Current chopping mainly occurs in

(A) air blast circuit breaker.
(B) vacuum circuit breaker.
(C) SF6 circuit breaker.
(D) oil circuit breaker.

Answer: (A) air blast circuit breaker.

Explanation:
Air blast circuit breakers retain the same distinguish power irrespective of the magnitude of the current to be interrupted. When breaking low current with such breakers, powerful de-ionising effect of air blast causes. The current to fall abruptly to zero before the natural current zero is reached. This phenomenon is known as current chopping and result in the production of high voltage transient across the contact of the circuit breaker.



More Earthing MCQs with Full Explanation and Important Notes

1.  The neutral of the power system may be connected to the earth

2. Grounding of substation provides

3. Earthing is necessary to give protection against

4. Standard wire gauge used for earthing lead should not be thinner than

5. What should be the value of earthing resistance for large power stations?

6. The earthing wire should have

7. The size of the earth wire is determined by

8. The minimum length of pipe electrode used for earthing should not be less than

9. A ground wire is used to

10. Earth resistance in a typical domestic wiring is



More MCQs With Fully Explained 

1. Under overexcitation synchronous phase modifier works as

2. The neutral of the power system may be connected to the earth

3. The time to open the circuit breaker contact is called as

4. A 100 Ah capacity battery should deliver a current of 10 A for approximately _____ hrs.

5. For the 400KV line, The Spacing Between phase conductors is around 

6. Shunt capacitors in a sub-station

7. An alternator is said to be over excited when it is operating at

8. In the case of transformer Buchholz relay is used to protect from 

9. Series capacitors are used to

10. Disadvantage of low power factor is

11. The colour of neutral three core flexible cable is

12. The location of ground faults in underground cables can be found by

13. Fault location in an HV cable is done by

14. The insulation resistance of a cable of length 10 km is 1 MΩ. its resistance for 50 km length will be

15. Which of the following is not a valid advantage of bundle conductor?

16. Star-star power transformer is protected by current transformer having

17. The surge resistance of cables is

18. Skin effect is only noticeable at _______ frequencies. 

19. When transmission voltage is increased, the line losses are

20. Var compensators are used to

21. High voltage transmission lines use

22. The material used for insulators are

23. Which device is used for protection of equipment from from damage caused by overload or short circuit?   

24. Isolator in sub station is open under ------------- condition?

25. The surge impedance value of overhead lines is












38. A thermal protection relay provides protection against what?

39. Mho relays are used for the protection of which of the following lines?

40. The rate of rise of re-striking voltage is dependent upon

41. If sag in an overhead line increase, tension in the line

42. The secondary winding of which of the following transformers is always kept closed?

43. The neutral of the power system may be connected to earth

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