Re: Terry's DRSSTC - Buss cap damage...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Jerry,

That is a great idea!!

The damage was burning out at the interface between the 1/1000000 inch 
metalized film and the end plates.  Very hard to see really unless you 
compare it to a good cap.  The higher dV/dt rating of the 942 series (6x!) 
would probably prevent the damage.  The value is 1/2 but that is not really 
important.  The new ceramic caps will also take over the high dV/dt load 
and I don't plan on super short dead times now that seemed to have caused 
the problem in the first place.

When I ran the super short dead times, the caps must have seen some very 
high dV/dt that tore up the film connection.  The cap still measured the 
same value and loss (low power meter) but the higher frequency properties 
must have "gone away".

Cheers,

        Terry

At 11:41 PM 2/24/2005, you wrote:
> Hi Terry,
>
> Maybe you can use a couple of 942C6W2P5K caps in place of youjr 940C cap. 
> These are rated at:
>
> 2.5uf
> 600Vdc
> 300Vac
> ESR 3 milliohms
> ESL 37nh
> dV/dt 628 V/us
> Ipk 1570 amps
> Irms 19.5 amps
> Body size = 2.13x1.26 in
> Lead dia = 0.047 in
>
> Gerry R
>
>
> > Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
> >
> > So I tore apart the old 4.7uF 600V 940C 6W4P7K CD buss cap I still had, 
> > and a brand new one......
> >
> > I first noted the old one had an odor of "fried chicken" ;o)) I only have 
> > my new Buck 277 hunting knife and my Channellock 349 linesman's plier 
> > here tonight... But I think I see the end plate connections on the old 
> > cap are "fried"...  I think, "again", those weenie "metalized film" caps 
> > have let us Tesla coilers down as we push thousands of amps through them :o)))