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Re: The never ending saga: Ballasting



Malcolm all,

I am still not to sure what you mean. Power factoring doesn't make that
much sense, I am only using 16 uF.  Perhaps some sort of resonance
condition? But even that does not make sense, as I have also tried a new
inductor that I can get 10-50 mH (15KV-at-120mA neon primary with some core
material to adjust L) and I get just what I calculate. Only when I do not
add caps across lines after the inductor I get substantial voltage drop.
Nevertheless, it does seem to work very well for me even though I do not
really understand the how/why...

Regards,

David Trimmell

At 09:45 AM 3/3/00 , you wrote:
>Original Poster: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz> 
>
>Hi David,
>
>> Original Poster: "David Trimmell" <davidt-at-pond-dot-net> 
>> 
>> Hello,
>> 
>> A few days ago I posted questions regarding ballasting and was wondering
>> why the voltage drop. Tonight I have done some experiments, as empirical
>> data is needed for someone who barely understands this (ME!). I tried a
>> inductor in series with my PT, a 60 mA neon primary with secondaries
>> shorted together. I got almost a 40 volt drop to the PT, I was only getting
>> 100 V into it (0-140 volt variac). Then I tried 16 uF Cap across the mains
>> right after the inductor (neon primary), and heck if I was getting 135
>> volts, only dropping 5 volts from the variac supply! Now have I truly
>> missed the boat? Probably. But why didn't someone just mention that I
>> needed to place some C across the lines to get back lost voltage? I tried
>> it again with another inductor and found I could limit current to 15 amps
>> at 135 volts, with terminals shorted on the PT, and this followed my
>> calculations including DC resistive losses (as measured). Voltage drop from
>> impedance is something I don't quite follow. But it does seem that a little
>> capacitance in the inductive current limiting scheme is called for. I found
>> no indications of mains resonance, but can anyone explain how/why?
>
>Seems to me that some power factor correcting is going on. 
>Effectively you have a parallel resonant circuit in series with the  
>NST inductor so some of the inductance in the circuit is being 
>cancelled. Does this make any sense?
>
>Regards,
>Malcolm
>
>