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Re: Welder ballasts vs. other types



Hi John F., all,

> Original Poster: FutureT-at-aol-dot-com 
> 
> In a message dated 98-10-12 00:57:01 EDT, you write:
> 
> << snip
> >    From my experience above, it seems static/rotary combination gaps need
> the
> > resistance with inductive ballasting to work properly, however rotary gaps
> > alone work well with inductive only ballasting.  This is for my set up
> anyway,
> > others out there noting the same results?   
>  
> > Kevin E >>
> 
> Kevin, all,
> 
> I wonder if the 
> radically swinging inductances that may occur using inductive
> ballasting alone, cause peaks and valleys in the firing voltage,
> such that the gap misfires at times (due to a too low a voltage),
> and requires closer total gap spacing to insure firing, thus, the
> static series gaps can't be tolerated.  It would seem to be a
> voltage related thing.  Another possibility is simply that the
> pure inductive ballasting is creating such high peak outputs,
> that the system needs to be spaced/insulated better to handle
> the higher voltages.  Very interesting the way these factors
> work together.  Yes, I'd like to hear of other's experiences and
> views on this too.
> 
> John Freau

There was a neat analysis done by an engineer named Jamieson some 
time back which investigated the causes of firing jitter in TC 
designs. It turned out that the real problem was the charging circuit
resonance not matching that of the breakrate. In fact it was more 
complex. There were beating effects going on between the mains 
frequency, the charging L/C frequency and the rotary gap firing 
frequency. The program which also had a .doc file with it was named 
"ROTJIT". Someone here might have a copy. I don't know where mine is
but could probably find it if necessary.

Malcolm