Re: NST TEST GRAPHS (was NST power test)

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

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

)
 >
 > 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.

and it's just the "nominal" short circuit current at that...

 >
 > 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.

Using RC loads and measuring voltages essentially allows you to measure
watts...the reactive part of the load lets you differentiate reactive and
active power (with a bit of math and some possible measurement uncertainty),
and as you say, this might open up some interesting areas.


I think the real interesting part will be the behavior at the edge of
non-linearity.  Given that we tend to try to push the variac to "11", and
that we have a load which is very "non-neon-sign-like", it would be good to
get a feel for what happens when you start to saturate the core, for
instance. The simple model assumes an ideal transformer, and as you note, it
adequately models all the NSTs and their ilk (microwave oven transformers,
illumination transformers, There might be interesting things as we add in
the non-ideal aspects.  For instance, the magnetic path through the shunts
is different for the primary and secondary, so the fluxes in the two loops
can be conceivably different.  At saturation, this might lead to
"interesting" effects.


 >
 > 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.
 > >
 > >
 > >
 > >
 > >
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