Railways NTPC (Technical Ability) Power and Control System Question Bank

done Power System Total Questions - 50

• question_answer1)
  In a minimum oil circuit breaker the oil is used
  A)
   to act as circuit breaking medium only done clear
  B)
   for circuit breaking and providing insulation done clear
  C)
   for providing insulation only done clear
  D)
   for none of the above purposes done clear
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• question_answer2)
  Series capacitor is used in a transmission line to
  A)
   compensate the voltage drp done clear
  B)
   reduce line loss done clear
  C)
   limit short circuit current done clear
  D)
   improve load power factor done clear
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• question_answer3)
  Corona loss in a transmission line is dependent on
  A)
   diameter of the conductor done clear
  B)
   material of the conductor done clear
  C)
   height of the conductor done clear
  D)
   none of these done clear
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• question_answer4)
  A fault is more severe from the view point of RRRV if it is a
  A)
   Short length fault     done clear
  B)
   Medium length line fault done clear
  C)
   Long length line fault done clear
  D)
   None of these done clear
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• question_answer5)
  Skin effect in conductor is proportional to
  A)
   \[{{(diameter\,\,of\,\,conductor)}^{1/2}}\] done clear
  B)
   diameter of conductor done clear
  C)
   \[{{(diameter\,\,of\,\,conductor)}^{2}}\] done clear
  D)
   \[{{(diameter\,\,of\,\,conductor)}^{4}}\] done clear
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• question_answer6)
  For constant voltage transmission, the voltage drop along the line is maintained constant by installing
  A)
   capacitors done clear
  B)
   inductors done clear
  C)
   resistors done clear
  D)
   synchronous phase modifiers at the receiving end done clear
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• question_answer7)
  Neutral earthling is provided for
  A)
   the safety of personnel from electric shock done clear
  B)
   reducing the vulgate stress on lines and equipment with respect to earth under various operating and Ault conditions done clear
  C)
   controlling the earth fault currents for protective relaying done clear
  D)
   both [b] and [c] done clear
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• question_answer8)
  In which of the following cases are delay fuses used?
  A)
   For the protection of light circuits done clear
  B)
   For the protection of power out-let circuits done clear
  C)
   For the protection of fluorescent lamps done clear
  D)
   Tor the protection of motors done clear
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• question_answer9)
  Different types of insulators used for transmission lines are
  A)
   pin type only done clear
  B)
   suspension type only done clear
  C)
   strain type only done clear
  D)
   pin type, suspension type and shackle type done clear
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• question_answer10)
  The function of steel wire in an ACSR conductor is to
  A)
   compensate for skin effect done clear
  B)
   take care of surges done clear
  C)
   provide additional mechanical strength done clear
  D)
   reduce inductance done clear
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• question_answer11)
  AC network analyzer is employed for solving the problems of
  A)
   load flow done clear
  B)
   load flow and stability done clear
  C)
   load flow and short circuit done clear
  D)
   load flow, stability and short-circuit done clear
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• question_answer12)
  Which of the following method or techniques can be used for the measurement of high [d] [c] voltages?
  A)
   Generating voltmeter done clear
  B)
   Electrostatic voltmeter done clear
  C)
   Peak voltmeter        done clear
  D)
   Half effect generators done clear
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• question_answer13)
  If two synchronous generators connected in parallel loose synchronism, it will lead to
  A)
   stalling of generators done clear
  B)
   wild fluctuations in current done clear
  C)
   wild fluctuations in current and voltage done clear
  D)
   None of these done clear
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• question_answer14)
  The insulation of the modem EHV lines is designed based on
  A)
   corona               done clear
  B)
   switching voltage done clear
  C)
   lightening voltage     done clear
  D)
   all of these done clear
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• question_answer15)
  In a transformer, the exciting current will be in phase quadrature with the impressed voltage provided?
  A)
   only the leakage impedance drop is ignored done clear
  B)
   only the core loss is ignored done clear
  C)
   both the leakage impedance drop and the core loss are ignored done clear
  D)
   only the no-load copper loss is ignored done clear
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• question_answer16)
  The voltage measurements using uniform spark gap are
  A)
   affected by dust particles done clear
  B)
   affected by polarity of supply done clear
  C)
   affected by temperature done clear
  D)
   none of these done clear
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• question_answer17)
  The change in excitation in an alternator connected to an infinite line provides a corresponding change in
  A)
   terminal voltage done clear
  B)
   speed of rotor done clear
  C)
   power generated done clear
  D)
   power factor done clear
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• question_answer18)
  The function of Lightning arrester is
  A)
   to limiting the short-circuit fault current done clear
  B)
   to provide path to high voltage surge to earth done clear
  C)
   to reduce arcing done clear
  D)
   none of these done clear
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• question_answer19)
  The conductor connecting consumer's terminals to the distributor is called the
  A)
   feeder               done clear
  B)
   distributor done clear
  C)
   service main                  done clear
  D)
   none of the above done clear
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• question_answer20)
  In order to improve the voltage profile of the line compensation is resorted by providing
  A)
   capacitors at the receiving end done clear
  B)
   reactors at the receiving end done clear
  C)
   resistors at the receiving end done clear
  D)
   none of these done clear
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• question_answer21)
  The ripple voltage in dc output is small if
  A)
   frequency of supply voltage is small done clear
  B)
   the filtering capacitor is small done clear
  C)
   load current is small done clear
  D)
   none of these done clear
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• question_answer22)
  A differential relay responds to
  A)
   algebraic difference of two or more similar electrical quantities done clear
  B)
   vector difference of two or more similar electrical quantities done clear
  C)
   algebraic difference between two currents done clear
  D)
   algebraic difference between two voltages done clear
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• question_answer23)
  In case of Impulse Thermal break down of solid insulating materials, the critical electric field is proportional to     
  A)
   critical absolute temperature done clear
  B)
   square of critical absolute temperature done clear
  C)
   square of Ty done clear
  D)
   none of these done clear
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• question_answer24)
  A booster is connected in
  A)
   series with the feeder done clear
  B)
   parallel with the feeder done clear
  C)
   both [a] and [b] are correct done clear
  D)
   none of these done clear
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• question_answer25)
  Which of the following techniques is used for the measurements of [a] [c] high frequency voltages?     
  A)
   Peak voltmeter done clear
  B)
   Series resistance micro-ammeter done clear
  C)
   Resistance potential divider done clear
  D)
   All of these done clear
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• question_answer26)
  The power transmitted will be maximum when
  A)
   line reactance is high                              done clear
  B)
   corona losses are minimum                     done clear
  C)
   sending end voltage is more done clear
  D)
   receiving end voltage is more done clear
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• question_answer27)
  Surge impedance of a transmission line is           
  A)
   independent of its length done clear
  B)
   dependent of its length done clear
  C)
   independent on its temperature done clear
  D)
   none of the above done clear
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• question_answer28)
                             Which fault gives rise to symmetrical fault currents?
  A)
   Single line to ground fault done clear
  B)
   line to line fault done clear
  C)
   Double line to ground fault done clear
  D)
   Three phase fault done clear
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• question_answer29)
  High voltage Schring bridge is used to measure
  A)
   large capacitance without additional element done clear
  B)
   small capacitance without additional element done clear
  C)
   medium value capacitance done clear
  D)
   None of these done clear
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• question_answer30)
  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 done clear
  B)
   power frequency and impulse voltage done clear
  C)
   all kinds of voltages done clear
  D)
   none of these done clear
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• question_answer31)
  The passive element that is used as interconnecting element for the stable operation of interconnected system is
  A)
   reactor              done clear
  B)
   resistor done clear
  C)
   capacitor                      done clear
  D)
   resistor and capacitor done clear
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• question_answer32)
  The sage of a transmission line is least affected owing to
  A)
   weight of the conductor done clear
  B)
   current through the conductor done clear
  C)
   atmospheric temperature done clear
  D)
   ice deposited on the conductor done clear
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• question_answer33)
  The conductor carries more current on the surface in comparison to its core. This phenomenon is called the
  A)
   Skin effect         done clear
  B)
   Corona done clear
  C)
   Ferranti effect    done clear
  D)
   Lenz's effect done clear
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• question_answer34)
  Draw-in-system of laying underground cables has the drawback (s) of
  A)
   higher cost done clear
  B)
   reduced current carrying capacity of the cables done clear
  C)
   requirements of much deeper and wider trenches done clear
  D)
   All of the above done clear
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• question_answer35)
  By transmitting power at high voltage
  A)
   it will give poor voltage regulation done clear
  B)
   it will give better voltage regulation done clear
  C)
   it will not effect voltage regulation done clear
  D)
   None of these done clear
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• question_answer36)
  Use of additional shunt capacitor can be made for increasing the capability of line as it
  A)
   reduces surge impedance \[{{Z}_{0}}\] done clear
  B)
   increases phase shift \[\beta \] done clear
  C)
   increase in \[\alpha \] done clear
  D)
   all of the above done clear
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• question_answer37)
  Fuses have got advantages of
  A)
   cheapest type of protection done clear
  B)
   inverse time-current characteristic done clear
  C)
   no maintenance done clear
  D)
   current limiting effect under short-circuit conditions done clear
  E)
   all of the above done clear
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• question_answer38)
  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                             done clear
  B)
   0.375 done clear
  C)
   1.33                             done clear
  D)
   None of these done clear
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• question_answer39)
  Which statement about the daily load curve is valid?
  A)
   The area under the curve gives the average demand. done clear
  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. done clear
  C)
   The peak of the curve gives the installed capacity of the plant done clear
  D)
   The area of the curves divided by the number of hours gives load factor. done clear
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• question_answer40)
  Resistance witching is normally resorted in case of
  A)
   Air blast CB                  done clear
  B)
   Bulk oil CB done clear
  C)
   Minimum oil CB            done clear
  D)
   All types of CBs. done clear
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• question_answer41)
  What is the main disadvantage of phase advancers?
  A)
   Cannot be used for motors below 200 H.P done clear
  B)
   Produces noise done clear
  C)
   Can be used where synchronous motor is un admissible done clear
  D)
   None of these done clear
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• question_answer42)
  What is the advantage of the static capacitors?
  A)
   Low losses done clear
  B)
   Easy installation done clear
  C)
   Lower maintenance done clear
  D)
   All of the above done clear
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• question_answer43)
  Power factor can be improved by connecting which among these?
  A)
   Static capacitors. done clear
  B)
   Resistors. done clear
  C)
   Synchronous condensers. done clear
  D)
   Both [a] and [c]. done clear
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• question_answer44)
  Lower power factor is usually not due to ____.
  A)
   Discharge lamp done clear
  B)
   Arc lamps done clear
  C)
   Incandescent lamps done clear
  D)
   Induction furnace. done clear
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• question_answer45)
  What is maximum value of power factor?
  A)
   0.5                               done clear
  B)
   1 done clear
  C)
   1.5                               done clear
  D)
   0.95 done clear
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• question_answer46)
  What is the power factor tariff?
  A)
   It considers only maximum demand. done clear
  B)
   It considers only semi fixed charges and the power factor. done clear
  C)
   It considers only power factor. done clear
  D)
   It considers the load factor. done clear
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• question_answer47)
  Which tariff is most ideal tariff for the consumer?
  A)
   Two part tariff done clear
  B)
   Three part tariff done clear
  C)
   Both [a] and [b] done clear
  D)
   None of the above done clear
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• question_answer48)
  What is tariff?
  A)
   The rate at which electrical energy is produced in the plant. done clear
  B)
   The rate at which electrical energy is supplied to the consumers. done clear
  C)
   Both [a] and [b]. done clear
  D)
   None of these. done clear
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• question_answer49)
  What are fixed charges?
  A)
   Cost of investment irrespective of energy generated. done clear
  B)
   Operating cost of the fuel along with cost of investment plant. done clear
  C)
   Operating cost only. done clear
  D)
   None of the above done clear
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• question_answer50)
  Annual operating cost of a generating plant consists of
  A)
   Fixed charges done clear
  B)
   Semi fixed charges done clear
  C)
   Operating or running charges done clear
  D)
   All of these done clear
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