238 



ALTERNATING CURRENTS 



if v is constant, e will be a maximum when B is a maximum, 

 etc. Therefore, it may be said that e, the emf . per conductor, is 

 in space-phase with the flux. It further follows that the wave 

 shape of the emf. in a single conductor is the same as the shape of 

 the space-distribution curve of the flux. 



(a) Current belt in space-phase with flux wave when- 

 rotor reactance is low 



(b) Space distribution of current and flux 

 when in space-phase with each other 



FIG. 227. Alternating-current torque when current and flux are in space-phase. 



At small values of slip, the angle a, between the induced emf. 

 in each conductor and the current in the conductor, is small and 

 therefore the current in each of the conductors, Fig. 227 (a) is 

 practically in phase with its induced emf. As the induced emf. 



