Delta VS Wye Explained | CivicSolar
A Wye (Y) configuration is when all the loads in an AC system are connected at a single point. Normally, the loads are unbalanced in a Y configuration. A neutral cable is connected at that centre point where the three phases meet. Most of the low voltage distribution lines that you see are Y configuration (Red, Yellow, Blue and Neutral).
The Delta configuration has the 3 phases connected like in a triangle. They don't normally have a neutral cable. In Delta configuration, the phase voltage is equal to the line voltage whereas in Y configuration, the phase voltage is the line voltage divided by root 3 (sqrt(3) = 1.732).