Re: Arc welder as pig ballast not working right

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Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hello Seanick,

You wrote:

Original poster: "seanick" <edgarsbat@xxxxxxxxxxx>

< I have noticed <lately that when I use the lowest power setting <it 
works great, however at any other setting past <that, my coil does 
not run continuously but <becomes staccato and has much reduced 
output. I <am using a synchronous rotary (@3600 rpm) with 4x <3/16" 
tungsten rotating electrodes and two <stationary electrodes at 180 
degrees offset, <which are both adjustable remotely while the coil 
<is running similar to Bart Anderson's rotary; <adjusting the phase 
for the different power <levels does not result in longer arcs than 
with <the lowest setting though. I am only getting <something like 4 
feet which is WAY too low for the components I am using.


Yes, I have to agree with you. That is pretty dismal performance 
considering the tremendous power that
you have at your disposal. The one time that I
tried to run a pig synch, I noticed the same effect
that you mentioned about the arcs getting no long-
er with an increase in input voltage once the phase
is adjusted for maximum output at a lower input
voltage/power setting.  Never could quite figure
that one out myself so I went straight back to the
the proven way that I know to get awesome performance
from a pig system - go back to an ASYNCHRONOUS
rotary spark gap. Some people have had good success
using an SRSG and a relatively large primary cap with
a pig system, but I'm not one of them ;^/

<The ballast at the lowest setting draws 17 amps <when in series with 
the pig, and 50 at the <highest setting, according to a clip-on 
ammeter. <The arc welder itself works as expected; each <higher 
setting results in more heat at the weld. <What could cause this 
behavior? So far I only <have two theories but I doubt either of 
these are the problem...

Well it sounds like your powers supply is functioning
properly. It's really hard to say. That thing you mentioned
in your previous paragraph about it running erratically
in a "stacatto" sputtering makes me wonder if you don't have a 
partial short circuit somewhere that manifest itself when
you turn the voltage up. Double check your pig transformer
and primary capacitor to make sure that they aren't on the blink. I 
suppose you could also be experiencing inductive
resonace rise between the pig and the welder that could
be causing the erratic output with an increase in input voltage.

<1. Quenching of the gap - reason I think this <might be it is that I 
threw an electrode with an <earlier revision of this gap. I have 
since <installed aluminum sleeves with set screws to <hold the 
electrodes. this seemed to cure the <problem; now the electrodes are 
not even all that <warm right after a relatively long run.(15 minutes 
of tuning cycles...)

It sounds like you now have pretty good quenching
going on now.  .04 uFd is really kind of a small primary
capacitance for a pig system, though  especially since you're trying 
to run synch. Some coilers suggests even going LTR on
the primary cap with pig coil systems when running synch.
Even running asynch at 300 to 500 bps, you should still
have at least twice your current .04 uFD for your primary
cap. I use .1 uFd in my asynch 15 kVA pig system.

<2. power factor? I don't really know, this is grasping at straws.

I highly doubt that your problem lies there, too.
Pole pig systems generally don't really need power
factor correction because of their huge power availabili-
ty. Try checking the things that I mentioned above and
see if the problem dosen't show itslef.


David