For a delta-wye transformer, the primary voltage is in phase with the secondary phase voltage.
Assuming it is an ABC (positive) sequence system with counter clock wise rotation and that phase A to the neutral voltage on the secondary is at 0 degrees. Then voltage between phase A and B on the primary would be in phase with the phase to neutral voltage on the secondary. Since, for a wye connection the line to line voltage leads the phase voltage, this means that for a delta-wye connection the secondary line voltages leads the primary voltages.
However, as stated below it's the opposite. Am I right? I tried understanding the wording but I think I am not getting it accurately.
SOURCE:
Power System Analysis
John J. Grainger and William D. Stevenson
McGraw-Hill Series in Electrical and Computer Engineering
1994
ISBN 0-07-113338-0
