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Re: Sudden Jump in NST Current



Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Esondrmn-at-aol-dot-com>

In a message dated 1/13/02 10:17:29 PM Pacific Standard Time, tesla-at-pupman-dot-com
writes: 


>
> 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, 

I would expect your transformers to draw about 15 to 16 amps with perfect power
factor correction.  15 kv at 90 ma is 1,350 watts / 120 volts = 11.25 amps at
maybe 75% efficiency would be 15 amps. 

It sounds like the primary cap and transformer are reaching resonance but the
quick calcs I did say the 30 nf cap is 2x calculated resonance (LTR) so that
should not be the case - but it does act like it.  Maybe the pfc caps are
causing this calculated relationship to change so that resonance is indeed
occuring. 

Seems that the coil is performing well.  One long streamer means that you have
exactly the right size toroid.  I get multiple streamers on both of my coils,
and I have built many toroids.  Not exactly the right one yet I guess. 

Ed Sonderman