CONVERTERS 



385 



formly distributed over the circumference of the armature and 



it is therefore less than that of a concentrated winding in the 



2 

 ratio - . (Fig. 367.) The m.m.f rf the direct current in the arma- 



7T 



ture of a converter is thus 



Z I_ 2 



2*2'7T 



Z7 



27T 



(364) 



in quadrature behind the field m.m.f. 



If the machine is connected as an n-phase converter, the number 



of turns per phase is x and the effective value of the alternating 

 current in each is 



I' = ^ J , 



nsin- 

 n 



Chord 



FIG. 367. 



FIG. 368. 



and the m.m.f. per phase in effective ampere turns is 



zr zi 



2n V2n 2 sin-' 

 n 



(365) 



