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Re: Other changes

Tesla List wrote:
> 
> >From Esondrmn-at-aol-dot-comTue Sep 17 22:44:43 1996
> Date: Tue, 17 Sep 1996 17:16:49 -0400
> From: Esondrmn-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Re: Other changes
> 
> In a message dated 96-09-14 17:48:13 EDT, you write:
> 
> << Ed,
> 
>  Not Likely. The grounding system would influence coil behavior AFTER the
>  gaps fired, but should have no influence on the initial breakdown
>  voltage of the gaps. [A note: over the long term you may want to
>  re-verify the integrity of your ground since the salt solution may
>  attack the galvanized steel due to the shorted battery (galvanic
>  corrosion) formed by the copper groundrod and the flashing.]
> 
>  Does your welder start growling when your gaps are NOT firing, and does
>  it seem to rather abrubtly increase in volume as you slowly increase the
>  variac setting? What is minimum gap length of your static and rotary
>  gaps respectively? If your gaps begin sporadically firing at relatively
>  low settings, and you hear growling at relatively low voltage settings
>  you may be resonating your tank cap/ballast. This condition can make the
>  coil run VERY well while in 60 Hz resonance, and significantly less so
>  when you increase/decrease ballast inductance and drive the system out
>  of the peak.
> 
>  Recent changes you've made to the system (especially removing the
>  ballast resistors) increase the 60 Hz Q of the system, making the region
>  of 60 Hz resonance significantly narrower but much "hotter" when you hit
>  it. Although Tank/Ballast resonance can make a coil run VERY well (even
>  "synergistically" so...), it CAN over-stress a tank cap particularly
>  when used with a rotary gap. The peak cap voltage will rise to QxVout
>  unless the cap shorts or the primary gaps or safety gap clamp it to a
>  lower (nondestructive) value. With no resistors across your ballast
>  inductor, your 60 Hz Q may be quite high. This may take out your cap if
>  your rotary misfires...
> 
>  Try measuring the pig input voltage with a CHEAP multimeter. Do you see
>  any differences in voltage for a given variac setting when the coil is
>  working versus when its not? Do you see any sudden increases? By taking
>  and recording a number of strategic measurements and noting any other
>  behavioral differences between when the coil is working properly and
>  when its not, we should be able to get to the bottom of this!
> 
>  Safe (but intermittent) coilin' to ya!  :?)
> 
> 
>  -- Bert -- >>
> 
> Bert,
> 
> The minimum gap length for the rotary is determined by the uneven height of
> the acorn nuts and runout of the wheel.  Last time I adjusted it I think I
> had about .020 clearance between the fixed electrode on one side and somewhat
> less on the other side.  A good estimate would be .030 to .040.  The static
> gap in series is presently using three gaps of .030 each.
> 
> You mentioned the tank capacitor can be overstressed due to 60 HZ resonance -
> remember I did just blow one of the C.P. capacitors.  It was rated at 15KV,
> the current cap is the same only rated at 20KV.  I do have analog panel
> meters monitoring the pig input current and voltage.
> 
> My notes from the last couple of runs show when the gaps would fire, the
> voltage and current readings looked normal - this is with the resistive load
> disconnected.  With the resistive load connected in parallel with the welder,
> the pig input voltage was normal (nice, smooth control with the variac) but
> the primary current was low and sputtered up and down as the gaps would just
> barely fire.
> 
> I will check on the primary readings again and note welder and pig growling
> next time I get it set up.
> 
> Thanks for the ideas,   Ed Sonderman

You're welcome!  

By my calculations, you're not able to jump a gap which is about 130
mils long(!?). This would seem to imply that you're not even getting 5
KV across the gap. Could you have a bad connection in the short-circuit
path on the secondary of the welder??

-- Bert --