[TCML] SISG Damage Report
piranha at drsstc.com
Fri May 16 17:51:55 MDT 2008
Great that the SIDACs at least try to fail shorted and take the load to
protect the IGBTs :D But they won't take the big load for long.
They are also real cheap even if they are hard to get hold of at times.
PIRANHA has all the drive electronics really well shielded out of harms way.
It also won't kill you if you fall over on it!! :D Heheheha! It is
"still" way far ahead of its time :D
Looking very forward to hearing of Bart's testing of the new low cost
FIFTYGUY at aol.com wrote:
> Finally, I've got some useful info!
> Today I repaired the SISG4 board I blew up in my last run. I thought I
> only had one bad module, but when I looked closely, I realized that I'd blown
> two on the same board. Amazing how the coil keeps running fine when the
> circuit boards are on fire! Try that with your DRSSTC...
> The important thing is, this board had the 2nd and 3rd modules
> (sections) that I'd blown up. Here's the damage report from all the bad sections so
> 1st blown section I had posted about earlier. I believed at the time
> that it suffered a direct secondary strike to the SISG4 board. This section had
> all 3 SIDACs failed, 1 blown wide open, the other 2 with their cases cracked.
> In fact the blown one arced so bad, it welded its lead into the copper board
> trace.The 24V TVS failed with its case visibly cracked. The IGBT looked
> fine, but it was a dead short to all three leads.
> The 2nd blown section also had all three SIDACs failed, 1 with a cracked
> open case, the other 2 looked fine but were dead shorts. Again the 24V TVS
> failed (even though it looked OK). And again the IGBT failed, even though it
> looked fine.
> Now for the good part:
> The 3rd blown section again had all 3 SIDACs failed. Again, one blew up
> so violently the fiberglass board material was cratered and the traces
> completely vaporized. Carbon coating everything nearby. The other 2 SIDACs look OK
> but were again dead shorts.
> The 24V TVS is fine!
> The IGBT is fine!
> In all 3 cases, the 33V TVS's were OK. And all the little 40V Schottky
> Diodes were OK. As far as I can tell all the .1 uF caps were OK, too. But I
> replaced all the semi's and caps anyhow (cheap insurance). I'm keeping the good
> IGBT, though!
> All this leads me to believe that the SIDACs are the weak link.
> Obviously they failed in the 3rd module, but the IGBT is still fine. I know the IGBTs
> are getting mighty hot with the abuse I've been giving them. But I'm
> thinking of gluing on heatsinks to the SIDACs to help them out.
> What do you electronics guys think?
> In other news, maybe we'll be using Silicon Carbide transistors in our
> TC's one day:
> 514/_ (http://powerel
> -Phil LaBudde
> Center for the Advanced Study of Ballistic Improbabilities
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