In a 3 phase system the voltage is lowered or raised either by a bank of 3 single phase transformer or by three phase transformer. The windings may beconnected inY – y, A-d, Y-d, OR A – y Three phase Transformer Diagram
When compared to a group of 3 single phase transformer, a single three phase transformer has the following advantages.
1.It occupies less space
2. The weight of three phase transformer is less.
3.The cost of three phase transformer is usually15% less than that of three single phase Readmore