[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Terry's DRSSTC - First light ;-))

Original poster: "Paul B. Brodie" <pbbrodie@xxxxxxxxxxxxx>

That is some beautiful workmanship on your primary coil in the picture of your new strike rail!!! Are the white spacers ordinary plastic push pins? What spacing does that give you between each turn? It doesn't look like enough space to prevent arching.

----- Original Message -----
From: "Tesla list" <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
To: <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
Sent: Sunday, March 06, 2005 9:41 PM
Subject: Re: Terry's DRSSTC - First light ;-))

> Original poster: Terry Fritz <<mailto:teslalist@xxxxxxxxxxxxxxxxxxxxxxx>teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
> At 10:41 AM 3/6/2005, you wrote:
>>It still seems to be somewhat of a mystery as to why primary strikes
>>are so catastrophic to a DRSSTC. Some of my coils have survived many
>>primary strikes, other times just a hint of a streamer forming on the
>>primary will kill the thing. ...........
> I modeled a secondary strike to the primary. It gave this messy event:
> <http://drsstc.com/~terrell/pictures/PrimaryHitModel.gif>http://drsstc.com/~terrell/pictures/PrimaryHitModel.gif
> I(Ct) is the secondary current that was at say 4 amps but it suddenly loops
> down to -70A!! That is why the streamer had a bright flash to it. That
> current runs back through the driver and causes the following messy things
> to happen:
> The antiparallel diode on IGBT3 goes in and out of conduction at 20 and 35
> amps in like 40 nS pulses.
> IGBT3 follows the reverse of that.
> IGBT2 follows a slower current crossing path.
> Not sure what IGBT1 is doing...
> But all this happens in less than 100nS!! So something goofs up and it
> cross conducts and blows. The high current pulse simply messes up the
> timing and cross conduction in the bridge and she blows... Our little high
> speed IGBT high speed current dance just goes haywire... The model quickly
> crashes at this point...
> Depending on the coil and exactly when the streamer hits probably has all
> kinds of good and bad results... If the primary current were say 300 amps,
> it would not reverse bias anything and all would be fine. But much of the
> time the current pulse will drive the silicon backwards and then it is all
> over... So it looks like a high current pulse from the stored charge in
> the top load goes back and reverse biases the silicon at super high speed
> and it looses control.
> I just got my new strike rail installed ;-))
> <http://drsstc.com/~terrell/pictures/StrikeRail.JPG>http://drsstc.com/~terrell/pictures/StrikeRail.JPG
> Cheers,
> Terry