Re: Paper/Oil Capacitors

["Malcolm Watts" <M.J.Watts-at-massey.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi Terry, Ed,

On 19 Aug 00, at 17:26, Tesla list wrote:

> Original poster: "Edward Wingate" <ewing7-at-rochester.rr-dot-com> 
> 
> Tesla list wrote:
> > 
> > Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
> > 
> > Hi Greg,
> > 
> >         Two years ago, 1/4 of the posts on this list delt with oil/poly
> caps.  In
> > only a year, MMCs have virtually obsoleted homemade oil caps (I am waiting
> > for them to obsolete the commercial ones too!).
> > 
> >         Rather than list the problems with paper and oil caps, I'll just
> say that
> > MMC caps are better, cheaper, faster, more reliabile, adjustable, don't
> > drift, exact value, don't leak, don't explode......  A number of people who
> > were in the middle of making oil caps stopped in the middle of making them
> > and went to MMCs.  They really are that much better.
> > 
> > http://users.better-dot-org/tfritz/site/MMCinfo/MMC.html
> > 
> > Cheers,
> > 
> >         Terry
> 
> Hi Terry,
> 
> That's a pretty strong statement.
> 
> I think you will have a long wait for MMCs to obsolete commercial pulse
> caps, or have you built quite a few small and large coils using both MMC
> and commercial pulse caps? I just wondered what comparisons your
> statement was based on. I don't expect to see Maxwell, PCI, CP, et all
> offering MMCs any time in the near future!

You're probably right but I do wonder. When I made my comment 
about spending money on MMCs I had several things in mind:

#1 - the cost of getting the CP caps, shipping to NZ, exchange 
rate, duty etc. By the time mine were landed, I think I'd 
parted with $1500NZ-odd for two of them i.e. $1500NZ for 50nF 
-at- 20kVAC. If I took peak working voltage as being 29kVDC-odd 
and taking advantage of a bulk buy of the PP caps I've used I 
would need to spend roughly $400 ignoring bleed resistors to 
build an MMC to the same spec (and run it at that voltage 
knowing it wasn't going to demise).

#2 - dealing with a catastrophic failure like an explosion of 
oil is not a worry.

Regards,
Malcolm