Experiments for Multiphase Flashover Study in Medium-voltage Line due to Direct Lightning Hit

This paper describes an experimental study of multiphase flashover in 6.6kV medium voltage line of Japan. The experiments simulate a direct lightning stroke to the top of a reinforced concrete pole of the distribution line. Single-phase flashover in non-grounded distribution line is naturally recovered because of low fault current. Multiphase flashover causes a short circuit. Therefore, a study on multiphase flashover is very important to establish the rational lightning protection design for the medium voltage line of Japan. An influence of parameters such as the combination of insulators and crest value of applied voltage on the multiphase flashover is discussed. A solid core insulator and a pin type insulator, which are normally used in the medium voltage lines of Japan, are adopted in the experiments. Measurements of fifty percent flashover voltage are carried out and discussed. This paper discusses an influence of the use of different insulators on the reduction of two-phase flashover.