............transformer is always delta /star connected.

The distribution transformer is always delta/star connected.

Here's why:

1. The primary side (high voltage side) is delta connected. This is because the delta connection allows the flow of third harmonic components of current which helps in the functioning of the transformer.

2. The secondary side (low voltage side) is star connected. This is done to provide a neutral point which can be grounded for safety reasons. The star connection also allows the use of three phase as well as single phase loads.

So, in a distribution transformer, the high voltage side (primary) is delta connected and the low voltage side (secondary) is star connected.