1. If variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors, the total annual cost will be minimum and the corresponding size of conductor will be most economical. This statement
is known as
Correct : A. Kelvin's law
2. are the conductors, which connect the consumer's terminals to the distribution
Correct : B. Service mains
3. The underground system cannot be operated above
Correct : D. 66 kV
4. Overhead system can be designed for operation upto
Correct : C. 66 kV
5. The wooden poles well impregnated with creosite oil or any preservative compound
have life
Correct : C. 25 to 30 years
6. Which of the following materials is not used for transmission and distribution of
electrical power ?
Correct : D. Tungsten
7. Galvanised steel wire is generally used as
Correct : D. all of the above
8. The usual spans with R.C.C. poles are
Correct : C. 80—100 metres
9. The corona is considerably affected by which of the following ?
Correct : D. All of the above
10. Which of the following are the constants of the transmission lines ?
Correct : D. All of the above
11. 310 km line is considered as
Correct : A. a long line
12. The phenomenon qf rise in voltage at the receiving end of the open-circuited or lightly
loaded line is called the
Correct : B. Ferranti effect
13. The square root of the ratio of line impedance and shunt admittance is called the
Correct : A. surge impedance of the line
14. Which of the following is the demerit of a 'constant voltage transmission system' ?
Correct : A. Increase of short-circuit current of the system
15. Low voltage cables are meant for use up to
Correct : D. llkV
16. The operating voltage of high voltage cables is upto
Correct : D. llkV
17. The operating voltage of supertension cables is upto
Correct : D. 33 kV
18. The operating voltage of extra high tension cables is upto
Correct : D. 66 kV
19. Which of the following methods is used for laying of underground cables ?
Correct : D. All of the above
20. Due to which of the following reasons the cables should not be operated too hot ?
Correct : D. All of the above
21. Which of the following D.C. distribution system is the simplest and lowest in first cost?
Correct : A. Radial system
22. A booster is a
Correct : A. series wound generator
23. Besides a method of trial and error, which of the following methods is employed for solution of network problems in interconnected system ?
Correct : D. All of the above
24. Which of the following faults is most likely to occur in cables ?
Correct : D. All of the above
25. The cause of damage to the lead sheath of a cable is
Correct : D. all of the above
26. The voltage of the single phase supply to residential consumers is
Correct : C. 230 V
27. Most of the high voltage transmission lines in India are
Correct : B. overhead
28. The distributors for residential areas are
Correct : C. three-phase four wire
29. The conductors of the overhead lines are
Correct : B. stranded
30. High voltage transmission lines use
Correct : A. suspension insulators
31. Distribution lines in India generally use
Correct : B. R.C.C. poles
32. The material commonly used for insulation in high voltage cables is
Correct : B. paper
33. The loads on distributors systems are generally
Correct : B. unbalanced
34. The power factor of industrial loads is generally
Correct : B. lagging
35. Overhead lines generally use
Correct : C. A.C.S.R. conductors
36. In transmission lines the cross-arms are made of
Correct : D. steel
37. The material generally used for armour of high voltage cables is
Correct : B. steel
38. Transmission line insulators are made of
Correct : B. porcelain
39. The material commonly used for sheaths of underground cables is
Correct : A. lead
40. The minimum clearance between the ground and a 220 kV line is about
Correct : C. 7.0 m
41. The spacing between phase conductors of a 220 kV line is approximately equal to
Correct : C. 6 m
42. Large industrial consumers are supplied electrical energy at
Correct : C. 66 kV
43. In a D.C. 3-wire distribution system, balancer fields are cross-connected in order to
Correct : D. equalize voltages on the positive and negative outers
44. In a D.C. 3-wire distributor using balancers and having unequal loads on the two sides
Correct : C. balancer connected to lightly- loaded side runs as a motor
45. Transmitted power remaining the same, if supply voltage of a D.C. 2-wire feeder is increased 100 percent, saving in copper is
Correct : B. 50 percent
46. A uniformly-loaded D.C. distributor is fed at both ends with equal voltages. As compared to a similar distributor fed at one end only, the drop at the middle point is
Correct : A. one-fourth
47. As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum
voltage to earth uses only
Correct : A. 31.25 percent of copper
48. Which of the following is usually not the generating voltage ?
Correct : B. 8.8 kV
49. For an overhead line, the surge impedance is taken as
Correct : C. 100—200 ohms
50. The presence of ozone due to corona is harmful because it
Correct : B. corrodes the material
51. A feeder, in a transmission system, feeds power to
Correct : A. distributors
52. The power transmitted will be maximum when
Correct : C. sending end voltage is more
53. A 3-phase 4 wire system is commonly used on
Correct : D. secondary distribution
54. Which of the following materials is used for overhead transmission lines ?
Correct : D. Any of the above
55. Which of the following is not a constituent for making porcelain insulators ?
Correct : D. Silica
56. There is a greater possibility of occurence of corona during
Correct : D. humid weather
57. Which of the following relays is used on long transmission lines ?
Correct : B. Mho's relay
58. The steel used in steel cored conductors is usually
Correct : C. mild steel
59. Which of the following distribution systems is more reliable ?
Correct : C. Ring main system
60. Which of the following characteristics should the line supports for transmission lines possess ?
Correct : D. All of the above
61. Transmission voltage of llkV is normally used for distances upto
Correct : A. 20—25 km
62. Which of the following regulations is considered best?
Correct : D. 2%
63. Skin effect is proportional to
Correct : C. (conductor diameter)
64. A conductor, due to sag between two supports, takes the form of
Correct : D. catenary
65. In AC.S.R. conductors, the insulation between aluminium and steel conductors is
Correct : D. no insulation is required
66. Which of the followingbus-bar schemes has the lowest cost ?
Correct : B. Single bus-bar scheme
67. Owing to skin effect
Correct : B. portion of the conductor near the surface carries more current and core of the conductor carries less current
68. By which of the following methods string efficiency can be improved ?
Correct : D. Any of the above
69. In aluminium conductors, steel core is provided to
Correct : D. increase the tensile strength
70. By which of the following a bus-bar is rated ?
Correct : D. Current, voltage, frequency and short time current
71. A circuit is disconnected by isolators when
Correct : B. there is no current in the line
72. For which of the following equipment current rating is not necessary ?
Correct : B. Isolators
73. In a substation the following equipment is not installed
Correct : A. exciters
74. jCorona usually occurs when the electrostatic stress in air around the conductor
exceeds
Correct : D. 30 kV (maximum v^lue)/cm
75. The voltage drop, for constant voltage transmission is compensated by installing
Correct : C. synchronous motors
76. The use of strain type insulators is made where the conductors are
Correct : C. any of the above
77. The current drawn by the line due to corona losses is
Correct : A. non-sinusoidal
78. Pin type insulators are generally not used for voltages beyond
Correct : D. 33 kV
79. Aluminium has a specific gravity of
Correct : B. 2.7
80. For transmission of power over a distance of 200 km, the transmission voltage should
be
Correct : A. 132 kV
81. For aluminium, as compared to copper, all the following factors have higher values
except
Correct : B. electrical conductivity
82. Which of the following equipment, for regulating the voltage in distribution feeder,
will be most economical ?
Correct : D. Booster transformer
83. In a tap changing transformer, the tappings are provided on
Correct : B. secondary winding
84. Constant voltage transmission entails the following disadvantage
Correct : B. short-circuit current of the system is increased
85. On which of the following factors skin effect depends ?
Correct : D. All of the above
86. The effect of corona can be detected by
Correct : D. all of the above
87. For transmission of power over a distance of 500 km, the transmission voltage should
be in the range
Correct : A. 150 to 220 kV
88. In the analysis of which of the following lines shunt capacitance is neglected ?
Correct : A. Short transmission lines
89. When the interconnector between two stations has large reactance
Correct : C. the stations will fall out of step because of large angular displacement between the stations
90. The frequency of voltage generated, in case of generators, can be increased by
Correct : C. adjusting the governor
91. When an alternator connected to the bus-bar is shut down the bus-bar voltage will
Correct : C. remain unchanged
92. The angular displacement between two interconnected stations is mainly due to
Correct : A. armature reactance of both alternators
93. Electro-mechanical voltage regulators are generally used in
Correct : B. generators
94. Series capacitors on transmission lines are of little use when the load VAR
requirement is
Correct : B. small
95. The voltage regulation in magnetic amplifier type voltage regulator is effected by
Correct : C. varying the reactance
96. When a conductor carries more current on the surface as compared to core, it is due to
Correct : C. skin effect
97. The following system is not generally used
Correct : A. 1-phase 3 wire
98. The skin effect of a conductor will reduce as the
Correct : A. resistivity of conductor material increases