I just about wrote an essay related to this topic last week:

https://www.electrical-contractor.net/ubb/Forum7/HTML/000358.html You cannot define phase angle with a single circuit. You only get a phase angle measurement when you have _two_ or more circuits, and can describe the phase angle difference between them.

If you supply a single phase line to line load from a three phase source, than as far as that load is concerned, there is no phase angle. You only have two terminals, with first one then the other alternatively being relatively positive.

Once you have two circuits defined, _then_ you can find a phase angle difference. With your 'V' primary, you have three circuits; neutral to A, neutral to B, and A to B. If we _define_ the phase of the neutral to A circuit as zero degrees, then the neutral to B circuit is 120 degrees. I believe that the A to B circuit has a phase angle of 150 degrees with an amplitude of 1.732 * the amplitude of the neutral to A circuit, but I'm not going to swear to that without doing the math out on paper.

-Jon