For ease of discussion [not sure what that means??
- joke], let's only view the secondary of this transformer.
FYI: The primary could be either Delta or Wye, it makes no difference to the secondary.
This monster is using the before mentioned single phase split coil transformers [covered in the "Delta schematic" thread].
It's using 3 separate transformers - one for each "phase".
This schematic would be how a 208Y/120 VAC 3 phase 4 wire Wye is connected - using split coil transformers having 120/240 VAC outputs.
For a 480Y/277 VAC 3 phase 4 wire Wye, the transformers might be split coil [if there's any which have 480/277 outputs], but most likely the transformers will have a single coil, which is wound for 277 VAC output.
Back to the above schematic:
The split coil secondaries on each transformer are connected in parallel, so the output voltage from each transformer coil is 120 VAC [much different than the delta one, isn't it??].
The X2/X4 ends of each transformer connect to the common jumper, whereas the X1/X3 ends run straight out - forming the output for that phase. Relative polarity in this case is setup so that each coil is in a series additive connection through the "jumper wire" and their respective X2/X4 outputs.
BTW: X1/X3 get connected together - so do X2/X4.
The "jumper wire" on this arrangement is tapped into and thus becomes the common neutral. If this was to be a 3 wire system only, no tap to the jumper is made. Tapping the jumper makes it a 4 wire [AKA multiwire] system.
Reviewing the schematic, you will see that each transformer coil's output is 120 VAC - so if you take your Wiggy and measure voltage from any one of the output phase ends to the common jumper wire, you will get a reading of 120 VAC.
Connecting the Wiggy across any two phase outputs will give a reading of 208 VAC [120 VAC x 1.732].
If you have an intellegent Octopus, it could simultainiously connect Wiggys across all of the phases, showing that theres also 208 VAC potential between L-L-L [3 phase].
If you own such Octopus, please let me know where to get one!! Needed ASAP!!
Scott SET - putting the "Wye" in "Why the heck won't he just make some sense"