ROTARY CONVERTERS. 



177 



Again, if / is the direct current, and 7i the E.M.S. value of the 

 alternating-current per phase, we have 



nE 



FIG. 76. 



FIG. 77. 



therefore 



2\/2/ 



'1 = 



n 



(5) 



Also the current / between two adjacent lines is given by 

 IE = 



therefore 



. TT 

 T=- sin - 



\/2 n 



A/2 



n sin - 



n 



(6) 



121. Applying this to the cases in which the armature is 

 tapped at three and four equidistant points and connected to three 

 and four collector-rings respectively, we get, taking continuous 

 voltage and current as unity 



1st. Tri-phase converter 



Volts between collector-ring and neutral point = ^= = 0'354 



Volts between adjacent collector-rings = ^ sin 60= -- = 0'612 



N 



