Control Systems - Study Mode

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[#126] For the system $$frac{2}{{s + 1}},$$ xa0the approximate time taken for a step response to reach 98% of its final value is

(A) 1 s

(B) 2 s

(C) 4 s

(D) 8 s

Correct Answer

(C) 4 s

[#127] Gain cross over frequency is the frequency at which gain is

(A) unity

(B) 0

(C) ∞

(D) 2

Correct Answer

(A) unity

[#128] Consider the following statements relating to synchros: 1. The rotor of the control transformer is either disc shaped. 2. The rotor of the transmitter is so constructed as to have a low magnetic reluctance. 3. Transmitter and control transformer pair is used as an error detector. Which of these statements are correct?

(A) 1, 2 and 3

(B) 1 and 2

(C) 2 and 3

(D) 1 and 3

Correct Answer

(C) 2 and 3

[#129] Consider the following statements for a.c. series motors: 1. The rotor is designed so that its R/X ratio is small. 2. dT/dω < 0 where T and ω are torque and speed respectively. 3. The reference and control voltages should be in phase quadrature, but their magnitudes need not be equal. Which of the statement given above are correct?

(A) 1, 2 and 3

(B) 1 and 2

(C) 2 and 3

(D) 1 and 3

Correct Answer

(B) 1 and 2

[#130] Which one of the following is NOT a correct statement about the state-space model of a physical system?

(A) State-space model can be obtained only for a linear system

(B) Eigen values of the system represents the roots of the characteristic equation

(C) [mathop { m{X}}limits^ cdot ] = AX + BU represents linear state-space model of a physical system

(D) X(t) represents the state vector of the system

Correct Answer

(A) State-space model can be obtained only for a linear system