Ok, would the opposite be true if the convertor is fed from a single ø 208/120V Wye? Meaning would the derived voltages be in a Wye configuration?
Hmmm. Let's see . . .
The input would still be L-L and without the neutral; the output voltage would probably mirror the input voltage.
That's a good question: What would be the derived phase's voltage and angle relative to the source neutral?
I think an experiment is in order. On the other hand, if you have two lines of a wye, you already have 3ph available.
A couple of weeks ago, I was asked to run a new circuit for a used band saw in a grocery store. The nameplate specified 3ph, and the cord, though 4-wire, had a 3-prong twist plug on it. I priced the job, bought a 3p 20a breaker, and a 4-prong plug, receptacle, and box and cover. I reused an existing 3/4" EMT feeding a 50a 1ph receptacle.
(I'm too tired to use the correct NEMA nomenclature.)
After I completed the installation, I turned my attention to the saw. I installed a 4-prong twist plug, noting that the red wire was the unused color. Not assuming anything, I traced the wiring inside, and discovered a static converter, and that the saw has been set up for 1ph operation. I removed the converter and wired it to match the new circuit.
I also replaced the 1p switch with a 2p switch. Only after I did all of this did the store owner put me on the phone with the equipment distributor, who informed me that the saw had been set up for use on 1ph with a static converter, and that he told the customer this. It could have run on the original 1ph circuit with just a new receptacle. Oops.
Oh, well. I got paid for my work and materials. Let the customer and distributor argue over who should foot the bill for the extra/unnecessary work, although I think that the work I did really is the better installation, since there is 3ph here. Plus, the converter was labeled 240v 1ph, not 208/240v 1ph, so I didn't really consider leaving it in on 208v.