Abstract
In Hokuriku Electric Power Company, surge arresters or distribution equipments, such as insulators with MO varistors and current-limiting arcing horns with a MO varistor, are installed on all high-voltage distribution poles in the area where a large number of lightning outages occurred. General distribution systems in Japan are isolated neutral systems, and if sparkover of insulators occurs only at one phase due to lightning-related overvoltages, a follow current will naturally disappear because of a small ground-fault current. Therefore, if the surge arresters are installed on only two phases, it is possible to prevent short circuits which cause phase-wire breakings. In the case of the two-phase arresters, sparkover of one phase without an arrester may reduce currents flowing through arresters of other phases, and may prevent failures of other phase arresters. However, this lightning protection effect has not yet been studied sufficiently. In this paper, we present that the lightning protection effect of distribution lines with non-surge arresters on one phase were obtained by experiments and EMTP simulations.
