THE INDUCTION MOTOR. 



85 per cent smaller than according to the formula. By taking this 

 into account, we find for 



b = 17.0 cm. 



80. We leave in in the middle of the iron a space of i.o cm for radial 

 ventilation, so that the width of the iron becomes 18.0 cm. 



81. The" slots are represented in Fig. 22. The slots in the field are 2 

 ins. deep; in the armature i^ ins. These slots represent about the 



FIG. 23. 



largest size that should be used in polyphase motors. If possible, it 

 is preferable to keep the slots smaller than those in Fig. 22. The 

 wire used for the field coils is No. 3 of B. & S. wire gauge, having a 

 diameter of 0.229 in. 

 The maximum induction in the iron teeth is 13000. 



46 



