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Re: nonresonant cap = imcomplete charge ?



Original poster: "Laurence Davis by way of Terry Fritz <twftesla-at-qwest-dot-net>" <meknar-at-hotmail-dot-com>

If the larger tank cap draws more energy from the NST,
wouldn't this also distort the secondary's waveform?
Perhaps the main gap holds the peak voltage setting,
but the inductive reactance would increase the rise
time of the secondary voltage.  This should be measurable
I would expect.

or perhaps my lack of knowledge now shows. :)
perhaps a reshaping of the current waveform instead? (increased
rise time)

larry.

>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: nonresonant cap = imcomplete charge ?
>Date: Wed, 23 Oct 2002 11:25:34 -0600
>
>Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><biomed-at-miseri.winnipeg.mb.ca>
>
>
>Hello,
>
>I partially disagree your statement.  The capacitive reactance of the tank
>capacitor will cancel out some of the inductive reactance of the NST and in
>resonance, all the inductive reactance.  Which causes the primary current
>of the NST to increase up past the VA rating of the transformer.  The
>inductive reactance in the secondary of the NST and its magnetic shunts
>limit the current and  therefore VA power draw.
>
>My system uses an unmodified NST, 12kv 60mA, 720 VA, which should give 6
>amps of primary current but my system, measured with a RMS meter, pulls 13
>amps or so.  Cap value is LTR 0.0212 uF.
>
>Shaun Epp
>
>----------------original message------------------
>Larry,
>
>An interesting thing about resonant sized caps, is that this
>seems to be the only type that can cause an unmodified NST to
>draw more than its rated power without using a step-up type variac.
>This may not be true in all cases however.
>However there's more danger of NST failure with a resonant
>value cap.  More robust non-shunted types of transformers can run
>successfully with resonant sized cap value.  Of course
>in these cases, resonant value is determined by the external
>ballast setting, rather than by the transformer characteristics.
>
>A disadvantage of resonant operation with a typical primary
>circuit ballast is that it steps up the transformer primary
>voltage and can cause saturation and poor efficiency.
>Ballasting the secondary for resonant systems is therefore
>preferable, but is rarely done.
>
>In general, an LTR cap in an NST system can provide a
>reasonable bang size because although the voltage is lower,
>the uF value is larger which compensates to a degree.
>
>John