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Re: [TCML] Synchronous Gap understanding



Good discussion, but I would think that the only thing that controls the firing time is the spacing of the gap. It would seem that it would be good to have the firing a little before minimum distance (we used to call it top dead center) for less jitter. But I have a blown stationary gap, so when it comes to synch gaps I am only an egg, as Michael Valentine Smith would say. Am I grokking this right?

(My dad also used to say that there is no such thing as a silly question. One day I asked him why there is no such thing as a silly question. He said, "Well, that's a silly question.")

(Should send a copy of this to Kurt Goedel.)

---Carl




On 2/6/2015 6:17 AM, David wrote:
Thanks Scott - Hmmm ,,, So If I understand you, you are saying that the gap begins to fire when the moving electrode is approaching the still electrode (_before_ alignment) , do to the high voltage on the cap, and not _at_ or _afte__r_ alignment. And that the Freau controller delays, as apposed to advancing, the 60hz phase to the sync motor so as to delay the arrival of the moving electrode to firing spot, There by allowing adjustment to the optimal firing point just after peak voltage on the cap.

Dave

On 2/5/2015 12:38 PM, Scott Bogard wrote:
Not quite...
Pretend for a moment, you live in a perfect world. In this perfect world,
the spark gap arcs, at the precise moment where spark gap electrodes are
perfectly aligned.  In this world, a Freu controller will allow us to
change the level of charge in the tank capacitor, by changing the point in
time where those electrodes align.  Ideally we want that firing to occur
when the input AC cycle is at it's highest, because if we do it sooner, the
tank cap has more charging to do, and if we do it later, the tank cap is
discharging back into the transformers and hence the line.  This has
nothing to do with the spacing that the arc stretches across.

But we don't live in a perfect world... In reality the electrodes do arc early, because they are impatient, and as soon as they get close enough to
arc static gap style, they do.  To compensate for this we use our Freu
controller to set the system out of phase by a degree or two, so that when
that premature arcing occurs, is exactly at the peak of the AC input
cycle.  The adventurous (with a huge budget, and a strong will for
efficiency) will design spark gaps with enough gaps in series so that the premature arc is almost not premature at all. This way as soon as your arc
occurs (at perfect alignment), it is getting stretched LONGER and can
quench faster, which traps more energy in the secondary. I hope this helps
clear things up a bit, and remember, there are no silly questions...

On Thu, Feb 5, 2015 at 11:36 AM, David <zipo@xxxxxxxxxxx> wrote:

Hello every one - I just wanted to double check my understanding of how
the electrodes "close" in a sync gap .
If I understand this correctly, a sync gap fires as the moving electrode approaches the stationary electrode, by the arcing distance of the voltage on the cap and not when the the electrode is moving away? Right? And the John Freau phase controller delays the arrival of the moving electrode so
as to increase the distance to the stationary electrode, there by
increasing the voltage on the cap? Is this correct?
I know these are silly questions but I just want to be absolutely sure I
under stand this correctly.

Thanks
Dave

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