151. In Fig. ideal moving iron voltmeters M₁ and M₂ will respectively read—
     
     
     

1. 1. 141·4 V, 141·4 V

   
   
   

   2. 0, 141·4 V

   
   
   

   3. 0, 200 V

   
   
   

   4. 141·4 V, 0

   
   
   

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   NA

   Correct Option: B

   NA

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152. Consider the following statements regarding speed control of induction motors by means of external rotor resisters:
     1. Reduction in speed is accompanied by reduced efficiency
     2. With a large resistance in the rotor circuit, the speed would vary considerably with variation in torque.
     3. The method is very complicated. The disadvantage of such a method of speed control would include:
     

1. 1. 1 and 3
      

   
   
   

   2. 2 and 3
      

   
   
   

   3. 1 and 2
      

   
   
   

   4. 1, 2 and 3

   
   
   

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   NA

   Correct Option: A

   NA

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153. Consider the following statements: The Diode in a voltage source inverter (Mc Murry inverter) should be able to—
     1. Withstand a large voltage in the reverse direction
     2. Carry the commutating current excess of load current
     3. Provide the required reverse bias to the outgoing thyristor.
     4. Feedback the reactive current to the source of these statements
     

1. 1. 1, 2 and 3 are correct
      

   
   
   

   2. 1, 3 and 4 are correct
      

   
   
   

   3. 2, 3 and 4 are correct
      

   
   
   

   4. 1, 2 and 4 are correct

   
   
   

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   NA

   Correct Option: C

   NA

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154. For the switching wave form shown in fig. for a power transistor, the average value of switch on power loss at a switching frequency of 10 kHz is—
     
     
     
     

1. 1. 1 ω
      

   
   
   

   2. 2 ω
      

   
   
   

   3. 3 ω
      

   
   
   

   4. 4 ω

   
   
   

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   NA

   Correct Option: B

   NA

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155. If the commutation angle of a Diode rectifier (due to source inductance effect) is γ. Then the inductive voltage regulation will be—
     

1. 1. 1 + cos ψ

      2

      
      

   
   
   

   2. 1 +	cos ψ
      	2

   
   
   

   3. 1 -	cos ψ
      	2

   
   
   

   4. 1 - cos ψ

      2

   
   
   

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   NA

   Correct Option: D

   NA

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