Re: Primary Resonance

>From: Graham Armitage <armitage-at-tiac-dot-net>
>To: tesla-at-pupman-dot-com
>Subject: Primary Resonance
	Sorry for taking so long to reply, but, I just figured out how
to simulate neon trannies and spark gaps using microsim pspice. FTP
over to my ftp site: 

ftp.bdt-dot-com/home/jim.fosse and look at the files
neon_output_open_circuit.jpg and neon_sch.jpg

I'm finding a resonant beat between the neon leakage inductance, the
primary cap, and the  mains line frequency. (I'm using my numbers, I
don't have yours)

given this level of modeling, the neon secondary voltage reaches
120kV.  This type of modeling  also matches, using a separate ballast
inductor, the measured results for my pole pig -- 75kV.

The 2 loose wires in the schematic are connections for the variac (as
soon as I get the model working).



>When I begin to turn up the variac (at about 20%) it begins to fire,
>indicating 15kV across the secondary. Obviuosly I do not want to open my
>gaps as this would be disastrous. I know that with matching capacitance the
>system should want to resonante at 60Hz, however there is something else
>that I am observing. With capacitance almost matching there is a distinct
>beat discharge. I investigated this with a HV probe and the scope and found
>a superimposed frequnecy on the 60Hz cycle. This frequency increased (as did
>the beat - as expected) when the variac was turned up. I immediately assumed
>that the changing variac inductance was somehow influencing this. By
>calculation based on these observations I estimate the output voltage would
>be 130kV at full power (if it could have gone this high)!
>I have just fried one of my caps and was wondering how people have tackled
>this problem in the past? Malcolm has had the same frustrations and I guess
>now it's my turn. I never used a variac in the past and never had this
>problem. Any ideas would be most welcome.
>[ NOTE: Scott is currently on vacation. -- Chip ]