I concur with Tyler. Old “buzzbox” stick welders are just about the best readymade, adjustable reactor ballast available for a pole pig current control. With their 240 volt input in series with the input to the outer LV bushings of the pig, and the welding leads shorted, you can even use the welder’s current selector to give a a range of control over the current input to the pig. Even though they typically have a rather low duty cycle, it is still more than adequate for the average coiler. I got my used Lincoln 225 amp AC arc welder off Craigslist a few years ago for $100, although I have so far only used my welder for its actual intended purpose! 😉
David
Sent from my iPhone
> On Dec 17, 2018, at 8:18 PM, Tyler LaVite <tlavite@xxxxxxxxx> wrote:
>
> Best bet just get a cheap arc welder that’s what I did for my 25kva pole pig found a welder for 125 on Facebook market place.
>
> Sent from my iPhone
>
>> On Dec 17, 2018, at 2:31 PM, Daniel Kunkel <dankunkel@xxxxxxxxx> wrote:
>>
>> Hello Tesla Coil Friends,
>> I have recently acquired a 2kva potential transformer and am eager to get
>> it powering my current setup (RIP NST).
>>
>> For the ballast I opted for a 500ft spool of 12 awg stranded THHN. I then
>> used a signal generator and oscilloscope and calculated the inductance to
>> be 10.6 mH. The spool also measures .9 ohm of DC resistance. I did the math
>> and predicted 29.22 amps. I my jaw hit the floor when my measurements and
>> math proved to be spot on when I shorted out the PT!
>>
>> However, I still need to reduce amp draw down to 22 amps (or a total of
>> around 14 mH of ballast), and I was thinking about using an additional
>> ballast in series with my 12 awg spool. Right now I am leaning to using the
>> (liberated from the tar) 15/30 NST core. I figure I can use the primary
>> windings only (omitting the secondary windings and the magnetic shunts).
>> But I am unsure about the aspect of core saturation...and if that occurs,
>> what will happen in terms of ballasting?
>>
>> Maybe if I get crazy I will convert the aforementioned NST core setup into
>> a magamp! I am sure it will take some research, but I will need to figure
>> out how many turns will be needed on the control windings as well as
>> voltage and amperage. Heck, maybe I can just stick various sized magnets on
>> the core to achieve the right amperage!
>>
>> ~Dan
>> Kansas City area
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