46. In order to obtain static voltage equalization in series connected SCRs, connections are made of—
    

1. 1. One resistor across the string
      

   
   
   

   2. Resistors of different values across each SCR
      

   
   
   

   3. Resistors of the same value across each SCR
      

   
   
   

   4. One resistor in series with the string

   
   
   

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   NA

   Correct Option: C

   NA

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47. In given fig. capacitor C is charged to V0 = 50 V with upper plate positive. Switch S is closed at t = 0. Current through the circuit at t = 0 and final voltage across are respectively—
    
    
    
    

1. 1. 15 A, 200V
      

   
   
   

   2. 20 A, 200V
      

   
   
   

   3. 25 A, 250V
      

   
   
   

   4. 15 A, 150V

   
   
   

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   NA

   Correct Option: A

   NA

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48. In a convertional reverse blocking thyristor—
    

1. 1. External layers are lightly doped and internal layers are heavily doped

   
   
   

   2. External layers are heavily doped and internal layers are lightly doped

   
   
   

   3. The P-layers are heavily doped and the n-layers are lightly doped
      

   
   
   

   4. The P-layers are lightly doped and the n-layers are heavely doped

   
   
   

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   NA

   Correct Option: D

   NA

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49. In a 3-phase rectifier circuit, thyristor number 1, 2 and 3 are connected respectively to R, Y, and B phases of the star connected transformer secondary. When the current is being commutated from thyristor No. 1 to No. 2 the effect of the transformer leakage and the a.c. system inductance will be such that it will—
    

1. 1. Prolong the conduction in No. 1 at the scheduled time but delay the turn ON of No. 2 correspondingly
      
      

   
   
   

   2. Stop the conduction in No. 1 at the scheduled time but delay the turn-ON of No. 2

   
   
   

   3. Produce conduction in both No. 1 and No. 2 in parallel for an overlapping period through a transient
      

   
   
   

   4. Double the voltage o/p through a commutation transient

   
   
   

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   NA

   Correct Option: C

   NA

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50. A-3 phase converter feeds a pure resistive load at a firing angle of α = 60°. The average value of current flowing in the load is 10 A. If a very large inductance is connected in the load circuit, then the—
    

1. 1. Average value of current will remain as 10 A
      

   
   
   

   2. Average value of current will become greater than 10A
      

   
   
   

   3. Average value of current will become less than 10A.
      

   
   
   

   4. Trend of variation of current cannot be predicted unless the exact value of the inductance connected is known

   
   
   

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   NA

   Correct Option: A

   NA

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