Thought experiment:

Three single phase pole mount transformers 4160/240 CT

High voltage is 4160 Wye, Low votage 120/240 CT delta.

High voltage and low voltage share common neutral/earth.

Car accident isolates neutral from rest of power distribution network. The three 4160 lines are still intact, the earth connection via building bonds still intact.

Q1) If transformers are equally loaded, no shift on high voltage side. Correct?

Q2) Assuming stable transformer loading, no shift on low voltage side too?

Q3) What happens when most of 3 phase loads dissapear, leaving a significant single phase load?

Thanks

LarryC