Re: ScanTesla program - Lowering the coupling may be better...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Daniel.

I was meaning the main power variac setting.  You said you adjusted it 
mechanically so you dont have the Freau controller.  The main power variac 
setting will affect the phase of the charging waveform so you will need to 
readjust the firing phase of the SRSG as you increase the variac output and 
make a final adjustment at maximum output.  As the main variac output is 
increased, the peak charging point will pull up in time and if the SRSG was 
only adjusted at medium variac output, this will have the effect of firing 
too late at maximum variac output and result in rough operation.  Some 
power sources can saturate during this late timing thus reducing the 
effective inductance of the power source.  This in turn can cause mains 
resonance even though you thought you were LTR (called ferroresonance).  As 
the power source inductance decreases, the charging peak will also pull up 
in time and could cause the SRSG to stop firing entirely and result in 
uncontrolled resonant rise.  Adjust your SRSG to fire sooner in the cycle 
until the roughness disappears and see if you still have racing 
sparks.  See interspersed comments.


> Original poster: Daniel Hess <dhess1@xxxxxxxxxx>
>
>
> Hi Gerry;
>
> motor under power, while the coil is operating. When I retarded the RSG 
> motor (CCW) the performance of the coil increased dramatically but alas, 
> eventually came the racing sparks and the cap safety gap began firing as I 
> continued to retard.

This is exactly what I would expect.  When you retard too much (too late in 
the cycle),  the charging wavefore also happens sooner (increased current 
causes a different operating point on the B/H curve - beginnings of 
saturation and reduced inductance) and the SRSG starts to miss.  Firing 
after peak can be unstable if retarded too much cause changes in the firing 
point also changes the timing of the charging waveform.  Rough operation 
results and resonant rise causes the safety's to fire.


> To answer your last question, the operation sounded rough, very rough to 
> me. I attribute this to the fact that the cap safety gap was firing 'all 
> over the place.' But then again, the safety gap firing is akin to a 
> misfire; You would expect rough operation under those circumstances, yes?

To me, it is a chicken and egg problem.  The misfire of the SRSG can cause 
the safety to fire.  A safety firing occuring while the SRSG is operating 
normally can also cause the SRSG to misfire.   A safety firing will 
introduce a transient response with a timing different then when the SRSG 
fires and screw up the charging waveform.  In either case, rough operation 
will occur.

Gerry R.