An Analytical Study on Effective Lightning Protection Measures for Pole‐Mounted Distribution Transformers on Terminal Poles

Abstract

In Hokuriku area, where lightning strikes with a large amount of electric charge occur in winter, failure rate of lightning protection devices such as surge arresters and devices with built‐in zinc oxide (ZnO) elements tends to be high. In order to prevent failure of surge arresters, 5 kA surge arresters which have a larger energy capability are installed on terminal poles of distribution lines. As for lightning protection of pole‐mounted distribution transformers, insulators with ZnO are utilized to support medium‐voltage drop wires connected to the transformers on non‐terminal poles. In this paper, we have studied the effect of insulators with 5 kA ZnO which have a larger energy capability as a lightning protection measure for transformers on terminal poles using lightning‐surge analysis. The lightning outage rate, which is the total of insulation breakdown rate and failure rate of a lightning protection device, is found to be lower in the case of insulators with 5 kA ZnO than in the case of 5 kA surge arresters. In addition, by replacing 5 kA surge arresters with insulators with 5 kA ZnO, a cost reduction effect is found to be also expected. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.