Research of Effect of Wind-Blown Rain on Power Frequency Flashover Characteristic of Conductor-Tower Air Gap

At 1:1 ratio scale simulated tower, the effect of rainfall, wind and wind-blown rain on power frequency flashover characteristic of conductor-tower air gap was initial systematically researched at inner and outdoor. The result is that, rainfalK wind speedy wind direction^ wind-blown rain can effect the power frequency flashover characteristic of air gap. The rain reduce the flashover voltage obviously, especially the air gap is small. When the air gap is 1.2m, and the rainfall intensity is 14.4mm/min, the flashover voltage reduced 13.3%, when the air gap is 0.6m, the flashover voltage reduced 16.2% with the same rainfall intensity. The resistivity of rainwater also has influence on the power frequency flashover characteristic of air gap, but its influence is less than that of rainfall intensity. When the resistivity of rainwater is greater than 4x10
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Omegaldrcm, as the resistivity increase further, the increasing of flashover voltage has the tendency of saturation; when the resistivity of rainwater is less than 2x10
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Omegaldrcm, the flashover voltage decreases rapidly as the decreasing of the resistivity, and when the resistivity decreases further, the decreasing speed of flashover voltage has the tendency of increasing. The influence of rainfall path is not obviously to the flashover. The wind direction and speed also influence the flashover voltage, when the wind direction is parallel to the discharging path, the strong wind decreases the flashover voltage of conductor-tower air gap, when the wind direction is vertical to the discharging path, the strong wind increases the flashover voltage of conductor-tower air gap. When there is wind-blown rain, and the wind path is parallel to the discharging path, the flashover voltage is less than that when there is only rainfall. And in the test, the influence of wind-blown rain to the power frequency flashover of air gap is about the lineal superposition of the influence on only rainfall and only wind. Through the test, the following result is putted forward, in the extremely atrocious weather, the air gap of which the power frequency withstand voltage is more than the maximum operating phase voltage of 500kV transmission line is 1.25m when there is no step bolt (The data is not corrected to the high altitude localities.).The research could supply technical base for the design of minimum air gap space of electric transmission line in adverse weather, reduce the windage yaw discharge fault and accident rate, and improve safety operation level and economic benefit of transmission line construction.