Voltage Ratios of an Inverted Rotary Converter. 161 



Let AB be points of connexion of a pair of rings to the 

 winding. 



The P.D. between the rings due to drop is zero at AB, 

 increases uniformly till A is under the brush at P, and then 

 remains constant until B comes under the brush V. It 

 decreases to zero again with A 180 phase degrees from its 

 first position, 



2ir 



Let — = angular distance in phase degrees from A to B, 



and let 6 = phase displacement of the centre T of the section 

 AB from the line OP. 



As 6 changes from to - the P.D. between A and B due 



n 2CR . 1 



to ohmic drop increases from to — as AB is the - th 

 1 n n 



part of a single path between the brushes. 



The value of this P.D. for an intermediate value of 6 may 

 be written as 



2CR 0_ __ 2CR0 



n ' it it ' 



n 



77- 



For further increase of 6 up to it this drop is constant 



and equal to 



n 



IT 



n 



From it to 7r the ohmic drop diminishes to zero again, 



n . IT 



in the same manner as it rose in the section to - 



The other half of the cycle is similar with the polarity of 

 the rings reversed. 



Let V = voltage on brushes, then the total instantaneous 

 voltage on the rings is given by : — 



20R/9 7T 



Cv _(TE0 sm ~~" sm ^ "I ~ — when is between and — . . 



(V-CR)sin^sin0 + - „ „ -andTr 



(V-CR)sin-sin(9 + 



The R.M.S. value of the voltage on the rings can be 



IT . Q 2CR 7T _ , 7T 



sine/ 4 „ » 



n n n n 



-, n ^.2C^^).. „ .--and. 



Phil. Mag. S. 6. Vol. 10. No. 55, July 1905. 



M 



