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----- Original Message ----- From: "Dave Leddon" <dave@xxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> Sent: Monday, September 14, 2009 3:30 PM Subject: Re: [TCML] Looking for pulse cap
Herr Zapp,I've been discussing igbt current limits with Steve Ward who felt that 2400 Amps should be the upper limit for my CM600 bridge. The operating frequency of my coil is 37 khz with a tank capacitance of 0.5 mfd. At that frequency the impedance of the cap is 8.6 ohms and so at 2400 amps that works out to 20647 volts. My present MMC array consists of three strings of 12 each 942C8W2K-F capacitors 2 mfd at 850 vdc, 360 vac which limits me to something less than 1000 amps. Steve suggests using the peak value of the ac rating to insure longevity, which in this case would be 509 volts. Using this conservative peak rms voltage rating I would require 11 strings of 41 each of the 942C8W2K-F caps for a total of 451 and at about $5 each that works out to $2255. I could save a little bit my using the 940C8W2K-F which has a 450 v rms rating and slightly lower cost but the bottom line is that the single surplus pulse cap is bound to be the better deal.Regards, Dave At 01:36 PM 9/14/2009, you wrote:Dave - A few questions: 1. How are you calculating the voltage requirements for the tank cap?2. How large a multiplier are you using to define the capacitor's voltage margin (safety factor)?3. What is the manufacturer's voltage rating for the IGBTs you will be using?4. What is the calculated peak primary current? Regards, Herr Zapp ----- Original Message ----- From: "Dave Leddon" <dave@xxxxxxxxxx> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> Sent: Monday, September 14, 2009 11:19 AM Subject: [TCML] Looking for pulse capHi all,I'm working on a fairly large DRSSTC and I find that an MMC adequate to the task may be out of my financial reach. If I were to push the igbt bridge to its limits I would require a cap rated at 20 kv at 0.5 mfd. This begins to sound like pole pig territory. If anyone has a cap like this that they would consider selling, or if they know of a resource that I can pursue, please let me know.Thanks, Dave Pleasanton, Ca _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxhttp://www.pupman.com/mailman/listinfo/tesla
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