86. The single phase line of 230 V and 3 phase line of 400 V which feed different domestic circuits and industrial loads represent
    

1. 1. primary distribution

   
   
   

   2. secondary distribution

   
   
   

   3. secondary transmission

   
   
   

   4. none of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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87. If an induction machine is run at above synchromous speed, it acts as

1. 1. a synchronous motor

   
   
   

   2. an indcution generator

   
   
   

   3. an inductor motor

   
   
   

   4. none of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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88. The main criterion for selection of the size of a distribution for a radial distribution system is

1. 1. voltage drop

   
   
   

   2. corona loss

   
   
   

   3. temperature rise

   
   
   

   4. capital cost

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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89. The velocity of travelling wave through a cable at relative permittivity 9 is

1. 1. 9 × 10⁸ metre/sec

   
   
   

   2. 3 × 10⁸ metre/sec

   
   
   

   3. 10⁸ metre/sec

   
   
   

   4. 2 × 10⁸ metre/sec

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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90. For effective use of a counterpoise wire

1. 1. its leakage resistance should be greater than the surge impedance

   
   
   

   2. its leakage resistance should be less than the surge impedance

   
   
   

   3. its leakage resistance should be equal to the surge impedance

   
   
   

   4. two resistance may have any relation

   
   
   

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1. View Hint View Answer Discuss in Forum

   If surge impedance will be smaller than the leakage resistance, then positive reflections will occur and the potential of the tower will be raised which will result in flash over of the insulator discs and finally a line-to-ground fault will occur.

   Correct Option: B

   If surge impedance will be smaller than the leakage resistance, then positive reflections will occur and the potential of the tower will be raised which will result in flash over of the insulator discs and finally a line-to-ground fault will occur.

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