RE: RSG and NST's

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <gary.lau@xxxxxx>

Hi Dr.

I don't agree that the hazard associated with async RSG's and NST's is
due to excessively high break rates.  With an NST, as an RSG's break
rate increases, the bang voltage will go down, making it LESS stressful
to everything.  The same effect may be achieved by reducing the spacing
of a static gap - lower bang voltage and higher bang rate - and I think
all agree that narrow static gaps are the least stressful.  Even if bang
voltages did not diminish with increasing BPS, I still don't see how the
NST would be any more stressed at higher BPS.

On the other hand, it's easy to demonstrate via simulation the
consequence of having a too-slow BPS, resulting in mains resonant-rise.

I'll be the first to admit that my opinions are based solely upon theory
and simulations, and I have not personally attempted an async RSG and
seen an NST fail. If you have experience demonstrating that high BPS is
in fact more stressful, I would enjoy hearing it, as well as your theory
as to the actual stress mechanism that increases with BPS.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Friday, November 26, 2004 8:07 PM
> To: tesla@xxxxxxxxxx
> Subject: Re: RSG and NST's
>
> Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>
>
>
> Technically, a NST is designed to provide an ignition voltage for a
plasma
> tube, ie, 9-15 kV to quickly ignite the gas in the tube, and then the
xmfr
> voltage drops back considerably, usually down to 400-600 VAC to
sustain the
> plasma.  At this point it becomes a current source to keep the plasma
> bright.
>
> In short, a NST is not designed to provide a continuous source of HV.
They
> do, and they work well with TCs firing 120 bks/sec.  They will also
work at
> higher break rates but one must be very very careful to provide
excellent
> filtering to prevent ANY high freq transients from getting back into
xmfr
> windings.  A "Terry Filter", named in honor of its inventor, Terry
Fritz, is
> commonly employed to provide this high level of filtering.  Perhaps
Terry
> could post this location in his extensive archives collection.
>
> http://hot-streamer.com/TeslaCoils/Misc/NSTFilt.jpg
>
> The other area, that must be carefully monitored, is the total spark
gap
> setting when running a NST.  Usually 0.220 to 0.250 is the absolute
MAXIMUM
> total spark gap setting that should be used with a NST.  Larger gaps
invite
> problems and failures on the NSTs.  It's always advisable to keep your
total
> gap setting at the maximum size (or less) that provides the
performance you
> want.
>
> RSGs can run asynchro IF you use a good filter with safety spark gaps
and
> total gap settings in the recommended range.  Not using all these
cautions
> invites trouble.  I would suggest less than 400 bks/sec as a max for
NSTs.
>
> I've been working for quite some time now for a reliable replacement
for the
> NST especially since the 60 mA units seem to be disappearing rapidly
from
> local suppliers.  Our unit contains two separate 8 kV coils and a LOT
of
> mylar under both coils so they can be either operated as a CT ground
unit
> (like NSTs) or, the coils may be connected in series, for a 16 kV to
ground
> unit.  These units are designed to be operated in oil so that the
final
> product should be quite robust.  A standard "Tupperware" type plastic
> container will serve as a suitable xmfr tank.  For greater mobility,
we
> intend to offer a steel tank with a phenolic top that is sealed with a
> gasket.
>
> There has been a lot of delays.  We finally received the two sets of
test
> coils and are awaiting the laser cut cores from Magnetic Metals.  We
hope to
> have them in our lab and tests completed prior to Dec. 20th.
>
> After that, we can start ordering production quantities which will
determine
> final pricing of these units.
>
> Dr. Resonance
>
>  >
>  > Several posts lately are discussing the use of rotary spark gaps
with
> NST's.
>  > I was under the impression that a RSG was not for use with NST's as
they
>  > cause them to fail.  Is this not right?
>  >
>  > randyaz
>  >
>  >
>  >
>