RE:New Tesla Coil Testing - (was : doing something right??)

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

Original poster: "John H. Couture" <couturejh-at-mgte-dot-com> 


Gerry -

Thank you for sending me the JAVATC data of your coil. I came up with the
approximate JAVATC results using the JHCTES Ver 3.42 program.

With my tests I use a voltmeter, ammeter, and wattmeter at the input. These
meters will give you the VA, watts, and power factor at the input. To get
the correct output information you have to have a constant load. With Tesla
coil sparks as a load this can be a problem because of the intermittent
sparking. The closest you can come to a constant load is to have a
continuous horizontal sparking between the secondary terminal and a suitable
ground point. This means you have to reduce the spark length until the
sparking appears to be continuous sparking at 120 sparks per second (60
hertz). You can then determine a "spark length/joule" for your TC.

The problem with a "spark length/joule" test is that large TC's such as 10
KVA with 15 foot sparks give only about a 2 inch spark per joule. A small TC
will give 8 to 10 inches per joule. This would indicate that small coils are
much more efficient than large coils. The reason is that the spark length is
based mostly on voltage and currents are ignored. This is also the reason
why calculating the spark length using only the wattage gives inaccurate
results.

Another big question regarding TC testing is that with my tests why do the
TC power factors vary so greatly? This has nothing to do with the
characteristics of the NST or other TC power transformers. My tests are all
using the same power supply. These TC power factors are due to the different
types of TC loading which are mostly resistive/reactive with charge,
discharge, short circuit, etc. This means that trying to determine the true
input wattage of a TC is much more complicated than metering the typical RCL
electrical load. It is obvious that there is much more research to be done
to understand how a Tesla coil works and how it should be properly metered
and tested.

John Couture

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-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Saturday, November 22, 2003 9:42 AM
To: tesla-at-pupman-dot-com
Subject: Re: doing something right??


Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>

Hi John,

These are my coil parameters using JAVATC.  I will intersperse some comments
worth noting:

J A V A T C v.10 - CONSOLIDATED OUTPUT
Friday, November 21, 2003 10:53:52 PM

------------------   big snip