Delta Connections

Three sources are connected in series, and the connection points are used as terminals for connections for the rest of the circuit.

Warning

Not used for single phase loads

You can also have delta connection impedances connected to each delta terminal.

Note

Here, you only have line-to-line or phase-to-phase voltages ($V_{ab}$), no neutrals

Y-Delta

Here is how you can make different three phase transformations
$Z_Y=\frac{1}{3}{Z}_{\Delta }$
$Z_{\Delta }=3Z_Y$