Railways NTPC (Technical Ability) Electrical Measurement and Instrumentation Question Bank

done Electrical Measurement and Instrumentation Total Questions - 50

• question_answer1)
  A man hold both the terminals of a 500 V megger, but still safe due to
  A)
   high voltage                  done clear
  B)
   very low current done clear
  C)
   high resistance of the body done clear
  D)
   low resistance of the body done clear
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• question_answer2)
  On testing an electric iron on megger, the reading of the megger is infinity. This indicates
  A)
   short circuit of the heating element done clear
  B)
   short circuit of the supply terminal done clear
  C)
   loose terminal connections done clear
  D)
   open circuit of the heating element done clear
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• question_answer3)
  Using a C.T. has
  A)
   poorer overload capacity than a P.T. done clear
  B)
   the same overload capacity as a P.T. done clear
  C)
   a higher overload capacity than a P.T. done clear
  D)
   none of the above done clear
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• question_answer4)
  An alternator is being synchronized to the bus bars of frequency 50 Hz. The synchroscope lamp flickers at a frequency of 5 Hz. The frequency of the alternator is
  A)
   45 Hz               done clear
  B)
   55 Hz done clear
  C)
   45 of 55 Hz done clear
  D)
   none of the above done clear
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• question_answer5)
  Tow voltmeters of\[0-300\,\,V\]range are connected in parallel to an ac circuit. One voltmeter is moving iron type and reads 200 V. If the other volmeter is moving coil type, its reading will be
  A)
   \[200\sqrt{3}\,\,V\]                    done clear
  B)
   \[200~\times 1.41\,\,V\] done clear
  C)
   slightly less than 200 V done clear
  D)
   zero done clear
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• question_answer6)
  Which of the following meter mechanisms is adaptable to a greater variety of measurement?
  A)
   Inclined coil         done clear
  B)
   Moving-iron vane done clear
  C)
   Electrodynamometer done clear
  D)
   Permanent magnet-moving coil done clear
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• question_answer7)
  To measure 2 volts, if one selects \[0-100\]volt range voltmeter which is accurate within \[\pm 1%,\]the error in his/her measurement may be up to
  A)
  \[\pm 0.02%\]                 done clear
  B)
   \[\pm 1%\] done clear
  C)
  \[\pm 2%\]                                 done clear
  D)
   \[\pm 50%\] done clear
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• question_answer8)
  In a two wattmeter method of measuring power in a 3-phase system one of the watt meters reads negative implying
  A)
   wattmeter connection is faulty done clear
  B)
   load is unbalanced done clear
  C)
   power flow is in the reverse direction done clear
  D)
   power factor is less then 0.5 done clear
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• question_answer9)
  Which of the following is not an advantage of semi-conductor gauges as compared to conventional strain gauges?
  A)
   Excellent hysteresis characteristics done clear
  B)
   Least sensitive to temperature changes done clear
  C)
   High fatigue life done clear
  D)
   Smaller size done clear
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• question_answer10)
  In indicating instruments the damping is usually adjusted
  A)
    at critical value done clear
  B)
   to the value slightly higher than critical value done clear
  C)
   to the value slightly higher than critical value value done clear
  D)
   to any value done clear
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• question_answer11)
  Electrodynamometers are used extensively for the measurement of
  A)
   magnetic lines of force done clear
  B)
   resistivity done clear
  C)
   capacitor networks done clear
  D)
   power done clear
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• question_answer12)
  Electrostatic instruments
  A)
   can be used on dc only done clear
  B)
   when used on ac measure rms value whatever the waveform done clear
  C)
   are highly sensitive to eddy current errors done clear
  D)
   none of the above done clear
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• question_answer13)
  Before connecting a meter to measure an unknown current or voltage, it is best to
  A)
   start with the highest range and work down done clear
  B)
   start with the lowest range and work down done clear
  C)
   select an estimated mid-range done clear
  D)
   use the trial and error method done clear
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• question_answer14)
  Quadrant type electrostatic instruments can be used for measurement of ac voltage
  A)
   only when heterostatically connected. done clear
  B)
   only when idiostatically connected. done clear
  C)
   in either heterostatic connection or idiostatic connection done clear
  D)
   None of the above done clear
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• question_answer15)
  Capacitor potential transformers are used
  A)
   for primary voltage exceeding 100kv (Phase) done clear
  B)
   because these are cheaper than the conventional type above a certain voltage done clear
  C)
   for keeping the transformation ratio constant irrespective of the burden with certain adjustments done clear
  D)
   all of the above done clear
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• question_answer16)
  For measuring a low resistance by ammeter-voltmeter method, the voltmeter is connected directly across the resistance under measurement
  A)
   there is an error in measurement as the ammeter measures current flowing through the voltmeter in addition to the current flowing through the resistance under measurement done clear
  B)
   there is an error in measurement as the voltmeter measures voltage drop across the ammeter in addition to that across the resistance under measurement done clear
  C)
   both [a] and [b] done clear
  D)
   none of above done clear
  View Solution play_arrow

• question_answer17)
  The rectifier instrument is not free from
  A)
   Temperature error          done clear
  B)
   Frequency error done clear
  C)
   Wave shape error           done clear
  D)
   All of the above done clear
  View Solution play_arrow

• question_answer18)
  An accurate ammeter must have a resistance of
  A)
   High value                    done clear
  B)
   Low value done clear
  C)
   Very low value  done clear
  D)
   None of the above done clear
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• question_answer19)
  The source of energy for operating an ohmmeter is obtained from?
  A)
   the line being measured done clear
  B)
   any 120 volt source done clear
  C)
   a rectifier cell done clear
  D)
   a battery done clear
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• question_answer20)
  Which of the following is not the method for reducing H residual inductance in resistors?                     
  A)
   Faraday's winding method                      done clear
  B)
   Card wound resistor                            done clear
  C)
   Chaperon winding method                      done clear
  D)
   Curtis and Rower winding method   done clear
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• question_answer21)
            \[{{W}_{1}}\]and\[{{W}_{2}}\]are the readings of two watt meters used to measure power of a 3-phase balanced load. The reactive power drawn by the load is            
  A)
   \[{{W}_{1}}\]+\[{{W}_{2}}\]              done clear
  B)
   \[{{W}_{1}}-{{W}_{2}}\] done clear
  C)
   \[\sqrt{3}\,\,({{W}_{1}}+{{W}_{2}})\] done clear
  D)
   \[\sqrt{3}\,\,({{W}_{1}}-{{W}_{2}})\] done clear
  View Solution play_arrow

• question_answer22)
  Half wave rectifier type AC meters are used as voltmeter They cannot be used as ammeters because
  A)
   pointer would oscillate with AC        done clear
  B)
   AC current would be too small to read          done clear
  C)
   AC current would be excessive                done clear
  D)
   AC is changed to DC     done clear
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• question_answer23)
                      Which of the following does not have the same units as the others? The symbols have their usual meanings.  
  A)
   \[\frac{L}{R}\]                          done clear
  B)
   RC                done clear
  C)
   \[\sqrt{LC}\]                 done clear
  D)
   \[\frac{1}{\sqrt{LC}}\] done clear
  View Solution play_arrow

• question_answer24)
  The ratio of maximum displacement deviation to full scale deviation of the instrument is called the            
  A)
   static sensitivity done clear
  B)
   accuracy            done clear
  C)
   linearity                        done clear
  D)
   precision            done clear
  E)
   dynamic deviation   done clear
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• question_answer25)
                           Two 200 V D.C. voltmeters having resistances of \[15\,\,k-ohm\]and\[10\text{ }k-ohm\]are connected in series. The safe voltage which can be measured by this combination will be  
  A)
   400 V               done clear
  B)
   \[200\sqrt{2}\,V\]            done clear
  C)
   200 V   done clear
  D)
   100 V      done clear
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• question_answer26)
          The Q-meter works on the principle of             
  A)
   mutual inductance         done clear
  B)
   self inductance      done clear
  C)
   series resonance done clear
  D)
   parallel resonance    done clear
  View Solution play_arrow

• question_answer27)
  The pressure coil of a dynamometer type wattmeter is
  A)
   highly inductive done clear
  B)
   highly resistive      done clear
  C)
   purely resistive   done clear
  D)
   purely inductive done clear
  View Solution play_arrow

• question_answer28)
       The bridge method commonly used for finding mutual inductance is                                 
  A)
   Heavy side Campbell bridge                 done clear
  B)
   Schering bridge                              done clear
  C)
   De Sauty bridge                            done clear
  D)
   Wien bridge  done clear
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• question_answer29)
                              What is the correct sequence of the following type ammeters and voltmeters with increasing accuracy?   1. Moving-iron                                 2. Moving-coil permanent magnet               3. Induction                               Select the correct answer using the codes given below
  A)
   1, 3, 2              done clear
  B)
   1, 2, 3              done clear
  C)
   3, 1, 2              done clear
  D)
   2, 1, 3     done clear
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• question_answer30)
         Which of the following bridges can be used for inductance measurement?                                     1. Maxwell's bridge          2 Schering bridge    3. We in-bridge               4.Hay's bridge      5. Wheatstone bridge                         Select the correct answer using the codes given below
  A)
   1 and 2            done clear
  B)
   2 and 3 done clear
  C)
   3, 4 and 5                     done clear
  D)
   1 and 4 done clear
  View Solution play_arrow

• question_answer31)
  Which one of the following digital voltmeters is most suitable to eliminate the effect of period noise?
  A)
   Ramp type digital voltmeter done clear
  B)
   Integrating type digital voltmeter done clear
  C)
   Successive approximation type digital voltmeter done clear
  D)
   Servo type digital voltmeter done clear
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• question_answer32)
  Electrostatic instruments are normally used for
  A)
   low current measurements done clear
  B)
   high current measurements done clear
  C)
   low voltage measurements done clear
  D)
   high voltage measurements. done clear
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• question_answer33)
  Which instrument has necessarily the 'square law type
  A)
   Permanent magnet moving coil. done clear
  B)
   Hot wire instruments done clear
  C)
   Moving iron repulsion done clear
  D)
   None of the above done clear
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• question_answer34)
  In a single-phase power factor meter, the controlling torque is
  A)
   provided by spring control done clear
  B)
   provided by gravity control done clear
  C)
   provided by stuffiness of suspension done clear
  D)
   not required done clear
  View Solution play_arrow

• question_answer35)
  If an induction type energy meter runs fast, it can be slowed down by
  A)
   at lag adjustment done clear
  B)
   light load adjustment done clear
  C)
   adjusting the position of braking magnet and moving it closer from the centre of the disc done clear
  D)
   adjusting the position of braking magnet and moving it away from the centre of the disc. done clear
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• question_answer36)
  Which one of the following statements is correct? The deflection of hot wire instrument depends on
  A)
   r. m. s. value of the a. c. current done clear
  B)
   r. m. s. value of the a. c. voltage done clear
  C)
   average value of the a. c. current done clear
  D)
   average value of the a. c. voltage done clear
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• question_answer37)
  Which one of the following decides the time of response of in indicating instrument?
  A)
   Deflecting system done clear
  B)
   Controlling system done clear
  C)
   Damping system done clear
  D)
   Pivot and Jewel bearing done clear
  View Solution play_arrow

• question_answer38)
  Piezoelectric crystal is generally employed for the measurement of which one of the following?
  A)
   Flow                             done clear
  B)
   Velocity done clear
  C)
   Acceleration                  done clear
  D)
   Temperature done clear
  View Solution play_arrow

• question_answer39)
  The deflection expression\[\theta \propto {{V}^{2}}=\frac{dc}{d\theta }\]corresponds to
  A)
   moving iron type instrument done clear
  B)
   electro dynamic type instruments done clear
  C)
   electrostatic type instrument done clear
  D)
   induction type instruments done clear
  View Solution play_arrow

• question_answer40)
  The full range of audibility in audio frequency oscillator is
  A)
   0 to 20 Hz                    done clear
  B)
   20 Hz to 2 kHz done clear
  C)
   20 Hz to 20 kHz done clear
  D)
   20 Hz to 20 MHz done clear
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• question_answer41)
  Which devices used to measure the temperature of an object?
  A)
   Potentiometer    done clear
  B)
   Odometer done clear
  C)
   Thermometers   done clear
  D)
   Galvanometer done clear
  View Solution play_arrow

• question_answer42)
  A liquid crystal display requires
  A)
   An AC drive                  done clear
  B)
   A DC drive done clear
  C)
   Both AC and DC drive done clear
  D)
   None of the above done clear
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• question_answer43)
  A moving iron frequency meter consists of
  A)
   Two inductive circuits connected in parallel done clear
  B)
   One inductive and one non inductive circuit connected in parallel done clear
  C)
   Two non inductive circuits connected in parallel done clear
  D)
   One inductive and one non inductive circuit connected in series done clear
  View Solution play_arrow

• question_answer44)
  The earth resistance can be measured by
  A)
   Fall of potential method done clear
  B)
   Using an earth tester done clear
  C)
   Doctor ohmmeter method done clear
  D)
   Only [a] and [b] done clear
  View Solution play_arrow

• question_answer45)
  In AC bridges, the Wagner earth devices are used to
  A)
   Remove all the earth capacitances from the bridge circuit done clear
  B)
   Remove harmonics done clear
  C)
   Reduce error caused by stray electric field done clear
  D)
   All of the above done clear
  View Solution play_arrow

• question_answer46)
  Electrostatic voltmeter instruments are suitable for
  A)
   AC work only    done clear
  B)
   DC work only done clear
  C)
   Both AC and DC work    done clear
  D)
   None of these done clear
  View Solution play_arrow

• question_answer47)
  Electrostatic instruments are generally used as
  A)
   Voltmeters        done clear
  B)
   Ammeters done clear
  C)
   Watt meters                  done clear
  D)
   Watt-hour meters done clear
  View Solution play_arrow

• question_answer48)
  In a measurement system,
  A)
   A single measurement components may have both random errors and systematic errors done clear
  B)
   A measurement system consists of several components with each component having separate errors done clear
  C)
   Both the statement [a] & [b] are true done clear
  D)
   Neither statement [a] nor statement [b] is true done clear
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• question_answer49)
  Which of the following instruments used for the measurement of pressure?
  A)
   Bellows             done clear
  B)
   Diaphragms done clear
  C)
   Fiber optic pressure sensors done clear
  D)
   All of the above done clear
  View Solution play_arrow

• question_answer50)
  The errors mainly caused by human mistakes are
  A)
   Gross error                    done clear
  B)
   Instrument error done clear
  C)
   observational error         done clear
  D)
   Systematic error done clear
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