The Wye-Delta (or Yd) components are three-phase transformers with wye primary and delta secondary windings.
The base name of each component is Ydij, where ij are two digits that specify the phase shift between the primary and secondary windings. The numbers range from 0 to 12 and correspond to the hours on the face of a clock. For example, 01 corresponds to a phase shift of 30 degrees.