RE: Ballasting a Pole Pig (Revisited)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Conner <steve@xxxxxxxxxxxx>

I don't think it's as simple as "Reflected Xc" vs "No reflected Xc". 
Anyone who has played with a sync rotary knows that the line current, 
power factor, and spark output can be varied over a huge range by 
altering the gap phasing, so it's obvious that whatever method you 
use to size the ballast must take the spark gap behaviour into 
account, not just the primary capacitor.

If you want to accurately predict how much power/current a given coil 
will draw through a given ballast, you need to work through pages of 
differential equations that include the discontinuities at spark gap 
firing times, or just simulate the whole coil system using PSpice. 
Richie Burnett shows how to do that on his site.

With an async rotary running at high break rate, it may be somewhat 
easier, and you could probably take half the line voltage divided by 
the ballast impedance as a reasonable assumption for the current.

FWIW, I don't believe the 120mH figure either :-P I'd guess that Dr. 
R's ballast is saturating. As a rule of thumb, if a ballast has fewer 
turns than a transformer of the same core area and a winding voltage 
equal to the line voltage you are running off, it is liable to 
saturate. (but not guaranteed to)

Steve Conner
http://www.scopeboy.com/

Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: "Jim Mora"

Gerry,

Thanks for figuring out the "reflected XC" issue. Do others concur with this
reasoning? Must this XC on the transformer output always be taken into
account when adding an inductive ballast in the primary of a disruptive
coil? I was baffled by the XL=120mh and 30 amps as well.