7 . ability to resist filthy : filtering devices , insulation of the electricity than from indoor climbing type not less than 2 . 0cm kv as opposed to system maximum working voltage ; outdoor type not less than 2 . 5cm kv filthy area to be re - statement 7 .抗污穢能力:濾波裝置各外絕緣的爬電比距戶內(nèi)型不小于2 . 0cm kv相對于系統(tǒng)最高工作電壓戶外型不小于2 . 5cm kv重污穢地區(qū)使用需聲明。