Wednesday, 25 December 2013

Control System

                                            CHOOSE THE CORRECT ANSWER

1.      Feedback control systm are,
a.       Insensitive to feedback path and forward path parameters change
b.      Less senative to feedback path parameter changes than to forward path parameters changes
c.       Less sensitive to feedback path parameter changes than to forward path parameters changes
d.      Equally

2.      Pick up the correct sentence among the following which represent the good characterstics of a system
a.       Sensitive to parameter variation
b.      Insensitive to input commands
c.       Neither sensitive to parameter variation nor to input commands
d.      Insensitive to parameter variation about sensitive to input commands

3.      If a system has inherently zero intial conditions then physically it means
a.       The system is at rest but stores energy
b.       The system is working but does not store energy
c.       The system is at rest (or) no energy stored in any of its parts
d.      The system is working with zero reference input

4.      The system described by the equation y=k1x+k2 for k1>0 k2>0 represents,
a.      Linear
b.      Non-linear
c.       Time varying
d.      Dynamic

5.      The basic elements of a mechanical rotational systems are
a.       Moment of inertia
b.       Dash-pot
c.       Spring
d.      All the above

6.      The basic elements of a mechanical translation system are
a.       Mass
b.      Spring
c.        Dash-pot
d.      All the above

7.      A few names of synchro’s are
a.       Selsyn
b.      Autosyn
c.       Telesyn
d.      All the above

8.      Block diagram can be used for,
a.       Only linear systems
b.      Only non-linear systems
c.       Both linear and non-linear systems
d.      Time-invariant as well as time-varying systems

9.      A node which has both incoming and out going branches is,
a.       Sink
b.      Source
c.       Mixed node
d.      None

10.  Laplace transform of an impulse function is given by,
a.      One
b.      Zero
c.       None of the above
d.      I/S

11.  The transient response of a system depends on,
a.       Only on the inputs applied
b.      Only on the system poles
c.       Both the system poles and inputs
d.      None of the above

12.  If the value of time constant is large, then it corresponds to the system
a.       Faster
b.      Under damped
c.       Sluggish
d.      Over damped

13.  The velocity error constant is given by
a.      Lims-0 SG(S)H(S)
b.      Lims-0 S2G(S)H(S)
c.       Lims-0 G(S)H(S)
d.      None of the above

14.  The order of a control system with an integral control,
a.       Decrease
b.      Increases
c.       Remains unaffected
d.      None

15.  The system that has non-repeated poles on jw-axis is a,
a.       Conditionally stable
b.      Stable
c.       Un-stable
d.      Marginally stable

16.  Integrator’s are,
a.      Marginally stable
b.      Absolutely method
c.       Conditionally stable
d.      None of these

17.  The ROUTH stability critirion for testing the stability is an,
a.      Graphical method
b.      Alzebric method
c.       Both
d.      None

18.  The root locus technique is an,
a.   Graphical method
b.   Alzebric method
c.   Both
d.   None

19.  The root locus technique is used to study,
a.       Absolute stability of system
b.      Relative stability of system
c.       Both
d.      None of these

20.   An octave is the range of frequencies given by,
a.      W2=2w1
b.      W2=8w1
c.       W2=10w1
d.      W2=14.14w1

21.  Db’s are unis of
a.       20logeG(jw)
b.      G(jw)
c.       20log10G(jw)
d.      10log10G(jw)

22.  A unity feedback system has G(s)=100(s+2)/(s2(s+1)(s2+2s+1)). The slope of the low frequency asymptote is
a.       -20db/decade
b.      -80db/decade
c.       -40db/decade
d.      80db/decade

23.  The log magnitude of a system with transfer function e-0.1 is,
a.       Unity
b.      -20
c.       -46.05
d.      0

24.  If a system consists of oe zero and five poles the final slope of the magnitude plot is
a.       80db/decade
b.      -80db/decade
c.       -60db/decade
d.      60db/decade

25.  In a magnitude plot of a system the slope changed by +20dbs at w=10rad/sec. The corresponding factor in the loop transfer function is,
a.      (1+0.1jw)
b.      1/(1+0.1jw)
c.       10/jw
d.      10jw

26.  For a large gain margin or phase margin the system is
a.       Stable
b.      Sluggish
c.       Both
d.      None

27.  Addition of a zero at origin to a transfer function results in rotation of the polar plot through an angle of                 at both 0 and infinite frequencies is,
a.       -900
b.      0
c.       1800
d.      900

28.  A unity feedback system is G(s)=1/(1+10s). For the inverse polar plot of this system, the magnitude and phase angle at zero frequency are,
a.      1,0
b.      0,1,0
c.       Infinite, 900
d.      Infinite, -900
29.  The loop transfer function of a system is 1/(s2(1+s)(1+10s)(1+100s))
a.       –ve real, +jw, +ve real
b.      Only +ve imaginary
c.       +ve jw and +ve real
d.      Only –ve imaginary

30.  The loop transfer function of a system is G(s)H(s)=1/(1+s). The magnitude and phase angle at infinite frequency are,
a.       0, n/2
b.      0,-n/2
c.       Infinite, -900
d.      Infinite, 900

31.  The polar plot of a system passes through the point (-1+j0). The GM is
a.       -1db
b.      <1db
c.       1db
d.      0db

32.   Adding a pole at s=0 to a loop transfer function will,
a.       Not affect the stability of closed loop system
b.      Increase the stability of closed loop system
c.       Reduce the stability of the closed loop system
d.      None of these

33.  Addition of zeros to the loop transfer function affects the closed loop stability in the following manner
a.      It is improved
b.      It is reduced
c.       It is not affected
d.      The exact effect depends on the loop transfer function

34.  In control system design GM and PM are usually provided to
a.       Make the system respond fast
b.      Account for the uncertainties in the system
c.       Reduce the overshoot in the stop response
d.      Reduce the steady state offers

35.  In the frequency domain design if the open loop gain is increased the gain cross over frequency w1 and phase cross over w2 on the bode plots get affected in the following manner
a.       Both w1, w2 move to right
b.      Both w1, w2 remain constant
c.       W2 is constant while w1 moves to right
d.      W1 moves to right while w2 remains constant
36.  If the gain is increased the magnitude plot of bode plot,
a.      Shifts up
b.      Shifts down
c.       Does not get affected
d.      Gets totally changed and shifts down

37.  For a lead componesator the value of ‘a’ should be,
a.       1<a<0
b.      1
c.       0<a<1
d.      0

38.  With a lead compensator the rise time of the system will,
a.       Increase to the extent which depends to the loop transfer function of the system
b.      Increase
c.       Remain same
d.      Decrease

39.  In a lag compensator the sensitivity function is greater than unity. This is true for,
a.       Frequency equal to bandwidth
b.      Entire frequency range
c.       Frequencies lesser than bandwidth
d.      Frequencies greater than bandwidth

40.  In the time domain, the phase lag control generally will,
a.       Decrease rise time and setting time
b.      Increase rise time and setting time
c.       Both increase and decrease setting time
d.      Decrease rise time and increase setting time

41.  The typical value of b choosen in the lag compensator is usually,
a.       0
b.      0.1
c.       10
d.      Infinite

42.  When a sinusoidal signal is appied to a lag network, phase lag and phase lead occur in the output in            and               frequency regions
a.       Low and low
b.      Low and high
c.       High and high
d.      High and low

43.  By using lag lead compensation the order of the system will,
a.       Become doubled
b.      Increase by one
c.       Remain same
d.      Increase by two

44.  The phase lead portion of a lead lag compensator is used in                 rise time and                  bandwidth
a.      Smaller, higher
b.      Smaller, smaller
c.       Higher, higher
d.      Higher, smaller

45.  A PD controller,
a.       Decrease both BW and rise time
b.      Increase both BW and rise time
c.       Increases BW and reduces rise time
d.      Decreases BW and increases rise time

46.  A PI controller
a.      Increase rise time and decreases BW
b.      Increase both BW and rise time
c.       Increase BW and reduces rise time
d.      Decreases BW and increases rise time

47.  A PID controller
a.      Improves both steady state but transient response
b.      Improves steady state but transient response is not affected
c.       Improves transient state but steady state is not affected
d.      Does not affect either steady station or transient respone

                                     FILL IN THE BLANKS

  • 1.      Sprinkler is an example of open-loop system.
  • 2.      The input quantity is also known as excitation or command signal
  • 3.      The output quantity is also known as response
  • 4.      An a.c servo meter is 2-phase induction meter
  • 5.      A signal flow graph is applicable only to linear systems
  • 6.      The synchro meter transmitter and receiver are combinedly known as synchro pair
  • 7.      Impulse signal is a signal whose value is zero at t-0, where its magnitude is infinite
  • 8.      Unity is the area under a unit-impulse function
  • 9.      The steady state error of a control system due to derivation feedback control gets increased
  • 10.  Root locus technique applied to both multiple loop system
  • 11.  The zero input stability is also known as asymptotic stability
  • 12.  The stability is the important characteristic of a transient response
  • 13.   Bandwidth is inversely proportional to input frequency
  • 14.  An all pass system has pole zero pattern anti symmetric about imaginary axis
  • 15.  Corner frequency is also called as break frequency
  • 16.  Nyquist stability criterion is used to determine closed loop stability
  • 17.  If a real pole is added to loop transfer function then only at infinite frequency
  • 18.  A lead compensator is a high pass filter
  • 19.  In a lead network the noise immunity is low

  • 20.  The PI controller increases the type of the system by one 


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