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Re: Welder Selection for Current Limiting

Hi Chuck,

> I'd like to ask the group a question on the selection of
> a welder for pole pig current limiting.  At this time I have
> started the assembly of my power cabinet, which will be in
> need of a means of current limiting.  The selection of a
> welder is where I am hesitating right now.  I do not know if
> all brands of welders provide the appropriate design features
> to do a good job.  I presently understand that some use a
> form of a shunt plate system, similiar to a neon transformer
> in order to create an adjustable current limiting.  I was
> looking at a flyer on a Lincoln Model AC-225 welder and there
> was no mention of how they chose to accomplish the current
> limiting.  It  looked like a nice unit, about the size that I
> could hide from the wife (just kidding).  It appeared to have
> a switch that functioned (by feel) more like a tap switch,
> for various output voltages from the secondary.  Might anyone
> have already reviewed various manufacture's designs? I wonder
> which brands would be good for Tesla work.  Model numbers
> would be great.  Thanks in advance for any comments.

I think you will find that all AC welders of this size will do
the job.  They will allow a maximum of about 48 amps to flow
through their primary with the secondary shorted and at set to
maximum.  The only other concerns you may have are the resisive
drop of the primary of the welder and how to change the power
settings.  A tapped type allows only a certain number of settings.
I movable core unit has an infinite adjustable range.  It is also
possible to change the current setting on one of these movable
core units while under load.  The primary wire size is relevant if
you are concerned with voltage drop.  However, unless you want to
spend a small fortune on the welder, the units similar in size to
the Lincoln you saw are about the only choice.  The drop on one of
these units won't be more than about 5 volts.  Besides, if you
are unsing a variac, you can run the input voltage up a little
higher to overcome this drop.

I recently purchased a Century "Powerdisk" 230 amp AC welder.  I
found it at Quality Farm & Fleet for $189.95.  It is and infinitely
adjustable movable core unit with a high and a low range.

Scott Myers