71. A second order system has a transfer function given by:

If the system initially at rest is subjected to a unit step input at t = 0, the second peak in the response will occur at:

(a) 𝜋 sec

(b) 𝜋/3 sec

(c) 2𝜋/3 sec

(d) 𝜋/2 sec

(a) 𝜋 sec

(b) 𝜋/3 sec

(c) 2𝜋/3 sec

(d) 𝜋/2 sec

**Answer: (a)**

72. A lag compensator:

1. Improves the steady state behaviour of the system

2. Speeds up the transient response

3. Nearly preserves its transient response

1. Improves the steady state behaviour of the system

2. Speeds up the transient response

3. Nearly preserves its transient response

Which of the above statements are correct?

(a) 1, 2 and 3

(b) 1 and 2 only

(c) 2 and 3 only

(d) 1 and 3 only

(a) 1, 2 and 3

(b) 1 and 2 only

(c) 2 and 3 only

(d) 1 and 3 only

**Answer: (d)**

73. For a state model:

**Answer: (a)**

74. If the transfer function does not have pole-zero cancellation, the system can always be represented by:

(a) Unity feedback

(b) Characteristic equation

(c) Completely controllable and observable state model

(d) Neither completely controllable nor observable

(a) Unity feedback

(b) Characteristic equation

(c) Completely controllable and observable state model

(d) Neither completely controllable nor observable

**Answer: (c)**

75. For the given transfer function:

The corner frequencies will be respectively:

(a) 2 rad/sec and 10 rad/sec

(b) 4 rad/sec and 10 rad/sec

(c) 2 rad/sec and 5 rad/sec

(d) 4 rad/sec and 5 rad/sec

(a) 2 rad/sec and 10 rad/sec

(b) 4 rad/sec and 10 rad/sec

(c) 2 rad/sec and 5 rad/sec

(d) 4 rad/sec and 5 rad/sec

**Answer: (b)**

76. A single phase transformer has total core loss of 1000 𝑊 at 420 𝑉 , 60 Hz and total core loss of 400 𝑊 at 210 𝑉 , 30 Hz . The total core loss at 350 𝑉 , 50 Hz will be nearly:

(a) 593.4 𝑊

(b) 685.4 𝑊

(c) 777.8 𝑊

(d) 869.8 𝑊

(a) 593.4 𝑊

(b) 685.4 𝑊

(c) 777.8 𝑊

(d) 869.8 𝑊

**Answer: (c)**

77. In a transformer, the core loss is 120 𝑊 at 40 Hz and 82.5 𝑊 at 30 Hz . Both losses are measured at the same flux density. The hysteresis and eddy current losses at 50 Hz will be:

(a) 100 𝑊 and 62.5 𝑊

(b) 95 𝑊 and 62.5 𝑊

(c) 100 𝑊 and 52.5 𝑊

(d) 95 𝑊 and 52.5 𝑊

(a) 100 𝑊 and 62.5 𝑊

(b) 95 𝑊 and 62.5 𝑊

(c) 100 𝑊 and 52.5 𝑊

(d) 95 𝑊 and 52.5 𝑊

**Answer: (a)**

78. What is the condition for progressive winding in dc machine?

**Answer: (a)**

79. A dc shunt generator has an induced voltage on open circuit of 127 𝑉 . When the machine is on load, the terminal voltage is 120 𝑉 . For the field resistance of 15 Ω, armature resistance of 0.02 Ω and by ignoring armature reaction, the load current will be:

(a) 360 𝐴

(b) 354 𝐴

(c) 348 𝐴

(d) 342 𝐴

(a) 360 𝐴

(b) 354 𝐴

(c) 348 𝐴

(d) 342 𝐴

**Answer: (d)**

80. A 100 kVA, 6600/330 𝑉 , 50 Hz , single-phase transformer took 10 𝐴 and 436 𝑊 at 100 𝑉 in a short-circuit test, referring to the high voltage side. The voltage to be applied to the high voltage side on full-load at 0.8 𝑝.𝑓. lagging when the secondary load voltage is 330 𝑉 will be:

(a) 6914 𝑉

(b) 6734 𝑉

(c) 6452 𝑉

(d) 6172 𝑉

(a) 6914 𝑉

(b) 6734 𝑉

(c) 6452 𝑉

(d) 6172 𝑉

**Answer: (b)**

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