Re: Pig Question

[FutureT-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

In a message dated 8/2/00 5:44:54 PM Pacific Daylight Time, tesla-at-pupman-dot-com 
writes:

> John,
>  
>  >I use a homemade ballast which is about 300 turns of
>  >#12 pvc insulated solid wire wound on a 3" by 18" pvc pipe and
>  >filled with transformer "I's" from junked NST's.  There are a bunch
>  >of taps on the ballast which connect to a rotary selector switch
>  >to select the desired inductance.  It works very well.
>  
>  
>  This pretty much what I wanted to do, but I didn't know what size 
>  tube/windings to use. will those same specs above be ok with 10+ kva ? 
will 
>  a solid piece of iron work or does it need to be plates or powered? to 
>  increase the current flow you just slide the iron middle section out of 
the 
>  PVC right?
>  
>  thanks for your help,
>  
>  Dan

Dan,

I've used my ballast up to 5kVA,  I assume it would be OK at
10kVA, but it is probable that it would be better to use 10 awg wire
instead of 12.  You can simply slide the metal in or out of the form
to adjust the inductance, but I used taps connected to a rotary
switch to select various amounts of inductance.  I could slide
the metal to get a finer inductance adjustment.  Originally, this
ballast had a bunch of welding rods and threaded steel rods as
a core, but I replaced these with the NST "I"'s.  It worked about
the same in either case, but the NST "I"'s gave more inductance.
It's best if the steel is not one large solid piece, eddy current-wise.
I'm not sure how much the rods helps with that.... The rods did
get hot when I used them.

Cheers,
John Freau