Re: Capacitor Sizing for Power

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

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

Hi Matt,

I get ~110nF...  I used MMCCalc and the Geek's caps...

------------------------
MMC Calculator  Ver. 2.2   9/12/2000  Terry Fritz
Transformer voltage =  15000 
Transformer current =  .24 
Firing voltage =  21213.15 
Fo =  200000 
Break rate =  120 
Thermal dissipation constant =  22 
Individual cap value =  1.5E-07 
 
Strings  Caps/Str  Capacitance  Voltage   Temp C    Cost              I Arms
  3        4        112.50         8000    26.73   27.00  :-((  :-((  33.66 
  5        7        107.14        14000     8.73   78.75  :-((  :-)   32.06 
  6        8        112.50        16000     6.68  108.00  :-((  :-)   33.66 
  8       11        109.09        22000     3.53  198.00  :-))  :-))  32.64 
--------------------------------------------------------------------
  9       12        112.50        24000     2.97  243.00  :-))  :-))  33.66 
 10       13        115.38        26000     2.53  292.50  :-))  :-))  34.53 
 10       14        107.14        28000     2.18  315.00  :-))  :-))  32.06 
 11       15        110.00        30000     1.90  371.25  :-))  :-))  32.92 
---------------------

This is based of the calculations at:

http://hot-streamer-dot-com/TeslaCoils/MMCInfo/MMCPower4.html

Cheers,

        Terry


At 06:35 PM 7/18/2001 -0400, you wrote: 
>
> Hi All! 
>          
>         I just started working up the requirements for my 15/240 NST farm 
> coil and decided to try the P=rate*0.5*C*V^2 method. using a SRSG -at-120 BPS. I
>
> have read that this is a "good ballpark figure" for minimum cap size needed 
> to handle the power. 
> Now 15KV*240mA= 2700 W Substituting gives us 
> 2700=120*0.5*15000^2*C  or 
> 2700=60*15*15*1E6*C which reduces to   
> 3/15*1E-6=C  or 
> 0.20uF=C = 200nF 
>
> Using the resonance relationship to calculate the minimum capacitance: 
> XL=2*pi*f*L=Xc=1/(2*pi*f*C) 
> if R<<XL then Z=E/I ~XL 
> XL=15000/.240=62500=377*L or L=166.8Hy 
> Xc=1/(2pi*f*C) 
> 62500=1/377C or 2.35625*1e7=1/C 
> 4.244*1e-8=C or, 
> C=42.44nF 
> A difference of 470% is not close in my ballpark. Even doubling the value for
>
> LTR gives an error >230% 
> Am I missing something obvious or am I just brain dead this week? 
>
> Matt D.