BECTIFYING DEVICES 



377 



is much more complete than in a single-phase converter, 

 also the heating of the different coils becomes more nearly 

 alike as the number of phases is increased. It is possible 

 to develop an expression for the heating in the various 

 coils for different numbers of phases;* such an analysis 

 yields results as shown in Fig. 247. 



The base line of this set of curves represents the distance 

 between consecutive taps; it would correspond to half the 



Slip 1 ring Slip ring 



Relative beating In' cofls of a rotary 

 converter. C. load same for all cucyes. 



FIG. 247. Comparative Heating in the Coils between Adjacent Tapa 

 of a Synchronous Converter. 



circumference for a single-phase, bi-polar converter, one 

 third for a three-phase, one-sixth for a six-phase, etc. 

 The ordinates represent the relative heating in the different 

 coils for a given c-c. output of the converter. It is seen 

 how the heating of the co?ls decreases and becomes more 

 nearly alike in the different coils as the number of phases is 

 increased. 



* Alternating Currents, Hay, p. 241 et seq. 



