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Multiple Choice Questions Related with Switch Gears.
#1. An air break switch is designed to open a circuit under.....?
#2. An isolator is designed to open a circuit under.....?
#3. The outdoor type switchgear is used for voltages beyond.....kV?
#4. Isolator is an ..... switch?
#5. Short circuit current are due to....?
#6. When all the three phases are short circuited, it gives rise to ....currents?
#7. The most common type fault in over head lines is.....?
#8. Reactors are used in power system is to .....?
#9. Reactors are connected ..... with the powe system?
#10. A 500 kVA transformer has a reactance of 5%. its reactance at 1000kVA base is.....?
% reactance at base kVA=( base kVA/rated kVA)×%reactance at rated kVA
=1000/500 × 5
#11. The primary function of a fuse is to....?
#12. Buchholz relay is used on....?
#13. Mho relay is used to protect.....?
#14. The leakage resistance of a 50km long cable is 1Mohm. for a 100 km long cable is.....?
#15. The rating of fuse is expressed in terms of.....?
#16. Reactance relay are employed for phase fault in....?
#17. An air blast circuit breaker is usually employed for.....?
#18. Buchholz relay cannot be used on.....?
#19. Lightining arrestor is connected....?
#20. Differential relays are connected to protect the equipment against.....?
#21. If the percentage reactance of the system upto the fault point is 20% and the base kVA is 10000 then short circuit kVA is....?
#22. In a balanced 3 phase system, negative and zero phase sequence currents are....?
#23. Merz price protection is employed for protection of....?
#24. Which relay is used for detect and protect internal faults of a transformer?
#25. The over voltage surges in power systems may be caused by...?
#26. Lightning arresters are used in power system to protect electrical equipments against....?
#27. Series capacitor is used in a transmission line to....?
#28. Which of the following is the protective device against lightning over voltages?
#29. Fusing factor is the ratio of.....?
#30. fusing factor of HRC Fuse is....?
#31. A relay is connected to a 400/5 current transformer and set at 150%. with a primary fault current of 2400A, Calculated the Plug setting multiplier?
pick up value= rated sec.current x current setting= 5 x 1.5=7.5A
fault current in relay coil= 2400 x (5/400)=30A
#32. Location of lightning arrestor should be near....?
#33. During arcing ground conditions, the phase voltage of the system rises to.....?
#34. Isolators are capable of breaking.....?
#35. Compare to the breaking capacity of a circuit breaker, its making capacity should be....?
making capacity= 2.55 x brekimg capacity
#36. Fusing factor of LRC fuse will be.....?
#37. The transient voltage that appears across the contacts at or near current zero during arcing period is called.....?
#38. Phenomenon of current interruption before the natural current zero is reached is called.....?
#39. The peak value of current during the first cycle of current wave after the closure of circuit breaker is known as.....?
#40. In circuit breaker, the length of the arc increases, its resistance is .......?
#41. Current chopping mainly occurs in ...... circuit breakers?
#42. Surge absorber ...... the energy of travelling waves?
#43. In low oil circuit breakers, which type of material used for insulation purpose?
#44. Fuse material is made by alloy of .....?
#45. A lightning arrester provides.....?
#46. The operating time of a fuse is ..... than that of circuit breaker?
fuse= 0.002 sec..
CB = 0.1 to 0.2 sec
#47. A fuse element have .......?
#48. The value of fusing factor is......?
#49. A balanced 3 phase system consists of....?
#50. The material used in liquid fuse is.....?
#51. Main purpose of oil in Oil circuit breaker is to....?
#52. The air blast circuit breakers for 400kV system are designed to operate in.....?
#53. Time current characteristics of a fuse is......?
#54. Fuse element is generally made of.....?
#55. Breaking capacity of fuse ...... than circuit breaker?
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