372 



ELEMENTS OF ELECTRICAL ENGINEERING. 



The group a of stator conductors is a group in which currents 

 flow away from the reader, the group b of stator conductors is 

 a group in which currents flow towards the reader, and these two 

 groups travel along with the curve MM as the curve moves to 

 the right, although, of course, the stator conductors themselves 

 remain stationary. 



Figure 5 represents a portion of the stator and rotor of a mul- 

 tiphase induction motor, and the ordinates of the moving curve 

 MM represent the values of the current in the stator conductors 



ill iimmmi M T \ mtmt IIH iiiiitit^itit i j 1 1 i^tuiitiiiiii pim 



:>:#yXto}^ 



curves moving 



Fig. 5. 



as in Fig. 4. A careful study of the figure will show that the 

 groups a and b of Fig. 4 produce magnetic flux which crosses 

 the gap space as indicated in Fig. 5, the regions 5, N, S, etc., 

 being regions of south polarity, north polarity, and south polarity, 

 respectively, of the stator iron, and these polar regions travel 

 along with the moving curve MM. The flux density at any 

 point in the gap space is represented by the ordinate b of the 

 curve BB. The currents in the stator conductors, which are 

 represented by the dots and crosses in Fig. 5, constitute what are 

 called the magnetizing currents of the motor, inasmuch as their 

 sole effect is to produce the moving state of magnetism which is 

 represented by the moving curve BB. 



