Re: OLTC II- advice on tank cap

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

Original poster: "K. C. Herrick by way of Terry Fritz <teslalist-at-qwest-dot-net>" <kchdlh-at-juno-dot-com>

Stephen-

Take a look at my recent postings re:  A triggered-s.g. 1-turn primary/
Herrick's pizza-pan primary for perhaps some useful information.

Ken Herrick

On Tue, 06 May 2003 08:02:17 -0600 "Tesla list" <tesla-at-pupman-dot-com>
writes:
 > Original poster: "Stephen Conner by way of Terry Fritz
 > <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>
 >
 > Hi folks,
 >
 > I just received a nice pair of 1200V 600A IGBT bricks today. Thanks
 > Terry!
 > It gives me an evil feeling of power just looking at them. Now comes
 > the
 > hard part. I need to design a MMC cap that will store at least 2J,
 > preferably 5-10J, at 1000V. So we're talking between 2 and 10uF. You
 > might
 > think this is easy enough, but it needs to have very low inductance,
 > and
 > deliver a peak current that could be more than 10,000A.
 >
 > Proper film and foil caps seem to be out, because I can't buy them
 > in large
 > sizes. It would cost a fortune and be very bulky. So I'm thinking
 > metallized polypropylene. 10 to 50 of .22uF 1000V caps in parallel
 > would be
 > needed. Can anyone comment on this choice or suggest any particular
 > kinds
 > of cap? I used .47uF 500V LCR metallized film caps in my original
 > OLTC with
 > no problems. Even though they were only rated 40V/us but I ran them
 > nearer
 > 200. They got a bit warm though.
 >
 > Last of all, the construction, how should I arrange the caps for
 > lowest
 > inductance and even current sharing? If I had axial caps (leads come
 > out
 > the ends) I could drill a grid of holes in two copper-clad PCBs or
 > thin
 > copper plates, sandwich the caps between the plates, and solder them
 > in
 > place. Would this be a good layout, or would the caps in the middle
 > pass
 > less current than the ones at the edges?
 >
 > Your advice would be much appreciated,
 >
 > Steve C.
 >
 >
 >
 >
 >