APPENDIX B. 



371 



15. A simple representation of the action of the polyphase in- 

 duction motor. A clear idea of the action of the induction motor 

 may be obtained with the least difficulty by considering an induc- 

 tion motor of which the stator is supplied with an indefinitely large 

 number of phases of alternating current, each phase, of course, 

 being supplied by a separate source. Figure 4 shows a scheme 



J 



one phase 

 of winding 



o 



curve moving 



Fig. 4. 



for representing the flow of currents in the stator conductors of 

 such a multiphase induction motor. The small circles with dots 

 and crosses represent the stator conductors (end view), and one 

 phase of the winding is indicated in the upper part of the figure. 

 Consider the sine curve MM, and imagine it to travel in the 

 direction of the arrow along the axis 00. Then the ordinate 

 m of this curve at any point represents the value of the current 

 at the given instant in the stator conductor which is directly 

 above m. Thus, the crosses of different sizes in the group a of 

 stator conductors represent currents of different values flowing 

 away from the reader ; and the dots of different sizes in the group 

 b represent currents of different values flowing towards the reader. 



