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Re: [TCML] Looking for pulse cap



David -

The current General Atomics/Maxwell datasheet for the Model 31427 gives a design life of 1.5X10E4 (15,000 shots) at 25KA, 100KV, and 20% voltage reversal. The life projections increase dramatically with reduced operating voltage and reduced voltage reversal.

http://www.maxwellcapacitors.com/series-s-ss-de-capacitors.html

See especially the operating voltage vs life and the voltage reversal vs life curves at the bottom of the spec page.

Regards,
Herr Zapp

----- Original Message ----- From: "David Rieben" <drieben@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, September 15, 2009 6:35 PM
Subject: Re: [TCML] Looking for pulse cap


Hi Herr,

Wow, your Maxwell that you pulled out of storage sounds
VERY familiar to the 4 that I have. Mine are the same case
style and size that you stated except mine are model 31915
and are rated at 0.44 uFd, @ 100 kVDC. They do have
the same RMS and peak current rating as yours though and
are also rated at just 1 pps. I actually got in touch with one
of the capacitor engineers at GA and found the only caviat-
they are only rated for 6200 shots. Of course, that would
be at the full rated voltage, too, though and the life span
of a cap tends to go up like exponentially with a correspond-
ing drop in the working voltage below the max rated voltage
value, i.e. they would probably last nearly for ever being
pushed with a 14.4 kV pig in a typical ARSG coil system,
assuming they weren't pushed too hard in the RMS cur-
rent department.

David Rieben

----- Original Message ----- From: "Quarkster" <quarkster@xxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, September 15, 2009 6:19 PM
Subject: Re: [TCML] Looking for pulse cap


Dave -

After a little searching, I found a 0.4uF, 100KV Maxwell in my storage area. It's a model 31427, white single-ended plastic case, about 4" X 6" X 29" tall. I bought this as a "used" part directly from Maxwell in San Diego during a "garage sale" several years ago. It's history is completely unknown, but I haven't done anything with it since I bought it.

Maxwell's datasheet shows a peak current rating of 25K amps, RMS current of 25 amps, and an inductance of 20nH. However, rep rate is only 1Hz.

The question is, what kind of a pulse rate "derating" could be applied if it was only used at 10KV and 2500 amps?

Regards,
Herr Zapp

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