Influence of Waterdrop on Wire Surface on Negative Creeping Discharge along Aerial Insulated Wire

Abstract

The aerial insulated wire is supported by the insulator and binding wire at the reinforced concrete pole. A compound insulation system consisting of the conductive wire core, wire insulation layer, insulator and binding wire exists on the wire supporting point. When the overvoltage due to the inductive lightning surge invades to the conductive wire core, the creeping discharge can develop along the wire surface from the free end of the binding wire just after a flashover at the post insulator. This creeping discharge may give rise to the accidents such as a melting or snapping of the wire. Generally, it has a lot of rain with the generation of a thundercloud that causes lightning strike, and then the insulated wire surface is the wet condition with waterdrops. In the previous paper, we have reported the characteristics of negative creeping discharge along the wire surface at the wet condition under the inductive lightning surge with the peak value V_m ≤ 80kV for the space restriction of the laboratory. In the experiment, the wire height is 75cm on the ground. Therefore, V_m = 80kV in the experiment is equivalent to V_m = 120kV in the real system. This paper presents the characteristics of negative creeping discharge at V_m ≥ 80kV (V_m ≥ 120kV in the real system) for the wet condition. It is reported that the propagation of negative creeping discharge is influenced greatly by the positive corona discharges occurring from the waterdrops surface under the wet condition.