Re: Step-Up Xfrmr Question

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

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<Gary.Lau-at-compaq-dot-com>
> 
> For reasons that I don't yet understand, NST's will draw far in excess of
> their faceplate ratings under Tesla Coil operation.  I would go with the
> larger isolation xfmr.
> 
> Gary Lau
> Waltham, MA USA

	No mystery here at all.  The capacitive load "cancels" part or all of
the leakage reactance built in for current limiting.  A primary with a
so-called "matched" capacitor would be series resonant and one could
draw current limited only by the transformer resistance; a couple of
amps for the 12 kV 60 ma transformers I have which have about 5000 ohms
terminal-to-terminal.  Of course, the transformer would fail due to
insulation breakdown, even though the core would saturate.....  Thinks
are quite different with spark loading of the capacitor, which reduces
the effective Q of the secondary to a degree depending on the details of
the spark gap.  If you get "greedy: and in the effort to get longer
streamers widen the gap too far you get the sort of disaster reported
here quite frequently.

	It seems to me that the use of PFC's with a capacitor-loaded
transformer is problematic at best and may do nothing more than help
keep down line-to-line impulses on the primary of the transformers.

Ed