Does anybody have an idea how to draw vector diagram of primary and secondary of a three phase transformer? For instance, if I need to draw vector diagram for Yzn5 diagram and then also draw the winding connections? All I know is that primary is in star connection, secondary in interconnected star and the phase between voltages is 150 degrees (5*30). Also, how to determine this vice-versa (phase number) from an already drawn transformer windings. Is there a good book or internet source covering this field? Thank you very much!