paul-- There used to be a link to an older {but still in service} New York turnstile bridge that used two 2-phase motors, but the link seems to have dried up.
http://www.coned.com/documents/elec/018-024.pdf See: §III. 2. (D and (E) for DC and 2-phase servce.
http://www.powerlineman.com/pictures/2001/march/g_good/good.htm Poster refers to it as “scotts system.” It looks like it is a true utilty-owned Scott-Tee transformation. A rare bird I’m sure.
Sometimes referred to incorrectly as 2-phase—a 3-wire 208Y/120-volt utility-furnished service tapped from two phases and a neutral is correctly called “Network Service” in the US.
Lastly, I have no idea why, but Table 430-149 in the 1999 NEC deals exclusively with 2-phase motors. I once mentioned in an IAEI chapter code-change session that it may be of limited use and possibly time to request its deletion, but the suggestion was not on the agenda so maybe I should use proper parliamentary decorum; wait 3 years and resubmit it for the next code cycle. [Unbelievably but sadly, I lost interest.]
