Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

327 OK ENGINEERING FORMULÆ. Electrical Formuler, by Paget Higgs, LL.D., C.E., and R. 8. Bbough—continued. Then ./(I - W)(I - w)r * ~ V W - w ’ W - u> l = l-i, and should be positive and less than unity. When I — i = I (I — w), L = 2 (I — i) . I(W-w) , ,, , and —-----—- should be = r. 1 — W Let n — number of miles the line is in length, then insulation per mile = n X i. Let m = the “ reduced length ” of the line in terms of the standard wire, then conductor resist- •i L ance per mile = — . ■ m 7. Fault Testing. 1. Earths. (a) Single Line. Blavier’s Formula: _______ x = w — J (I — w) (L — w). Schvendler’s Formula: W - w '