Re: Power in a TC System

• To: tesla-at-pupman-dot-com
• Subject: Re: Power in a TC System
• From: "Gavin Dingley" <gavin.dingley-at-astra.ukf-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Fri, 19 May 2000 17:58:17 -0600
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi John,
I know a bit about coiling, but tend to get lost with definitions (I only
learnt
the other day what an MMC was, but had been using them for the last few
years!).

A matched primary capacitor? Is this when the capacitors impedance matches
the NST
secondary's at the line frequency, i.e. forms a resonant circuit?

What is LTR? Is this when the impedance of the primary capacitor loads the
NST to
it's maximum power capacity:-

Xc = Vout / Imax

Sorry for these elementary questions, but I have got to know some time!

Thanks for your help,

Gavin.

Tesla List wrote:

> Gavin,
>
> Using the standard formula to obtain a "matched" size cap for a
> 12/30 NST gives about 0.006uF.  This particular size cap does seem
> to "neutralize" the NST's leakage reactance and permits a lot of
> current to be drawn.  My 12/30 NST drew 620 watts (as measured
> with a wattmeter) with that sized cap, and the VA was about the
> same when I used PFC.  Although I used a similar sized cap for
> a few years in my coil with no trouble, some folks on the list
> questioned the wisdom of letting the resonant voltage build up
> so high, and they advocated used a larger (LTR) sized cap.  The
> LTR sized cap draws about the same input power as far as I can
> tell, and gives the same spark length for a given power input,
> although I do use a 140V step up type variac.  One test that I did
> seemed to show that a NST can draw more than its rated power
> only with a matched sized cap, if the step up variac is not used
> (I'd have to check my notes to be sure).  In any case, I'd say that
> the use of this LTR sized cap is simply to keep the voltage lower to
> protect the NST.  Inductive kick charging permits the NST to
> deliver a good amount of power to an LTR cap.  If you use a non-
> shunted transformer such as a pole pig, these can use a larger
> than expected capacitor because a pig can deliver a lot more power
> than it's rated for.  In addition the external ballast can be adjusted for
> various capacitor sizes.
>
>
> Cheers,
> John Freau
>

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