240 ARMATURE CONSTRUCTION 



open or semi-closed slot ; in the latter case the bar would be pushed 

 into the slot from the end. 



The question of an open or closed slot is largely one of experi- 

 ence in manufacture, and either can be used, but if the semi-closed 

 slot is used the bars must be shaped as sketch D. 



FIG. 281. Winding for a Three-phase Rotary Converter, Six-circuit Single-winding 

 with 108 Conductors, Six Poles. Front Pitch 19, Back Pitch, 17. 



II. CLOSED-CIRCUIT WINDINGS. 



As was stated at the beginning of this chapter (p. 163), any 

 continuous-current winding can in general be employed for 

 alternating current work, by dispensing with the commutator and 

 tapping the windings at a few suitable points and connecting from 

 these points to the slip rings or stator terminals. 



To convert a two-circuit (or wave) winding into a single-phase 

 alternating current winding it is necessary to tap it at only two 



