
> I agree with your excellent comments below, however, I believe it should
be
> pointed out that the energy transfer in all magnetic circuits is 100%
> because there are no losses in magnetic circuits. Electric losses are only
> in electric circuits and the efficiency is the ratio of output/input. This
> means that when reffering to electrical efficiency the input and output
> calcs should be shown. This can be a difficult task when talking about
Tesla
> coils.
>
> I understand the voltage can be used to find the joules (energy) in the
> primary capacitor but how do you determine the energy in the secondary
> circuit when the secondary voltage of an operating TC is an unknown? I
> avoided this problem by using a light bulb for the secondary load in my
> test.
>
> When we say the TC efficiency can be about 90/95% what are the input and
> output conditions? Coilers talk about TC efficiencies but I have never
seen
> any published input/output calcs. In my TC Construction Guide page 14-4 I
> show a simple efficiency test I made with a small TC and the input/output
> calcs were shown. Have any other coilers made these tests? The test showed
> an overall efficiency of 56%. Larger coils have efficiencies much lower.
> What are the input and output calcs for the 90 to 95% efficiencies? How do
> they relate to the overall efficiency? How do these 90/95% efficiencies
vary
> with TC size?
>
> John Couture
>
> ----------------------------
>
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Sunday, July 08, 2001 9:02 PM
> To: tesla-at-pupman-dot-com
> Subject: Re: Math help...
>
> Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <bert.hickman-at-aquila-dot-net>
>
> Josh and all,
>
> That's an excellent question, Josh - and it goes to show that very few
> things are truly simple in coiling... :^)
>
> Malcolm is correct. Previous experiments have measured primary tank
> capacitor voltage during a complete primary-secondary-primary energy
> transfer cycle. These have shown that the efficiency of the first
> primary-to-secondary transfer (from an initially charged tank capacitor to
> a fully resonating secondary) can indeed exceed 90%. However, this makes
no
> statement regarding how efficiently we were able to charge the tank cap
> from the mains supply in the first place. For that, we need to talk a bit
> more about capacitor charging circuits...
>
> -------------------   snip

```