Calculation of protection of a transmission line by ground conductors

This paper discusses the well-known calculation of the degree of protection afforded to a transmission line by ground conductors, on the assumption of the sudden disappearance of a vertical potential gradient caused by a charged cloud. Formulas are given for the protective ratio due to one and two ground conductors. It is shown that for any number of ground conductors, it is not necessary to compute the charges on the power conductors.