Important Questions of Protection of Alternators and Transformers:

1. Discuss the important faults on an alternator.

2. Explain with a neat diagram the application of Merz-Price circulating current principle for the protection of alternator.

3. Describe with a neat diagram the balanced earth protection for small-size generators.

4. How will you protect an alternator from turn-to-turn fault on the same phase winding ?

5. What factors cause difficulty in applying circulating current principle to a power transformer 7

6. Describe the construction and working of a Buchholz relay.

7. Describe the Merz-Price circulating current system for the protection of transformers.

8. Write short notes on the following :

(i) Earth-fault protection for alternator

(ii) Combined leakage and overload protection for transformers

(iii) Earth-fault protection for transformers

9. What is the difference between an earth relay and over-current relay ?

10. How does grounding affect relay application ?

11. Why is overload protection not necessary for alternators ?

12. Can relays be used to protect an alternator against

(i) one-phase open circuits (ii) unbalanced loading (iii) motoring (iv) loss of synchronism ?

13. How many faults develop in a power transformer ?