CHAPTER XII. 

 REACTANCE OF TWO-PHASE AND THREE-PHASE LINES. 



Reactance, Two-phase. The reactive drop in a single- 

 phase line, in which round wire is used, is 



2JI X 2 7^80.5 + 741.1 log-j 



volts per mile of line. In a two-phase four-wire line, the 

 drop will be the same as the above, when / is the current 

 in one phase. 



K V A 



Now 2 7 = ' ' = the total amperes. 



rL 



Therefore the reactive drop per mile of line, in absolute 

 value, is 



K.V.A. 



X 2 7T/Y 80.5 + 74I.I log-J 



E 



K.V.A. 



Xx, 



wnere x is the tabulated value of reactance. 



Reactance, Three-phase, Irregular Spacing. When the 

 conductors of a three-phase line are spaced so that they are 

 not exactly equidistant, the voltage drop due to reactance 

 is not the same in the different phases. It is the practice 

 with such lines to interchange, or transpose, the conductors 

 at intervals along the line, so that the different reactive 

 voltages are applied to an equal extent to all three con- 

 ductors. Such a line, when carrying a balanced load (equal 

 currents in each conductor, at 120 in phase from each 



79 



