56. The transfer function of a phase lead controller is (1 + 3Ts)/ (1 + Ts). The maximum value of phase provided by this controller is—
    

1. 1. 90
      

   
   
   

   2. 60
      

   
   
   

   3. 45
      

   
   
   

   4. 30

   
   
   

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1. View Hint View Answer Discuss in Forum

   Try-yourself

   Correct Option: D

   Try-yourself

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57. In a synchronous error detector, the output voltage is proportional to [ω(t)]n where ω(t) is the rotor velocity and n equals to—
    

1. 1. – 2
      

   
   
   

   2. – 1
      

   
   
   

   3. 1
      

   
   
   

   4. 2

   
   
   

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1. View Hint View Answer Discuss in Forum

   In a synchronous error detector the output voltage is proportional to [ω(t)]n where ω(t) is rotor velocity and n = 1.

   Correct Option: C

   In a synchronous error detector the output voltage is proportional to [ω(t)]n where ω(t) is rotor velocity and n = 1.

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58. The Laplace transform of the function i(t) is
    

    I (s) =	10s + 4
    	s(s + 1)(s2 + 4s + 5)

    
    Its final value will be—
    

1. 1. 4/5
      

   
   
   

   2. 5/4
      

   
   
   

   3. 4
      

   
   
   

   4. 5

   
   
   

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1. View Hint View Answer Discuss in Forum

   According to final value theorem,
   _{t → ∞}lim I(t) = _{s → 0}lim sl/(s)
   = lim s → 0 s(10s + 4) s(s + 1) (s2 + 4s + s)
   = 4/5

   Correct Option: A

   According to final value theorem,
   _{t → ∞}lim I(t) = _{s → 0}lim sl/(s)
   = lim s → 0 s(10s + 4) s(s + 1) (s2 + 4s + s)
   = 4/5

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59. A phase-lag compensation will—
    

1. 1. improve relative stability
      

   
   
   

   2. increase the speed of response
      

   
   
   

   3. increase bandwidth
      

   
   
   

   4. increase overshoot

   
   
   

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1. View Hint View Answer Discuss in Forum

   Refer synopsis. A phase lag compensation will increase overshoot.

   Correct Option: D

   Refer synopsis. A phase lag compensation will increase overshoot.

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60. Consider the following statements regarding a first order system with a proportional (P) controller which exhibits an offset to a unit step input.
    1. increase the gain of the P controller
    2. add derivative mode
    3. add integral mode Of these statements—
    

1. 1. 1, 2 and 3 are correct
      

   
   
   

   2. 1 and 2 are correct
      

   
   
   

   3. 2 and 3 are correct
      

   
   
   

   4. 1 and 3 are correct

   
   
   

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1. View Hint View Answer Discuss in Forum

   Refer synopsis.

   Correct Option: B

   Refer synopsis.

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