Re: Primary RMS Current calculation

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

Original poster: "R.E.Burnett by way of Terry Fritz <twftesla-at-uswest-dot-net>" <R.E.Burnett-at-newcastle.ac.uk>


Hi Terry and all,

The equations in MMCPower4.html do not seem to include the surge impedance
of the primary circuit which I thought was important to calculate the RMS
current in the primary ???  (Also I thought the conduction time of the
spark gap would have an effect ???)

I'm not sure how the W0 equation determines the power dissipation
in the capacitors without knowing the load (primary) impedance ???  It is
intuitive to me that using few primary turns would result in a higher RMS
current,  and more of the cap's energy would be dissipated in its internal
resistance.  Conversely I would think that a large primary would present a
higher impedance and result in less dissipation in the ESR of the tank
capacitor.

I am probably overlooking something here,  as it is the first time that I
have looked at this.  In the past I have run a simulation on Microsim to
determine the RMS current through the tank capacitor.

Feel free to flame me if I haven't been paying attention again ;-)

							Cheers,

							-Richie,

> Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
> 
> Hi All,
> 
>         I have received a number of inquiries about primary circuit RMS
> current and using MMCCalc for different types of capacitors.  MMCCalc
displays
> the current:
> 
> http://hot-streamer-dot-com/TeslaCoils/programs/Mmccalc2.zip
> 
> The RMS current is calculated using the formulas in MMCPower4.html.  The
> equations for resistance of a single cap (Rcap) and power dissipated in a
> single cap (Wo) can be used to find current by simply using Ohm's law.
> 
> P = I^2 x R  ==>  I = SQRT(P / R)
> 
> So the RMS current in a single cap (which is the same for a single string)
> is:
> 
> Irms = SQRT (Wo / Rcap)
> 
> The Primary RMS current is simply that number multiplied by the number of
> strings
> 
> Iprms = SQRT (Wo / Rcap) x Nstring
> 
> MMCPower4 is at:
> 
> http://hot-streamer-dot-com/TeslaCoils/MMCInfo/MMCPower4.html
> 
> Cheers,
> 
>         Terry Fritz