Transformer adventures

[innovate.invent]

Hey all, so years back I bought this transformer that was supposedly for an arc welder. It came with no documentation or identifying marks what so ever. I keep coming back to this thing trying to learn more from it so that perhaps one day I could start a DIY arc welder project for shits and giggles. I saw similar projects using a microwave transformer but would rather use the real deal.
Anyhoo!
So heres where I am at:
-I have a transformer with three separate coil pairs on the same core leading me to believe that it is a three phase transformer.
-Each coil pair (primary/secondary) is tied together making it almost look like a single center tapped coil if it weren't for the significantly different gauges of the windings. From this I can only guess that it is intended to be in a star-star configuration with a common neutral.
-I tried to hook the primary of one of the coil pairs up to a 116V supply and it blew the 30A breaker instantly.
-I hooked up the same coil in series with a 65W light bulb and got roughly a 0.8V drop across the coil
-I then hooked up the same coil again to a 12VAC supply and it cranked out 9.6A before starting to burn out.

the best I could calculate is that this thing wants to draw somewhere between 40A and 60A unloaded on a 116V source.
Does this mean that the transformer has a nasty internal short or is my lack of understanding of how a transformer works messing me up. Am I having these problems because I am not running all three phases at once?
I was told to put a variable resistor in series with the transformer and balance the voltages across both of them to get the impedance but I cant find a ~2ohm 7200W+ variable resistor :P

I could just go and hook this thing up and see what happens, but then again I could also just take a sledge hammer to my phase converter. I would rather do a bit of testing first to see why its drawing so much current with an unloaded secondary. Does anyone have any ideas?

[fsmyth]

Your description sounds like a 3-phase auto-transformer.
Try 110v across two of the primary inputs (smaller wire
in the windings).  Use a ballast bulb like you have been.
IF that works out OK, the try 110v across one input and
the center-tap.  This should give the correct voltage on
the secondaries, assuming a 230v 3-phase winding on
the input.
It seems doubtful that it would be a welder transformer,
since there would be no isolation on the output.
<als>

[dumb as a stump]

Just a thought  go to a welder supplier web site (like lincoln or miller) and look for the owners manuals section.  in them there will be a schematic and it give you an idea what's going on inside the xformer. but you may have to look at a few to find a x former that has the same lead configuration...