156 



PRINCIPLES OF ELECTRICAL DESIGN 



tation is due to the currents in all the neighboring parallel con- 

 ductors comprised in the parallelogram ADVC. The direction 

 of flow of current in these parallel conductors is indicated by the 

 arrows, being outward (i.e., from A to B) on the left-hand side 

 of the communicating zone, and inward (from B to A) on the 

 right-hand side. The intensity of the field produced on A B by 

 any one of these wires, if the lines of force are assumed to be cir- 

 cles in a path consisting entirely of air (the proximity of masses of 

 iron being for the present ignored), will be inversely proportional 



FIG. 60. Developed view of armature end connections. 



to the distance of the wire considered; and the extent to which 

 this wire will be effective in producing a field along AB will 

 depend upon its length. Thus, a conductor such as EF will pro- 

 duce not only a stronger component of the resulting field in the 

 commutating zone than the wire GH, but a field of which the 

 extent is measured by the length EF, while the more distant 

 wire will produce a weaker field over a length equal to GH only. 

 Thus the effect of the more distant wires in building up the flux 

 over the commutating zone decreases very rapidly with increase 

 of distance. 



