why is there a 30 degree phase shift in delta-wye transformer?

A 30-degree phase shift in a delta-wye transformer occurs due to the transformation of the connection type. In a delta configuration, the line voltage is equal to the phase voltage, while in a wye configuration, the line voltage is ?3 times the phase voltage. This difference in voltage relationships results in a phase shift of 30 degrees between the primary (delta) and secondary (wye) sides, affecting the phase alignment of the voltages in the system.