Re: NST TEST GRAPHS (was NST power test)

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

Original poster: "Kurt Schraner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <k.schraner-at-datacomm.ch>

Hi Jim,all,

Richard Hull's valuable measurements are indeed easily and satisfactory 
represented by a simplyfied transformer model, as is always implicitely 
used by coilers, when calculating a resonant primary cap: an ideal 
transformer connected to leakage inductance (as seen from the secondary 
side). With optimized parameters, for example the 5/30 NST:


         U2o/U1=42     485 H    i2 (i2k=27.6mA -at- R=0)
o---------L ¦¦ L------LLLLLLL---->--o------.
          L ¦¦ L                    ^      ¦
          L ¦¦ L                    ¦      R
U1=120V   L ¦¦ L  U2o=5.03kV       U2      R
(60Hz AC) L ¦¦ L                    ¦      R
          L ¦¦ L                    v      ¦
o---------L ¦¦ L--------------------o------.

One important thing, which is missing in Richard Hull's measurements, is 
the short circuit current i2k (->when R=0), which is 30mA, by the nameplate 
of the transformer, and had to be slightly modified to 27.6mA, for best 
representation of  the tests. I had a closer look at the data, using Excel 
97, see:

http://home.datacomm.ch/k.schraner/Neon_Hull_Sk.xls  (53kB)

Relevant for this "closer look" was, to verify, that the whole range of 
operation of this NST can be represented with a single value of the 
stray-inductance. I guess, sometimes it goes forgotten, that the nameplate 
current of an NST is the short-circuit current, if not mentioned otherwise.

If extending tests, like the one of Richard Hull, carefully including 
capacitive loads in the investigation may add to the value of the results 
for TC-coilers. More elaborate models, including copper and iron losses are 
opened, when including a wattmeter in the investigations.

Cheers,
       Kurt Schraner


Tesla list schrieb:

>Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><jimlux-at-earthlink-dot-net>
>
>
>While Richard Hull's measurements are interesting, his paper contains a 
>fallacy.. the shunts don't "start to come into effect"... they're there 
>all the time, along with the leakage reactance they produce.
>
>Perhaps you really need to measure the reactive and active powers 
>separately (current probes on the cap and resistor with an oscilloscope 
>would do nicely..)
>
> From a power transfer standpoint (which might not be what you want), you 
> want the "conjugate match".. that is, considering the source as a series 
> combination of an inductor (leakage inductance) and a resistor(copper 
> losses, in this case, referenced to the secondary side)
>
>you'd want the load to be the equivalent of a series resistor of the same 
>value and a capacitor of equal reactance.
>
>
>   (magnetizing inductance and core losses don't apply for the matching 
> condition..)
>
>
>In your setup, you've got a a parallel RC, which you'd need to transform 
>(mathematically) to the equivalent series circuit..
>
>What we want in a TC, though, is a bit trickier.. it's not a steady state 
>sinusoidal circuit, but, rather, a transient one, where you are charging a 
>capacitor through an inductor and resistor.  I suspect that a time domain 
>simulation might be a better way to approach the problem.
>
>The measurements of NST output with RC loads, though, will give you a good 
>way to confirm that a linear model of the NST as a resistor and inductor 
>is a good one.
>
>
>
>
>>Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
>>
>>Hi John,
>>
>>I have been doing tests too :-))  Although still very rough draft like, it
>>is at:
>>
>>http://hot-streamer-dot-com/temp/NSTva.html
>>
>>It is not done yet, but I thought I would mention it now for
>>suggestions.  I could only get 260VA out of a 360VA NST using just
>>caps.  Any ideas are welcome ;-))  It is all set up and just waiting.
>
>
>
>
>