The primary and secondary windings are wrapped on each other to reduce:
- Copper losses
- Iron losses
- Resistance of windings
- Leakage reactance
Correct answer: 4. Leakage reactance
Explanation: In a practical transformer, the primary and secondary windings are wrapped one on top of the other in such a way that the low-voltage winding innermost, while high voltage winding is above the low voltage winding.
Doing so insulates high voltage winding from the core of the transformer as well as leakage reactance is reduced.