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Re: hooking up an arc welder

>From: Cabbott Sanders <cabbott-at-cyberis-dot-net>
>
>Im glad charles brush told me how to hook up that arc welder. THANKS
CHARLES!!
>
>it may seem AMAZING, but i almost fired it up, with the SECONDARY
terminals of
>the arc welder in series with the 15 KVA PIG!!  I'm glad i didnt do this..
>'coulda started a fire!! (?)

Cabbott,

I didn't realize that you were unsure about that part of your wiring or I
would have spelled it out better.  I am glad that you inferred the correct
wiring from my message though.  Hooking up the pig to the welding leads
(welder's secondary) probably would have given you somewhere around 3kv out
of the pig, but your hookup wiring might not have liked the amount of
current that could have been pulled if the pig had been arced or shorted.

A typical hookup for a pole pig and welder is as follows:  The pig is wired
in series with one leg of the 240v line feeding the welder.  The welding
leads are then shorted together, so that current can be adjusted via the
welder's variable shunt.  Why short the leads?   Well if you don't,
practically no current will flow anywhere in the circuit which is not
really the idea. ;-)   Welders are designed to current limit because when
you start an arc to make a weld, you are essentially shorting out the
welder.  The arc itself also only represents a few ohms of resistance once
it's started,  so without some kind of internal limiting your breakers
would trip pretty quickly.  The idea is to keep the pole pig from pulling
any more current than the welder could by itself if you were welding.
Connecting it in series with one leg of the 240v into the welder, and
shorting the welding leads does exactly this (resonant effects with system
caps etc. aside).  Once again please be extremely careful with that system.


Zap!


Charles Brush
http://www.foundrygroup-dot-com/cbrush

P.S. Regarding the discussion about resistance:  Adding resistance is a way
of tweaking and fine tuning a system, but it is one more variable that may
not be necessary at this point.  With a welder, variac, and pig you have
everything you need to get started and get some excellent results (do you
have a rotary?).  Just my two cents.