Re: Sudden Jump in NST Current

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Dave,

As the chart at:

http://hot-streamer-dot-com/temp/MMCcapSales.gif

shows, you can increase your primary cap to 41.5nF.  This may help things.

I think your NSTs are saturating their current limiting shunts.  The steel
sheets are just seeing too much flux and they are "going away" allowing the
NSTs to run without effective current limiting.  NSTs can run at
substantial over current but the voltage may be rocketing up too which is
not so good.  Your 20 amp fuse is just the right value for your system and
should not be altered (perhaps replaced now and then :-))  I would suggest
maybe adding 11.5nF to the primary cap.  Other than that, your system is
maxed out ;-))

The Freau formula does suggest that your coil should get 62 inch streamers.
 Maybe the added capacitance will help that.  Saturating the shunts is not
a good thing since it could destroy the NSTs.  I would add the extra 11.5
nF and see what happens.  I think it will be "good" ;-))

Cheers,

	Terry


At 11:29 PM 1/13/2002 -0600, you wrote: 
>
>Coil Specs:
>
>20 Amp Variac power controller
>
>3 x 15KV at 30ma Transco transformers for a total of 15KV at 90ma
>
>210uf PFC capacitor
>
>Standard Terry RC neon protection circuit (less MOVs)
>
>SRSG using .1 inch Thoriated Tungsten electrodes with a static safety gap in 
>parallel
>
>John s SRSG LC phase circuit 
>
>.03 uf at 70 KV Maxwell capacitor bank 
>
>Primary - 14 turns .25 copper tubing currently tapped at turn 10 
>
>Secondary 6.25 inch PVC with 36 inches of #22 wire 
>
>24 inch spun aluminum toroid
>
> 
>
>First let me express my thanks to the participants of this list for the 
>awesome assistance that has enabled me to exceed my goal of achieving 36 
>inch arcs. After some serious tuning I have observed greater than 36 inch 
>streamers and I am sure there is more to be had. But I am seeing significant 
>current consumption that I am unable to explain.
>
> 
>
>I did my initial current tests with a Jacobs s ladder and saw a max of about 
>10 Amps with the PFC caps. When tuning the coil I find that as I bring the 
>voltage up I first get multiple dancing 18 inch streamers with a very raspy 
>sound from the SRSG. Current draw appears to be in the range of 10 to 15 
>Amps. Then as the input voltage reaches about 100 volts a dramatic 
>transformation takes place. The sound becomes a singing 60Hz and a single 
>very strong streamer starts to reach out and slowly circle the toroid. The 
>combination of the sound and the bright streamer reaching out over 36 inches 
>is impressive if not a bit daunting. But a look at the meter shows the 
>current jumping to greater than 30 amps and after a minute or two the 20 amp 
>fuse in the Variac blows. I also noted the NST protection circuit resisters 
>get very warm suggesting a significant jump in NST output.
>
> 
>
>Might this be the NST going into some kind of saturation mode and if so am I 
>running into trouble?
>
> 
>
>Dave
>
> 
>
>=========================================
>Dave Kyle
>Austin, TX USA
>Email: dave-at-kyleusa-dot-com
>
> 
>