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 Matt,

On 9 Jul 2002, at 7:26, Tesla list wrote:

> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Mddeming-at-aol-dot-com>
> 
> In the discussion of the complexities of TC efficiency even the simple
> definition of output/Input is muddied in trying to achieve a consensus of
just
> what constitutes the "output load". But this  brings up another question
on the
> input side: Where does the Tesla Coil begin; just where is the "input
point"? 
> At the wall plug? At the Variac output (if it exists)? At the HV
> transformer/PFC input? At the HV transformer output? Filter system
output? How
> much of the control cabinet (if it exists),  or the power cabinet (if it
> exists), or the protection filter system (if it exists) , etc., are part
of the
> "input" in the efficiency equation?
> With muddy feet,
> Matt D.

Excellent comments/questions IMO. My basic approach is to leave the 
losses of the charging system aside while considering the coil alone 
to quantify *it's* losses. Doing so has allowed me to find the 
lossiest component in the system, to quantify its losses and come up 
with solutions to reduce its losses. The charging system can also be 
considered separately with similar results. In my mind and that of 
others, there is some question about using an inductor designed for 
50Hz sinusoidal operation and subjecting it to step functions 
repeated at a far higher frequency. I have observed considerable 
heating in ballasted transformers. The mass and heat capacity of iron 
masks this for short runs but shows itself up with long runs. This is 
with transformers both pushed close to core saturation and not. In 
both cases, the windings were through-putting power well beyond the 
faceplate ratings so copper losses were not insignificant. A 
transformer operated at or below its continuous load rating would 
show whether my suspicions about the core losses were justified or 
not. I haven't done this (yet).

Regards,
Malcolm