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Re: OLTC update - primary IGBT loss
Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
At 09:05 PM 9/4/2002 +0100, you wrote:
>> Wonder what happens if one refires 180 degree off from the present
>> ring... That should send some shock waves up the secondary ! :o))
>Oh, what madness is this!
>I modeled the situation where: just as the primary energy is
>momentarily zero at the peak of the first beat, we re-stock the
>primary cap with another bangs worth of energy (eg by switching
>to a second cap bank - one that you charged up while the 1st bank
>was going through its first half-beat).
>The normal ringdown, without quenching, is
>and the double-bang event is in
>The second cap is switched in at 50uS. Following this, instead
>of the secondary energy ringing down, it does another cycle or so at a
>slightly higher Vtop. Note that the Ipri and Vpri don't exceed
>their original values, so no extra device stress. The follow up bang
>roughly doubles the number of cycles that the secondary could be
>extending streamers over.
It appears that the SonoTube will not be transmuted into gold bullion from
this exercise ;-)) However, the possibility to change very pure silicon
into a molten blob of SiO2 is high. We'll just forget that one ;-)))
>> I need to try wrapping another coil to see if that affects
>> anything like Antonio suggested.
>Well if you do, ping the coil before and after so we can see how much
Darn..., got too late tonight to do this :-(
>> I did not retune the coil for the added probe C since I didn't
>> want to fiddle too much
>Yeah, that's fine. I don't care what the tuning is, so long as it
>stays put. It's a major ball ache to recompute everything if something
Yeah, Don't wan't to go changing too many things at one time. Models
don't care if it is out of tune... They still work anyway...
>> Is a pin point OK?
>Depends what we want to know. My particular interest is in witnessing
>the expected 26kV/cm surface gradient in action, and to observe the
>extent of the topvolts clamping action. For that we need a predictable
>breakout surface, so a point is out. I can manage with a small ball,
>or a rod with a smooth hemispherical tip. The rod or ball must be
>vertically above the axis of the coil/toroid so that the whole system
>has cylindrical symmetry. Single shot only for now.
I could not find any really good stuff for this. So I ordered up some
threaded brass balls from MSC. 1, 1+3/8, and 1+7/8 inch diameter. 1/4 and
3/8 inch thread to match my stuff. Next week... My other post tonight
shows that I can see breakout and streamer formation to a very high accuracy.
>But then if we simply want to know whether streamers evolve over
>part of a cycle, a couple of cycles, or several consecutive bangs,
>then any old breakout point would do I suppose.
But real ROCs are best. Best to eliminate as many variables as possible
>Don't need a topvolts
>measurement for that, just the current to the breakout point, along
That is toooooo easy!!!!!! ;-)))
>We might find that we can go a long way just on that
>basis, eg we can integrate the breakout current to see how much charge
>is upheld. We can tabulate upheld charge with observed streamer length.
>We can also look for signs of streamer evolution preferentially on
That be the negative polarity ;-)) Bandwidth is a problem. I can go to
40MHz on the streamer current and 20MHz on I base. I hope Ibase is well
and fine. But I worry if 40MHz is good enough for Istreamer... Maybe HP
has higher speed optics now... Doubtful, since Carly has totally nuked the
HP place >:-(( Maybe the Chinese have a higher-performance replacement...
>Either way, tons of stuff to go at.
Oh!! You think secondaries were fun!!! Steamers... we're talking fire