Re: Up and running again
>Subject: Up and running again
>I fired the system at low power (welder set at minimum) and got good results.
> The primary current was about 17 amps and we set about trying to find the
>best tune. Shortly, the gaps started to fire erratically. I unplugged the
>oven elements (6000 watts) that are in parallel with the welder and it ran muc
>h better. Primary current jumped up to 20 to 25 amps and the discharge
>length almost doubled. The sparks are now much hotter. This is still very
>puzzling to me. With the resistors out of the circuit the primary current
>should have went down, not up. Must be related to this synergistic tune that
>Richard Quick identified earlier.
review my post last week "pig ballasting" here is a short
snippet: (this test was just with ballast, pig, cap and gap. no TC
primary or secondary!) Westinghouse 10+ LL-65 pig (7.2kV), 9.7mH hand
wound ballast, and ~6nF of hand rolled cap. and 0-10K rpm rotary gap.
----------------------- begin include ------------------------------
Then I scoped my secondary.
Grounded input level: less than 1 volt.
I hooked my scope probe to an 18" test lead hung 9' away from my
system and measured the RF hash. 0.2us period (5MHz) and 175-200++ V
peak! That's right between 3 and 4 divisions at 50V per division.
I connected my scope probe to my HV divider. The RF hash measured
200+V and a 10K divide ratio. Grounding the scope input switch: 30V.
The RF has a period of 0.5uS (2Mhz). I had to move things around to
connect up the divider, this may have caused the period change.
I changed scales to look at the "60Hz" output voltage. about 28kV with
occasional 75kV peaks! Yes I check this 3 times. No wonder I'm
seeing/hearing such a difference between resistive and inductive
Given the pig secondary, cap, and rotary were all in parallel, I was
getting bad quenching on my rotary gap. Most of the time I had 2" - 3"
power arcs, but occasionally I would light up the entire circumference
of my 8" rotary gap! That was quite a sight (and sound).
again note: all of these were superimposed on the 220V mains sine
Input current was under 10A. into the pig primary.
I've answered my basic question about the effect of inductive ballast
in the primary circuit: each time the spark gap quenches, the
inductive ballast does kick the voltage going into the pig primary.
(by 600 to 800 volts!)
-------------------------- end include -------------------------
p.s. Richard, I promise to never ever run my gap at this speed;
except with a disposable cap.;););) for this test I was running only
several hundred BPS (20/120 volts) I did not log the BPS.