Most important mcq for upcoming BREB examination - এখান থেকে বহু প্রশ্ন হুবুহু কমন এসেছে

 1. The following circuit breaker does not use pneumatic operating mechanism

a) Air break circuit breaker

b) Air blast circuit breaker

c) Bulk oil circuit breaker

d) SF6 circuit breaker

Ans: (c)

2. Fault diverters are basically

a) Circuit breakers

b) Fast switches

c) Relays

d) Fuses

Ans: (b)

3. Circuit breakers are essentially

a) Current carrying contacts called electrodes

b) Arc extinguishers

c) Transformers to isolate two systems

d) Circuits to break the system

Ans: (a)

4. Which of the following circuit breakers takes minimum time installation?

a) Bulk oil circuit breaker

b) Minimum oil circuit breaker

c) Air blast circuit breaker

d) SF6 circuit breaker

Ans: (d)

5. The following medium is employed for extinction of arc in air break circuit breakers?

a) Air

b) Oil

c) Water

d) None of these

Ans: (a)

6. In a power system, the rate of rise of restriking voltage depends upon

a) Circuit power factor only

b) Switching condition only

c) Both (a) and (b) above

d) None of these

Ans: (c)

7. In a circuit breaker, are is initiated by the process of

a) Thermal emission

b) Alternators

c) Field emission

d) Transmission lines

Ans: (d)

8. For a 400 kV system, the capacity of lightning arrester should be

a) 1 kA

b) 5 kA

c) 10 kA

d) 50 kA

Ans: (c)

9. The voltage across the circuit breaker pole after final current zero is

a) Restriking voltage

b) Supply voltage

c) Recovery voltage

d) None of these

Ans: (c)

10. In a circuit breaker, the arcing contents are made of

a) Aluminium

b) Electrolytic

c) Copper tungsten alloy

d) Tungsten

Ans: (c)

11. Bulk oil circuit breaker is suitable for voltages upto

a) 4 kV

b) 25 kV

c) 10 kV

d) 36 kV

Ans: (d)

12. Arc voltage produced in ac circuit breaker is always

a) In phase opposition to the arc current

b) In phase with the arc current

c) Iagging the arc current by 45°

d) Leading the arc current by 90°

Ans: (b)

13. Which of thermal protection switch is provided in power line system to protect against?

a) Over voltage

b) Short circuit

c) Temperature rise

d) Overload

Ans: (d)

14. Air blast circuit breakers are preferred for

a) Short duty

b) Repeated duty

c) Intermittent duty

d) None of these

Ans: (b)

15. For remote operation, circuit breaker must be equipped with

a) Inverse shunt trip

b) Shunt trip

c) Time delay trip

d) Both (a) and (c) above

Ans: (b)

16. The power factor of the arc in a circuit breaker is

a) Zero leading

b) Zero lagging

c) Unity

d) Any value from zero to unity

Ans: (c)

17. Lightining arrestor should be located

a) Away from the circuit breaker

b) Near the transformer

c) Away from the transformer

d) Near the circuit breaker

Ans: (b)

18. A high speed circuit breaker can complete its operation in

a) 2 to 3 cycles

b) 6 to 12 cycles

c) 3 to 8 cycles

d) 10 to 20 cycles

Ans: (c)

19. The dielectric strength of air at 25°C and 76 cm of mercury is

a) 2.11 kV rms/cm

b) 21.1 kV rms/m

c) 211 kV rms/cm

d) 2110 kV rms/m

Ans: (b)

20. Which of the following circuit breaker is generally used in applications in railways?

a) Bulk oil circuit breakers

b) Minimum oil circuit breakers

c) Air break circuit breakers

d) None of these

Ans: (c)