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Re: [TCML] SISG - now with a "real" pig coil



Thanks Phil for the update.

I heed your "experience" here. I'm likely going to have some real problems myself as I'm looking at running only .06uF. I'll be using 6 boards as well. I've built a flat ribbon primary for the coil and this put a hold on my SISG coil. This weekend (between watching the Olympics) I managed to finish up the primary. However, I will be making several tests for the TSSP group on ribbon primaries and also basic round conductor primaries, so I won't be getting back to the SISG coil until those tests are complete.

I wanted to add my own progress to your report.

Take care,
Bart

FIFTYGUY@xxxxxxx wrote:
Folks-
Last night I finally got around to running the SISG on my 12" secondary "pig" coil. Previously I had reported on running the SISG on a 6" coil, but with a 10kVA pig. That coil was a bit small for the power. I only ran for about 30 seconds before I saw a flash from the electronics under the primary and the coil quit working. Once again, a section of one of the rectifier legs blew out (diodes vaporized, the string in several pieces). After investigating today, I found that during that brief run one of the SISG boards was damaged. One SIDAC vaporized, its two brethren cracked, and the IGBT in that section shorted as well. Although the IGBT has 10 ohms of DC resistance from gate to C and E, the collector and emitter are a dead short. The SIDACS explode, but you can't tell a dead IGBT without a meter. FWIW, I'm still running the same .220 uF total primary tank. Calculated ~55 uH of primary, 50kHz Fres calc and measured. Pig ballasted to 60A max, variac'ed for 280V out. I didn't crank the variacs past where the gap fired rhythmically, since I'm running STR and I didn't want the BPS to run away (easy with a SISG). Six SISG-4 boards for 21.6kV firing point. I had just finished doing some runs with the same setup with the RSG. I had just finished my "Terry Filter" for the pig earlier that day, and it appeared to eliminate much of the kickback I was having to the control panel. I simply removed the ARSG and installed the SISG and rectifier. Based on my experience so far, I wouldn't push the IRGPS60B120KDP IGBTs past 5kVA. The instantaneous currents seem to cause damage very quickly. All my previous caveats about high-powered SISG coils still apply as well. FWIW I was getting 10'+ sparks from it before it died, around 10kVA input (based on the panel volt and ammeters for the pig input). I haven't bothered fine-tuning the coil yet, as I'm working on other issues. -Phil LaBudde
Center for the Advanced Study of Ballistic  Improbabilities



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