Q.01 Which of the following is/are main properties of conductor used for transmission and distribution of electric power?
A. low specific gravity
B. high electrical conductivity
C. low cost
D. all of the above
Ans.: D
Q.02 Which of the following conductor materials commonly used for over head line?
A. aluminum
B. copper, galvanized steel
C. steel-cored aluminum
D. cadmium copper
E. all of the above
Ans.: E
Q.03 Copper used for transmission of electrical power is made up of ___
A. soft drawn copper
B. hard drawn copper
C. hot drawn copper
D. cold drawn copper
Ans.: B
Q.04 What are the advantages of copper conductor?
A. high current density
B. smaller cross sectional area required
C. high scraps value
D. all of the above
Ans.: D
Q.05 The conductivity of aluminum is ____ of copper.
A. 60%
B. 50%
C. 90%
D. 120%
Ans.: A
Q.06 The diameter of aluminum is about ____times the diameter of copper for the same resistance.
A. 2
B. 2.5
C. 1.26
D. 4
Ans.: C
Q.07 The specific gravity if copper is of ____ order.
A. 8.9 gm/cc
B. 1.5 gm/cc
C. 5.9 gm/cc
D. 10.9 gm/cc
Ans.: A
Q.08 The increased cross sectional is of aluminum
A. exposes a greater surface to wind pressure
B. greater transverse strength of supporting tower
C. higher tower with greater sag
D. all of the above
Ans.: D
Q.09 The specific gravity if aluminum is ____
A. 2.00 gm/cc
B. 2.71 gm/cc
C. 3.71 gm /cc
D. 4.71 gm/cc
Ans.: B
Q.10 Which of the following is true?
A. Aluminum is cheap and light as compared to copper
B. aluminum is more costly and light as compared to copper
C. aluminum is cheap and heavy in weight as compared to copper
D. aluminum is more costly and heavy in weight as compared to copper
Ans.: A
Q.11 In which conductor make greater sag?
A. copper
B. Aluminum
C. hard drawn copper
D. soft drawn copper
Ans.: B
Q.12 If aluminum conductor being light,
A. liable to greater swings
B. liable to greater sag
C. liable to long span
D. all of the above
Ans.: A
Q.13 _____ conducting material required larger cross arms.
A. copper
B. Aluminum
C. hard drawn copper
D. soft drawn copper
Ans.: B
Q.14 The aluminum conductor has___ the weight of equivalent copper conductor.
A. almost doubled
B. almost three times
C. almost one-half
D. almost one-four times
Ans.: C
Q.15 Why copper is not used for transmission conductor?
A. due to heavy weight
B. due to high cost
C. due to less transverse to wind
D. due to low sag
Ans.: B
Q.16 Why the sag is greater in aluminum conductor?
A. due to higher co-efficient of expansion
B. due to low tensile strength
C. Both A and B
D. due to higher tensile strength and low co-efficient of expansion
Ans.: C
Q.17 To increase the tensile strength, the aluminum conductor is reinforced with a core of _____ wire.
A. galvanized steel
B. cadmium
C. iron
D. copper
Ans.: A
Q.18 What is full form of A.C.S.R?
A. aluminum core steel reinforced
B. Aluminum conductor steel reinforced
C. amalgam core steel reinforced
D. alkaline coated steel-aluminum rigidity
Ans.: B
Q.19 What are the advantages of steel core aluminum conductors?
A. tower of smaller heights can be used due to smaller sag with steel core aluminum conductor
B. It will produce smaller sag and longer span
C. reinforcement with steel increases the tensile strength
D. all of the above
Ans.: D
Q.20 In ACSR the
A. central core of galvanized steel wire surrounded by a number of aluminum strands
B. central core of galvanized aluminum wire surrounded by a number of steel strands
C. central core of hard drawn copper wire surrounded by a number of aluminum strands
D. central core of galvanized steel wire surrounded by a number of copper strands
Ans.: A
Q.21 Galvanized steel ___
A. has very high tensile strength
B. used for extremely long span
C. found very suitable in rural areas where cheapness is main consideration
D. all of the above
Ans.: D
Q.22 Why Galvanized steel is not used for transmission of bulk electrical power?
A. due to poor conductivity
B. due to high resistance of steel
C. Both A and B
D. due to high mechanical strength
Ans.: C
Q.23 The supporting structure of line support posses following properties?
A. light in weight
B. high mechanical strength
C. longer life and easily accessible of conductor for maintenance
D. all of the above
Ans.: D
Q.24 Why cadmium copper conductor is not used now a days?
A. due to low mechanical strength
B. due to high cost
C. due to high weight
D. due to low conductivity
Ans.: B
Q.25 The choice of supporting structure for particular is depends upon____
A. cross sectional area
B. cost and local condition
C. line voltage and line span
D. all of the above
Ans.: D
Q.26 Wooden poles are made up of _____.
A. seasoned wood
B. Neem wood
C. Pine wood
D. Sagwan wood
Ans.: A
Q.27 Wooden pole is used up to ____span length.
A. 100 km
B. 50 km
C. 150 km
D. 80 km
Ans.: B
Q.28 The life of wooden pole is about____ years.
A. 20-25
B. 25-30
C. 35-40
D. 50-60
Ans.: A
Q.29 The wooden poles generally rot ____
A. above the ground
B. below the ground
C. at the top of the poles
D. any of the above
Ans.: B
Q.30 What are the disadvantages of wooden poles?
A. less mechanical strength
B. required periodic inspection
C. smaller life
D. all of the above
Ans.: D
Q.31 Wooden pole cannot be used for voltage higher than____
A. 20 KV
B. 33 kV
C. 66 kV
D. 1 132 KV
Ans.: A
Q.32 In order to prevent rot below the ground level and foundation failure, wooden pole below the ground level is impregnated with preservative compound like____
A. crude oil
B. Creosote oil
C. Grease
D. varnished
Ans.: B
Q.33 The steel poles are__
A. posses greater mechanical strength
B. often used as substitute for wooden poles
C. longer life and permit longer spans
D. all of the above
Ans.: D
Q.34 The steel poles are of __
A. Tubular poles type
B. Rolled steel joint type
C. Rail poles type
D. all of the above
Ans.: D
Q.35 The steel poles type of supports needs ___ in order to increase or prolong its life.
A. painted
B. galvanized
C. Both A or B
D. cemented foundation
Ans.: C
Q.36 Which of the following pole becomes very popular for distribution of electrical energy?
A. wooden poles
B. RCC poles
C. Steel poles
D. steel towers
Ans.: B
Q.37 RCC poles have___
A. longer life
B. greater mechanical strength
C. permits longer span than steel poles
D. all of the above
Ans.: D
Q.38 Why holes are provided in RCC poles?
A. to facilitate the climbing
B. to reduce the weight of line supports
C. to reduced transverse wind pressure
D. all of the above
Ans.: D
Q.39 What are the advantages of RCC poles?
A. requires little maintenance
B. good outlook
C. good insulating properties
D. all of the above
Ans.: D
Q.40 Which of the following is main difficulty with RCC poles?
A. high cost
B. heavy weight
C. Both A and B
D. light in weight and low strength
Ans.: C
Q.41 Following poles are manufactured at site.
A. RCC poles
B. Steel poles
C. Wooden poles
D. steel tower
Ans.: A
Q.42 For long distance transmission of high voltage, ___ are employed.
A. RCC poles
B. steel tower
C. steel poles
D. Tubular poles
Ans.: B
Q.43 Steel towers have___
A. longer spans
B. greater mechanical strength
C. longer life
D. all of the above
Ans.: D
Q.44 Which of the following structure of tower can withstand most sever climatic conditions?
A. Steel towers
B. RCC poles
C. steel poles
D. Wooden poles
Ans.: A
Q.45 Which of the following tower structure requires more maintenance?
A. Steel towers
B. RCC poles
C. steel poles
D. Wooden poles
Ans.: D
Q.46 The insulator provides necessary insulation between ____
A. conductor and conductor
B. conductors and supports
C. supports and earth
D. conductor and earth
Ans.: B
Q.47 The insulators should have _____ properties.
A. high mechanical strength
B. high relative permittivity
C. high electrical resistance
D. all of the above
Ans.: D
Q.48 The materials used for insulators is___
A. Glass
B. Steatite
C. Porcelain
D. all of the above
Ans.: D
Q.49 Which of the following insulating material is the most commonly used?
A. Glass
B. Steatite
C. Porcelain
D. all of the above
Ans.: C
Q.50 The porcelain has ___ properties.
A. mechanical stronger than glass
B. gives less trouble from leakage
C. less affected by change in temperature
D. all of
the above
Ans.: D
Q.51 The permittivity of insulators is affected by
A. impurities
B. cracks
C. porous
D. all of the above
Ans.: D
Q.52 Why electrical resistance of insulator is high?
A. in order to avoid leakage currents to earth
B. in order to avoid leakage currents to conductors
C. in order to avoid leakage currents to insulators
D. in order to avoid leakage currents to poles
Ans.: A
Q.53 The puncture to flash over ratio of insulators is ___
A. unity
B. high
C. zero
D. infinite
Ans.: B
Q.54 Porcelain is produced by firing a high temperature a mixture of ___
A. Sand, quartz
B. kaolin, quartz and feldspar
C. quarts and feldspar
D. Feldspar, sand, iron powder
Ans.: B
Q.55 The dielectric strength of insulators is ___
A. high
A. high
B. low
C. zero
D. not definite
Ans.: A
Q.56 Types of insulators used in transmission line is/are
A. Pin type, shackle type
B. Suspension type
C. strain type
D. all of the above
Ans.: D
Q.57 In pin type insulators there is a groove on the upper end of the insulator for ___
A. mounting of insulators
B. housing the conductors
C. insulate the conductor from support
D. all of the above
Ans.: B
Q.58 Pin type insulators are used up to__ for transmission and distribution of electric power.
A. 66 KV
B. 132 KV
C. 33 KV
D. beyond 132 KV
Ans.: C
Q.59 The electrical breakdown of the insulator may occurs by__
A. puncture
B. flash over
C. Either A or B
D. mechanical cracks
Ans.: C
Q.60 Safety factor of insulator is the ratio of ___
A. flash over voltage to puncture strength
B. puncture strength to flash over voltage
C. puncture strength to rated voltage
D. rated voltage to flash over voltage
Ans.: B
Q.61 In puncture of insulator, the discharge occurs from____
A. pin to conductors
B. conductor to pin
C. pin to earth
D. earth to conductor
Ans.: B
Q.62 Why it is desirable that the value of safety factor is high?
A. because flash over takes place before the insulator gets punctured
B. because flash over takes place after the insulator gets punctured
C. because flash over takes place at the time of insulator gets punctured
D. any of the above
Ans.: A
Q.63 The value of safety factor for pin type insulator is about ____
A. Unity
B. Zero
C. Ten
D. infinity
Ans.: C
Q.64 In suspension type insulators, it consists of number of porcelain discs connected in ____ by metal links in the form of string.
A. parallel
B. series
C. series-parallel
D. any of the above
Ans.: B
Q.65 Suspension type insulators are used ____ voltage level.
A. up to 33 KV
B. up to 22 KV
C. beyond 33 KV
D. beyond 132 KV
Ans.: C
Q.66 Pin type insulators is not economical ____ KV
A. beyond 33
B. beyond 66
C. up to 66
D. beyond 132
Ans.: A
Q.67 In suspension type insulator the conductor is ______
A. suspended at the top of the string
B. suspended at the bottom of the string
C. suspended at the cross arms
D. suspended at the top of the tower
Ans.: B
Q.68 Each disc of the insulators is designed for voltage___
A. 33 KV
B. 66 KV
C. 11 KV
D. 132 KV
Ans.: C
Q.69 What are the advantages of suspension type insulator over pin type insulator?
A. cheaper voltage beyond 33 KV
B. provide flexibility to line
C. it partial protect the conductor from direct lighting
D. all of the above
Ans.: D
Q.70 If transmission line is dead ended or there is corner or line takes turn, following type of insulators is used.
A. suspension type insulator
B. strain type insulators
C. pin type insulator
D. any of the above
Ans.: B
Q.71 For low voltage lines less than 11 kv,____ insulator is used as strain insulator.
A. shackle type insulator
B. strain type insulator
C. Suspension type insulator
D. pin type insulator
Ans.: A
Q.72 Shackle type insulators are__
A. used for low voltage distribution lines
B. used either in vertical or horizontal position
C. directly fixed to the poles with a bolt or in the cross arms
D. all of the above
Ans.: D
Q.73 String efficiency is the ratio of voltage across the _____ to the product of number of disc and the voltage across the disc nearest to the conductor.
A. whole string
B. top most disc
C. line conductor
D. flash over voltage of disc
Ans.: A
Q.74 If the string efficiency is greater,____
A. the more uniform is the voltage distribution
B. less uniform is the voltage distribution
C. transmission of high voltage
D. transmission of low voltage
Ans.: A
Q.75 In an ideal case the string efficiency is ____
A. less than 100%
B. more than 100%
C. 100%
D. any of the above
Ans.: C
Q.76 In suspension insulator string the capacitance between each disc form a capacitor is called____.
A. self capacitance
B. mutual capacitance
C. shunt capacitance
D. Both A or B
Ans.: D
Q.77 Capacitance exist between metal fitting of each disc and tower or earth of suspension insulator string is known as____
A. self capacitance
B. mutual capacitance
C. shunt capacitance
D. Both A or B
Ans.: C
Q.78 Due to which of the following charging current is not the same through all the discs of the string?
A. shunt capacitance
B. mutual capacitance
C. self capacitance
D. Both A or B
Ans.: A
Q.79 The voltage across each disc of the string will be ___.
A. same
B. different
C. zero
D. any of the above
Ans.: B
Q.80 In suspension insulator string the maximum voltage appears across the disc ____.
A. nearest to the line conductor
B. at intermediate disc of the string
C. at the top disc of the string
D. on the conductor
Ans.: A
Q.81 If the voltage impressed across the string is D.C then voltage across each unit/ disc would be__
A. maximum
B. same
C. minimum
D. none of the above
Ans.: B
Q.82 In insulator string_____ is likely to be more punctured.
A. disc at the top of string
B. intermediate disc
C. unit nearest to the conductor
D. at clamping
Ans.: C
Q.83 If the value of the shunt capacitance to self capacitance is more then__
A. more is the string efficiency
B. less is the efficiency
C. efficiency is 100%
D. all of the above depend on voltage magnitude
Ans.: C
Q.84 String efficiency can be improved by
A. by grading the insulators
B. by using a guard ring
C. by using longer cross-arms
D. all of the above
Ans.: D
Q.85 The string efficiency depend on the ratio of __
A. mutual capacitance to shunt capacitance
B. shunt capacitance to mutual capacitance
C. mutual capacitance to self capacitance
D. self capacitance to shunt capacitance
Ans.: B
Q.86 Voltage across the string is ___
A. equal to the voltage between line and earth
B. equal to the voltage between conductor and arms
C. equal to the voltage between each unit and conductor
D. any of the above
Ans.: A
Q.86 Which of the following is true?
A. line voltage = √2 x voltage across the string
B. line voltage = voltage across the string
C. line voltage = √3 x voltage across string
D. line voltage = phase voltage
Ans.: C
Q.87 Following is true of insulator string
A. shorter string has less efficiency than larger string
B. shorter string has more efficiency than larger string
C. shorter string has equal efficiency than larger string
D. none of the above
Ans.: B
Q.88 When an insulator is permanently damaged?
A. due to break down
B. due to flash over
C. due to cracks
D. all of the above
Ans.: A
Q.89 If the nearest unit to the conductor breaks down in suspension insulator string then ___
A. only one disc will break
B. other unit will also breakdown
C. top most unit will breakdown
D. none of the disc will breakdown
Ans.: B
Q.90 By using a guard ring , string efficiency is ___
A. remains same
B. decreases
C. increases
D. none f the above
Ans.: C
Q.91 When an alternating voltage applied across two conductor is exceeds a certain limit or value is known as____.
A. corona
B. critical disruptive voltage
C. ionization
D. all of the above
Ans.: B
Q.92 The phenomenon of violet glow, hissing noise and production of ozone gas in an overhead transmission line called___
A. corona
B. critical disruptive voltage
C. ionization
D. breakdown voltage
Ans.: A
Q.93 The phenomenon of corona is accompanied by a____
A. production of ozone
B. power loss and radio interference
C. hissing sound
D. All of the above
Ans.: D
Q.94 A flash over will occurs between the conductors due to the ___
A. applied voltage is increased to breakdown value
B. applied voltage is decreased to breakdown value
C. applied voltage is increased to visual disruptive value
D. any of the above
Ans.: A
Q.95 If the given conductors are polished and smooth then corona glow will be___
A. non uniform throughout the length of conductor
B. not occurs throughout the length of conductor
C. uniform throughout the length of conductor
D. appears bright at some point in the length of conductor
Ans.: C
Q.96 Why some ionization is always present in air?
A. due to ultraviolet radiations
B. due to cosmic rays
C. due to radioactivity
D. all of the above
Ans.: D
Q.97 What are factors affecting corona?
A. Conductor size and line voltage
B. spacing between conductors
C. Atmosphere
D. all of the above
Ans.: D
Q.98 The minimum phase to neutral voltage at which corona occurs is called__
A. visual critical voltage
B. critical disruptive voltage
C. power loss due to corona
D. corona glow
Ans.: B
Q.99 Corona is formed or occurs due to _____
A. ionization of insulators
B. ionization of air between conductor and earth
C. ionization of air surrounding the conductor
D. ionization of air between conductor and insulator
Ans.: C
Q.100 In the stormy weather condition of atmosphere the corona occur at___
A. much less voltage than fair weather condition
B. high voltage than fair weather condition
C. doesn’t occurs
D. not definite
Ans.: A
Q.101 Which of the following will gives rise to more corona?
A. rough conductor surface
B. smooth conductor surface
C. Both A and D
D. irregular conductor surface
Ans.: C
Q.102 What happens If the spacing between the conductor is made very large as compared to diameter of conductor?
A. irregular corona will occurs
B. uniform corona will occurs
C. corona may not occurs
D. any of the above
Ans.: C
Q.104 Which of the following is true of corona?
A. it is affected by the physical condition of atmosphere
B. it depends upon the shape and size of conductor
C. it depends upon the line voltage
D. all of the above
Ans.: D
Q.104 In rough surface of conductor, the corona glow will ___
A. appear bright at rough point
B. not occurs
C. smooth at rough point
D. any of the above
Ans.: A
Q.105 If the transmission voltage is D.C, the corona will occurs__
A. non uniform throughout the conductor length
B. uniform throughout the conductor length
C. different in the appearance of the two wires
D. not occurs
Ans.: C
Q.106 Corona loss can be avoided by__
A. large spacing between conductors
B. by using smooth surface conductors
C. low line voltage
D. all of the above
Ans.: D
Q.107 The breakdown strength of air is __(max).
A. 33 kV/cm
B. 30 kV/cm
C. 11 kV/cm
D. 66 kV/cm
Ans.: B
Q.108 When corona is formed when the value of potential gradient is ____.
A. less than the breakdown strength of air
B. more than the breakdown strength of air
C. equal to the breakdown strength of air
D. either A or B
Ans.: C
Q.109 The breakdown strength of air at 76 cm of mercury and 25°C is
A. 21.2 KV/cm (r.m.s)
B. 30 KV/cm (r.m.s)
C. 33 KV/cm (r.m.s)
D. 31.3 KV/cm (r.m.s)
Ans.: A
Q.110 The breakdown strength of air is____
A. inversely proportional to the air density
B. directly proportional to the air density
C. directly proportional to the square of air density
D. inversely proportional to the square of air density
Ans.: B
Q.111 The value of air density factor under standard condition is __
A. less than unity
B. more than unity
C. unity
D. depend upon the weather condition
Ans.: C
Q.112 Irregularity factor of polished conductor is ____
A. unity
B. less than unity
C. more than unity
D. zero
Ans.: A
Q.113 The minimum phase to neutral voltage at which corona glow appears all along the line conductor is known as__
A. disruptive critical voltage
B. visual critical voltage
C. breakdown voltage
D. all of the above
Ans.: B
Q.114 Power loss of energy loss due to which is dissipated in the form of ____
A. chemical action
B. heat and light
C. sound
D. all of the above
Ans.: D
Q.115 Irregularity factor for stranded conductors is____
A. 0.98 to 0.92
B. 0.87 to 0.8
C. 1.00
D. 0.00
Ans.: B
Q.116 Which of the following is true irregularity factor for conductors?
A. 1.00 for polished conductors
B. 0.98 to 0.92 for dirty conductors
C. 0.72 to 0.82 for rough conductors
D. all of the above
Ans.: D
Q.117 what are the advantages of corona?
A. virtual diameter of conductor is increased which reduced the electrostatic stresses between the conductors
B. it reduces the effects of transients produced by surges
C. Both A and B
D. neither A or B
Ans.: D
Q.118 Corona effect can be reduced by____
A. increasing conductor spacing
B. increasing conductor size
C. using stranded conductor
D. all of the above
Ans.: D
Q.119 Followings are the disadvantages of corona.
A. corrosion of corona due to chemical action
B. loss of energy
C. cause inductive interference with neighboring communications lines or system
D. all of the above
Ans.: D
Q.120 The current drawn by line due to corona is ____.
A. sinusoidal in wave
B. triangular in wave
C. non sinusoidal in wave
D. cosine in wave
Ans.: C
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