Re: tesla-d Digest V2006 #502

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Russell L Thornton <Russell.L.Thornton@xxxxxxxx>


HI Terry,
I am just trying to follow along here.  With the information given I 
plugged the values into TC-Plan in Excel namely:
9000 KV, 30mA and I assumed 120 BPS.  With 205 kHz it computes 23.06 
nF and not the 13.3 nF.  Where did I go wrong?
I am a different Russ than Russ Dischar so call me Russell.
Thanks,
Russell

>To:
tesla@xxxxxxxxxx
>Subject:
Re: need some capacitor help
>
>Hi Russ,
>
>A 9000 Vrms NST will have a peak voltage of 9000 x SQRT(2) =
>12700V.  That voltage will arc about 1/2 inch between sharp points in
>air and maybe a little more along a surface.  So if the arc over
>areas are less than say 3/4 inch you might want to increase the
>distance or stick some plastic in there.  If you are easily arcing
>longer than that, the voltage might be way to high.
>
>If your NST is 30mA, it has a resonance at 8.8nF which should be
>avoided or the voltage can resonant up way too high and damage the
>caps or NST.  You value is 6.8nF which "might" be close enough to do
>that with the 30mA NST.  In that case, you might be getting very
>excessive voltages on the caps and NST.  The solution there is to go
>to a "LTR" cap size which as far safer:
>
>9kV 30mA = 13.3nF
>9kV 60mA = 26.5nF
>
>Note: 1nf  = 1000pF = 0.001uF
>
>The higher load of the bigger cap will keep the voltage down to the
>rating.  You can add more caps in parallel if needed.
>
>You could also set the main gap close enough that it fires there
>instead of across the cap.  But the best solution is more capacitance.
>
>Try not to let it short across the cap much, the current is super
>high and it might hurt the caps.
>
>Your 20kV caps should be fine as far as voltage goes.  When you get
>it running be careful if they start to get too warm though.
>
>Cheers,
>
>         Terry