INDUCTION MOTOR 



337 



which would be generated in the rotor at standstill by the flux $ ff . 

 E% does not remain constant as the motor is loaded, since the flux 

 3> ff does not remain constant but decreases about 30 per cent from 

 no load to standstill when the rotor is locked and slip is unity. 

 Up to full load $0 and E 2 may be considered to remain constant. 

 The impedance of the rotor at slip s is 



2 2 = Vr 2 2 + s 2 z 2 2 (303) 



The rotor current is 



-T^-T (304) 



The rotor power factor is 

 cos 6% = 



Vr 2 2 



(305) 



211. Rotor Input. The power transferred from the stator to 

 the rotor per phase is the product of the back voltage E f , generated 

 in the stator by the flux 3> , the load component of the stator 

 current /' and the cosine of the angle between them; it is 



p r = ET cos 2 (see Fig. 319) .... (306) 



FIG. 319. 



but 

 and 



