REACTANCE OF WIRE, SINGLE-PHASE 63 



where I is measured in absolute electromagnetic units. 

 When / is in amperes, the field at distance x is 



lines per sq. cm. (i) 



IOX 



A l* s 'i\ 1 



A^ Pi i /T> 



9* 



Fig. 13. 



In Fig. 13 is shown the cross section of a single-phase 

 transmission line. The lines of force in the path of thick- 

 ness dx surrounding the wire A are 



21 j 



dx 



IOX 



per centimeter of the transmission line. These lines cut 

 the wire A and produce an alternating voltage in it which 

 is 90 out of phase with the current and is equal to 



jco dx X io~ 9 volts, 



x 



where co = 2 TT X number of cycles per second, and where 

 7 is in amperes. 



The voltage drop between the wires A and B, due to 

 flux in the air produced by the current in A, is obtained by 

 integrating the above expression from x = p to x = s. 

 The integration is not carried beyond x = s, since flux 

 which cuts both A and the return wire B does not produce 

 any voltage between them. The voltage drop is equal to 



,27 5 



'co dx X IO~ 9 = jw 2 7 loge - X IO" 9 . 



X p 



