254 



ELEMENTS OF ELECTRICAL ENGINEERING. 



adjustable resistance. Figures 224 and 225 are taken from the 

 publications of the General Electric Company. 



Fig. 225. 



124. Action of the induction motor.* The stator windings of 

 the polyphase induction motor produce a rotating magnetism 

 which acts upon the short-circuited rotor in the same way that 

 the rotor would be acted upon by a mechanically rotated direct- 

 current-excited field magnet, as indicated in Fig. 226. The action 

 of this mechanically rotated field magnet upon the short-circuited 

 rotor, as indicated in Fig. 226, is as follows : Electromotive forces 

 are induced in the rotor rods under the moving poles NSNS, 

 these electromotive forces produce currents in the short-circuited 

 rotor rods, and the field flux pushes sidewise on the rotor rods 

 because of the currents in the rods, and thus exerts a dragging 

 torque upon the rotor. 



The production of rotating magnetism by the stator windings. 

 As stated above the stator windings are arranged exactly like the 

 armature windings of a polyphase alternator armature. Figure 



* A very simple discussion of the action of the induction motor is given in Appendix 

 B, Art. 15. 



