TRANSMISSION OF I'tnVK If KY ALTERNATING CURRENT 387 



162. Three-phase System; Conductors Spaced Unsymmetri- 

 cally. If the conductors in a three-phase system are not sym- 

 metrically spaced, being located at the corners of a triangle 

 whoso sides may be of any length, as A, B, and C, Fig. 350(a), 

 the side D of the equivalent equilateral triangle, Fig. 350(6), 

 may be found as follows: 



(89) 



B D 



(a) (6) 



FIG. 350. Unsymmetrical spacing and equivalent symmetrical spacing. 



This value of D should be used as the distance between the 

 conductor centers of the equivalent system in transmission line 

 calculations. 



163. Single-phase Line Calculations. In determining the 

 voltage drop in an alternating-current line, both the resistance 

 and the reactance must be taken into consideration. The volt- 

 age to supply the resistance drop is in phase with the current, 

 and the voltage to supply the reactance drop is in quadrature 

 with the current and leading. 



FlO. 351.- Sinnl<--ph:i>.' line havini: n-^istanee and r 



In making t ransmi.-sion-liiu' calculat ions, it is conveni-nt in all 

 cases to work to unit ml. I'mim- ;;.",! shows a siimle-ph;i>e line 

 which has a resistance p<-r win- of A' ohms and a react am 

 win ,,f X ohms. The load takes a mrivnt / .-Mnprrcs at a power- 

 factor cos 0, and tin- total voltage at the load or n <( -iver i 

 The voltage to neutral at the receiver i- then-fore E R . The 

 t of til voltage at the sending or generating end is 2A'. 



