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Re: TC Secondary Terminal Design



to: John

Is Cs the total capacitance of the secondary system or just the capacitance
of the high voltage terminal?  If so, I presume you have included in your
equation some device to estimate and subtract the secondary inductor's
capacitance.  

DR.RESONANCE-at-next-wave-dot-net


----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: TC Secondary Terminal Design
> Date: Friday, November 20, 1998 4:34 PM
> 
> Original Poster: "John H. Couture" <couturejh-at-worldnet.att-dot-net> 
> 
> 
>   All -
> 
>   Finding the proper size secondary terminal has now become easier when
> using a new(?) equation that I have derived from several theoretical
> equations. This is not a precise solution but does get you a ballpark
figure.
> 
>  The sizing of the secondary terminal capacitance is part of the tuning
> process and must satisfy the  Lp Cp = Ls Cs  equation. However, the size
is
> also determined by the input voltage and wattage. When the input voltage
or
> wattage is increased the secondary terminal capacitance should be
increased.
> 
>   The equation I derived to do this is as follows:
> 
>       Cs = 12.34 * cuberoot(KVp^2 * Cp)
> 
>      Cs in pf      Cp in uf
> 
>   Note that Cs in this equation is based on input voltage and  also on
the
> input wattage when  
>   Cp = J/Vp^2  and  J = Input watts/ Breaks per second
> 
>   The equation is derived assuming the following:
> 
>   The secondary terminal is a sphere and
> 
>   Cs (pf) = sphere dia * 1.41    
> 
>   Secondary kilovolts = sphere dia * 32.5   
> 
>   Sphere breakout is 65 KV per inch radius 
> 
>   KVs = KVp * sqrt(Cp/Cs)
> 
>   When the secondary capacitance is found the approx. sphere dia can be
> found by subtracting the sec coil self cap from the secondary
capacitance.
> 
> -------------------------------------
> 
>   EXAMPLE -
> 
>   Given Primary volts 15 KV rms * 1.4 = 21 KV peak
>         Primary wattage 1000
>         Breaks per second 120
> 
>   Find  Primary capacitance Cp
>         Secondary capacitance Cs
> 
>   Watts per break = 1000/120 = 8.33
>   Cp = 8.33/21^2 = .019 uf
>   Cs = 12.34 * cuberoot(21^2 * .019) = 25 pf
> 
>   Sec volts = KVs = 21 * sqrt(.019/25*10^-6) = 579 KV
>   Sphere dia = 579/32.5 = 17.8 inches
> 
>   For a check use  Cs = sphere dia * 1.41 
>                       = 17.8 * 1.41 = 25 pf as above.
> 
> -------------------------------------
> 
>   This gives the approx. secondary terminal size when it is a sphere. The
> equations would have to be modified for a toroid. Does anyone want to
give
> this a try?
> 
>   Note that the Cp/Cs ratio is important because it fixes the Ls/Lp
> inductance ratio. You only have to decide on the secondary inductance or
> the primary inductance. The operating frequency can be found by 
>     F = 1/(6.283 * sqrt(L * C))
> 
>   Note also that this explains the apparent dilemma in the equation
>   KVs = KVp * sqrt(Cp/Cs)  that indicates the secondary capacitance (Cs)
> should be made very small to obtain a large secondary voltage.
>  
>   I would be interested in comments from coilers on this somewhat novel
way
> to find the secondary terminal size.
> 
>   I am obliged to make the following comment - the above can be more
easily
> implemented using the JHCTES computer program. Please forgive.
> 
>   John Couture
> 
> --------------------------------          
>