LEVEL 1

1. What is the difference between class 1 and class 2 power transformer?
2. Explain the working of buchholz relay?
3. What is a core type transformer?
4. What is a shell type transformer?
5. Explain the four oil preservation system designs?
6. Explain why instrument transformers are used ?
7. Go through the specification of any current transformer.

LEVEL 2

1. What is the function of OLTC in a transformer?
2. Mention the different types of tap changers available and the preference with reason.
3. Explain the principle of operation of OLTC. 10. Write a note on the impact of OLTC on voltage stability.
4. How might change in tap position affect differential protection in transformer? What steps can be taken to avoid the same?