IDMT relays are used to protect the power transformers against

A. External Short Circuits 

B. overloads

C. Internal Short circuits 

D. Both A & B 

Answer with Explanation:

A. External Short Circuits 

Explanation:

More Circuit Breaker MCQS with Full Explanation

1. Capacitor switching in 33kv power line is better done with ....... Circuit Breaker 

2. Isolators used in transmission lines are capable of breaking

3. The buchholz relay protects a transformer from

4. The relay used for phase fault protection of short transmission lines is

5. In a minimum oil circuit breaker the oil is used

6. The Surge Impedance of under ground Cable is of order of 

7. A circuit Breaker will Normally Operates

8. Surge impedance of overhead transmission line is of the order of 

9. Insulation resistance of HV circuit breaker is

10. Air blast circuit breaker is used for

11. Sparking Between contacts can be reduced by 

12. Merz price protection is used on

13. Mho relay is used for 

14. Which Relay is used for feeders ?

15. For remote operation circuit Breaker must be equipped with a

16. Thermal relays are used for the protection of motors against over current owing to

17. Buchholz Relay is 

18. Buchholz Relays are used on 

19. In an overcurrent protection the setting of the earth fault relay is 

20. Inverse Time current relays are used for the protection of 

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

11. From the point of view of safety, the resistance of the earthing electrode should be