FAA Lightning Protection Study:Lightning-Induced Transients on Buried Shielded Transmission Lines.

摘要

This report is primarily concerned with the analysis of induced transient current and voltage pulses on buried shielded transmission lines, due to earth conduction effects of nearby lightning discharges. Two basic analytical methods are presented in this report to describe the various kinds of coupling mechanisms between a lightning discharge to ground and an earth-return transmission line. The transmission line is assumed to be a long straight horizontal coaxial cable with an inner shield and an outer armor, terminated on both ends with typical communication equipment load impedances. The general case is considered here, in which the outermost conductor is not necessarily in perfect contact with the conducting earth but as a contact impedance with the earth, as in cables with an outer dielectric covering for corrosion or water protection. Both direct strikes to the cable via arcing from the terminal ground point of the lightning channel to the outer conductor of the coaxial cable and indirect strikes to the cable via conductive coupling mechanisms through the earth are considered. (Author)