how to improve realiability of a DRSSTC

Danielle, Sun Oct 28 2007, 12:14AM

I built another DRSSTC this one almost identical to Steav's DRSSTC 3 except I am using 2 30N60s instead of 40N60s and this one I am donating to my school for demmos. The coil works well I was able to make over 20" spray and play music. the teachers were very impressed although then the IGBTs blew after 12min playing music and I was raising the PW. I checked and the IGBTs were still cold!

My question is that I need to make it so the IGBTs caint fail as the control bord will limit anything that may cause a faluar coming from the interrupter how would I do this or what alse can I do to improve it they are paying for the coil if it works well.

The OCD just wont cut it as it limits properly with a standard interrupter but not with music if thats all I need to do then ok I will tell them it caint play music.

I replaced the IGBTs and ran it for 20 min with 25" arcs coming from music and then 1 IGBT failed I need this to be stable any ideas on what I can do to prevent these faluars?
Thanks for the help.
Re: how to improve realiability of a DRSSTC
101111, Sun Oct 28 2007, 12:31AM

Try to use shielding on your circuitry and CT. Don't push the current protection too high and use good filtering caps.

Now I am a tc noob but I am very sure that can help.
Re: how to improve realiability of a DRSSTC
Dr. H., Sun Oct 28 2007, 02:44PM

When you have it running for so long, and then the IGBT fail i think this is due to high voltage spikes. I had a similar problem with my wealder. After 10-15 min of work the IGBTs died. So i added TVSs and i haven't had any problems since then.