# Re: design questions

```In a message dated 1/12/99 2:41:48 PM Pacific Standard Time, tesla-at-pupman-dot-com
writes:

>
>  I am myself designing a tank supply with a 20 kVrms pig, but a 50 kVA one.
>  Modeling it with MicroSim I reached the same numbers.
>
>  Vpeak = 1.41 * 20000 = 28200 V
>
>  Using DC (not AC!) resonant charging actually you MORE than double that
>  figure because the resonant charging reactor gets already some startup
>  current when the tank supply is short circuited by the RSG. Let's say:
>
>  Vcpeak = 2.1 * Vpeak = 60 kV
>
>  Now, if you also suppose that the primary capacitor has left some voltage
>  Vr on it when the RSG opens (and this voltage is of opposite polarity to
>  the charging voltage), the charging reactor will sink more current into the
>  capacitor and will charge it to about:
>
>  Vc'peak = 2.1 * Vpeak + 2 * Vr !!!!
>
>  In reality we know that this Vr is very small so that should not represent
>  a problem.
>
>  Instead to oversize the capacitor to ? * 60 kV I tought to leave some
>  margin (probably use a 100 kV capacitor) and use a safety gap on it "just
>  in case..."
>
Just out of curousity, what is a 100 kv capacitor in the .05 ufd to .10 ufd
range likely to cost for this application?  Sounds like serious money.

Ed Sonderman

```