Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

328 Molesworth’s pocket-book Electrical Formulae, by Paget Higgs, LL.D., C.E., and R. S. Brough—continued. (b) Double Line. Loop test, (Loop = w"; localization = w'.) a' b" w" — a" V w' a" (a' + b') ’ When a = a = a, and b = b = b, x — —--------- , ’ a 4- b 1 W" ~ W' When a — b, x =-----— . Correction for “ partial ” earth (Schwendler) : T , , resistance of fault to be localized resistance of resultant fault a w" — b w’ „ d w" Then* = - 6 (1 + Cl -j- 9 ^5 -(!+</) to' When a = b, x =--—'—*— ’ 2 By capacity (cable):— X = true resistance to break; R = measured resistance of cable and break; k — capacity per unit of conductor resistance, or total capacity -i- total resistance when fault free; f = resistance of battery; g of gals.; d = discharge deflection from cable; D from condenser of 1 unit cap.; 3/ 3d X = R-a/ R3-—(^ + R)(/+R) If resistance of break = o, two-thirds of charge return to charging end.