CONTINUOUS-CURRENT WINDINGS 141 



above it. The former plan is employed in the so-called two- 

 circuit windings, the latter in the multiple-circuit windings- 

 Fundamental ly, therefore, the windings may be identified by these 

 characteristics namely (at any rate, in the case of windings with 

 one turn per segment), as will be fairly readily seen from an 

 inspection of an armature, that the connections at the front and 

 back ends of a multiple-circuit winding are in the same direction 

 when any particular conductor is considered, as seen in the left hand 

 diagram of Fig. 167 ; and in opposite directions in the case of two- 

 circuit windings, as seen in the right hand diagram of Fig. 167. The 

 conductors designated respectively 3 and " equivalent of 3 " in Fig. 

 166 are evidently at all times situated in fields of polarity opposite 

 to that of the fields in which conductor No. 50 may be situated. 



Multifile Circuit 



Tyro Circuit 



FIG. 167. Line representations of Multiple Circuit and Two-circuit Windings. 



In Figs. 168 and 169 are shown, side by side, photographs of 

 windings of these two types, and in which these characteristics are 

 seen at a glance. 



In Fig. 170 is given the diagram of a two-circuit winding, 

 developed by the method which we applied in Fig. 165 to a 

 multiple-circuit winding. 



It would be out of place in the present treatise to enter upon 

 the theory of these two types of winding, as this is a subject 

 which can only concern those individuals whose duty it is to 

 carry out the electro-magnetic pre-calculations. Suffice it to 

 point out here, that for a given number of face conductors 

 and poles, a given magnetic flux from each pole, and a given 

 speed, a multiple-circuit armature will have a lower voltage 

 at the commutator than will a two-circuit winding. If it 

 is a 4-pole machine, the multiple-circuit winding will have 

 f, i.e. i the voltage; if a 6-pole machine, f, i.e. J the volt- 



