BRIDGE METHODS FOR LOCATING RESISTANCE FAULTS 397 



location, in ohms from End 2, of the resultant of these two resultants, 

 as indicated in Fig. 12. 



Fig. 12 — ^Equivalent circuit^double Varley method. 



Again applying the Rule of Resultant Faults: 



_ Nx{M - F) 



^' ~ M{F + iV) + F{M + N) ' 



For the Varley measurement from End 1 of the cable: 



cz = 



V, 



Equating these two values of Cs and solving for x: 



X = 



Fi 



il/+ F 



+ 



2MF 



M - F ' N{M - F) 

 Likewise, for the Varley measurement from End 2 of the cable: 



M + F , 2MF 



X = r 



2 



M - F ' N{M - F) 



(7) 



(8) 



By equating the two values of x found in (7) and (8), the value of the 

 "correction factor" for the Varley measurements can be determined: 



M + F 



IMF 



2r 



M - F ' N{M - F) Fi + F2 

 Substituting this value of the correction factor in Formula (7) 



X = 



Fi+ F2 



(9) 



