Re: NST/cap sizes - was RE: Coil Woes

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

Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net> 

Hi Dr R,

The context of this is with a SRSG where one can get inductive kick to
higher voltages.

Gerry R.

 > Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
 >
 > No --- this is not correct.  No matter how much available potential your
 > xmfr has, the firing potential is determined by the sparkgap setting not
the
 > xmfrs peak potential.  Ask Terry to post my sparkgap chart and you will
see
 > it's usually around 16-18 kV for typical NST settings (200-260 mils).
 >
 > http://hot-streamer-dot-com/TeslaCoils/Misc/SGapVolt.jpg
 >
 > We usually apply a HV power supply and see where the gap starts firing ---
 > using our 50 kV DC probe to monitor and rectified HV from the NST.  Use
this
 > value and not the calculated peak value of the NST.
 >
 >
 > Dr. Resonance
 >
 >
 >  >
 >  > C V-Bang 120*.5*C*Vbang*Vbang
 >  > .02uF 24.4kV 714W
 >  > .03uF 21.9kV 863W
 >  > .04uF 19.6kV 922W
 >  > .05uF 17.1kV 877W
 >  >
 >  > Note that with LTR caps, Vbang is considerably less than the peak cap
 >  > charging voltage.  For the .04uf cap, the peak voltage was about
22.2kV.
 >  >
 >  > I'm not sure that our NST simulation models accurately predict what
 >  > happens when the mains voltage is raised above nominal and the
magnetics
 >  > become non-linear.
 >  >
 >  > Regards, Gary Lau
 >  > MA, USA
 >  >
 >  >
 >  >
 >  > Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
 >  >
 >  > Hi John,
 >  >
 >  > That could very well be.  Unless I'm misinterperating the post, Gary's
 >  > 4.0*Cres was the results of an experiment with a dummy load.  I'm just
 >  > trying to get closure on results in a running SRSG system and if the
4.0
 >  > Cres continued to hold up.  I'm most interested in the bang voltage of
 >  > the
 >  > 15/60 system with 4.0 Cres.
 >  >
 >  > Gerry R
 >  >
 >  >
 >  >   > Original poster: FutureT-at-aol-dot-com
 >  >   >
 >  >   > In a message dated 10/12/04 11:59:27 AM Eastern Daylight Time,
 >  >   > tesla-at-pupman-dot-com writes:
 >  >   >
 >  >   > >Hi Gary,
 >  >   > >
 >  >   > >I remember your post.  Since Cres for your 15/60 NST is 10.6 nf
 >  > (call it
 >  >   > >0.01uf), your experiment would correspond to ~ 1 to 5 * Cres.  Im
 >  > wondering
 >  >   > >if the dummy load is affecting the results.  My computer
simulations
 >  > show
 >  > at
 >  >   > >values above 3*Cres, the inductive kick can not get things fully
 >  > charged.
 >  >   > >My actual measurements were between 1.6 and 2.5 * Cres where I
 >  > scoped the
 >  >   > >primary durning actual SRSG operation.  At 2.5 * Cres, I was
drawing
 >  > 1080
 >  >   > >watts from the power cord and charging to 24KV at the time of bang
 >  > (900
 >  >   > >watts thru the gap).  I haven't gone larger than 2.5 * Cres cause
I
 >  > ran
 >  > out
 >  >   > >of cap.  So far the measured results agree with the simulation so
Im
 >  >   > >wondering if 4 * Cres would hold up during real operation.
 >  >   > >
 >  >   > >Gerry R.
 >  >   >
 >  >   >
 >  >   > Gerry,
 >  >   >
 >  >   > It think possibly the secret is that Gary's NST is robust
 >  >   > and may deliver more current than expected.  This may be
 >  >   > partly due to the use of 140volts input voltage.   It seems
 >  >   > that all NST's are not the same regarding their current
 >  >   > capability.
 >  >   >
 >  >   > Cheers,
 >  >   > John
 >  >   >
 >  >   >
 >  >
 >  >
 >  >
 >
 >