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Re: SISG IGBT Timing Resistors

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Gerry,

At 11:58 PM 7/14/2006, you wrote:
Hi Terry,

I think what you are doing is great for a static gap replacement. What Im thinking is applying the SISG concept for a SRSG so one can get the low loss benefit and still charge a larger Cp. But then again, maybe I dont know what the limits are on the Cp value with the full bridge rectifier.

I would "think" resonant or LTR charging would work just the same with a rectified voltage.

For comparison sake, lets assume a 15KV 30ma NST:

1. Static gap AC application,  1.6*Cres is 8.5nf
2. SRSG AC application,  2.8*Cres is 14.8nf

The real question is: if one uses the SISG on this NST with a full bridge rectifier, what is the max Cp that can be charged and get 120BPS??? Im not sure this is really understood yet since, iirc, some have experienced a muchlarger BPS than what they thought they should have. Maybe this means that Cp needs to be increased to get the BPS down to around 120.

I think the Static gap case would work just the same with a SISG and LTR static gap primary cap (1.6 x Cres). Rectifying and firing on a polarized gap should be invisible to the NST. Of course, the sync application needs different timing (although some LTR sync coils do fire near the voltage peak).

But is it "easier" just to rectify the high voltage?? My rectifier here is like $10 of 1N4007 diodes, a pipe cap and a lot of epoxy:


No doubt what you are doing is easier (and probably cheaper). Im not worried about that at this point. Im just trying to answer a question if more performance can be had using a given power source by applying the SISG concept with SRSG timing than using a conventional SRSG design.

If you can trigger the gap, it should work fine.