Re: cap firing voltage scope measurements question

In a message dated 99-06-21 16:16:18 EDT, you write:

<< Original Poster: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz> 
> Hi all,
>          I just had to add another musing to this topic. I think the 
> voltage hike is really being "tuned in" by adjusting the rotary gap 
> phase setting for best sparks. Again, I am amazed that a NST should 
> take it on the nose without dying. I think the better option is to 
 >have a stiff transformer and a separate charging reactor in the 
> secondary circuit to take half the charging voltage burden. 

Malcolm, all,

Not only is it more robust to use a stiff transformer and separate
ballast as I'm doing, but it allows a complete tuning of the charging
system, such that the peak cap voltage can be made to coincide
with the best firing phase.  An NST system may require a 
compromise in the firing time.

> the choke on the primary side of the pig achieves the same end but 
> then subjects the transformer secondary to the entire voltage rise.
>     One can weigh up the pros and cons of where to place the inductor 
> thus:
>                         CONS                   PROS
> Secondary side - high inductance needed   takes half Vcharge burden 
 >               - high V insulation reqd.
> Primary side - low inductance needed       transformer primary and   
>               (transformed to a large    secondary are stressed and 
 >             inductor by turns ratio^2)   core saturation may occur
> Malcolm >>

Well, pigs and PT's are designed to withstand great stresses.

John Freau