Influence of Duration of Wave Front of Impulse Voltage on Creeping Discharges along Aerial Insulated Wire.

Abstract

In high voltage aerial distribution systems, creeping discharges develop along the wire surface from the free end of the binding wire when overvoltages caused by the lightning surge invaded to the central line of an insulated wire. Then, the various disasters such as punch-through breakdown, disconnection and melting of wire, often occur at these systems. In our previous studies, it has been clarified that the lengths and aspects of creeping discharges under a 1.2/50μs impulse voltage condition can be affected remarkably by the change of the electric field intensity on the wire surface. However, the lightning impulse surges which may invade to a central line of wire have various values of duration of wave front. This will more complicate the creeping discharge phenomena due to a lightning.In this paper, we report the influence of the duration of wave front both on the lengths and the aspects of the creeping discharges which develop on the wire under the application of lightning impulse voltages. It has been clarified that the behavior of negative creeping discharges reveals a remarkable change by the duration of wave fronts in the applied voltages.