Re: Current-limiting with an arc-welder...

> Dan  <klineda-at-univscvm.csd.sc.edu> wrote:

> Hi all,
> About to fire-up in a couple of weeks! I'm only waiting for the capacitor
> from Scott Meyers (applause :)
> I finally got an arc-welder to use as a current-regulator and was just
> curious about how to hook it up. I'm guessing that it's in series with
> one side of the supply-line, but it's so much easier to just ask, isn't it.

Hi Dan,

All you need to do is use the primary side of the welder in series with the pole transformer.  It 
might go something like this; variac, pole transformer, welder primary, all in series.  Simply 
short out the welder outputs to one another.

One last detail.  You will need a large power capability resistor in parallel with the welder.  
This is to "soften" the current phase lag caused by the welder.  I am told that if you operate 
the system without this resistor(s), it can be a problem.  The lag can be a second or two.  The 
variac will pull against you, trying to slam itself full to 100%.  A value of about 2 Ohms is 
needed here.  Ed Sonderman found that old oven heating elements work well.  These elements are 2 
KW a piece.  Ed uses 3 in parallel, I think.  Train brake resistors would work too.  Or if you 
want to spend money, a couple of those 1 Ohm, 1 KW power resistors.  They can be gotten surplus 
for about $20 each.

Talk to you later,
Scott Myers