APPENDIX 



113 



assumed for each wire. Considering the cable as a 

 single conductor, its inductance will be 



Z, = L' 



49 

 Changing to practical units and referring to the 



maximum radius of the cable, 

 P = 2>r, 



we 



have L = (103.3 + 74 I - 



I 3 



io 



henrys per mile of conductor. 



J.L 



FIG. 14. 

 (a) 3-Wire Strand. (b) 7-Wire Strand. (c) iQ-Wire Strand. 



Applying the above method to a strand of n wires, 

 composed of p layers around a centre wire (Fig. 14 b 

 and c), 



. . . . +6Xp 



, 

 log, 3 



and L = 2 log e + + 2 log e 



^ | 4 log e 2 + 2 X 13 loge 4 + 3 X 28 log 6 + ---- 

 n ( 



. . . .+p(n- 3 p) loge (2 p) 



