what is the vector group of power transformer?

The vector group of a power transformer indicates the phase relationship between the primary and secondary windings, as well as the connection type (delta or wye). It is represented by a code, such as Yd11 or Dd0, where the first letter indicates the primary connection, the second letter the secondary connection, and the numbers denote the phase shift in degrees. Understanding the vector group is crucial for ensuring proper synchronization and load sharing in power systems.