RE: Maxwell capacitor question

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

Original poster: "Phil Heslin" <pheslin-at-cox-dot-net> 

Hi David,

   I found an original spec sheet for the 31350 caps and you were right on
with you assumptions. The specs are as follows:

.1 uf +/- 10%, 100KV tested -at-105KV, 500 Joules, 20% rated voltage reversal,
80% max voltage reversal, Peak current 25KA, rep rate 1pps, max RMS current
25A, max operating temp 40 deg c, min 10 deg C, design life 30K full
charge/discharge cycles, DC life 1000 hours, Inductance 20nH, non PCB
impregnant and all the single ended plastic caps over 60KV require
submersion to operate at those voltages.

    I have often wondered if it would worth it to build a rectifier to avoid
the voltage reversals and extend the life of the cap(s).


           Phil



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