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Re: Question about ballasting and VA

In a message dated 00-03-04 11:52:43 EST, you write:

<< >Original Poster: "Barton B. Anderson" <tesla123-at-pacbell-dot-net> 
 

> Hi Ross,
 
> I do use inductive ballasting and I haven't (maybe others have) found that 
my
> variac acts as an impedance matching component. I do notice that there is a
> maximum amunt of current that the coil won't process further. However, 
turning
> up my variac beyond this point does not reduce my spark length (like 
turning it
> down will). On the other hand, my input current will climb and if I keep 
going,
> I will pop the breakers even though the spark length doesn't increase. To 
me,
> it is acting as a simple current limiter.

Bart,

I found too that my ballast behaved more like a current limiter
in my old pig powered coil with the async gap.  My 120 bps sync gap 
(potential xfrmer powered TC's) require very precise ballasting.  If I turn 
the ballast tap knob one click either higher or lower, the coil will often 
give no spark output at all, or just an extremely feeble spark.  This is
because I run the coil in resonant charging mode at 120 bps, which 
gives excellent power factor by the way.  I don't remember if the 
ballast positon was was quite so critical at 240 bps.

In an async coil, because the firings are so random and frequent, the
resonant charging voltage build up is greatly reduced, which lets the
coil function over a wider range of ballast settings.  Still, there should
be a best setting for efficiency.

> increasing the current until the point of takeoff. When your turning it up,
> there is a point where you start charging the caps to a potential to conduct
> consistently at the gap rate. Thats when the sparks really fly and best arc
> lengths are achieved. However, as I said, increasing current hasn't shown
> itself in a decrease in spark length - just input current going somewhere 
other
> than the sparks. 

This extra current draw is probably simply caused by the power factor
becoming very poor. 

 >At least, that's what I've seen thus far and it "appears" as
> though the coil itself just cannot process further current into spark 
lengths
> without making some kind of change to the coil itself.

The extra current is just apparent power and is reflected back out
of the system, and just heats the wires and components and trips
your breaker due to the poor power factor created by those ballast
settings.  

Cheers,
John Freau
 
 >Bart
  >>