CHAPTER V 



VOLTAGE RATIO IN SYNCHRONOUS CONVERTERS WITH SPECIAL 

 REFERENCE TO THE SPLIT-POLE CONVERTER 



Resume of paper by C. A. ADAMS, Proc. A.I.E.E., June, 1908 



THE author of this paper shows how the ratio of the D.C. to 

 the A.C. voltage of a synchronous converter may be varied by 

 means of the split pole, without introducing seriously large harmonics 

 into the counter E.M.F. and current. Incidentally a new method 

 is employed for calculating the E.M.F. between adjacent commu- 

 tator brushes the brush E.M.F. and the corresponding E.M.F. 

 between collector rings the tap E.M.F. for any given flux dis- 

 tribution. 



The elementary E.M.F. induced in a single conductor cutting 

 through the gap-flux at constant speed is proportional to the density 

 of the flux, and when plotted, will obviously have the same shape as 

 that of the gap-flux curve. It may be expressed thus: 



sin G)/+</a3 sin 30)^+905 sin 5(0^+. . . 



-\-qam sin ww/+etc. 

 ^61 cos o)2+<7&3 cos 3(o/+<75 cos 50)^+. . . . 



-\-qbm cos ww/-f-etc. (i) 



where a> = 2TW and n is the fundamental frequency. 



The brush voltage which is proportional to the area of the e' curve 

 between brushes, is 



e = 



or 



(2) 



(3) 



where N is the number of conductors in series between brushes. 



The tap E.M.F. is the geometrical sum of the E.M.F.'s of the 

 several coils connected in series between taps. The E.M.F. of each 



225 



