Five-Year Field Investigation of Lightning Effects on Transmission Lines II-Instrumentation and Installations

In the transmission-line study, masts were attached to the tower tops, connected to the towers by resistors, around which were connected kineklydonorgraphs (KKs). Only mast current, if struck, was recorded in the beginning. Later, ground wires were insulated from the towers in several installations, but were again connected to the towers through resistors shunted by KKs. Information on characteristics of currents in strokes to the masts was thus recorded, as were currents from ground wires to towers and vice versa. Large current changes in time intervals of 0.05 ¿s were registered. Electric field gradients, the occurrence of nearby strokes, and corona currents were recorded also. Five utilities in Illinois, Ohio, Pennsylvania, and New York participated. A tall building in Pittsburgh, surmounted by a 50-foot insulated mast, was equipped with all the recording devices used by cooperating companies.