Development of Polymer Insulator with Built-in ZnO Elements for 22kV Overhead Distribution Lines

摘要

The authors have developed a polymer insulator with built-in ZnO elements used for 22kV overhead distribution lines, which also functions as an arrester. Research has been made into how lightning faults can be prevented by using an insulator with a low insulation level, aiming to reduce distribution line construction and operation costs. The developed device met our initial standards. A unique mechanism applying a newly devised FRP-metal connection technique and pressure-release function is incorporated into the device. The results of both performance and pressure-release testing revealed that this pole-mounted insulator drastically contributes to lightning protection of the distribution line, while its electrical/mechanical properties are satisfactory, being equivalent to those of traditional ceramic insulators. However, the long-term reliability of polymer insulators in complex natural environmental conditions has not been adequately assessed, resulting in limitations of their widespread use. Given this situation, a 5,000-hour complex environmental test was conducted to measure leakage current. The results showed a little erosion on the polymeric material surface, but leakage current did not increase. No specific problems with the insulation's performance were seen. These experimental results revealed that the devised insulator's adequate performance could allow it to be put into practical use.