# Control System 11

Electrical Engineering MCQ Question Papers: Campus Placement

Subject: Control System 11

Part 5: List for questions and answers of Control System II

Q1. The value of ‘a’ to give phase margin = 45° will be G(s) = (as+1)/s²

a) 0.707

b) 1.414

c) 1.18

d) 0.9

Q2. In polar plots if the critical point ‘-1+j0’ is enclosed then the system is ——–

a) Stable

b) Unstable

c) Marginally stable

d) Critical stable

Q3. Resonant peak of a marginally stable system is

a) 0

b) Finite value

c) Infinite

d) Any of the above

Q4. What is the effect of gain margin when the system gain is doubled?

a) 2 times

b) 1/2 times

c) Remains unaffected

d) None of the above

Q5. A open loop transfer function is given as G(s) = (s+2)/(s+1)(s-1). Find the number of encirclements about ‘-1+j0’?

a) 1

b) 0

c) 2

d) 3

Q6. Find the stability for the following transfer function? G(s) = 50/s(s+5)

a) Unstable

b) Marginally stable

c) Stable

d) Critically stable

Q7. Find the corner frequency for the following transfer function? G(s) = 1/(s+2)

Q8. Error at corner frequency ?cf of first order system is ——-

a) ±1 db

b) ±2 db

c) ±3 db

d) ±4 db

Q9. The maximum phase lag occurs at the ——————- of the two corner frequencies?

a) Arithmetic mean

b) Geometric mean

c) Either 1 or 2

d) None of the above

Q10. If the transfer function of a phase lead compensator is (s+a)/(s+b) and that of a lag compensator is (s+p)/(s+q), then which one of the following sets of conditions must be satisfied?

a) A greater than b, p greater than q

b) A greater than b, p less than q

c) A greater than b, p less than q

d) A less than b, p greater than q

Q11. The compensator G(s) = 5(1 + 0.3s)/(1 + 0.1s) would provide a maximum phase shift of

a) 20°

b) 45°

c) 30°

d) 60°

Q12. Consider the following statements for phase lead compensation:

a) Phase lead compensation shifts the gain crossover frequency to the right

b) The maximum phase lag occurs at the arithmetic mean of the two corner

frequencies

c) Both 1 and 2

d) Nether 1 nor 2

Q13. With regard to filtering property, the lead compensator is

a) Low pass filter

b) Band pass filter

c) High pass filter

d) Band reject filter

Q14. A controller transfer function is given by C(s) = (1+2s)/(1+0.2s). What is its nature and parameter?

a) Lag compensator, ß = 10

b) Lag compensator, ß = 2

c) Lead compensator, a = 0.2

d) Lead compensator, a = 0.1

Q15.Which of the following is/are represents the lead compensator?

a) (s+2)/(s+1)

b) (s+2)/(s+5)

c) (s+5)/(s+6)

d) Both 2 and 3

Q16. Which of the following is/are represents the lag compensator?

a) (s+2)/(s+1)

b) (s+2)/(s+5)

c) (s+5)/(s+6)

d) Both 1 and 2

Q17. The transfer function of a phase lead compensator is given by: G(s) = (1 + 3Ts)/(1 + Ts)where T>0. What is the maximum phase shift provided by such a compensator?

a) 90°

b) 45°

c) 30°

d) 60°

Q18. The following transfer function represents a phase-lead compensator?

a) (s+4)/(s+6)

b) (4s+2)/(6s+1)

c) (s+4)/(3s+6)

d) 1/s

Q19. To achieve the optimum transient response, the indicating instruments are so designed as to

a) Be undammed

b) Be critically damped

c) Provide damping which is slightly less than the critical value

d) Provide damping which is slightly more than the critical value

Q20. In the cauer-2 form of LC network———is series element and ——–is shunt element respectively?

a) L and C

b) C and L

c) L and L

d) C and C

Part 5: List for questions and answers of Control System II