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Re: Commercial caps / MMC
Hi Sundog,
I too have heard this. But, I'm usually not satisfied until I've either seen it
first hand or enough people have compared the difference and a high consensus
is reached before I'm convinced. I run professional CSI pulse caps in my pig
system. Why? Well, when I needed caps, MMC's were not around and I managed to
get these (increadibly expensive caps) free simply due to a great contact and
the fact that the company I was working for at the time bought volumes and
volumes of pulse caps (you know, please the big spenders).
However, it may be very possible that MMC's can do just as well as these high
dollar pulse caps. I wouldn't be surprised if MMC's start replacing some of
these pulse caps in several applications. The cap manufacturers are the "true"
experts and I'm sure they too realize the unique ability and marketing value.
But could you imagine the costs?
I'd like to try to build a pig MMC, but as long as the caps I'm using a working
well, what's the point in spending all that money (which I little of). A pig
MMC would cost quite a bit and probably near what a pulse cap would, but then
again, replacing a string is far cheaper than a new pulse cap.
Take care,
Bart
Tesla list wrote:
>
> Original poster: "sundog" <sundog-at-timeship-dot-net>
>
> Hi All,
>
> Didn't say you couldn't, and truthfully, I'd prefer to do just that for the
> ability to choose my capacitance. At the higher power levels, I can see a
> problem with RMS current and the needed strings costing as much or more than
> a commercial cap. And the number of strings needed total for the current.
> For a reasonably long runtime, 1 min on, 2-3 min off), I'd like the caps to
> get warm to the touch, but not hot. I'm also talking a 15kva+ setup, where
> you're more likely to pop a breaker than anything. The cost for the MMC
> would grow fast at those power levels, and soon cost more than a commercial
> cap. I guess it'd be personal preference at that point. I've noticed that
> more pole-pig systems use commercial caps than MMC's. And I've read in the
> archives that commercial caps give better performance than MMC's. I'm just
> wonderin why.
> Caio
>
> Sundog
>
> -----Original Message-----
> From: Tesla list [<mailto:tesla-at-pupman-dot-com>mailto:tesla-at-pupman-dot-com]
> Sent: Thursday, September 14, 2000 8:42 PM
> To: tesla-at-pupman-dot-com
> Subject: Re: Commercial caps / MMC
>
> Original poster: "Robin Copini" <rcopini-at-merlin-dot-net.au>
>
> Hi Sundog,
>
> Why can't you use mmc's with a pig? I have a 0.07 to 0.09 uF mmc,
> (depending
> on how many panels I use), that I run with my pig - (270V in = 40500V out,
> or in
> p - p terms, 57476V). Running for 5 to 6 minutes at a time with a 200bps
> sync
> rotary gives no discernible heating whatsoever, and monster arcs. It's like
> everything else, you have to build the mmc to cope with the demands of your
> proposed system. At a certain point, mmc cost will be >= commercial cap,
> but then
> what would you prefer if either cap dies, replace an mmc string, or an
> entire
> cap?
>
> Best Regards,
>
> Robin in OZ.
>
> Tesla list wrote:
>
> > Original poster: "sundog" <sundog-at-timeship-dot-net>
> >
> > Hi all,
> >
> > Yup, more from the peanut gallery. This time, it's *que dramatic music*
> > Commercial cap vs MMC
> >
> > Why do commercial caps reportedly give better performance than an MMC?
> > Aren't they both an extended foil design? Is it the inductance of the
> > wiring in the MMC? The caps themselves? I made my strings, and last
> night
> > secured them in parallel to copper-clad PCBs, so I have a block of caps (7
> > strings of 11 in a 4x5x12 or so block). DC test charge-discharge worked
> > beautiful, and it looks nice too :) Hopefully lowered the inductance a
> > bit, and gave them a lot more conducting area.
> >
> > I know that for small coils, MMC's rock. They beat out commercial caps
> by
> > being "buildable", series/parallel them till you get what you want. You
> can
> > add and remove capacitance in small amounts to test/tune, replace a failed
> > string or individual cap, and not weep ower a blown commercial cap from
> > overvoltage. You all *are* using saftey gaps, right? *right!?!* :) I
> have
> > to admit, I'd be a lot less scared of blowing an MMC than a commercial
> cap.
> >
> > What are the specs on the Hosfelt caps being used, and the price each?
> > Maybe they can be ganged up on a pole-pig?
> >
> >
> Caio!
> > Sundog