why are 3-phase transformers delta-wye?

Three-phase transformers are often configured as delta-wye (?-Y) to provide several advantages. The delta connection on the primary side allows for better handling of unbalanced loads and provides a path for third harmonic currents. The wye connection on the secondary side offers a neutral point, which is beneficial for grounding and allows for the connection of single-phase loads. This configuration enhances system stability, reduces voltage drops, and improves overall efficiency in power distribution.