Electrical Knowledge - Transmission & Distribution MCQ

12/20/2017 ELECTRICAL KNOWLEDGE: TRANSMISSION & DISTRIBUTION MCQ
‫ﺗﺳﺟﯾل اﻟدﺧول‬ ‫إﻧﺷﺎء ﻣدوﻧﺔ إﻟﻛﺗروﻧﯾﺔ‬ «‫اﻟﻣدوﻧﺔ اﻹﻟﻛﺗروﻧﯾﺔ اﻟﺗﺎﻟﯾﺔ‬
ELECTRICAL KNOWLEDGE
THIS BLOG PROVIDES KNOWLEDGEABLE INFORMATION. PHOTOS AND VIDEOS IN WHICH YOU GET MORE INFORMATION O
GET MORE PRACTICAL KNOWLEDGE.
Home Q&A TRANSFORMER TRANSMISSION & DISTRIBUTION MCQ
Follow by Email
TRANSMISSION & DISTRIBUTION MCQ Email address
CONNECT WITH
 
Mi A1 (Rose Gold, 64
GB) LIKE US ON FAC
List Price: Rs.15999
Our Price: Rs.14999
Ele
5k l
1. Which of the following is not the transmission voltage in America ?

(A) 66 kV Like Page
(B) l32kV
(C) 264 kV Total Pageviews
(D) 400 kV
3 2 9 3
Get Answer
RECENT POST
C
2. Which of the following is usually not the generating voltage ?

(A) 6.6 kV
(B) 9.9 kV
(C) 11kV
(D) 13.2 kV.
Get Answer
B the alternato..
3. Boosters are basically

(A) inductors
(B) capacitors
induction mo
(C) transformers
(D) synchronous motors.
Get Answer
C
◄ Previous
4. Which of the following is not the distribution system normally used
(A) 3 phase-4 wire
Blog Archive
(B) 3 phase-3 wire
(C) Single phase - 3 wire ▼ 2017 (104)
▼ Decembe
(D) Single phase -4 wire.
What is fer
What is the
Get Answer lo...
Mention th
D moto...
What is rev
https://eeadda1.blogspot.com/p/transmission-distribution-mcq.html 1/28
What is the
elect...
5. Conductors for high voltage transmission lines are suspended from towers What will h
(A) to reduce clearance from ground prim...
(B) to increase clearance from ground State the m

Name the
(C) to reduce wind and snow loads cleaners
(D) to take care of extension in length during summer. What are t
of...
Explain ad
Get Answer
Explain the
B
What is sli
Why back
6. Transmission efficiency increases as its si...
(A) voltage and power factor both increase What are t

trans...
(B) voltage and power factor both decrease Why AC sy
(C) voltage increases but power factor decreases systems
(D) voltage decreases but power factor increases. Why star d

inductio
► Novembe
Get Answer
► October (5
A
Featured post
7. With same maximum voltage to earth, which ac system (with p.f. 0.8) will require more copper as
compared to dc 2 wire system How a Nuclea
(A) single phase. 2 wire (mid point earthed)

(B) single phase. 3 wire (neutral=1/2 outer)
(C) three phase three wire
(D) three phase-four wire (neutral = outer).
Get Answer
D
Popular Posts
8. When alternating current passes through a conductor

(A) it remains uniformly distributed throughout the section of conductor
(B) portion of conductor near the surface carries more current as compared to the core
(C) portion of conductor near the surface carries less current as compared to the core
(D) entire current passes through the core of the conductor.
Get Answer
B
the load. ...
9. The fact that a conductor carries more current on the surface as compared to core, is known as
(A) skin effect
(B) corona
(C) permeability MVA. In a Ge
(D) unsymmetrical fault.
Get Answer
A
10. The effective resistance of a conductor will be the same as ohmic resistance when
(A) current is in true sine wave form
(B) voltage is low
carries curren
(C) power factor is unity
(D) Current is uniformly distributed in the conductor cross-section.
Get Answer
D
11. Skin effect results in

(A) reduced effective resistance but increased effective internal reactance of the conductor
(B) increased effective resistance but reduced effective internal reactance of. the conductor
(C) reduced effective resistance as well as effective internal reactance Construction
(D) increased effective resistance as well as effective internal reactance.
Get Answer
B
12. Skin effect depends on

(A) size of the conductor
(B) frequency of the current
(C) resistivity of the conductor material
(D) all of the above.
Get Answer
D
Popular Posts
13. The skin effect of a conductor will reduce as the
(A) diameter increases
(B) frequency increases
(C) permeability of conductor material increases
(D) resistivity of conductor material increases.
Get Answer
D
the load. ...
14. Skin effect is proportional to

(A) diameter of conductor
(B) (diameter of conductor)1/2
(C) (diameter of conductor )2 MVA. In a Ge
(D) (diameter of conductor )2.
Get Answer
C
15. In overhead transmission lines the effect of capacitance can be neglected when the length of line is
less than
(A) 200 km
carries curren
(B) 160 km
(C) 100 km
(D) 80 km.
Get Answer
D
16. For constant voltage transmission the voltage drop is compensated by installing
(A) synchronous motors
(B) capacitors
(C) inductors
Get Answer
A
17. The disadvantage of constant voltage transmission is

(A) short circuit current of the system is increased
(B) load power factor in heavy loads
(C) large conductor area is required for same power transmission
(D) air of the above.
Get Answer
A
18. The surge impedance for over head line is taken as

(A) 10-20 ohms
(B) 50-60 ohms

(C) 100-200 ohms
(D) 1000-2000 ohms.
Get Answer
C
19. Pin insulators are normally used up to voltage of about

(A)100kV
(B) 66 kV
(C) 33 kV
(D) 25 kV.
Get Answer
D
20. Strain type insulator arc used where the conductors arc
(A) dead ended
(B) at intermediate anchor towers
(C) any of the above
(D) none of the above.
Get Answer
C
21. For 66 kV lines the number of insulator discs used are

(A) 3
(B) 5
(C) 8
(D) 12.
Get Answer
B
22. Ten discs usually suggest that the transmission line voltage is
(A) 11 kV
(B) 33 kV
(C) 66 kV
(D) 132 kV.
Get Answer
D
23. The effect of corona is

(A) increased energy loss
(B) increased reactance
(C) increased inductance
Get Answer
A
24. Corona usually occurs when the electrostatic stress in the air around the conductor succeeds
(A) 30 kV (maximum value)/cm
(B) 22 kV (maximum value)/cm
(C) 11 kV (rms value)/cm
(D) 6.6 kv (rms value)/cm.
Get Answer
A
25. Corona effect can be detected by

(A) hissing sound

(B) faint luminous flow of bluish color
(C) presence of ozone detected by odor
Get Answer
D
26. The current drawn by the line due to corona losses is

(A) sinusoidal
(B) square
(C) non-sinusoidal
Get Answer
C
27. Presence of ozone as a result of corona is harmful because

(A) it gives bad odor
(B) it corrodes the material
(C) it transfers energy to the ground
(D) reduces power factor.
Get Answer
B
28. Between two supports, due to sag the conductor takes the form of
(A) catenary
(B) triangle
(C) ellipse
(D) semi-circle.
Get Answer
A
29. The inductance of a single phase two wire line is given by (D is the distance between conductors and
2v is the diameter of conductor)
(A) 0.4 loge (D/r) mH/km
(B) 0.55 loge (D/r) mH/km
(C) 0.4 loge (r/D) mH/km
(D) 0.55 loge (r/D) mH/km.
Get Answer
A
30. The effect of ice deposition on conductor is

(A) increased skin effect
(B) reduced corona losses
(C) increased weight
(D) reduced sag.
Get Answer
C
31. The effect of wind pressure is more predominant on
(A) transmission lines
(B) neutral wires
(C) insulator
(D) supporting towers.
Get Answer
D
32. Which of the following statement is correct ?

(A) Wind pressure reduces corona effects
(B) Ice on conductors improves power factor
(C) Wind pressure is taken to act in a direction at right angles to that for ice
(D) Wind pressure and ice on conductors together improve regulation of power transmitted.
Get Answer
C
33. Which of the following statements is incorrect ?

(A) As the temperature rises the tension in the transmission line decreases
(B) As temperature rises the sag in transmission lines reduces
(C) Tension and sag in transmission lines are complementary to each other.
Get Answer
C
34. Wooden poles for supporting transmission lines are used for voltages up to
(A) 440 V
(B)11 kV
(C) 22 kV
(D) 66 kV.
Get Answer
C
35. If K is the volume of cable conductor material required to transmit power, then for the transmission of
the same power, the volume of cable conductor required for single phase 2 wise AC system is
(A) 2k
(B) k cosf
(C) k/ cos2f
(D) 2k/ cos2p
Get Answer
D
36. Maximum permissible span for wooden poles is

(A) 10 meter
(B) 20 meters
(C) 60 meters
(D) 200 meters.
Get Answer
C
37. When transformers or switchgears are to be installed in a transmission line, the poles used are
(A) I type
(B) J type
(C) H type
(D) L type.
Get Answer
C
38. For improving life, steel poles are galvanized. Galvanizing is the process of applying a layer of
(A) paint
(B) varnish
(C) tar coal
(D) zinc.
Get Answer
D
39. The disadvantage of transmission lines as compared to cables is

(A) exposure to lightening
(B) exposure to atmospheric hazards like smoke, ice, etc.
(C) inductive interference between power and communication circuits
Get Answer
D
40. ACSR conductor implies

(A) All conductors surface treated and realigned
(B) Aluminum conductor steel reinforced
(C) Anode current sinusoidally run
(D) Anodized Core Smooth Run.
Get Answer
B
41. The surge resistance of transmission lines is about

(A) 50 ohms
(B) 100 ohms
(C) 250 ohms
(D) 500 ohms.
Get Answer
D
42. During storm the live conductor of public electric supply breaks down and touches the earth. The
consequences will be
(A) supply voltage will drop
(B) supply voltage will increase
(C) current will flow to earth
(D) no current will flow in the conductor.
Get Answer
C
43. In transmission system a feeder feeds power to

(A) service mains
(B) generating stations
(C) distributors
Get Answer
C
44. For transmission lines the standing wave ratio is the ratio of
(A) maximum voltage to minimum voltage
(B) maximum current to minimum voltage
(C) peak voltage to rms voltage
(D) maximum reactance to minimum reactance.
Get Answer
A
45. In a transmission line following arc the distributed constants

(A) resistance and inductance only
(B) resistance, inductance and capacitance
(C) resistance, inductance, capacitance and short conductance.
Get Answer
C
46. The bundling of conductors is done primarily to
(A) reduce reactance
(B) increase reactance
(C) increase ratio interference
(D) reduce radio interference.
Get Answer
A
47. Which of the following regulation is considered to be the best

(A) 2%
(B) 30%
(C)70%
(D) 98%.
Get Answer
A
48. The characteristic impedance of a transmission line depends upon

(A) shape of the conductor
(B) surface treatment of the conductors
(C) conductivity of the material
(D) geometrical configuration. of the conductors.
Get Answer
D
49. For a distortion-less transmission line (G = shunt conductance between two wires)
(A) R/L = G/C
(B) RL=GC
(C) RG=LC
(D)RLGC=0
Get Answer
A
50. Guard ring transmission line

(A) improves power factor
(B) reduces earth capacitance of the lowest unit
(C) reduces transmission losses
(D) improves regulation.
Get Answer
B
51. When the power is to be transmitted over a distance of 500 km, the transmission voltage should be in
the range
(A) 33 kV - 66 kV
(B) 66 kV - 100 kV
(C) 110 kV - 150 kV
(D) 150kV - 220kV.
Get Answer
D
52. A relay used on long transmission lines is

(A) mho's relay
(B) reactance relay
(C) impedance relay

(D) no relay is used.
Get Answer
A
53. Total load transmitted through a 3 phase transmission line is 10,000 kW at 0.8 power factor lagging.
The I2R losses are 900 kW. The efficiency of transmission line is
(A) 60%
(B) 90%
(C) 95%
(D) 99%.
Get Answer
B
54. Litz wires are used for intermediate frequencies.to overcome

(A) corona effect
(B) skin effect
(C) radio interference
Get Answer
B
55. In order to reduce skin effect at UHF

(A) conductors are painted
(B) conductors are anodized
(C) copper lubes with silver plating are used
(D) copper rods with silver plating are used.
Get Answer
C
56. Shunt capacitance is usually neglected in the analysis of

(A) Short transmission lines
(B) Medium transmission lines
(C) Long transmission lines
(D) Medium as well as long transmission lines.
Get Answer
A
57. The chances of corona are maximum during

(A) summer heat
(B) winter
(C) dry weather
(D) humid weather.
Get Answer
D
58. The power transmitted will be maximum when

(A) Sending end voltage is more
(B) Receiving end voltage is more
(C) Reactance is high
(D) Corona losses are least.
Get Answer
A
59. Neglecting losses in a transmission system, if the voltage is doubled, for the same power transmission,
the weight of conductor material required will be
(A) four times
(B) double
(C) half
(D) one fourth.
Get Answer
D
60. When two conductors each of radius r are at a distance D, the capacitance between the two is
proportional to
(A) loge (D/r)
(B) loge (r/D)
(C) 1/loge (D/r)
(D) 1/loge (r/D).
Get Answer
C
61. In a transmission line having negligible resistance the surge impedance is
(A) (L+C)1/2
(B) (C/L)1/2
(C) (1/LC)1/2
(D) (L/C)1/2
Get Answer
D
62. A relay used on short transmission lines is

(A) Reactance relay
(B) Mho's relay
(C) Impedance relay
(D) None of the above.
Get Answer
A
63. In case the characteristic impedance of the line is equal to the load impedance
(A) all the energy will pass to the earth
(B) all the energy will be lost in transmission losses
(C) the system will resonate badly
(D) all the energy sent will be absorbed by the load.
Get Answer
D
64. For a properly terminated line

(A) ZR=ZO
(B) Z/R > ZO
(C) ZR < ZO
(D) ZR =Z0 = 0.
Get Answer
D
65. The dielectric strength of air at 250C and 76 cm/Hg is

(A) 1 kV/cm
(B) 1 kV/mm
(C) 3 kV/cm
(D) 30 kV/cm.
Get Answer
D
66. The chances of corona are maximum in

(A) domestic wiring
(B) distribution lines
(C) transmission lines
Get Answer
C
67. Transmission lines link

(A) service points to consumer premises
(B) distribution transformer to consumer premises
(C) receiving end station to distribution transformer
(D) generating station to receiving end station.
Get Answer
D
68. In case of open circuit transmission lines the reflection coefficient is

(A) 1
(B) 0.5
(C) -1
(D) Zero.
Get Answer
D
69. Impedance relay is used on

(A) Short transmission lines
(B) Medium transmission lines
(C) Long transmission line
(D) All the transmission lines.
Get Answer
B
70. Which type of insulators are used on 132 kV transmission lines ?

(A) Pin type
(B) Disc type
(C) Shackle type
(D) Pin and shackle type.
Get Answer
B
71. String efficiency can be improved by

(A) using Longer cross arm
(B) grading the insulator
(C) using a guard ring
(D) any of the above.
Get Answer
D
72. Minimum horizontal clearance of a low voltage transmission line from residential buildings must be
(A) 11/2 feet
(B) 3 feet
(C) 4 feet
(D) 8 feet.
Get Answer
C
73. If a 66 kV lines passes over a residential building, the minimum vertical clearance from the roof of the
building must be
(A) 8 feet
(B) 12 feet
(C) 13 feet
(D) 16 feet.
Get Answer
C
74. Alternating current power is transmitted at high voltage

(A) to safeguard against pilferage
(B) to minimize transmission losses
(C) to reduce cost of generation
(D) to make the system reliable.
Get Answer
B
75. Stranded conductors arc used for transmitting, power at high voltages because of
(A) increased tensile strength
(B) better wind resistance
(C) ease-in handling
(D) low cost.
Get Answer
C
76. For the same resistance of line the ratio, weight of copper conductor/ weight of aluminium conductor ,
is
(A) 0.50
(B) 0.75
(C) 1.50
(D) 2.0.
Get Answer
D
77. The function of steel wire in a ACSR conductor is

(A) to take care of surges
(B) to prevent corona
(C) to reduce inductance and hence improve power factor
(D) to provide additional mechanical strength.
Get Answer
D
78. In high voltage transmission lines the top most conductor is

(A) R-phase conductor
(B) Y- phase conductor
(C) B-phase conductor
(D) Earth conductor.
Get Answer
D
79. For 11 kV line the inductance per km per phase will be of the order of
(A) 1 H
(B) 0.1 H
(C) 1 mH
(D) 0.1 mH.
Get Answer
C
80. For 11 kV. line the capacitance per km per phase will be of the order of
(A) 1 Farad
(B) 0.1 Farad
(C) 0.01 Farad
(D) 0.01 microF.
Get Answer
C
81. If 3000 kW power is to be transmitted over a distance of 30 km, the desirable transmission voltage will
be
(A) 11 kV
(B) 33 kV
(C) 66 kV
(D) 132 kV.
Get Answer
B
82. The permissible voltage variation in transmission and distribution system is

(A) 0.1%
(B) 1%
(C)10%
(D)25%.
Get Answer
C
83. The voltage of transmission can be regulated by

(A) use of tap changing transformers
(B) switching in shunt capacitors at the receiving end during heavy loads
(C) use of series capacitors to neutralize the effect of series reactance
(D) any of the above methods.
Get Answer
D
84. The most economic voltage for transmitting given power over a known distance by overhead
transmission line is approximately
(A) 3.6 kV/km
(B) 1.6 kV/km
(C) 2.6 kV/km
(D) 3.6 kVkm.
Get Answer
A
85. String efficiency is given by

(A) (voltage across the string) / ((numbers of discs on the string) x (voltage across disc nearest to the
conductor))
(B) ((voltage across the string) x (numbers of discs on the string)) / (voltage across disc nearest to the
conductor)
(C) ( (voltage across disc nearest to the conductor) x (numbers of discs on the string)) / (voltage across the
string)
(D) (voltage across disc nearest to the conductor))/ ((numbers of discs on the string) x (voltage across the
string)
Get Answer
A
86. For a 66 kV line having span of 200 meters between towers the approximate sag will be
(A) 0.02 m
(B) 0.2 m
(C) 2 m
(D) 20 m.
Get Answer
C
87. In the above case if the span is doubled, the sag will be
(A) 2 m
(B) 4m
(C) 8m
(D) 1 m.
Get Answer
C
88. The reflection coefficient for a short circuit line is

(A) 1
(B) Zero
(C) 0.5
(D) - 1.
Get Answer
D
89. In case the height of transmission tower is increased

(A) the line capacitance and inductance will not change
(B) the line capacitance will decrease but line inductance will decrease
(C) the line capacitance will decrease and line inductance will increase
(D) the line capacitance will decrease but line inductance will remain unaltered.
Get Answer
D
90. In a transmission line if booster transformer are to be used, preferred location will be
(A) at the receiving end
(B) at the sending end
(C) at the intermediate point
(D) any where in the line.
Get Answer
C
91. A 70/6 ACSR conduction is an aluminium conductor steel reinforced, having
(A) cross sectional area of aluminium as 70 mm2 and the cross-sectional area of steel as 6 mm2
(B) cross-sectional area of steel as 70 mm2 and the cross-sections area of aluminium as 6 mm2
(C) 70 aluminium conductors and 6 steel conductors
(D) 80 steel conductors and 6 aluminium conductors.
Get Answer
C
92. In aluminium conductors steel reinforced, the insulation between aluminium and steel conductors is
(A) any insulator
(B) bitumen
(C) insulin
(D) no insulation is required.
Get Answer
D
93. Under no load conditions the current in a transmission line is due to

(A) corona effects
(B) capacitance of the line
(C) back flow from earth
(D) spinning reserve.
Get Answer
B
94. Which distribution system is more reliable ?

(A) Ring main system
(B) Tree system
(C) Radial system
(D) All are equally reliable.
Get Answer
A
95. Out of the following systems of distribution, which system offers the best economy ?
(A) Direct current system
(B) AC single phase system
(C) AC 3 phase 3 wire system
(D) AC 3 phase 4 wire system.
Get Answer
A
96. What are the advantages of dc transmission system over ac transmission system ?
(A) DC system is economical
(B) There is no skin effect in dc system
(C) Corona limits are highest for dc circuits as compared to ac circuits
(D) All of the above.
Get Answer
D
97. The main advantage of ac. transmission system over d.c. transmission system is
(A) Easy transformation
(B) Less losses in transmission over long distances
(C) ) Less insulation problems
(D) Less problem of instability.
Get Answer
B
98. Which curve correctly represents the relation between capital cost and dc voltage of transmission ?
(A) curve A
(B) curve B
(C) curve C
(D) curve D.
Get Answer
99. Step-up substations are associated with

(A) distributors
(B) consumer location
(C) concentrated load
(D) generating stations.
Get Answer
D
Questions 100 to 102 refer to figure given below :
100. A section of a single bus scheme is shown in the figure. In this figure B represents
(A) Isolator
(B) Circuit breaker
(C) Current transformer
(D) Inductance.
Get Answer
C
101. An isolator is represented by

(A) A
(B) B
(C) C
(D) A and D.
Get Answer
D
102. C represents
(A) circuit breaker
(B) Mho's relay
(C) Earth switch
Get Answer
A
103. When an alternator is connected to the infinite but bar and its excitation is gradually increased
(A) the terminal voltage will rise
(B) the terminal voltage will drop
(C) the terminal voltage will remain unaltered
(D) the terminal voltage will vary rapidly.
Get Answer
C
104. Consumers having low power factor equipment are advised to install
(A) tap changing transformer
(B) capacitor bank
(C) synchronous condensers
(D) none of the above.
Get Answer
B
105. A bus bar is rated by

(A) current only
(B) current and voltage only

(C) current, voltage, frequency
(D) current, voltage, frequency and short time current.
Get Answer
D
106. Material generally used for bus bar is
(A) copper
(B) aluminium
(C) steel
(D) tungsten.
Get Answer
B
107. Which of following properties has got higher value for aluminium as compared to copper?
(A) Melting point
(B) Specific gravity
(C) Electrical resistivity
(D) Thermal conductivity.
Get Answer
C
108. For carrying a 100 A (rms) current the cross-sectional area of aluminium bus bar should be at least
(A) 1 mm2
(B) 10 mm 2
(C) 25 mm 2
(D) 50 mm2
Get Answer
C
109. Isolators are used to disconnect a circuit when

(A) line is on full load
(B) line is energized
(C) circuit breaker is not open
(D) there is no current in the line.
Get Answer
D
110. Tap changing transformers are used for

(A) stepping up the voltage
(B) stepping down the voltage
(C) both stepping up and stepping down the voltage
(D) supplying low voltage current for instruments.
Get Answer
C
111. Which device automatically interrupts the supply in the event of surges
(A) Earthing switch
(B) Series reactor
(C) Isolator
(D) Circuit breaker.
Get Answer
D
112. In a substation the equipment used to limit short circuit current level is
(A) Series reactor

(B) Coupling capacitor
(C) Lightening switch
(D) Isolator.
Get Answer
A
113. Which of the following equipment is not installed in a substation ?

(A) Shunt reactors
(B) Exciters
(C) Voltage transformers
(D) Series capacitors.
Get Answer
B
114. Which bus bar scheme offers the lowest cost ?

(A) Single bus bar scheme
(B) Ring bus bar scheme
(C) Breaker and a half scheme
(D) Main and transfer scheme.
Get Answer
A
115. Which is the most expensive bus bar scheme ?

(A) Single bus bar scheme
(B) Ring bus bar scheme
(C) Double bus bar double breaker
(D) Main and transfer scheme.
Get Answer
C
116. Current rating is not necessary in case of

(A) Isolators
(B) Circuit breakers
(C) Load break switches
(D) Circuit breakers and load break switches.
Get Answer
A
117. Which of the following correctly represents the sequence of operations of isolator circuit breaker and
earthing switch while opening a circuit
(A) Close earthing switch - open circuit breaker open isolator
(B) Open isolator - close circuit breaker - open earthing switch
(C) Open circuit breaker - open isolator - close earthing switch
(D) Close circuit breaker - close isolator - open earthing switch.
Get Answer
C
118. Which of the following correctly presents the sequence of operations of isolator circuit breaker and
earthing switch while closing a circuit
(A) Ensure circuit breaker is closed - close isolator - open earthing switch
(B) Ensure circuit breaker is open - close isolator - open earthing switch if any close circuit breaker
(C) Ensure circuit breaker is open - open isolator - open earthing switch if any - close circuit breaker.
Get Answer
119. Which of the following type tests are conducted on isolators

(A) Temperature rise test
(B) Impulse stage with stand test
(C) Short time current test
Get Answer
D
120. In a balance 3 f , 4 wire AC system, the phase sequence is RYB. If the voltage of R phase is. 230 < 0
V, then for Y phase
(A) 230 < 0 V
(B) 230 < 60 V
(C) 230 < 90°V
(D) 230 < 120 V.
Get Answer
D
121. The relation between traveling voltage wave and current wave is
(A) e = i (L/C) 1/2
(B) e = i (C/L) 1/2
(C) e = i (iL/C) 1/2
(D) (L/iC) 1/2
Get Answer
A
122. Steepness of the traveling waves is attenuated by

(A) resistance of the line
(B) inductance of the line
(C) capacitance of the line
Get Answer
A
123. The protection against direct lightening strokes and high voltage steep waves is provided by
(A) earthing of neutral
(B) lightening arresters
(C) ground wires
(D) lightening arresters and ground wires.
Get Answer
D
124. Voltages under Extra High Voltage are

(A) 1 kV and above
(B) 11 kV and above
(C) 132 kV and above
(D) 330 kV and above.
Get Answer
D
125. In outdoor substation, the lightening arresters is placed nearer to

(A) the isolator
(B) the current transformer
(C) the power transformer
(D) the current breaker.
Get Answer
C
126. Stability of a system is not affected by

(A) Reactance of line
(B) Losses
(C) Reactance of generator
(D) Output torque.
Get Answer
B
127. A 10 MVA generator has power factor 0.866 lagging. The reactive power produced will be
(A) 10 MVA
(B) 8 MVA
(C) 5 MVA
(D) 1.34 MVA.
Get Answer
C
128. In order to increase the limit of distance of transmission line

(A) series resistances are used
(B) synchronous condensers are used
(C) shunt capacitors and series reactors are used
(D) series capacitors and shunt reactors are used.
Get Answer
D
129. A 30 km transmission line carrying power at 33 kV is known as

(A) short transmission line
(B) long transmission line
(C) high power line
(D) ultra high voltage line.
Get Answer
A
130. If K is the volume of conductor material required for 2 wire dc system with one conductor earthed,
then the volume of cable conductor material required for transmission of same power in single phase 3
wire system is (A) K/3 cos f
(B) 5K cos2f
(C) K/ 5 cos2f
(D) 5K/ 8 cos2f
Get Answer
C
131. The permissible voltage variable in voltage in distribution is

(A) 0.1%
(B) 1%
(C) 10%
(D) 50%.
Get Answer
C
132. Surge impedance of transmission line is given by

(A) (L/C)1/2
(B) (C/L)1/2
(C) (CL)1/2
(D) 1/(CL)1/2
Get Answer
A
133. 750 kV is termed as

(A) Medium high voltage
(B) High voltage
(C) Extra high voltage
(D) Ultra high voltage.
Get Answer
D
134. In case of transmission line conductors with the increase in atmospheric temperature
(A) length increase but stress decreases
(B) length increases and stress also increases
(C) length decreases but stress increases
(D) both length as well as stress decreases.
Get Answer
A
135. If the height of transmission towers is increased, which of the following parameters is likely to change
?
(A) Resistance
(B) Inductance
(C) Capacitance
Get Answer
C
136. For increasing the capacity of a transmission line to transmit power which of the following must be
decreased ?
(A) Voltage
(B) Capacitance
(C) Line inductance
Get Answer
C
137. In terms of constants A, B, C and D for short transmission lines, which of the following relation is valid
?
(A) A = B = 1
(B) B = D = 0
(C) A = C = 1
(D) C=0.
Get Answer
D
138.Which of the following is reduced due to the use of bundled conductors ?

(A) Capacitance of the circuit
(B) lnductance of the circuit
(C) Power loss due to corona
Get Answer
139. The ratio of capacitance from line to line capacitance from line to neutral is nearly
(A)1/4
(B) 1/2
(C) 1
(D) 2.
Get Answer
A
140. Following effects are associated with transmission lines

I. Corona effect
II. Proximity effect
III. Skin effect.
The effect resistance of a conductor is increased by
(A) I only
(B) II and III only
(C) I and III only
(D) I. II and III.
Get Answer
B
141. The sag of a transmission line is least affected by

(A) self weight of conductors
(B) temperature of surrounding air
(C) current through conductor
(D) ice deposited on conductor.
Get Answer
C
142. The sag of the conductors of a transmission line is 1.5 m when the span is 100 m. Now if the height of
supporting towers is increased by 20%, the sag will
(A) increase by 20%
(B) increase by 10%
(C) reduced by 20%
(D) remain unchanged.
Get Answer
D
143. ACSR conductor having 7 steel stands surrounded by 25 aluminum conductor will be specified as
(A) 7/25
(B) 7/32
(C) 25/7
(D) 25/32.
Get Answer
C
144. The networks associated with transmission lines are

I. T-network
II. π network
III. Tree net.
A two terminal pair of network of a transmission line can be represented by
(A) I only
(B) II only
(C) Either of I or II
(D) Either of I, II or III.
Get Answer
C
145. Which of the following relationships is not valid for short transmission lines ?
(A) B = Z = C
(B) A = D = 1
(C) Is = Ir
Get Answer
A
146. In order to improve the steady state stability of an overhead transmission lines, which of the following
methods can be adopted
(A) Reducing impedance between the stations
(B) Adopting quick response excitation systems
(C) Using series capacitors to make X = (3 R)1/2
(D) Any of the above.
Get Answer
D
147. Transient disturbances arc due to

(A) Switching operations
(B) Load variations
(C) Faults
(D) Any of the above.
Get Answer
D
148. Which of the following short circuit is the most dangerous ?

(A) Line to line short circuit
(B) Dead short circuit
(C) Line to ground short circuit
(D) Line to line and ground short circuit.
Get Answer
B
149. In case line to line fault occurs, the short circuit current of an alternator will .depend on its
(A) Synchronous reactance
(B) Transient reactance
(C) Short circuit resistance
Get Answer
A
150. Transient state stability is generally improved by ,

(A) using high speed governors on machines by
(B) using low inertia machines
(C) dispensing with neutral grounding
Get Answer
A
151. Aluminium is being favored as bus-bar material mainly because of
(A) case of fabrication
(B) low density
(C) low cost

(D) non availability of copper.
Get Answer
C
152. Which section can lie used for bus bar ?

(A) bars
(B) rods
(C) tubes
Get Answer
D
153. A string efficiency of 100% implies that

(A) shunt capacitance is 1 MF
(B) potential across each disc is same
(C) potential across each disc is zero
(D) one of the insulator disc is shorted.
Get Answer
B
154. Steel poles for transmission lines need protection against

(A) termites
(B) borer
(C) corrosion
Get Answer
C
155. Which type of copper wire will have highest tensile strength ?
(A) Soft drawn
(B) Medium drawn
(C) Hard drawn.
Get Answer
C
156. Guy wire is used to

(A) Support the pole
(B) Provide protection against surges
(C) Provide emergency earth route
(D) Protect conductors against short circuiting.
Get Answer
A
157. Which of the following is a leading power system ?

(A) Underground cables
(B) Reactors
(C) Mercury arc rectifiers
(D)Transformers.
Get Answer
A
158. Which of the following is a static exciter ?

(A) dc separately excited generator
(B) amplidyne
(C) retool
(D) rectifier.
Get Answer
D
159. The service mains connect

(A) distributor and consumer terminals
(B) distributor and transformer
(C) distributor and relay system
(D) transformer and earth.
Get Answer
A
160. System grounding is song

(A) so that the floating potential on the lower voltage winding for a transformer is brought down to an
insignificant value
(B) so that arcing faults to earth would not set up dangerously high voltage on healthy phases
(C) so that inductive interference between power and communication circuits can be controlled
(D) for all above reasons.
Get Answer
D
161. Hot template curves are plots of

(A) conductor sage and span lengths
(B) temperature and ground clearance curves
(C) temperature and humidity
(D) conductor weight and sag.
Get Answer
A
Questions 162 and 163 refer to data given below:
A 66 kV system has string insulator having five discs and the earth to disc capacitance ratio of 0.10.
162. The string efficiency will be

(A) 89%
(B) 75%
(C) 67%
(D) 55%.
Get Answer
C
163. The voltage shared by the individual discs will be

(A) 1.25 kV
(B) 2.50 kV
(C) 3.88 kV
(D) 5.28 kV.
Get Answer
D
164. The shape of heat rate (HR) versus power (P) curve for a power station will be as shown in
(A) figure A
(B) figure B
(C) figure C
(D) figure D
Get Answer
C
165. The reflection coefficient for the voltage wave in case of overhead lines is given by
(A) (RL - R0 )/ (RL+ R0)
(B) (RL + R0 )/ (RL- R0)
(C) (RL + R0 )/ (RL+ R0)
(D) (RL R0 )/ (RL- R0)
Get Answer
A
166. In a diesel engine the governor controls

(A) fuel pressure
(B) fuel flow rate
(C) fuel temperature
(D) fuel volume.
Get Answer
B
167. For overhead transmission line when the conductors are supported between two supports, the
variation of tension T will temperature is represented by
(A) Curve A
(B) Curve B
(C) Curve C
(D) Curve D.
Get Answer
C
168. If the voltage across the units in a two unit suspension insulator is 60% and 40% respectively of the
line voltage, the. ratio of capacitance of the insulator to that of its capacitance to earth will be
(A) 0.5
(B) 0.50
(C) 0.65
(D) 0.75.
Get Answer
B
169. In the analysis of short transmission lines which of the following is neglected ?
(A) I2 R loss
(B) Shunt admittance
(C) Series impedance
Get Answer
B
170. In medium transmission lines the shunt capacitance is taken into account in
(A) Tee method
(B) Pie method
(C) Steinmetz method
Get Answer
D
Questions 171 and 172 refer to data given below:
A transmission line has a capacitance of 0.01 micro F/km and an inductance of 2 mH/km and is connected
to a cable having an inductance of 0.25 mH/km. When voltage surge having peak value of 100 kV travels
along the cable towards the line, the resulting peak voltage at the junction of the cable and the line is 180
kV.
171. The surge impedance of the cable is

(A) 14.1 ohms
(B) 42.5 ohms
(C) 87.75 ohms
(D) 141.2 ohms.
Get Answer
D
172 . The capacitance of cable per km is

(A) 0.1 microF
(B) 0.7 microF
(C) 1.5 microF
(D) 10 microF.
Get Answer
A
Home
Subscribe to: Posts (Atom)
Popular Posts
Why AC systems are preferred over DC systems?

Due to following reasons, AC systems are preferred over DC systems: a. It is easy to maintain and change the voltage of AC electricity fo...
Why Transformer Rating In kVA, Not in KW?

In Simple words, There are two type of losses in a transformer; 1. Copper Losses 2. Iron Losses or Core Losses or Insulation Losses Cop...
What is the difference between isolators and electrical circuit breakers? What is bus-bar?
Isolators are mainly for switching purpose under normal conditions but they cannot operate in fault conditions .Actually they used for i...
Why Motor rated in kW instead of kVA?

We already know that Transformer rating may be expressed in kVA instead of kW as well as Generator and Alternator rated in kVA . De...
Mention the methods for starting an induction motor?

The different methods of starting an induction motor: a)DOL:direct online starter b)Star delta starter c)Auto transformer starter d)Resi...
What is ferrantic effect?
Output voltage is greater than the input voltage or receiving end voltage is greater than the sending end voltage.
What is the power factor of an alternator at no load?

At no load Synchronous Impedance of the alternator is responsible for creating angle difference. So it should be zero lagging like indu...
What will happen if DC supply is given on the primary of a transformer?

Mainly transformer has high inductance and low resistance.In case of DC supply there is no inductance ,only resistance will act in the e...
What is reverse power relay?

Reverse Power flow relay are used in generating stations's protection. A generating stations is supposed to fed power to the grid a...
Why AC rated in Tons, Not in kW?

AC (Air-conditions and Refrigeration are always rated in Tons. Air conditioners are always rated in T ons capacity instead of kW be...
Copyright © 2017 Electrical knowledge All Right Reserved . Theme images by merrymoonmary. Powered by Blogger.

Electrical Knowledge - Transmission & Distribution MCQ

Uploaded by

Copyright:

Available Formats

Electrical Knowledge - Transmission & Distribution MCQ

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Electrical Knowledge - Transmission & Distribution MCQ

Uploaded by

Copyright:

Available Formats

12/20/2017 ELECTRICAL KNOWLEDGE: TRANSMISSION & DISTRIBUTION MCQ

‫ﺗﺳﺟﯾل اﻟدﺧول‬ ‫إﻧﺷﺎء ﻣدوﻧﺔ إﻟﻛﺗروﻧﯾﺔ‬ «‫اﻟﻣدوﻧﺔ اﻹﻟﻛﺗروﻧﯾﺔ اﻟﺗﺎﻟﯾﺔ‬

Home Q&A TRANSFORMER TRANSMISSION & DISTRIBUTION MCQ

TRANSMISSION & DISTRIBUTION MCQ Email address

1. Which of the following is not the transmission voltage in America ?

2. Which of the following is usually not the generating voltage ?

3. Boosters are basically

(B) to increase clearance from ground State the m

(A) voltage and power factor both increase What are t

(D) voltage decreases but power factor increases. Why star d

(A) single phase. 2 wire (mid point earthed)

8. When alternating current passes through a conductor

11. Skin effect results in

12. Skin effect depends on

14. Skin effect is proportional to

(D) (diameter of conductor )2.

17. The disadvantage of constant voltage transmission is

18. The surge impedance for over head line is taken as

(B) 50-60 ohms

19. Pin insulators are normally used up to voltage of about

21. For 66 kV lines the number of insulator discs used are

23. The effect of corona is

25. Corona effect can be detected by

(A) hissing sound

26. The current drawn by the line due to corona losses is

27. Presence of ozone as a result of corona is harmful because

30. The effect of ice deposition on conductor is

32. Which of the following statement is correct ?

33. Which of the following statements is incorrect ?

36. Maximum permissible span for wooden poles is

39. The disadvantage of transmission lines as compared to cables is

40. ACSR conductor implies

41. The surge resistance of transmission lines is about

43. In transmission system a feeder feeds power to

45. In a transmission line following arc the distributed constants

(C) resistance, inductance, capacitance and short conductance.

47. Which of the following regulation is considered to be the best

48. The characteristic impedance of a transmission line depends upon

50. Guard ring transmission line

52. A relay used on long transmission lines is

(C) impedance relay

54. Litz wires are used for intermediate frequencies.to overcome

55. In order to reduce skin effect at UHF

56. Shunt capacitance is usually neglected in the analysis of

57. The chances of corona are maximum during

58. The power transmitted will be maximum when

62. A relay used on short transmission lines is

64. For a properly terminated line

65. The dielectric strength of air at 250C and 76 cm/Hg is

66. The chances of corona are maximum in

67. Transmission lines link

68. In case of open circuit transmission lines the reflection coefficient is

69. Impedance relay is used on

70. Which type of insulators are used on 132 kV transmission lines ?

71. String efficiency can be improved by

74. Alternating current power is transmitted at high voltage

77. The function of steel wire in a ACSR conductor is

78. In high voltage transmission lines the top most conductor is

82. The permissible voltage variation in transmission and distribution system is