ARMATURE WINDINGS AND SLOT INSULA TION 85 



shape shown in Fig. 26 The finished coil may consist of any 

 number of turns, but as there are two coil-sides in each slot, 

 there will be an even number of inductors per slot. The portion 

 of the armature periphery spanned by each coil is approximately 

 equal to the pole pitch r, because it is necessary that one coil 

 side shall be cutting positive flux while the other coil side is 

 cutting negative flux. If the two coil sides lie in slots exactly 



FIG. 26. Form-wound armature coil. 



one pole pitch apart, the winding is said to be full pitch. If 

 the width of coil is less than r, the winding is said to be short 

 pitch or chorded. The shortening of the pitch slightly reduces 

 the length of inactive copper in the end connections. Some 

 designers claim that it gives better commutation; but, on the 

 other hand, it reduces the effective width of the zone of commu- 

 tation, and it is doubtful if either winding has a distinct 

 advantage over the other. 



There are two entirely different methods of joining together 



