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Latest TNPSC CES Exam Question (Objective Questions), MCQ in English
Subjects : Electrical Engineering
Question Bank TNPSC Combined Engineering Service Electrical Engineering Exam (Paper-I) - English
Electrical Engineering
Q 1 :
Resistance switching is normally resorted in case of
A.Air blast CB
B.Bulk oil CB
C.Minimum oil CB
D.All types of CB
Q 2 :
By transmitting power at high voltage
A.it will give poor voltage regulation
B.it will give better voltage regulation
C.it will not effect voltage regulation
D.None of these
Q 3 :
Which statement about the daily load curve is valid ?
A.The area under the curve gives the average demand
B.The ratio of the area under the curves to the total area of rectangle in which it is contained gives the load factor for the day
C.The peak of the curve gives the installed capacity of the plant
D.The area of the curves divided by the number of hours gives load factor
Q 4 :
High voltage Schring bridge is used to measure
A.large capacitance without additional element
B.small capacitance without additional element
C.medium value capacitance
D.None of these
Q 5 :
Draw - in - system of laying underground cables has the drawback (s) of
A.higher cost
B.reduced current carrying capacity of the cables
C.requirements of much deeper and wider trenches
D.repairs, alterations or additions difficult
E.all of the above except
Q 6 :
Surge impedance of a transmission line is
A.independent of its length
B.dependent on its length
C.independent on its temperature
D.none of the above
Q 7 :
If two synchronous generators connected in parallel loose synchronism, it will lead to
A.stalling of generators
B.wild fluctuations in current
C.wild fluctuations in current and voltage
D.None of these
Q 8 :
A differential relay responds to
A.algebraic difference of two or more similar electrical quantities
B.vector difference of two or more similar electrical quantities
C.algebraic difference between two currents
D.algebraic difference between two voltages
Q 9 :
The conductor carries more current on the surface in comparison to its core. This phenomenon is called the
A.Skin effect
B.Corona
C.Ferranti effect
D.Lenz's effect
Q 10 :
A booster is connected in
A.series with the feeder
B.parallel with the feeder
C.both (a) and (b) are correct
D.none of these
Q 11 :
Fuses have got advantages of
A.cheapest type of protection
B.inverse time - current characteristic
C.no maintenance
D.current limiting effect under short - circuit conditions
E.all of the above
Q 12 :
The power transmitted will be maximum when
A.line reactance is high
B.corona losses are minimum
C.sending end voltage is more
D.receiving end voltage is more
Q 13 :
The connected load of a consumer is 2 kW and his maximum demand is 1.5 kW. The load factor of the consumer is
A.0.75
B.0.375
C.1.33
D.None of these
Q 14 :
In a transformer, the exciting current will be in phase quadrature with the impressed voltage provided
A.only the leakage impedance drop is ignored
B.only the core loss is ignored
C.both the leakage impedance drop and the core loss are ignored
D.only the no - load copper loss is ignored
Q 15 :
Which of the following techniques is used for the measurements of a.c. high frequency voltages ?
A.Peak voltmeter
B.Series resistance mircro - ammeter
C.Resistance potential divider
D.All of these
Q 16 :
Use of additional shunt capacitor can be made for increasing the capability of line as it
A.reduces surge impedance Z0
B.increases phase shift β
C.increase in α
D.all of the above
Q 17 :
The sag of a transmission line is least affected owing to
A.weight of the conductor
B.current through the conductor
C.atmospheric temperature
D.ice deposited on the conductor
Q 18 :
In case of Impulse Thermal break down of solid insulating materials, the critical electric field is proportional to
A.critical absolute temperature
B.square of critical absolute temperature
C.square of T0
D.none of these
Q 19 :
The insulation of the modern EHV lines is designed based on
A.corona
B.switching voltages
C.lightning voltage
D.all of these
Q 20 :
For constant voltage transmission, the voltage drop along the line is maintained constant by installing
A.capacitors
B.inductors
C.resistors
D.synchronous phase modifiers at the receiving end
Q 21 :
AC network analyser is employed for solving the problems of
A.load flow
B.load flow and stability
C.load flow and short - circuit
D.load flow, stability and short - circuit
Q 22 :
The change in excitation in an alternator connected to an infinite line provides a corresponding change in
A.terminal voltage
B.speed of rotor
C.power generated
D.power factor
Q 23 :
Different types of insulators used for transmission lines are
A.pin type only
B.suspension type only
C.strain type only
D.pin type, suspension type and shackle type
Q 24 :
The conductor connecting consumer's terminals to the distributor is called the
A.feeder
B.distributor
C.service main
D.none of the above
Q 25 :
Which of the following method or techniques can be used for the measurement of high d.c. voltages ?
A.Generating voltmeter
B.Electrostatic voltmeter
C.Peak voltmeter
D.Half effect generators
Q 26 :
The ripple voltage in dc output is small if
A.frequency of supply voltage is small
B.the filtering capacitor is small
C.load current is small
D.none of these
Q 27 :
The voltage measurements using uniform spark gap are
A.affected by dust particles
B.affected by polarity of supply
C.affected by temperature
D.none of these
Q 28 :
Neutral earthing is provided for
A.the safety of personnel from electric shock
B.the safety of equipment and personnel against lightning and voltage surges
C.reducing the voltage stress on lines and equipment with respect to earth under various operating and fault conditions
D.controlling the earth fault currents for protective relaying
E.both (c) and (d)
Q 29 :
The function of Lightning arrester is
A.to limiting the short - circuit fault current
B.to provide path to high voltage surge to earth
C.to reduce arcing
D.none of these
Q 30 :
In which of the following cases are delay fuses used ?
A.For the protection of light circuits
B.For the protection of power out - let circuits
C.For the protection of fluorescent lamps
D.For the protection of motors
Q 31 :
In order to improve the voltage profile of the line, compensation is resorted by providing
A.capacitors at the receiving end
B.reactors at the receiving end
C.resistors at the receiving end
D.none of these
Q 32 :
Skin effect in conductor is proportional to
A.(diameter of conductor) 1/2
B.diameter of conductor
C.(diameter of conductor)2
D.(diameter of conductor)4
Q 33 :
The function of steel wire in an ACSR conductor is to
A.compensate for skin effect
B.take care of surges
C.provide additional mechanical strength
D.reduce inductance
Q 34 :
A fault is more severe from the view point of RRRV if it is a
A.Short length fault
B.Medium length line fault
C.Long length line fault
D.None of these
Q 35 :
Protective resistance to be connected between the sphere gap and the test equipment is required while measuring
A.power frequency and higher frequency a.c. voltage
B.power frequency and impulse voltage
C.all kinds of voltages
D.none of these
Q 36 :
Series capacitor is used in a transmission line to
A.compensate the voltage drop
B.reduce line loss
C.limit short circuit current
D.improve load power factor
Q 37 :
The passive element that is used as interconnecting element for the stable operation of interconnected system is
A.reactor
B.resistor
C.capacitor
D.resistor and capacitor
Q 38 :
Corona loss in a transmission line is dependent on
A.diameter of the conductor
B.material of the conductor
C.height of the conductor
D.none of these
Q 39 :
In a minimum oil circuit breaker the oil is used
A.to act as circuit breaking medium only
B.for circuit breaking and providing insulation
C.for providing insulation only
D.for none of the above purposes
Q 40 :
Skin effect is
A.proportional to frequency
B.proportional to square of frequency
C.inversely proportional to frequency
D.independent of frequency
Q 41 :
Rated making capacity of breaker is equal to
A. X rated symmetrical breaking capacity
B.2.55 X rated symmetrical breaking capacity
C.1 X rated symmetrical breaking capacity
D.none of these
Q 42 :
The main reason for using high voltage for long distance power transmission is
A.reduction in transmission losses
B.reduction in time of transmission
C.increase in system reliability
D.none of the above
Q 43 :
Bus - coupler is very essential in
A.single bus - bar arrangement
B.ring bus - bar arrangement
C.double bus, double breaker arrangement
D.main and transfer bus
Q 44 :
With the rise in temperature, the insulation resistivity
A.remains unchanged
B.decreases linearly
C.increases linearly
D.reduces exponentially
Q 45 :
The effect of bonding the cable is
A.to increase the effective resistance and inductance
B.to increase the effective resistance but reduce inductance
C.to reduce the effective resistance and inductance
D.to reduce the effective resistance but increase the inductance
Q 46 :
Increase in temperature in overhead transmission lines causes
A.increase in stress and length
B.decrease in stress and length
C.decrease in stress but increase in length
D.none of the above
Q 47 :
The insulation resistance of the cable decreases with the
A.increase in length of cable
B.decrease in length of cable
C.electric stresses
D.none of these
Q 48 :
Corona has the disadvantage(s) of
A.power loss
B.interference with neighbouring communication circuits
C.introducing the harmonics, predominately third harmonics, into the transmission lines
D.all of the above
Q 49 :
In a load duration curve for an intergrated power system the uppermost crest represents the energy contributed by
A.base power stations
B.major thermal stations
C.peaking hydro or gas turbine stations
D.non - conventional power stations
Q 50 :
At bridge crossing and near the railway track ternary lead cables are used because they
A.are of high tensile strength
B.are of low coefficient of thermal expansion
C.are of low specific gravity
D.can withstand shocks and vibrations
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TNPSC Combined Engineering Service Electrical Engineering Exam (Paper-I) Question Bank Book - English
The heat produced at the contact point owing to flow of electric current is least affected by
A.temperature of the surrounding medium
B.contact resistance
C.magnitude of electric current flowing
D.duration of flow of current
Q 52 :
A stationary alternator should not be connected to the live bus - bar because
A.it is likely to operate as a synchronous motor
B.it will get short - circuited
C.it will reduce bus - bar voltage
D.all of the above
Q 53 :
In a transmission system the feeder supplies power to
A.transformer substations (step - up)
B.service mains
C.distributors
D.all of the above
Q 54 :
For a given amount of power to be transmitted over a certain distance with fixed power loss, the volume of copper required is
A.directly proportional to voltage
B.inversely proportional to voltage
C.inversely proportional to the square of voltage and pf of the load
D.directly proportional to the square of the voltage and pf of the load
Q 55 :
Power despatch through a line can be increased by
A.installing series capacitors
B.installing shunt capacitors
C.installing series reactor
D.installing shunt reactor
Q 56 :
In the figure shown which curve represents the variation of cost of generation per kWh with the load factor, for a thermal power plant ?
​
A.Curve A
B.Curve B
C.Curve C
D.Curve D
Q 57 :
Under 'no load conditions the current in a transmission line is because of
A.capacitance effect
B.corona effect
C.proximity effect
D.back flow from earth
Q 58 :
The only advantage of corona is that it
A.produces a pleasing luminous glow
B.makes line current sinusoidal
C.works as a safety valve for surges
D.ozone gas is produced
Q 59 :
Earth wires are made of
A.copper
B.aluminium
C.iron
D.galvanised stranded steel
Q 60 :
The connected load of a consumer is 2 kW and his maximum demand is 1.5 kW. The demand factor of the consumer is
A.0.75
B.0.375
C.1.33
D.none of the above
Q 61 :
A lightning arrester connected between the line and earth in a power system
A.protects the terminal equipment against travelling surges
B.protects the terminal equipment against direct lightning stroke
C.suppresses high frequency oscillations in the line
D.reflects back the travelling waves approaching it
Q 62 :
Oil filled cables have the advantage(s) of
A.smaller overall size
B.most perfect impregnation
C.easy detection of fault
D.all of the above
Q 63 :
A bus coupler circuit breaker is utilised in a substation for
A.joining the transmission line with station bus - bar
B.joining main and transfer bus in a substation
C.joining the generator with transfer
D.joining the neutral of the generator with earth
Q 64 :
The fluids used in circuit breakers should be of
A.high dielectric strength and thermal stability
B.non - inflammability
C.are extinguishing ability
D.all of the above
Q 65 :
Feeder is designed mainly from the point of view of
A.its current carrying capacity
B.voltage drop in it
C.operating voltage
D.operating frequency
Q 66 :
Power output per unit volume of an MHD generator is proportional to
A.specific electrical conductivity of gas
B.square of the magnetic field strength
C.square of the fluid velocity
D.all of the above
Q 67 :
Increase in frequecy of transmission line causes
A.no change in line resistance
B.increase in line resistance
C.decrease in line resistance
D.decrease in line series reactance
Q 68 :
A dc series generator can excite itself
A.only on zero load current
B.only when load current is not zero
C.irrespective of the value of load current
D.none of the above
Q 69 :
Thermal relays are used for protection of motors against over - current owing to
A.short - circuits
B.heavy loads
C.earth fault
D.all of these
Q 70 :
Transmission efficiency of a transmission line increases with the
A.decrease in power factor and voltage
B.increase in power factor and voltage
C.increase in power factor but decrease in voltage
D.increase in voltage but decrease in power factor
Q 71 :
While using air - blast circuit breaker, current chopping is a phenomenon often observed when
A.a long overhead line is switched off
B.a bank of capacitors is switched off
C.a trasformer on no - load is switched off
D.none of these
Q 72 :
The contact resistance of a circuit breaker is about
A.20 Ω
B.2 Ω
C.20 mΩ
D.20 μΩ
Q 73 :
Metallic shielding is provided on underground cables to
A.reduce thermal resistance
B.reduce corona effect
C.control the electrostatic voltage stress
D.all of the above
Q 74 :
The most economical limit of power factor correcting is governed by
A.original power factor
B.relative costs of the supply and power factor correction equipment
C.both (a) and (b)
D.none of the above
Q 75 :
A short - circuit current is identified by
A.heavy current flow
B.voltage rise
C.voltage drop
D.none of these
Q 76 :
Which of the following materials is not used for transmission and distribution of electrical power ?
A.Tungsten
B.Copper
C.Aluminium
D.Cadmium copper
Q 77 :
Which of the following alternators will have maximum number of poles ?
A.Alternator coupled to hydraulic turbine
B.Alternator coupled to steam turbine
C.Alternator coupled to gas turbine
D.All will have same number of poles
Q 78 :
In humid weather, the corona occurs at a voltage
A.much less than the needed in fair weather
B.much higher than that needed in fair weather
C.equal to that needed in fair weather
D.none of the above
Q 79 :
Short - circuit currents are due to
A.single phase to earth fault
B.phase to phase fault
C.all the three phases to earth fault
D.all the three phases short - circuited
E.any of the above
Q 80 :
Over - current protection respond to
A.increase in current above pick - up value
B.single line to earth faults
C.double line to earth faults
D.all of the above
Q 81 :
A fuse is
A.always connected in series with the circuit
B.always connected in parallel with the circuit
C.normally connected in series with the circuit
D.none of these
Q 82 :
Standard impulse testing of power transformer requires
A.one application of chopped wave followed by one application of full - wave
B.two applications of chopped wave followed by an application of a full - wave
C.one application of chopped wave followed by two application of a full - wave
D.none of these
Q 83 :
The presence of earth in case of overhead lines
A.increases the capacitance
B.increases the inductance
C.decreases the capacitance and increases the inductance
D.does not effect any of the line constants
Q 84 :
Partial discharge measurement on a cable gives
A.p.f of the cable
B.loss angle of the cable
C.location of fault
D.None of these
Q 85 :
Any leakage of air into the condenser destroys the vacuum and causes
A.an increase in air pressure in the condenser limiting the useful heat drop in the steam turbine
B.lowering of the partial pressure of the steam and of the saturation temperature along with it
C.undercooling of the condensate more severe
D.all of the above
Q 86 :
The intersheaths in cables are used to
A.provide proper stress distribution
B.minimize the stress
C.provide protection against moisture and voltage surges
D.provide protection against current and voltage surges
Q 87 :
The string efficiency of insulators can be increased by
A.reducing the number of strings
B.increasing the number of strings
C.correct grading of insulators of various strings
D.none of these
Q 88 :
Which one of the following statements regarding the position of minimum copper loss in a phase of rotary convertor is true ?
A.The position of minimum copper loss is in the middle of the phase whatever may be the power factor
B.The position of minimum copper loss varies with the variation in power factor and this position is displaced from the middle of the phase by the power factor angle
C.The position of minimum copper loss is the tapping point whatever may be the power factor
D.None of the above
Q 89 :
In order to have lower cost of electrical generation
A.the load factor and diversity factor should be high
B.the load factor should be low but diversity factor high
C.the load factor should be high but diversity factor low
D.the load factor and diversity factor should be low
Q 90 :
The stability limit of system is defined as the value of power below which
A.the system is stable and above which also stable
B.the system is unstable and above which it is stable
C.the system is stable and above which it is unstable
D.none of these
Q 91 :
Swing equation represents
A.the variation of power with respect to time
B.the variation of torque angle with respect to time
C.the variation of input power with respect to time
D.none of these
Q 92 :
In case of Impulse Thermal breakdown of insulating materials, the critical time to breakdown is
A.proportional to critical electric field
B.inversely proportional to critical electric field
C.proportional to square of critical absolute temperature
D.none of these
Q 93 :
Economiser in a steam power plant
A.improves the boiler efficiency by 10 - 12 %
B.saves fuel consumption by 5 - 15 %
C.becomes a necessity for pressure
D.none of these
Q 94 :
Conductor configuration determine
A.inductance
B.sag
C.voltage
D.current
Q 95 :
If the length of the arc of circuit breaker increases, its resistance
A.be extinguished
B.decreases
C.remains same
D.none of these
Q 96 :
If the frequency of a transmission system is changed from 50 Hz to 100 Hz, the string efficiency
A.will increase
B.will decrease
C.remain unchanged
D.may increase or decrease depending on the line parameters
Q 97 :
The pressurised water reactors employ
A.light water and natural uranium
B.heavy water and enriched uranium
C.light water and enriched uranium
D.none of the above combinations
Q 98 :
The suitable turbine used for harnessing tidal power is
A.Francis turbine
B.Pelton turbine
C.Kaplan turbine
D.None of these
Q 99 :
In an AC Transmission line, difference in phase of voltages at the two ends of the line is due to
A.resistance of line
B.system voltage
C.reactance of line
D.insulators
Q 100 :
Steam power plants work closely on
A.Binary vapour cycle
B.Brayton cycle
C.Rankine cycle
D.Carnot cycle
Q 101 :
If the tariff for electrical energy charges provides incentive by way of reduced charges for higher consumption, then it may be concluded that the
A.load factor is high
B.power factor is high
C.plant has sufficient reserve capacity
D.power is generated through hydro - power plant
Q 102 :
In overhead lines, the presence of earth wire causes
A.increase in the capacitance
B.increase in the inductance
C.decrease in the capacitance
D.decrease in the inductance
Q 103 :
The use of reactors permits circuit breakers of the installation of
A.lower rating
B.higher rating
C.same rating
D.none of these
Q 104 :
In power plants, the condenser normally used is
A.Surface type
B.Jet type
C.Both surface and jet type
D.Regenerative type
Q 105 :
The critical mass of a nuclear reactor depends upon
A.the enrichment of the fuel used
B.the moderator material used
C.both the enrichment of fuel and moderator material
D.none of these
Q 106 :
When the load on a transmission line is equal to the surge impedance loading
A.the receiving end voltage is less than the sending end voltage
B.the sending end voltage is less than the receiving end voltage
C.the receiving end voltage is equal to the sending end voltage
D.none of these
Q 107 :
In a power plant, a reserve generating capacity which is not in service but is in operation is known as
A.hot reserve reserve
B.cold
C.firm power
D.spinning reserve
Q 108 :
What is the advantage of hydro - electric power stations over thermal power stations ?
A.The initial cost of hydro - electric power stations is low .
B.Their operating cost is low .
C.Hydro - electric power stations can supply the same power throughout the year .
D.Hydro - electric power stations can be constructed where electric energy is required .
Q 109 :
Galvanised steel wire is usually used as
A.stay wire
B.earth wire
C.structural components
D.all of the above
Q 110 :
It is always economical to improve the p.f. of an installation to
A.zero
B.unity
C.a little less than unity
D.a little more than unity
Q 111 :
The efficiency of a transmission line
A.increases with the decrease in load p.f.
B.is independent of load p.f.
C.increases with the increase in load p.f.
D.decreases with the increase in load p.f.
Q 112 :
If the source is not able to supply charging current required by the test cable, it is desirable to use
A.shunt capacitor
B.series capacitor
C.series inductor
D.none of these
Q 113 :
Isolated neutral transmission system is not recommended as the
A.system insulation is overstressed due to over - voltages
B.insulation overstress may lead to its failure resulting in phase to phase faults
C.system is not adequately protected against earth fault
D.all of the above
Q 114 :
The power loss in an overload transmission line is mainly due
A.impedance of the line conductor
B.resistance of each conductor
C.inductance of each conductor
D.capacitance of each conductor
Q 115 :
Sulphur hexafluoride cable is insulated by
A.impregnated paper
B.polyvinyl chloride
C.high pressure oil
D.compressed gas
Q 116 :
The voltage of a bus can be controlled by controlling the
A.phase angle
B.reactive power of the bus
C.active power of the bus
D.phase angle and the reactive power
Q 117 :
A three phase breaker is rated at 2000 MV A, 33 kV, its making current will be
A.35 kA
B.70 kA
C.89 kA
D.160 kA
Q 118 :
The insulation used in a cable designed for use on 1000 kV is usually
A.impregnated paper
B.compressed SF, gas
C.PVC
D.any of the above
Q 119 :
The main function of under voltage protective device generally employed with a motor starter is to power
A.open the supply circuit on failure of supply
B.control the motor voltage
C.prevent the opening of supply circuit
D.none of the above
Q 120 :
Which of the following power plants is free from environmental problems ?
A.Diesel engine
B.Nuclear
C.Hydro - electric
D.Steam
Q 121 :
Which of the following is not a secondary nuclear fuel ?
A.Pu239
B.U233
C.U235
D.None of above
Q 122 :
The purpose of the moderator in a nuclear power plant is to water inlet
A.control the flow of
B.control the amount of nuclear fuel into the reactor
C.control the nuclear fission or fission rate by slowing down the neutrons
D.control the steam flow to the turbine
Q 123 :
Rotating machines are protected against lightning surges by a combination of
A.lightning conductor and capacitor
B.lightning conductor and lightning arrester
C.lightning arrester and capacitor
D.none of these
Q 124 :
The gas turbine power plant can be used in combination with steam power plants by
A.using exhaust gases from gas turbine power plant in heating of feed water coming from the steam trubine condenser
B.using exhaust gases from gas turbine power plant as combustion air in steam boiler
C.using gas from a supercharged boiler for expansion in gas turbine
D.any of the above
Q 125 :
Skin effect
A.increases the effective resistance and effective internal reactance
B.reduces the effective resistance and effective internal reactance
C.increases the effective resistance but reduces the effective internal reactance
D.reduces the effective resistance but increases the effective internal reactance
Q 126 :
The critical clearing time is related to
A.steady state stability limit
B.transient stability limit
C.short - circuit current limit
D.none of these
Q 127 :
As compared to air the relative dielectric strength of sulphur hexafluoride is nearly
A.1.5 times
B.2.5 times
C.4.0 times
D.5.0 times
Q 128 :
The relay best suited for phase fault relaying for medium transmission lines is
A.mho relay
B.reactance relay
C.impedance relay
D.none of these
Q 129 :
In parallel operation of alternators, the synchronising power will be maximum when
A.armatures have resistances equal to their reactances
B.armatures have resistances more than their reactances
C.armatures have resistances lesser than their reactances
D.none of the above
Q 130 :
An adjustable blade propeller turbine is called a
A.Pelton turbine
B.Kaplan turbine
C.Francis turbine
D.None of them
Q 131 :
The criterion for selection of size of conductor for a feeder is
A.Voltage drop
B.Corona loss
C.Temperature rise
D.Radio interference
Q 132 :
Inverse time - current protection of relays are used for the
A.feeders
B.transformers
C.alternators
D.both (a) and (b)
Q 133 :
Surge voltage originate in power system due to
A.lightening
B.switching operations
C.faults
D.all of these
Q 134 :
The proximate analysis of coal gives percentage by weight of
A.moisture and volatile matter
B.moisture, volatile matter, fixed carbon and ash
C.carbon, hydrogen, oxygen, nitrogen, sulphur and ash
D.carbon, hydrogen and oxygen
Q 135 :
A gas turbine works on
A.Carnot cycle
B.Brayton cycle
C.Dual cycle
D.Rankine cycle
E.Regenerative cycle
Q 136 :
Which of the following protects the underground cables against mechanical injury ?
A.Armouring
B.Bedding
C.Sheath
D.None of these
Q 137 :
Coal and peat is not generally used in gas turbines as fuel because of
A.coal handling and ash handling problems
B.their higher costs
C.their non - availability
D.all of the above
Q 138 :
A 1000 kVA transformer with 5% reactance will have a reactance of 10% at
A.1000 kVA base
B.2000 kVA base
C.3000 kVA base
D.4000 kVA base
Q 139 :
In circuit breakers the contact space is ionized by
A.field emission from the contact surface
B.thermal emission from the contact surface
C.thermal ionization of gas
D.any of the above
Q 140 :
When extra stop buttons are added to an existing starter control circuit they must be
A.in series with the contactor coil
B.parallel to the overload
C.parallel to the start button
D.in series with the motor
Q 141 :
In a transmission line, if the load is suddenly increased in the receiving end of the system, the phase shift will
A.decrease
B.become zero
C.increase
D.not be affected
Q 142 :
In case of inter - connected system for stable operation the passive element that can be used as interconnecting element is
A.capacitor
B.reactor
C.resistor
D.any of these
Q 143 :
The rate of rise of restriking voltage depends upon
A.the type of Circuit Breaker
B.the inductance of the system only
C.the capacitance of the system only
D.the inductance and capacitance of the system
Q 144 :
To increase the transmission capability of a high voltage long line
A.the resistance can be increased
B.the resistance can be decreased
C.the series reactance can be reduced
D.the shunt admittance can be reduced
Q 145 :
In Van de Graff generator, output voltage is controlled by
A.controlling the corona source voltage
B.controlling the belt speed
C.controlling the lower spray point
D.all of these
Q 146 :
In a dc 3 - wire distributor using balancers and having unequal loads on the two sides
A.both balancers operate as generators
B.both balancers operate as motors
C.balancer connected to lightly loaded side operates as a generator
D.balancer connected to heavily loaded side operates as a generator
Q 147 :
In context of corona which statement is not true ?
A.Corona is voltage effect .
B.Corona takes place on short transmission lines .
C.Corona is accompanied with power loss .
D.Corona attenuates lightning surges .
Q 148 :
The frequency of voltage generated can be increased by
A.adjusting the governor
B.increasing the excitation
C.reducing the excitation
D.any of the above
Q 149 :
The advantage of transmitting power at high voltage is
A.magnitude of current will be small
B.it will reduce the voltage drop in the line impedance
C.power loss will be less
D.all of these
Q 150 :
If the height of the transmission tower is changed, which of the following parameters is likely to change ?
A.Resistance
B.Inductance
C.Capacitance
D.None of the above
Q 151 :
The sag of a power line with 100 m span is 1m, what will be the sag if the height of the line increased by 20 %
A.1.6 m
B.1.5 m
C.2 m
D.2.5 m
Q 152 :
A synchronous condenser is virtually a / an
A.induction motor
B.over excited synchronous motor
C.under excited synchronous motor
D.commutator motor
Q 153 :
The thickness of insulation layer provided on the conductor in cables depends upon
A.operating voltage
B.current to be carried
C.power factor
D.none of these
Q 154 :
A single phase line is transmitting 1,100 kW power to a factory at 11 kV and at 0.8 pf lagging. It has a total resistance of 2 Ω and a loop reactance of 3 Ω The voltage at sending end, percentage regulation and transmission efficiency will be respectively .
A.11854 V; 7.76 % and 94.62 %
B.11426 V; 3.73 % and 97.24 %
C.11426 V; 3.87 % and 97.24 %
D.11426 V; 3.87 % and 94.62 %
Q 155 :
The steepness of the wave front can be reduced by connecting
A.an inductor in series with the line
B.a capacitor between line and earth
C.either (a) or (b)
D.an inductor between line and earth or a capacitor in series with the line
Q 156 :
Which of the following is correct statement regarding insulators and lightning arresters ?
A.The insulators and lightning arresters should have high impulse ratio .
B.The insulators and lightning arresters should have low impulse ratio .
C.The insulator should have high impulse ratio and lightning arrester low .
D.The lightning arrester should have high impulse ratio but insulator low .
Q 157 :
The distribution transformers is generally connected in
A.Delta / Delta
B.Star / Delta
C.Delta / Star
D.Star / Star
Q 158 :
In a two stage gas turbine power plant intercooling and reheating
A.improves the work ratio but reduces the thermal efficiency
B.reduces the work ratio but improves the thermal efficiency
C.improves both of the work ratio and thermal efficiency
D.reduces both of the work ratio and thermal efficiency
Q 159 :
Directional over - current relay is used for protection of
A.long transmission line
B.large power transformer
C.ring main distribution line
D.radial distribution line
Q 160 :
What is the most serious problem in vacuum circuit breaker ?
A.Poor arc quenching
B.Low thermal stability
C.Current chopping
D.All of these
Q 161 :
If the dielectric strength of the medium between contacts builds up more rapidly than the restriking voltage. Then the arc will
A.be extinguished
B.not be extinguished
C.increase
D.none of these
Q 162 :
The operation of thermo - electric generator is based on
A.Seebeck effect
B.Hall effect
C.Peltier effect
D.None of these
Q 163 :
Oil filled cables have the advantage(s) of
A.no ionisation, oxidation and formation of voids
B.possibility of increased temperature range in service
C.more maximum permissible stresses
D.all of the above
Q 164 :
In a static over - current relay, inverse time characteristics are obtained by
A.a transistor amplifier
B.an integrating circuit
C.a transistor switch
D.a differentiating circuit
Q 165 :
In a transmission line sag depends upon
A.span length
B.tension in conductors
C.weight of the conductor per unit length
D.all of the above
Q 166 :
The CANDU type reactor can be shut down by controlling
A.safety rod
B.shim rod
C.regulating rod
D.none of the above
Q 167 :
Buchholz relay is used for protection in case of a
A.transformer
B.synchronous generator
C.bus - bar
D.induction motor
Q 168 :
Run away speed of a pelton wheel is
A.full load speed
B.actual speed operating at no load
C.no load speed when governor mechanism fails
D.80% greater than the normal speed
Q 169 :
For a transmission line the standing wave ratio is the ratio of
A.peak voltage to rms voltage
B.maximum current to minimum current
C.maximum voltage to minimum voltage minimum
D.maximum impedance to impedance
Q 170 :
In a steam power plant water is used for cooling purpose in
A.condenser
B.turbine only
C.boiler tubes
D.boiler tubes and turbine both
Q 171 :
For low head and high discharge, the hydraulic turbine used is
A.Francis turbine
B.Kaplan turbine
C.Pelton wheel
D.None of these
Q 172 :
A Kaplan turbine is
A.inward flow, impulse turbine
B.outward flow, reaction turbine
C.a high head mixed flow turbine
D.low head axial flow turbine
Q 173 :
In which of the following circuits there may be zero sequence components ?
A.Line voltage of star circuit
B.Phase voltage of star circuit
C.Line current of delta circuit
D.None of these
Q 174 :
Which of the following relays does not make use of electromagnetic force ?
A.Attracted armature type relay
B.Solenoid and plunger type impedance relay
C.Static relay
D.Induction type relay
Q 175 :
The frequency of Trichel pulses
A.increases with voltage and gap pressure
B.increases with voltage and decreases with gap pressure
C.decreases with increase in voltage and pressure
D.none of these
Q 176 :
Which of the following equipments is installed in steam power plants to reduce air pollution ?
A.Desuper heater
B.Air filter
C.Air electrostatic precipitator
D.Stock
Q 177 :
An air blast circuit breaker is usually employed for
A.instantaneous duty
B.intermittent duty
C.repeated duty
D.short duty
Q 178 :
Thermal shielding is provided to
A.absorb the fast neutrons
B.protect the operating personnel from exposure to radiations
C.prevent the reactor wall from getting heated
D.all of the above
Q 179 :
In medium transmission lines the shunt capacitance is taken into account in
A.end condenser method
B.π method
C.T - method
D.all of the above
Q 180 :
Transient disturbances are caused by
A.sudden load changes
B.switching operations
C.inadvertent tripping of lines and generators
D.faults in the power system
E.all of the above
Q 181 :
Electromechanical breakdown of solid insulating materials occurs due to
A.magnetic hum
B.vibrations
C.mechanical stresses produced by the electrical field
D.electrical stresses produced by the voltage fluctuations
Q 182 :
Coal rank classifies coal as per its
A.specific gravity
B.degree of metamorphism
C.carbon percentage
D.ash content
Q 183 :
If the capacitance between two conductors of a 3 - phase line is 6 µF, the capacitance of each conductor to neutral will be
A.3 µF
B.6 µF
C.12 µF
D.1.5 µF
Q 184 :
If ACSR conductor has specification as 48 / 7, which of the following statement is correct for the conductor ?
A.The conductor has 48 strands .
B.The conductor has 55 strands .
C.The conductor has 48 aluminium and 7 steel strands .
D.The conductor has 48 steel and 7 aluminium strands .
Q 185 :
A generating station which has a high investment cost and low operating cost is usually operated as a
A.peak load station
B.base load station
C.medium load station
D.none of the above
Q 186 :
The nuclear reactor starts generation when
A.the safety rod is inserted into the core
B.the safety rod is withdrawn from the core
C.the shim rod is inserted into the core
D.the shim rod is withdrawn from the core
Q 187 :
When all the three phases are short circuited it gives rise to
A.asymmetrical fault currents
B.symmetrical fault current
C.zero current
D.none of these
Q 188 :
The string efficiency of a string of suspension insulators is dependent on
A.size of the insulators
B.number of discs in the string
C.size of tower
D.none of these
Q 189 :
SF6 circuit breakers have the advantages of
A.very much reduced electrical clearance, reduced moisture problem and minimum current chopping problem
B.noiseless operation, less arcing time resulting in less contact erosion
C.no reduction in dielectric strength of SF6
D.performance independent of ambient conditions
E.all of the above
Q 190 :
In order to have lower cost of electrical energy generation it is required to have
A.low load factor and low diversity factor
B.low load factor but high diversity factor
C.high load factor but low diversity factor
D.high load factor and high diversity factor
Q 191 :
The rate of rise of restriking voltage depends on
A.the type of circuit breaker
B.the inductance of the system only
C.the capacitance of the system
D.the inductance and capacitance of the system only
Q 192 :
The potential across the various discs of suspension string is different because of
A.series capacitance
B.shunt capacitance
C.series and shunt capacitance
D.none of these
Q 193 :
The dielectric strength of air under normal conditions is around
A.30 kV / cm
B.100 kV / cm
C.150 kV / cm
D.200 kV / cm
Q 194 :
For magnetic blow out of arc the magnetic field is produced
A.in the load circuit
B.at right angles to the axis of the arc
C.in line with the axis of the arc
D.any of the above
Q 195 :
The most suitable material for transformer core is
A.hot rolled grain oriented steel
B.cold rolled grain oriented steel (CRGOS)
C.cast steel
D.aluminium
Q 196 :
The torque developed by a 3 - phase induction motor depends upon
A.rotor phase resistance
B.rotor standstill phase reactance
C.applied voltage
D.slip
E.all of the above
Q 197 :
The breaking capacity of a 3 - phase circuit breaker is given as
A.service line voltage in volts x rated symmetrical current in amperes X 10-6 MVA
B.​ service line voltage in volts x rated symmetrical curent in amperes X 10-6 MVA
C.1.1 X service line voltage in volts x rated symmetrical current in amperes X 10-6 MVA
D. service line voltage in volts x rated symmetrical current in amperes X 10-6 MVA
Q 198 :
The factor that is not responsible for drop terminal voltage of a dc shunt generator load is
A.commutation
B.armature reaction
C.armature resistance drop
D.field weakening due to (b) and (c)
Q 199 :
A 3 - phase synchronous generator with constant excitation is supplying electrical power to an infinite bus - bar at lagging power factor. If the power input is reduced
A.both power factor and power angle will increase
B.both power factor and power angle will decrease
C.power factor will increase but power angle will decrease
D.power factor will decrease but power angle will increase
Q 200 :
The medium sized induction motor will operate at maximum power factor while operating at
X rated symmetrical breaking capacity
service line voltage in volts x rated symmetrical curent in amperes X 10-6 MVA
service line voltage in volts x rated symmetrical current in amperes X 10-6 MVA