ARMATURE WINDINGS. 



443 



If a winding element consists of a coil of n turns of wire instead 

 of two inductors, as explained in Art. 42, then it is convenient to 

 assign numbers to the consecutive bundles of n inductors each, 

 that is, to the consecutive half -coils, instead of assigning numbers 

 to the individual inductors. In this case the pitches, front and 

 back, are reckoned by counting consecutive bundles or half-coils. 

 In the case of slotted armatures wound with formed coils it is 



Six-pole drum simplex wave winding. Number of half-coils (which takes the place 

 of Z in the theory of the winding) 44, front pitch = -f- 7, back pitch = -{- 7, com- 

 mutator pitch = -f- 7, throw of coils = 3, number of paths = 2. 



Fig. 61. 



convenient to express the back pitch in terms of the number 

 of slots spanned by the coil, one side of the coil always being 

 in the top of one slot, and the other side being in the bottom of the 

 nth following slot, where n is the slot pitch. The number of slots 

 spanned by the coils is called the slot pitch or the throw of the 

 coils. When the throw of the coils is given, the only additional 



