Three Phase Wyes and Deltas

Three phase voltages can be generated and transformed as either a Wye or a Delta. Wye and Delta refer to the connections between the single phase windings which connect to create three phase voltages. Notice the polarity of each winding at the connection points. In a Wye all the ends or 2's are connected together while the beginnings or l's are connected to the three phase power source, Ll, L2, and L3. In a Delta the end (2) of one winding is connected to the beginning (1) of .another winding. Three phase power is connected to each of these 1, 2 junction points.

 Star or Wye (Y) Connection

In this method of interconnection, the similar ends say, ‘star’ ends of three coils (it could be ‘finishing’ ends also) are joined together at point N. 

Delta (Δ) or Mesh Connection

In this form, of interconnection the dissimilar ends of the three phase winding are joined together i.e. the ‘starting’ end of one phase is joined to the ‘finishing’ end of the other phase and so on. In other words, the three windings are joined in series to form a closed mesh.