This Schematic has been brought over from the "Theory Area" for your convenience.
 
 3 Phase 4 Wire Wye connections - using three individual 120 / 240 VAC 1 phase Transformers.
Secondary coils connected in Parallel on each Transformer.
Related Text From Original Post                                       Topic:   Wye schematic - 3rd in the series 
                     Scott35
                     Moderator 
                                         posted 05-11-2001 03:20 AM                                                                                                            
                                      Here's one of a 4 wire Wye, using three separate 1 phase transformers - as would be on a pole mounted
                                      transformer bank.
                                      Note the complete difference in how the coils are wired here, as to the Delta method??
                                      These coils [split coils] are in Parallel - so each transformer has 120 VAC output. On the Delta, each
                                      transformer's split coils are in series, so each transformer has 240 VAC output [the bottom coil is center
                                      tapped for the neutral].                                      
                                      Scott SET