Re: OLTC update - Coupling figured out :-)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "jimmy hynes by way of Terry Fritz <twftesla-at-qwest-dot-net>" <chunkyboy86-at-yahoo-dot-com>


terry's three turns in parralell would act like 1 turn if they were perfectly
coupled, however because the coupling isnt perfect the inductance goes down a
little. i was thinking about making a sstc with igbts and a quick rise time. i
found some igbts that could be used in hard switching applications up to
150khz. another one said 40khz in hard switching and >200 khz in resonant
switching. i intuitively  guessed that ss spark gaps would be less efficien
than sstcs. i checked that by making pspice models of both, it looked like (at
k=.15) i could get the same rise time with about 1/5 the average current as in
a spark gap design. with high coupling i guess ss spark gaps could do as good.
wouldn't higher k be attainable because of the electronic quenching? i know you
would still have to worry about the insulation, but it seems like you could
find  a good way to fix that. 

 Tesla list 
>
> wrote:  
> Original poster: "K. C. Herrick by way of Terry Fritz " 
>
> Jimmy (& all)-
>
> Yes, you remind me that Terry's turns are in parallel whereas mine are in 
> series, and that does give him a whole lot less resistance. But I think 
> that yields him exactly 1 turn, and not less than 1: you can't get from 
> here back to here in less than 1 turn. I believe I could approach that 
> if I used IGBTs instead of MOSFETs, and 1 (equivalent) turn instead of 3. 
> But I don't think IGBTs are going to switch satisfactorily at 140 
> KHz--unless they've been improved a lot since I last looked.
>
> As to the efficiency of a s.s. switch in one configuration vs. the other, 
> I'd think it wouldn't matter much. Not so?
>
> Ken Herrick
>
> On Sun, 25 Aug 2002 13:31:13 -0600 "Tesla list" 
> writes: 
> > Original poster: "jimmy hyn! es by way of Terry Fritz 
> > " 
> > 
> > 
> > the reason kens coil has such a slow ring up is that the switches 
> > cant handle 
> > any more power. with most coils and the oltc that is not a problem, 
> > because it 
> > is actually less stress on the switch the faster the energy is 
> > transferred. in 
> > the oltc the turns are in parralell making it like less than one 
> > turn instead 
> > of 3 turns. if you use ten big igbts in a s.s coil it would be 
> > possible to get 
> > quick ring ups on even bigger coils. using a switch as a spark gap 
> > isnt as 
> > efficient as using it in a s.s. coil 
>
> [snipped]
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> JImmy
>