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Re: Maxwell capacitor question



Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

At 03:03 PM 10/9/2003 -0600, you wrote:
>Original poster: "colin.heath4" <colin.heath4-at-ntlworld-dot-com>
>hi david,
>             i used the 80nf 100kv version of what you have. it performed
>well in my 6" coil at 400bps but got warm quickly so the inside must have
>been very warm.
>i assume this is due to the high break rate as like you say they are
>designed for lower break rates.
>i think they must be mica or mylar if they are so small at this voltage. i
>dont think they could possibly be polythene or polypropylene.
>i will be using this same cap in my maggie over the next couple of weeks at
>this same break rate. so ill let you know how it goes.
>cheers
>colin


My guess, judging from an old Maxwell data sheet, that the 31xxx series are 
the 1pps designs and the 37xxx are the high rep rate designs.
100kV 0.1uF doesn't show up in my chart, but, all the similar sized ones 
(they come in 2.3 and 4 inch thickness, 6 inches wide, and 10,12,and 28 
inches long (+/- an inch or so)
The 31190 is 0.08 uF -at- 100 kV and is 12.8 inches long...

They're all 25 kA peak current and 25 Amps RMS current.  They look like 
most are 30,000 shot life at 20%VR.  You can use Maxwell's equations for 
scaling the life for voltage, Q, etc... 
http://home.earthlink-dot-net/~jimlux/hv/caplife.htm

Just as a comparison, a .1 uF 50 kV high reprate unit has a life of 1E8 
shots, but is 2.3x5.9x19.5 inches.. doubling the voltage would require 
quadrupling the size...


>----- Original Message -----
>From: Tesla list <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Thursday, October 09, 2003 1:13 AM
>Subject: Maxwell capacitor question
>
>
> > Original poster: Tesla729-at-cs-dot-com
> >
> > Hi all,
> >
> > I have recently located and purchased (2) cat # 31350 100 kV,
> > 0.1 uFD Maxwell pulse caps (they're still enroute-haven't gotten
> > here yet) and was trying, with no availe, to locate some specs
> > on this particular capacitor. They are the single ended 2" x 6"
> > x 15.75" long plastic oil-filled case. I figure they're probably rated
> > for 1 pps at their rated voltage and probably 25 amps RMS and 25
> > kAmps peak per discharge -at- < 20% V reversals. I believe all
> > of the single ended 100kV rated Maxwells have to either be
> > submerged in oil or in one atmosphere of dielectric gas to operate
> > at the full rated 100 kV. Of course I will never be approaching
> > this max voltage limit for coiling so running them in open air
> > will be the way that I go.
> > Anyway, I was planning on trying to use them in my remodeled
> > 10 kVA pole pig coil. I figure they can be run at much higher bps when
> > the voltage is kept well below the max kV rating. 14.4 kVAC rms
> > would only reach about 20 kV peak (not considering resonant rise
> > of course). I was planning on parallelling them for 0.2 uFD and
> > maybe trying to go synch. They should handle 50 amps RMS in
> > this configuration but would that really be sufficientfor a pig? Of
> > course since they're used I don't know how many shots are left in
> > them and I think they are only rated at either 30K or 100K shots, at
> > the rated max voltage, at best. I have personally never had a Maxwell
> > cap fail from too many shots, though I have blown up a few lossy
> > polyester dielectric pulse caps (not Maxwells though) from over
> > current (get too hot and finally explode ;^O) but I know they do have
> > a limited "shot" life.
> >
> > As always, I value the advice from this list.....
> >
> > David Rieben
> >
> >
> >