Re: MOT Coil operational notes

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Ted, Greg,
               It's worth noting that mechanical dwell <> electrical
dwell. The two can be made to coincide by suitable choice of Fr and
k, which together can work to extinguish the primary arc at some
sufficient electrode separation while primary current is at a
minimum. I've yet to find a mechanical system which can disrupt an
arc in progress by brute force in a carefully timed matter of a uS or
two.
      The Corum's wish to use a specific primary arc time was to
bottle all energy up in the secondary at the first primary current
minimum. A more practical consideration may be to reduce the amount
of time the gap shorts the power supply to a minimum. However, it
doesn't always matter that much, particularly if the primary
cap/ballast is resonant at a frequency above the breakrate as energy
is stored in the ballast while the gap is alight.

Regards,
malcolm

On 3 Dec 2002, at 8:20, Tesla list wrote:

 > Original poster: "tesla by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
<tesla-at-paradise-dot-net.nz>
 >
 > Hi Greg et al
 >
 > 1) Yep I did miss the TENs and shorten it to 10uS my apologies. Having said
 > that the dwell time of tens of uS is still very short for a conventionally
 > coupled coil with K in the region of 0.1 I'd class 100uS diffferently than
 > 10's of uS but I'm not trying to split hairs on this. Others comments and
 > your own (thank you) re this point do perhaps resolve some of my questioning
 > about a  dwell time significantly shorter than the first notch period
 >
 > 2) The ARSG with 900bps would estimate dwell at 190uS which I think is about
 > is a good match for a first notch quench. This might explain reports of good
 > results around this bps assuming charging of the Cp is working well. The
 > SRSG dwell is about 280uS BTW
 >
 > 3) Your experience with improved results in the efficiency area with a
 > series static ONLY with the ASRG is particularly interesting. My coil is
 > designed so that the Static gap can quite easily be configured in this
 > manner. The idea will be experimented with later. Why this only applies to
 > the ARSG is a mystery to me however. Useful to note same experience with
 > series static with SRSG
 >
 > 4) An interesting note on shorting of the xfrmr. My PSU only registers BIG
 > current draw with a real load as I've got lots of PFC. A secondary  short
 > offers a largely inductive load and the PSU does not draw big current. Next
 > time its operating I'll reproduce this test and quantify the results. I make
 > this observation in relation to the efficiency improvment you reported with
 > the series static resulting possibly from less shorting of the xfrmr. I'd
 > speculate the the less intense ARSG arcing you noted may be the result of
 > increased losses in the static gap. As I say hope to report on this in the
 > future.
 >
 > 5) My own gut feeling is that getting the firing times optimised (bearing in
 > mind source impeance and load) in the SRSG will be my most rewarding path.
 > I've received serious encouragemnt and help here from Finn and am trying to
 > come to terms with microsim.
 >
 > I hope to contribute again to this discussion following some further
 > playing, I mean testing
 >
 > Best to all
 > Ted L in NZ
 >
 >
 >