Three phase / split phase

[ggunn]

My brain is working slowly this morning. Can you make 240V split phase with a transformer from two phases and neutral from a 208 three phase service?

 

[GoldDigger]

My brain is working slowly this morning. Can you make 240V split phase with a transformer from two phases and neutral from a 208 three phase service?

You can using an isolation transformer connected between the two phase lines. No connection to the neutral on the primary.
It would therefore be a single phase transformer. The output would be an SDS and your new neutral center tap would have to be grounded if you want it to look just like standard 120/240 single phase three wire.

If you had all three phases you could use a Leyton 3-2 hookup to derive a single phase secondary which draws power equally from all three input phases.
And, theoretically if not practically, you can derive the third phase from the two available phases using only transformers. Combine that with the Leyton circuit and you would also get single phase from two out of three phases, but there would be no point to it. Just use the first paragraph connection.