Lightning Protection of Medium Voltage Overhead Lines by Modular Long-Flashover Arresters

A long flashover arrester (LFA) which comprises three flashover modules using the creeping discharge effect is described in this paper. In this design the total arrester-stressing voltage is applied simultaneously to all the modules so that the voltage-time characteristics of the arrester are improved considerably assuring reliable protection of medium voltage (e.g. 10 kV) overhead power lines against both induced overvoltage and direct lightning strokes. A single LFA per support or pole is found to be sufficient to protect an overhead line against induced overvoltages. An LFA should be arranged in parallel with each insulator in order to protect a line against direct lightning strokes.