Auto Quenching - Re: OLTC update

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Antonio, and Marco too,

My small coil was designed for auto quenching using these methods.  "Auto
quenching" is a big subject I was always going to write up "someday"...  I
never did...

Here is the "short" explanation...

When you consider the losses of Rpri, Rsec, and streamer loading, the coil
looses power very quickly.  Subtle sweet spots indicated by the lossless
case are swamped by these giant losses.  Lower quenching allows all the
primary's energy to be impressed on the secondary in a single burst for
maximum secondary voltage.  I looks like a "ball" where the secondary rings
up to maximum voltage and then all the system's energy is gone.  There is
no second or third notch.  Modeling definitely suggests this is the optimal
situation and my small coil is a great performer given it's power.  My work
tonight with the OLTC shows that this is a great value for k as well.  It
is hard to "see" without actually "being there" or having a nice paper like
Marco's to explain it...  But just imagine the coupling is set to pump the
maximum voltage into the secondary in one single shot where we trap it
before all these nasty looses ruin it.

It may seem that high coupling is good, but it tends to restrict the
secondary voltage from ringing up to the best value too.  It seems that
hitting the secondary with a well planed single burst at lower coupling
allows the highest secondary voltage to build up in the "high loss" case.
Remember, that a streamer in a 1000 watt coil may be eating 300 watts of
power!!  You just "can't" ignore that giant load and it's effects!!

I know it is "unpleasant", but you really "need" to consider Rpri, Rsec,
and streamer loading in defining the best values for k.  Since there are no
closed form equations for the high loss case (or at least they have never
been found.  Perhaps a problem for computer math programs like "Maple"),
you will have to use iterative computer programs like MicroSim to find the
effects.

"My bad" for never following up on all this before...  But it is a giant
subject I never was able to grab hold of and explain properly...

Cheers,

	Terry


At 10:36 PM 8/28/2002 -0300, you wrote:
>Tesla list wrote:
>> 
>> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
>> 
>> Hi All,
>> 
>> I ran various MicroSim models with K going from 0.05 to 0.25 with primary
>> resistances of 0.5, 1.5, and 2.5 mOhms.  I found the resulting peak
>> secondary voltages:
>> 
>>         http://hot-streamer-dot-com/temp/OLTC08-28-01.gif
>> 
>>         http://hot-streamer-dot-com/temp/OLTC08-28-02.gif
>> 
>> I think the dip in the yellow line at 13 is a mistake in my data.  In the
>> low loss (r=0.0005) case you can see the effect of sweet spots above k=0.20.
>
>The results seem strange. Increasing the coupling should always reduce
>the loss, increasing the maximum secondary voltage. The sweet spots
>don't
>make great difference at these levels of coupling. The large increase
>observed for low coupling is very strange. Are you sure that
>you are measuring the output voltage with both polarities?
>
>Antonio Carlos M. de Queiroz
>