86 PROBLEMS IN ALTERNATING CURRENT MACHINERY 



INDUCTION MOTOR D VTA 



64. The two induction motors, N and P, are connected in 

 concatenation. The stator of the first receives power at its 

 rated voltage and frequency, and the stator of the second is 

 short-circuited. Neglect the no-load component of the current 

 and the core loss due to the leakage flux. Assume that the core 

 loss due to the mutual flux varies as the product of the frequency 

 and the square of the flux density. 



(a) What is the total output when the slip of the second motor 

 is 4.0 per cent.? 



(b) What is the power developed by each motor? 



(c) What are the copper losses in the stator and rotor of each 

 motor? 



(d) What are the core losses in the stator and rotor of each 

 motor? 



65. The two induction motors, M and N, are connected in con- 

 catenation. The stator of the first receives power at its rated 

 voltage and frequency, and the stator of the second is short- 

 circuited. Neglect the no-load component of the current. As- 

 sume that the loss caused by the leakage flux varies as the fre- 

 quency and the square of the current. Assume that the core 

 loss due to the mutual flux varies as the product of the frequency 

 and the square of the flux density. 



(a) What is the total output when the speed is 228 rev. per min. ? 



1 At the rated voltage. 



2 Assume that the ratio of the core loss in the stator to that in the rotor 

 for the same mean flux density and frequency is 4 to 3. 



