80' 



ELECTRICAL MACHINERY 



Examples of Armature Windings. In Fig. 42 is shown 

 a lap winding of the most elementary form. Twelve in- 

 ductors are to be arranged in a closed circuit winding and 

 must be so connected together that all conductors in series 

 in a path give an e.m.f. in the same direction in that 

 path; we might state it differently by saying that in 

 either path there must be no opposing e.m.fs. 



FIG. 42. Simple Bipolar Drum Winding. 



If the two paths in Fig. 42 are followed out it will be 

 seen that, in going from one brush to the other through 

 either path of the winding, all inductors give an e.m.f. 

 in the same direction. This winding is made up of six 

 coils of one turn each; it will be noticed that the commuta- 

 tor has as many segments as there are coils on the armature. 

 This will generally be the case; if a machine has 64 coils 

 there will be 64 commutator segments no matter how many 

 turns there are per coil or how the coils are connected. 



