240-480 volts 3ph transformer with phase converter?

I have something in my backyard that, I suspect, is a 480->240 volt three phase transformer. (less likely, it is a three phase isolation xfmr).

It has three wires coming in and three going out, so to speak. (notions of in and out are relative to what I want to do with it).

No tags on it.

It can be seen on the bottom left corner of this picture, inside the stand:

http://yabe.algebra.com/~ichudov/misc/ebay/Argon-O2-Bottle/Argon-O2-Bottle-4064.jpg

I am considering reversing it so that it would produce three phase 460v, with three phase 240v coming in.

I estimate (by just looking) that it is a 25 kVa transformer. My phase converter is 17.5 HP.

Any thoughts on a possibility of making 460v with it?

What you can do...

What you can do... if you're electrically inclined, savvy, and safe...

Is apply AC voltage across it on one side (pick any two) and measure the others, to see what comes out the other side.

Probably best if you used a lightbulb in series (say, a 120v 100w bulb in series with the windings under test) to limit current... and then measure. Your applied voltage won't be 120v ('cause of the bulb's voltage drop), but you can measure the applied voltage, and compare to output, to at least get some idea as to what the ratio is. Good guess would be 480 delta or wye, to 240 delta. Since you only have three wires to windings, any delta is obviously not center-connected.

The power capacity can be roughly estimated based on measuring the core size... I don't remember the quantity, but most ARRL Amateur Radio Handbooks have it listed in the Power Supply section.