46. A synchronous motor is running from busbars and has a torque angle of δ = 15°. The bus voltage and frequency are reduced by 10% while field current and load torque are held constant (all losses are negligible).The new torque angle will
    

1. 1. remain the same

   
   
   

   2. increase slightly

   
   
   

   3. decrease slightly

   
   
   

   4. the motor will lose synchronism

   
   
   

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   NA

   Correct Option: B

   NA

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47. Synchronous generator voltage obtained by the synchronous impedance method is
    

1. 1. higher than actual as it does not account for magnetic saturation

   
   
   

   2. lower than actual as it does not account for magnetic saturation

   
   
   

   3. nearly accurate as it accounts for magnetic saturation

   
   
   

   4. nearly accurate as the generator is normally operated in the unsaturated regi on of magnetization

   
   
   

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   NA

   Correct Option: A

   NA

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48. x_d = d-axis synchronous reactance, x_q = q-axis synchronous reactance In a salient pole synchronous machine
    

1. 1. x_q > x_d

   
   
   

   2. x_q = x_d

   
   
   

   3. x_q < x_d

   
   
   

   4. x_q = 0

   
   
   

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   NA

   Correct Option: C

   NA

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49. d = direct axis, q = quadrature axis, E_f = excitation emf. In a salient pole synchronous machine
    

1. 1. I_d and I_q are both in phase with E_f

   
   
   

   2. I_q is in phase with E_f and I_d at 90° to E_f

   
   
   

   3. I_q is at 90° to E_f and I_d is in phase with E_f

   
   
   

   4. I_d and I_q are at 90° to E_f

   
   
   

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   NA

   Correct Option: B

   NA

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50. Compare the per pole permeance of direct and quadrature of a salient pole synchronous machine
    

1. 1. Direct axis permeance is more than quadrature axis permeance

   
   
   

   2. Quadrature axis permeance is more than direct axis permeance

   
   
   

   3. Direct and quadrate axis permeances are equal

   
   
   

   4. Quadrature axis permanence is zero

   
   
   

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   NA

   Correct Option: A

   NA

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