404 ELECTRICAL ENGINEERING 



The inductance or coefficient of self-induction of each wire of the 

 line is, by equation 138, 



L! = A).74 logio ^r^ + 0.0805 W 3 henrys per mile, 

 and therefore the inductance of the line consisting of two wires is 

 L = 200 L! = 200 (o.74 logio^^ + 0.0805) 10- 3 = 0.392 henrys; 



the inductive reactance of the line is 

 x = 2 irfL 

 = 2 X 3.14 X 60 X 0.392 = 148 ohms. 



The capacity of each wire to neutral is, by equation 45, 



OQ 



C\ = - -fr - 10~ 9 farads per mile, 



I J-J Lit 



logio 

 and the capacity between wires is 



Ci = -y- = - - n' _ P ^~ 9 f ara -ds per mile of line; 

 logio ^r- 



therefore, the capacity of the line is 



1Q 4 



C = 100 C 2 = 100 X i 



I 



Iog 



025 



= 0.76 10~ 6 farads. 

 The condensive reactance is 



2 X 3.14 X 60 X 0.76 X 1Q- 6 = 348 hms> 



and the condensive susceptance of the line is 



The resistance of the line at 30 C. is 



r = 



= P . .. (Art. 56) 

 cir. mils 



lnQ 200X5280 



( 410)2 : 68 



