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RE: FW: Re: Tesla Coil Efficiency Test



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.

John Couture

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


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Monday, June 17, 2002 6:28 PM
To: tesla-at-pupman-dot-com
Subject: RE: FW: Re: Tesla Coil Efficiency Test


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

Hi John,

On 17 Jun 2002, at 16:58, Tesla list wrote:

> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
>
>
> Malcolm,
>
> Because the load varies so widely is the reason I thought the "black box"
> method of finding the TC efficiency would be better. The incandescent lamp
> load means we have complete control over the black box output load. The
lamp
> brightness will vary with slight changes in the coil and the light meter
> will detect the change. The voltage and current for this brightness can
then
> be found very accurately giving the TC output energy for the coil to
better
> than one percent.
>
> The wall plug to variac losses would not be included in this test.
However,
> these losses are very small compared to the total energy loss in the TC
> system. Note that I used a black box watts input based on the NST capacity
> and the voltage setting of the variac.  The variac output voltage and
> current should be measured to verify this input watts.
>
> John Couture

Before the discussion gets bogged down perhaps we should start by
defining exactly what we are trying to measure. Are we talking about
the percentage of primary energy (on a shot-by-shot basis) that is
being delivered to streamers? If so, are we talking about air
streamers or attached streamers (the efficiencies for those two case
will be vastly different)? Or the amount of primary energy that a TC
can deliver (again on a shot-by-shot basis) to a well-defined
resistive load?
Unless the load is defined, discussion won't be meaningful as the
efficiency is load-dependent. By the same token, any efficiency
figure measured for an incandescent lamp will not be applicable to
sparks. Personally, I'm interested in getting greatest possible
efficiency in turning electrical energy into hot glowing air.
     Just to add to the fun, the quality of the secondary ground is
also going to matter. For example, if we tested two identical systems
at the same altitude, same level of humidity, same degree of
isolation from surroundings, same primary energy and breakrate, same
type and size of cap etc. etc., we'd probably be comparing the
quality of the grounding systems.

Regards,
malcolm
<snip>