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

done Control System Total Questions - 50

• question_answer1)
  ____ has some roots with real parts equal to zero but none with positive real parts.
  A)
   Marginally stable done clear
  B)
   'Absolutely stable done clear
  C)
   Absolutely unstable        done clear
  D)
   Stable done clear
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• question_answer2)
  In a hybrid feedback control system carrier signals are
  A)
   d. c. only                      done clear
  B)
   a. c. only done clear
  C)
   both d. c. and a. c.        done clear
  D)
   none of these done clear
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• question_answer3)
  In a system non-linearity may be introduced due to
  A)
   backlash in gears done clear
  B)
   end positions in detectors done clear
  C)
   saturation effects in amplifiers done clear
  D)
   any of the above done clear
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• question_answer4)
  A system has the transfer function \[(1-s)\,\,(1+s)\] It is known as a
  A)
   1                                 done clear
  B)
   \[-0\] done clear
  C)
   \[-1\]                            done clear
  D)
   None of these done clear
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• question_answer5)
  Tow blocks having respective functions as \[{{G}_{1}}\] and \[{{G}_{2}}\] are connected in series cascade. Their resultant will be
  A)
   \[{{G}_{1}}\,\,{{G}_{2}}\]                  done clear
  B)
   \[{{G}_{1}}+{{G}_{2}}\] done clear
  C)
   \[{{G}_{1}}/{{G}_{2}}\]                     done clear
  D)
   \[{{G}_{2}}/{{G}_{1}}\] done clear
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• question_answer6)
  The Laplace Transform of unit step function and ramp functions respectively are
  A)
   \[\frac{1}{{{s}^{2}}},\,\,\frac{1}{s}\]              done clear
  B)
   \[\frac{1}{s},\,\,\frac{1}{{{s}^{2}}}\] done clear
  C)
   \[\frac{1}{s},\,\,\frac{1}{{{s}^{3}}}\]              done clear
  D)
   \[\frac{1}{{{s}^{3}}},\,\,\frac{1}{s}\] done clear
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• question_answer7)
  If a conventional servomotor is used for servo
  A)
   the applied voltages are always to be balanced done clear
  B)
   the rotor resistance is low done clear
  C)
   the rotor resistance is high done clear
  D)
   the rotor's diameter is large done clear
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• question_answer8)
  Which one of the following statements regarding state space method is NOT TRUE?
  A)
   It gives compact and convenient form. done clear
  B)
   It reduces complexity. done clear
  C)
   Direct programming is possible on analog computer. done clear
  D)
   None of these done clear
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• question_answer9)
  In pneumatic systems, electrical resistance is analogous to a
  A)
   restriction to flow           done clear
  B)
   volume of air done clear
  C)
   filled helical tube            done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer10)
  The transfer function of a system is used to determine
  A)
   the output for a given input done clear
  B)
   the type of system done clear
  C)
   the input for given output done clear
  D)
   the steady state gain done clear
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• question_answer11)
  Human system can be considered as a
  A)
   open-loop system done clear
  B)
   closed-loop system with single feedback done clear
  C)
   closed-loop system with single feedback done clear
  D)
   none of these done clear
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• question_answer12)
  The transfer function technique is considered inadequate with systems having
  A)
   stability problems done clear
  B)
   multiple input disturbances done clear
  C)
   complexities and non-line arties done clear
  D)
   all of the above done clear
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• question_answer13)
  The function \[u\,\,(t-{{t}^{0}})=\left[ \begin{matrix}    1 & t>{{t}_{0}}  \\    0 & t<{{t}_{0}}  \\ \end{matrix} \right]\,\,difines\]
  A)
   unit step function           done clear
  B)
   unit ramp function done clear
  C)
   unit impulse function      done clear
  D)
   none of these done clear
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• question_answer14)
  Damping due to back emf is observed in
  A)
   armature controlled d. c. motor done clear
  B)
   field controlled d. c. motor done clear
  C)
   a. c. servomotor done clear
  D)
   none of these done clear
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• question_answer15)
  A system has the transfer function\[(1-s)/(1+s)\]. What is its gain at 1 rad/sec?
  A)
   low?pass system done clear
  B)
   high?pass system done clear
  C)
   all?pass system done clear
  D)
   none of these done clear
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• question_answer16)
  Given that D=rotor diameter and L=axial length, a hid performance ac servo-motor is characterized by
  A)
   large D, large L  done clear
  B)
   large D, small L done clear
  C)
   small D, large L done clear
  D)
   small D, large L done clear
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• question_answer17)
  For the minimum phase system to be stable
  A)
   phase margin should be negative and gain margin positive done clear
  B)
   phase margin should be positive and gain margin negative done clear
  C)
   both gain margin and phase margin should be positive done clear
  D)
   both gain margin and phase margin should be negative done clear
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• question_answer18)
  Proportional band of a controller is defined as the range of
  A)
   measured variables from set value done clear
  B)
   measured variables through which the air output changes from maximum to minimum done clear
  C)
   air output as measured variable varies from maximum to minimum done clear
  D)
   none of these done clear
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• question_answer19)
  The sensitivity of a closed loop control system to variations in gain and load disturbance depends upon
  A)
   loop gain                      done clear
  B)
   frequency done clear
  C)
   forward gain                  done clear
  D)
   all of these done clear
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• question_answer20)
  An AC servomotor (2 ? phase induction motor) has a rotor with
  A)
   high resistance winding       done clear
  B)
   very small di ameter to reduce inertia done clear
  C)
   very small axial length to reduce inertia done clear
  D)
   both [a] and [b] done clear
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• question_answer21)
  5 percent?proportional band means control output
  A)
   change by 5 percent done clear
  B)
   change from maximum to minimum for 5 percent change in measured variable done clear
  C)
   changes by 95 percent done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer22)
                               Laplace Transform of the functions \[{{e}^{-1}}\]and\[{{e}^{-2t}}\] are    
  A)
   \[\frac{1}{s+1},\,\,\frac{1}{s-2}\]                      done clear
  B)
   \[\frac{1}{s-1},\,\,\frac{1}{s-2}\] done clear
  C)
   \[\frac{1}{s+1},\,\,\frac{1}{s-2}\]                      done clear
  D)
   None of these done clear
  View Solution play_arrow

• question_answer23)
  In pneumatic systems, electrical capacitance is analogous to
  A)
   restriction to flow           done clear
  B)
   volume of air done clear
  C)
   filled helical tube            done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer24)
  Backlash in a stable control system can cause
  A)
   over damping done clear
  B)
   low-level oscillations done clear
  C)
   underdamping done clear
  D)
   poor stability at reduced values of open-loop gain done clear
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• question_answer25)
  In force-current analogy, displacement is analogous to
  A)
   magnetic flux linkage      done clear
  B)
   capacitance done clear
  C)
   voltage             done clear
  D)
   inductance done clear
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• question_answer26)
  A transfer function of control system does not have pole-zero cancellation. Which one of the following statement  is true?
  A)
   System is neither controllable nor observable done clear
  B)
   System is completely controllable & observable done clear
  C)
   System is observable but uncontrollable done clear
  D)
   System is controllable but unobservable done clear
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• question_answer27)
  The transfer function Y (s) / U (S) of a system described by the state equations \[dx/dt=-2x+2u\]and \[y\,\,(t)=0.5x\] is:
  A)
   \[0.5/(s-2)\]                    done clear
  B)
   \[1/(s-2)\] done clear
  C)
   \[0.5/(s+2)\]                  done clear
  D)
   \[1/(s+2)\] done clear
  View Solution play_arrow

• question_answer28)
  In closed loop control system in which positive value of feedback then gain the overall gain of the system will
  A)
   Decrease                       done clear
  B)
   Increase done clear
  C)
   be unaffected                done clear
  D)
   None of these done clear
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• question_answer29)
  The analysis of multiple input multiple output is conveniently studied by;
  A)
   State space analysis done clear
  B)
   Root locus approach done clear
  C)
   Characteristic equation approach done clear
  D)
   Nicholas chart. done clear
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• question_answer30)
  The output of a feedback control system must be a function of
  A)
   Reference and output done clear
  B)
   Reference and input done clear
  C)
   Input and feedback signal done clear
  D)
   Output and feedback signal done clear
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• question_answer31)
  Zero initial condition for a system means?
  A)
   Input, reference signal is zero done clear
  B)
   Zero stored energy done clear
  C)
   "Initial movement of moving parts done clear
  D)
   System is at rest and no energy is stored in any of its components. done clear
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• question_answer32)
  Transfer function of a system is used to calculate which of the following?
  A)
   The order of the system done clear
  B)
   The time constant done clear
  C)
   The output for any given input done clear
  D)
   The steady state gain. done clear
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• question_answer33)
  The transient response, with feedback system,
  A)
   Rises slowly                   done clear
  B)
   Rises quickly done clear
  C)
   Decays slowly    done clear
  D)
   Decays quickly done clear
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• question_answer34)
  Which of the following statements is correct for any closed loop system?
  A)
   All the co-efficient can have zero value done clear
  B)
   All the co-efficient are always non-zero done clear
  C)
   Only one of the static error co-efficient has a finite non-zero value done clear
  D)
   Only two of the static error co-efficient has a finite non-zero value. done clear
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• question_answer35)
  Which among the following is not an advantage of an open loop system?
  A)
   Simplicity in construction & design done clear
  B)
   Easy maintenance done clear
  C)
   rare problems of stability done clear
  D)
   Requirement of system recalibration from time to time done clear
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• question_answer36)
  How is an output represented in the control systems?
  A)
   \[r(t)\]                           done clear
  B)
   \[c(t)\] done clear
  C)
   \[x(t)\]                          done clear
  D)
   \[y(t)\] done clear
  View Solution play_arrow

• question_answer37)
  The output signal is fed back at the input side from the ____point
  A)
   Summing                      done clear
  B)
   Differential done clear
  C)
   Take-off                        done clear
  D)
   All of the above done clear
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• question_answer38)
  In a signal flow graph, nodes are represented by small
  A)
   Circles              done clear
  B)
   Squares done clear
  C)
   Arrows              done clear
  D)
   Pointers done clear
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• question_answer39)
  In second order system, which among the following remains independent of gain (k)?
  A)
   Open loop poles done clear
  B)
   closed loop poles done clear
  C)
   Both a and b                 done clear
  D)
   None of the above done clear
  View Solution play_arrow

• question_answer40)
  In a parallel combination, the direction of flow of signals through blocks in parallel must resemble to the main
  A)
   Forward                        done clear
  B)
   Feedback done clear
  C)
   Opposite                       done clear
  D)
   Diagonal done clear
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• question_answer41)
  Where are the dummy nodes added in the branch with unity gain?
  A)
   At input & output nodes done clear
  B)
   Between chain nodes done clear
  C)
   Both a & b                        done clear
  D)
   None of the above     done clear
  View Solution play_arrow

• question_answer42)
            Which among the following are solely responsible in determining the speed of response of control system?
  A)
   Poles                done clear
  B)
   Zeros done clear
  C)
   Speed of input   done clear
  D)
   All of the above done clear
  View Solution play_arrow

• question_answer43)
  State space analysis is applicable even if the initial conditions are ___
  A)
   Zero                             done clear
  B)
   Non-zero done clear
  C)
   Equal               done clear
  D)
   Not equal done clear
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• question_answer44)
  What is the value of steady state error in closed loop control systems?
  A)
   Zero                             done clear
  B)
   Unity done clear
  C)
   Infinity             done clear
  D)
   Unpredictable done clear
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• question_answer45)
  Laplace transform of an impose response is regarded as ___ function of the system                   
  A)
   Analytic                        done clear
  B)
   Parabolic          done clear
  C)
   Transfer                        done clear
  D)
   Hypothetical    done clear
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• question_answer46)
     For the elimination of feedback loops, the derivation  based on transfer function of____ loop is use [d] 
  A)
   Open                done clear
  B)
   Closed-       done clear
  C)
   Both a & b                   done clear
  D)
   None of the above   done clear
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• question_answer47)
  In block diagram representation, what do the lines     connecting the blocks, known as?                
  A)
   Branches                      done clear
  B)
   Nodes             done clear
  C)
   Datums            done clear
  D)
   Sources     done clear
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• question_answer48)
        For which systems are the signal flow graphs applicable!
  A)
   Causal                                       done clear
  B)
   Invertible done clear
  C)
   linear time invariant system done clear
  D)
   Dynamic done clear
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• question_answer49)
  Type 0 systems are unsuitable ____
  A)
   For ramp inputs done clear
  B)
   If input is parabolic in nature. done clear
  C)
   Both a & b done clear
  D)
   None of the above done clear
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• question_answer50)
  A good control system should be sensitive to ____
  A)
   Internal disturbances done clear
  B)
   Environmental parameters done clear
  C)
   Parametric variations done clear
  D)
   Input signals (except noise) done clear
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