RE: FW: Re: Tesla Coil Efficiency Test

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi John,
          I have to take issue with your last statement:

On 18 Jun 2002, at 7:37, Tesla list wrote:

> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
> 
> 
> Malcolm,
> 
> You are right that this thread will go nowhere if we are talking about TC
> spark outputs because this has been discussed in the past with zero results.
> The reason I brought this matter up again was because I felt a resonable way
> to look at the Tesla coil would be as an electrical device that could
> produce a useful energy output in the form of light. The efficiency could
> then be determined by what I called the "black box" method. I show how I
> made this test for one of my coils in one of my books. The efficiency would
> be
>       efficiency = useful energy out/input energy
> 
> The coil details did not have to be known, only the input and output data
> was necessary. Any size  classical coil could be used for this test. If the
> coil was properly designed and tuned the efficiency would likely be about
> 85% for coils under 15 watts input and for coils over 15 watts
>       efficiency = 1/(log(input watts))
> The equation may have to be changed if indicated by tests.
> 
> A 1000 watt input coil would be about
>       efficiency = 1/(log(1000) = 33%
> 
> It is very obvious that if spark outputs are used finding the TC efficiency
> would require much more work and agreement on details by coilers. However,
> we can probably assume that the maximum efficiency for the lamp load type of
> test is the maximum efficiency for the spark load until proven otherwise.

I cannot agree and here's why: We *know* that efficiency for a single 
transfer can easily be made to exceed 80%. At ringup time there is 
virtually no loading of any kind on the coil. If that energy then 
gets dumped into an attached spark and drains the secondary before a 
further trade back to the primary can occur, the 80% figure stands. I 
*have measured* both conditions occurring in more than one coil. 
Imposing a steady load on the secondary prevents it from absorbing 
all primary energy before the energy is passed to the load. If the 
secondary is loaded to criticality, transfer time is prolonged and 
the gap loses more power. QED.

Regards,
Malcolm