Calculation of Minimum Safety Distances for Live-Line Maintenance A Statistical Method Applied to 765 kV AC Itaipu Lines

This paper presents a statistical method to calculate the minimum safety distance for live-line maintenance. The method takes into account the complexity of the tower gap configuration and the presence of the lineman working at the line potential. It includes the inherent dispersion of the dielectric characteristics of the air gaps such as the probability of flashover and the times-to-flashover. Laboratory tests were also performed to corroborate the results of the study, checking not only the performance of the various live-line tools but also the effectiveness of the by-passing insulators protective device and the occurrence of broken insulators in the string.