68 ELECTRICAL MACHINERY 



A diagram of the magnetic circuit is given in Fig 35, 

 showing the location of the field coils, leakage lines, etc. 

 The poles are made of laminated iron and are bolted to the 

 cast-steel yoke. The area of the teeth is taken as the 

 cross-sectional area of as many teeth as lie under the pole 



FIG. 35. Magnetic Circuit of Small, Modern, Bipolar Machine. 

 Field coils shown by cross-hatched area: leakage lines shown 

 dotted. 



face. Practically all the flux leaving the pole face crowds 

 into the teeth, very little of it going down to the armature 

 core by the slots. The leakage factor for the machine 

 is assumed to be 1.15; if the required armature flux is 

 1,200,000 lines the flux through the poles and yoke is then 

 1,380,000 lines. 



