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

[FIFTYGUY@xxxxxxx]

In a message dated 8/15/08 1:30:40 P.M. Eastern Daylight Time, f-h@xxxx  
writes:

>With a primary Z of  15.8 ohms and a firing voltage of 21.6kV  you are 

>looking at primary currents in the range of  1300Amps.
>

>If you are using the "standard" IGBT`s, I`d say that is too high a  current.



That's what I've been saying all along. I just  felt like throwing some money 
away to prove it. :) Anyhow, the absolute peak  pulse currents for the 
IRGPS60B120KDP was extrapolated to an estimated  800 Amps. I think that's actually a 
good number to stay below. 
    I suppose I could add some resistive ballasting  (as Dan Macauley 
discovered with his DRSSTC II). It would be interesting to  see if it still performs 
well. 
    The whole SISG section is unprotected. I think  for higher powered coils 
it needs to be enclosed in a steel box! Kinda hard to  protect it against 
transients (strikes to the cap or power supply) when the  SISG itself is one heck 
of a crowbar!


>If a IGBT fails, the sidacs are sure to follow in short  order.


And vice versa. I've had one IGBT where the gate  insulation was intact, but 
it still shorted the C to E on the body. That  definitely points to too high 
an instantaneous current.


>A Pearson is your best friend.
 
    Wanna mail me one? :)
    I had played around a bit with the coil  parameters before I built it to 
keep Z surge above 15 Ohms minimum, since that  seemed to be "within the 
bounds of good taste". As it is, I'm thinking of  going to a bigger toroid to get 
more primary Z, and maybe adding some series  static gaps as well as running 
the rotary.
    Terry Fritz suggested better tuning, which of  course I need to do 
anyhow. But it's a little iffy trying to tune just right  for a ASRSG at full power, 
and then expect it to be perfect for a SISG. And if  the tuning is just a 
hair off with the SISG, well, I killed one section in  about 20 seconds. 
    I think the SISG is fantastic -  just  respect the limitations 
as-designed. Some folks are working on BRSISG's using  BRicks. Maybe a nice fit since my 
Fres is down to 50kHz. BTW I'm working on a  portable small-twin coil setup 
using the SISG, where the quiet, dark,  maintenance-free factor is outstanding.
 
-Phil LaBudde

Center for the Advanced Study of Ballistic  Improbabilities





**************Looking for a car that's sporty, fun and fits in your budget? 
Read reviews on AOL Autos.      
(http://autos.aol.com/cars-Volkswagen-Jetta-2009/expert-review?ncid=aolaut00030000000007 )
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla