IMPORTANT QUESTIONS OF CIRCUIT BREAKERS:
1. What is a circuit breaker ? Describe its operating principle.
2. Discuss the arc phenomenon in a circuit breaker.
3. Explain the various methods of arc extinction in a circuit breaker.
4. Define and explain the following terms as applied to circuit breakers :
(i) Arc voltage
(ii) Restriking voltage
(iii) Recovery voltage
5. Describe briefly the action of an oil circuit breaker. How does oil help in arc extinction ?
6.Discuss the advantages and disadvantages of oil circuit breakers.
7. Explain with neat sketches the construction and working of the following circuit breakers :
(i) Plain explosion pot
(ii) Cross jet explosion pot
(iii) Self-compensated explosion pot
8. Explain the difference between bulk oil circuit breakers and low-oil circuit breakers.
9. Discuss the constructional details and operation of a typical low-oil circuit breaker ? What are its relative merits and demerits ?
10. Discuss the principle of operation of an air-blast circuit breaker. What are the advantages and disadvantages of using air as the arc quenching medium ?
11. Explain briefly the following types of air-blast circuit breakers :
(i) Axial-blast type
(ii) Cross-blast type
12. What are the important components common to most of circuit breakers ? Discuss each component briefly.
13. Write a short note on the rate of re-striking voltage:indicating its importance in the arc extinction.
14. Discuss the phenomenon of
(i) Current chopping
(ii) Capacitive current breaking
15. Write short notes on the following :
(i) Resistance switching
(ii) Circuit breaker ratings
(iii) Circuit interruption problems
16. Why do plain break oil circuit breakers have a low speed of circuit interruption ?
17. Is it logical to express the breaking capacity of a circuit breaker in MVA ? Discuss.
18. Why is current, interruption easier in an a.c. circuit than in a d.c. circuit ?
19. Why are circuit breakers designed to have a short-time rating ?
20. Is arc production in a circuit breaker unfortunate mainfestation ?