Abstract
UHV designed transmission lines have already been in operation at 500kV since 1992. UHV substation equipments have also been energized in the test yard since 1996. For rationalization in insulation design and cost reduction, it is important to evaluate the phenomena of lightning for the UHV designed transmission lines.
Some studies to observe current waveshapes have been conducted before, but they were ones conducted on independent towers and do not provide many data in a large-current region. So, we have been observing lightning currents on 60 transmission towers (mainly 500kV lines) since 1994. On UHV-class transmission lines with sections of 500kV-class insulation, lightning observations have been made to study the generation and the propagation of overvoltages into substations. Voltages and currents were recorded at the substations and at junction-tower footings on the UHV system. This paper describes the study of lightning phenomena and EMTP calculations on the UHV transmission lines.
