Surge behavior at the discontinuity of a vertical line over the ground

• By choosing the infinite point as the zero potential point, the surge impedance is defined uniquely.
• The formulas for evaluating the surge behavior by using the surge impedances defined above were derived.
• Surge behavior at the discontinuity on a vertical conductor is illustrated.
• The effect of the lossy conductor is too small to be considered when analyzing the surge behavior in discussed cases.

This paper discusses the surge propagation at the discontinuity of a vertical line over the ground. Similar to a traditional transmission line, surge transmission at the discontinuity can be determined by its surge impedances. However, the surge impedances of a vertical line are different from the characteristic impedance of the transmission line. They respond differently to incident, transmitted and reflected waves, and vary with time. In this paper, these surge impedances are discussed in detail, and the methods for impedance evaluation are presented. The formulas of voltage and current transmission coefficients at the discontinuity are presented. A numerical example is presented to illustrate the surge impedances of a vertical line and to verify the formula of the transmission coefficients at the discontinuity.