154 ARMATURE CONSTRUCTION 



odd, and must differ from one another by 2m. In this case, 'J/// 

 is equal to 4. Hence, if the front end pitch is taken at 35, then 

 the back end pitch should be taken as 35 + 4, or 39. The mean 

 pitch should be approximately equal to the number of face 

 conductors divided by the number of poles. In this case the 



mean pitch should be approximately equal to - , or 37*5. It is 



o 



taken as i - = 37. By keeping the front and back pitches 



Zi 



the same as in the diagram of Fig. 181, i.e. equal to 35 and 39 

 respectively, but employing only 298 conductors, as in the diagram 



of Fig. 182, we obtain a singly re-entrant duplex winding. This 



oqo 



is a consequence of the rule already enunciated ; for C = t - = 149, 



2 



and m = 2, and the greatest common factor of 149 and 2 is 1, i.e. 

 the winding is singly re-entrant. Hence it is impracticable to 

 show it in two different colours, as it is a symmetrical winding in 

 which no conductors belong more especially to one half than to 

 the other half of the duplex winding. The precise designation of 

 these windings is as follows : 



Fig. 181 Eight-circuit, doubly re-entrant duplex winding. 



Fig. 182 Eight-circuit, singly re-entrant duplex winding. 



We may also have triplex, quadruplex, quintuplex, etc., 

 windings, and these may have various degrees of re-entrancy, 

 Thus a triplex winding may be either singly or triply re-entrant, 

 and a quadruplex winding may be either singly, doubly, or 

 quadruply re-entrant. 



In Figs. 183 and 184 are shown eight-circuit triply and singly 

 re-entrant triplex windings with 300 and 298 face conductors 

 respectively. In both cases the pitches are 35 and 41 . 



TWO-CIRCUIT MULTIPLEX WINDINGS. 

 The fundamental formula for two-circuit multiplex windings is 



where C, n y and m have the same significance as heretofore. The 

 ra windings will comprise a number of independently re-entrant 

 windings, equal to the greatest common factor of y and m. 



In Figs. 185 and 186 are shown eight-pole, two-circuit, duplex 

 windings, each with 300 face conductors. In Fig. 185 the pitch 

 is 37 at the front end and 39 at the back end, the mean pitch 

 thus being 38. Hence, as y = 38 and m = 2, the winding is 



