That is the input and output voltages for the windings are the same. However, if the 3-phase transformer is connected in star–delta, ( Yd ) each star-connected primary winding will receive the phase voltage, VP of the supply, which is equal to 1/√3 x VL.

Explanation:
A distribution transformer is a type of transformer that is used to step down the voltage for distribution purposes. It is commonly used in electrical power distribution systems to deliver lower voltage levels to end-users.

Primary and Secondary Windings:
A distribution transformer has two windings - a primary winding and a secondary winding. The primary winding is connected to the high voltage side, while the secondary winding is connected to the low voltage side.

Connection Types:
There are different ways to connect the windings of a distribution transformer. The most common connection types are:

1. Star-Star (Y-Y)
2. Star-Delta (Y-Δ)
3. Delta-Delta (Δ-Δ)
4. Delta-Star (Δ-Y)

Correct Answer:
The correct answer in this case is option 'D' - Delta-Star (Δ-Y).

Explanation of Delta-Star Connection:
In a Delta-Star connection, the primary winding is connected in a delta configuration (Δ) and the secondary winding is connected in a star configuration (Y).

- In the primary winding, the three phases are connected in a loop. The voltage across each winding is the line-to-line voltage.

- In the secondary winding, the three phases are connected to a common neutral point, forming a star configuration. The voltage across each winding is the phase voltage.

Advantages of Delta-Star Connection:
The Delta-Star connection offers several advantages in distribution transformers:

1. Voltage Transformation: The Delta-Star connection allows for voltage transformation from high voltage to low voltage levels, which is essential for distributing power to end-users.

2. Grounding: The star connection on the secondary side provides a neutral point that can be grounded, allowing for the connection of single-phase loads and providing a reference point for grounding systems.

3. Flexibility: The Delta-Star connection provides flexibility in terms of voltage levels. It allows for the distribution of power at high voltages on the primary side and low voltages on the secondary side.

4. Fault Tolerance: The Delta-Star connection provides some fault tolerance. In case of a fault on one phase of the secondary side, the other two phases can still supply power to the loads.

Conclusion:
In conclusion, a distribution transformer is normally a transformer with primary and secondary windings connected in a Delta-Star (Δ-Y) configuration. This connection type offers advantages such as voltage transformation, grounding flexibility, and fault tolerance, making it suitable for distributing power to end-users in electrical power distribution systems.

Distribution transformers are always in delta to star, as its easy from there to have different voltage ratio because of presence of natural wire. One can have 220 or 440 v from a star connection.