Application of the stepping pendulum method to long tower arms in 765kV transmission line for live working

There are two types of the 765kV transmission line(hereinafter T/L), namely double and single circuit lines. But the single circuit line has no fungible line, so dead line work is very difficult. Moreover it's very hard to set a no-power day for maintenance of the line also. Due to such reasons the 765kV single circuit T/L will be maintained by live line work using bare-handing method and helicopter live working. But in case of the bare-hand method, it's difficult to approach conductors from tower posts because of the complicated tower structures with many step bolts and configuration. Especially tower arm length is very long. So in order to access to the live parts easily on the towers, this paper presents the stepping pendulum method by using two polymer insulator strings or two insulating supports. Moreover this paper proposes application propriety of the stepping pendulum method to long arms in UHV lines.