CONVERSION OF ALTERNATING CURRENT. 



189 



its commutator as compared with the commutator of a direct- 

 current generator having the same armature and field magnet 



300 kw. Three-phase Rotary Converter. 

 Fig. 156. 



structure. Thus, Fig. 156 shows a 300 kilowatt, three-ring, 

 synchronous converter of the General Electric Company. 



93. Instantaneous current in a given armature conductor of a rotary con- 

 verter. Let r and r 1 y Fig. 157, be the points of attachment of adjacent collecting 

 rings of an n-ring converter, and let the line OM bisect the arc rr f '. Consider an 

 armature conductor c between r and r', and let the angle cOM be represented 

 by a. The largest possible value of a is TT/H or one half of -the angle between r 

 and r f . 



Let (j)t be the angle between OM and the axis of the field. Then the alter- 

 nating current between the collecting rings r and r* ', that is, the alternating cur- 

 rent in the conductor c, is at its maximum value V 2f n when w/ = o. Therefore 



