Re: [TCML] SISG Damage Report

[piranha <piranha@xxxxxxxxxx>]

Cool!!

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.

http://drsstc.com/~piranha/p-2/p-2-index.html

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 
IGBTs!!!

Terry



FIFTYGUY@xxxxxxx wrote:
> Folks-
>  
>     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 
> far:
>  
>     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:
>  
> _http://powerelectronics.com/power_semiconductors/transic-competes-with-igbt-0
> 514/_ (http://powerel
> ectronics.com/power_semiconductors/transic-competes-with-igbt-0514/) 
>  
> -Phil LaBudde
> Center for the Advanced Study of Ballistic  Improbabilities
>
>
>
> **************Wondering what's for Dinner Tonight? Get new twists on family 
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>   

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