Automatic Control System MCQ-1

1. A system with large time constant corresponds to a _____ system.

(A) Fast
(B) Sluggish
(C) Both (a) and (b)
(D) None of these

2. The AC servomotor is basically a :

(A) Universal motor
(B) Capacitor motor
(C) 2-Phase induction motor
(D) 3-Phase induction motor

3. Error or actuating signal is generated in a :

(A) Open loop system
(B) Closed loop system
(C) Both (a) and (b)
(D) None of these

4. In a block diagram error detector _____

(A) Changes the input signal
(B) Compares the input & Output signal
(C) Changes the output signal
(D) None of these

5. The drag up rotor employed in a 2-phase induction motor to give :

(A) High inertia
(B) Low inertia
(C) Low torque
(D) High torque

6. Damping in a control system is a function of

(A) Gain
(B) √gain
(C) 1/√gain
(D) 1/gain

7. Root locus is the plot of the roots of the characteristic equation of a closed loop system against variation in :

(A) Gain K
(B) Frequency
(C) S
(D) None of these

8. Slope of factor K in plotting Bode Magnitude curve is :

(A) 0°
(B) 90°
(C) 45°
(D) 20°

9. If a zero appears in the first column of the Routh table, the system is :

(A) Marginally stable
(B) Necessarily stable
(C) Necessarily unstable
(D) Conditionally stable

10. Which of the following technique provide quick transient and stability response ?

(A) Nyquist criterion
(B) Nicholas plot
(C) Bode plot
(D) Root locus

11. The characteristic equation of a closed loop system is given by S²+4S+16=0. The undamped natural frequency in rad/sec is :

(A) 2
(B) 2√3
(C) 4
(D) 2√2

12. Which of the following may result in instability problem :

(A) Larger error
(B) High selectivity
(C) Noise
(D) High gain

13. In time domain specification, the delay time is the time required for the response to reach :

(A) 75% of final value
(B) 25% of final value
(C) 50% of final value
(D) 100% of final value

14. If all the roots of the characteristic equation lie in the left half of S-plane the system will be :

(A) Stable
(B) Unstable
(C) Critically stable
(D) None of the above

15. Root locus is used to calculate :

(A) Marginal stability
(B) Absolute stability
(C) Conditional stability
(D) Relative stability

16. Which of the test signal are best utilized by the stability analysis ?

(A) Impulse
(B) Step
(C) Ramp
(D) Parabolic

17. The critical value of gain for the system is 40. The system is operating at a gain of 20. The gain margin of the system is :

(A) 2 dB
(B) 3 dB
(C) 6 dB
(D) 4 dB

18. Addition of zero at the origin causes

(A) Improvement in transient response
(B) Reduction in steady state error
(C) Reduction in settling time
(D) Increase in damping constant

19. Multiple signals as input can be used in which systems :

(A) Feedback systems
(B) Non-feedback systems
(C) Any of (a) or (b)
(D) Both (a) & (b)

20. The characteristic equation of a system is given by 3S^4 +10S³+5S²+2=0. The system is :

(A) Stable
(B) Marginally stable
(C) Unstable
(D) Linear