162 ARMATURE CONSTRUCTION 



ductors of such windings. In this case an even number (20) of 

 commutator segments is employed. 



In the winding illustrated in Fig. 191 there are only 19 com- 

 mutator segments. In this case the turn comprising conductors 

 21 and 30 is not connected into the winding; indeed it is 

 frequently not placed on the armature, the space being occupied 

 by wooden strips. Thus to all intents and purposes Fig. 191 

 merely represents a winding with 38 conductors but with two 

 places at which there is greater space between adjacent con- 

 ductors than elsewhere. This winding gives better results the 

 greater y and the lower the reactance voltage. 



The type of winding illustrated in Figs. 192 and 193 involves 

 the use of an extra segment. Thus we have 40 conductors and 

 21 segments. On the whole, it is a more attractive method than 

 that shown in Fig. 190. Both methods have about the same 

 degree of pitch irregularities. 



SPECIAL MULTIPLE-CIRCUIT SIMPLEX WINDING. 



In Fig. 194 is shown a four-circuit simplex winding, which 

 has the property of the two-circuit winding of having in the 

 four branches a symmetrical distribution of the potential, even 

 when the armature is eccentric in the field. This winding is 

 derived from a two-circuit double winding by leaving out every 

 alternate commutator connection. Because of the above- 

 mentioned property, it should have a field of usefulness in 

 motors of those ratings requiring several turns per segment, and 

 it has the feature of superiority over the two-circuit winding that 

 it ensures an equal division of the current between all sets of 

 brushes of the same polarity. Very numerous similar windings 

 may be derived. One other of this class is given in Fig. 195. 



