61. A 10 kVA, 400 V/ 200 V, single phase transformer with a percentage resistance of 3% and percentage reactance of 6% is supplying a current of 50 A to a resistive load. The value of the load voltage is _______ V .

1. 1. 57 V

   
   
   

   2. 131 V

   
   
   

   3. 194 V

   
   
   

   4. 105 V

   
   
   

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   NA

   Correct Option: C

   NA

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62. The percentage resistance and percentage reactance of a 10 kVA, 400 V / 200 V, 3-phase transformer are 2% and 10% respectively. If the constant losses in the machine are 1%, the maximum possible percentage efficiency of the transformer is _______ .

1. 1. 97.25

   
   
   

   2. 57.25

   
   
   

   3. 67.75

   
   
   

   4. None of the above

   
   
   

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   NA

   Correct Option: A

   NA

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63. A 3– phase delta/star transformer is supplied at 6000 V on the delta-connected side. The terminal voltage on the secondary side when supplying full load at 0.8 lagging power-factor is 415 V. The equivalent resistance and reactance drops for the transformer are 1% and 5% respectively. The turns ratio of the transformer is _______ .
    

1. 1. 4

   
   
   

   2. 24

   
   
   

   3. 12

   
   
   

   4. All of the above

   
   
   

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   Turn ratio =	Phase voltage on primary side
   	Phase voltage on secondary side

   
   

   =	6000 × √3	= 24
   	415

   
   

   Correct Option: B

   Turn ratio =	Phase voltage on primary side
   	Phase voltage on secondary side

   
   

   =	6000 × √3	= 24
   	415

   
   

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64. The low voltage winding of a 400 / 230V, 1– phase, 50 Hz transformer is to be connected to a 25 Hz, the supply voltage should be _______ V .

1. 1. 75 V

   
   
   

   2. 315 V

   
   
   

   3. 115 V

   
   
   

   4. 65 V

   
   
   

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   NA

   Correct Option: C

   NA

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65. A 400 V/ 200 V/ 200 V, 50 Hz three winding transfor mer is connected as shown in the given figure. The reading of the voltmeter,V will be _______ V.
    

1. 1. 0 V

   
   
   

   2. 1 V

   
   
   

   3. 2 V

   
   
   

   4. 3 V

   
   
   

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   NA

   Correct Option: A

   NA

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