Re: [TCML] Two phenomena...

[Gary Lau <glau1024@xxxxxxxxx>]

Hi Joe,

I agree with John about the possibility of your motor losing synchronous
operation.  I think you said your phase adjuster has a 2uF cap?  I know that
when I set my phase Variac to the far end I lose sync with my motor.  Maybe
with your cap so small, you need to set the Variac to the far end to achieve
a useful phase delay?  Moving to a biggger cap will allow you to operate at
a less extreme Variac setting.

For the primary arcing - it sounds like you looked at all of the obvious
things.  Perhaps if you could post some more photos of the primary,
something will jump out at us?

Regards, Gary Lau
MA, USA

On Mon, Jul 26, 2010 at 12:18 AM, Joe Mastroianni <joe@xxxxxxxxxxxxxx>wrote:

> I managed to debug my rebuilt coil to the point I'm getting nice arcs.
> 15/90 NST.  41.8nf cap.  Primary is 17 turns of 1/4" refrigeration tubing
>  spaced  1/4" apart.  Using an SRSG consisting of a 1/30hp synchronous motor
> running at 1800rpm, a 7" G10 wheel, and eight 1/4" tungsten carbide
> electrodes.
>
>  Through painful trial and error (painful because I had to kneel on my
> garage floor) I managed to tweak the timing on the SRSG so that the safeties
> stopped going off.  Though I wound up leaving it in 240bps mode.  I figured
> I only have 45 degrees of "play" instead of 90.  Proved to be easier than
> tweak the 120bps setup, 2 or 3 degrees at a time, then trying to figure out
> if I had the turning straightened out correctly.  Trying to separate each
> problem and solve it in turn rather than trying to figure out how to fix 6
>  bad things happening at once.
>
> When I finally got to the point where the safety gaps weren't firing, I
> still had 2 things going on.
>
> 1) arcing between turns of my primary
>
> Never had this problem before.  Or if I did it was usually due to some
> piece of dirt or spider's web falling onto the primary, or worse, having my
> ground connection come free and the arc went between the bottom of the
> secondary and the primary.
>
> This is none of those situations, and it does indeed seem to be happening
> at the higher power levels.
>
> Now I am at the point of considering that the reason this is happening is
> the fact I'm running at higher power levels than before.  I tried cleaning
> off the primary, dusting/vacumming.  Deburring where ever I could find
> anything that seemed like a burr.   When all was said and done I still had
> arcing from the connection point between the MMC and the innermost turn of
> the primary.
>
> So, I had some g10 laying around, and also some polycarbonate scraps.  I
> positioned some of the G10 and polycarbonate between the offending region
> and the secondary and other turns.
>
> Well, it flashed over anyway.  And interesting: the flashover blew the
> polycarbonate scrap clean off the primary. (this is a piece about 2" by 1/2"
> by 1/2")
>
> Still trying to figure out how to stop the flashover.  Any ideas would be
> appreciated.
>
> Item #2, and perhaps weirder.
>
> At about 120V on the Variac the spark production is quite nice.  No
> flashover on the primary - BUT
>
> I started to notice a long-period (like 2-5 seconds) oscillation in the
> sparks - diminishing and increasing.  It seemed to me like some kind of
> weird timing synchronization issue, and indeed, it does "go away" when I
> adjust the Freau phase shifter - but then I get other problems.  It seems
> when I'm in  the "sweet spot" for timing, I get this slow oscillation.
>
> Now, I was thinking as well it could have something to do with the
> environs.  I'm running the coil in the garage and the sparks are ending up
> everywhere - like the wood studs, the aluminum garage door, the tracks, etc.
>   And when it arcs to something grounded, the arcs are brighter, and I can
> feel the current draw in the variac.  But this effect seems to be different
> from the long period oscillation.
>
> Just wanted to know if anyone else has experienced the same thing.
>
> Cheers,
>
> Joe
>
>
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