Re: Capacitor voltage - AC or DC

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

Somehow, someday, somebody, has to do something... :-))

Probably the "last unknown" of MMCs is how long the (CD 942C20P15K) 
will tolerate say 60Hz at 6000Vp-p....

Maybe do a bunch of different voltages to make a nice graph of 
'lifetime vs. over voltage'...

That would tell us all we still want to know...

Cheers,

        Terry



> One usually overrates the cap for AC use.  I suggest Erms x 2 as a 
> correct DC rating, so with your 15 kV AC xmfr, for a near bullet 
> proof cap bank, you want a cap bank rated at 30 kV DC.
>
> If you are using 0.15 uF 2 kV caps in your strings then each 15 cap 
> string would be rated .01 uF at 30 kV DC.
>
> With a 30 mA xmfr you need approx .014 uF capacitance so you cheat a 
> bit and use 11 caps in each string.  This gives you a single string 
> rated .0136 uF at 22 kV DC which will work fine with your 30 mA 
> xmfr.  You try to avoid a .01 uF match with the xmfr as the cap bank 
> might resonate with the xmfr and damage the xmfr.  Going a bit 
> higher usually works very well.   1.2-1.3 x Cres.
>
> Dr. Resonance