Positive Creeping Discharge along Aerial Insulated Wire Generated by Lightning Stroke

Abstract

SUMMARYThere are two causes, inductive lightning surge and direct lightning stroke, as the aerial insulated wire accidents accompanying lightning in a power distribution system. When the overvoltage due to the inductive lightning surge invades to the wire core, the creeping discharge can develop along the wire surface from the free end of the binding wire just after a flashover of the post insulator at the wire supporting point. This creeping discharge may give rise to the accidents such as a melting or snapping of the wire. The creeping discharge along the wire surface has the positive or negative polarity. Positive creeping discharge is restricted to the area where a positive lightning generates. Only a few examples have been reported on the positive creeping discharge, and its characteristic has many unsolved points. In the previous studies, we have observed the positive creeping discharges along the wire surface under the negative inductive lightning surge with the peak values in the range |Vm| ≤80 kV. In this study, the positive creeping discharges are examined newly in the range |Vm| > 80 kV. It is reported that the positive creeping discharges are greatly affected by the negative corona discharges generating from the wire surface in |Vm| ≥ 95 kV.