线路避雷器在防雷中的分流系数推导

The Deduction of Line Surge Arrester Shunting Coefficient at Line Lightning Protection

为了解决线路避雷器在防雷中的分流系数计算问题，针对雷电直击输电线路的杆塔顶部及档距中央避雷线和雷电绕击导线等三种雷害情况，建立线路避雷器动作时的等值电路，推导出线路避雷器在防雷中的分流系数计算公式。计算结果表明，线路避雷器除利用其动作后的钳电位作用有效防止被保护相绝缘子串闪络外，还可起到分流雷电流的作用：在一般情况下，当雷电直击杆塔顶部时，可向导线分流7％～10％的雷电流；当雷击档距中央避雷线时，可向导线分流6％～8％的雷电流；而当雷电绕击导线时，可向大地分流70％～75％的雷电流。

To solve the calculation problem of line surge attester shunting coefficient at line lightning protection, equivalent circuit of line surge arrester acting is built under three lightning damage conditions： direct lightning strike on top of transmission tower and on central span of overhead grounding wire, lightning shielding failure. Then the formula of line surge an＇ester shunting coefficient is deducted. Calculation results show that line surge arrester can not only effectively prevent flashover of the insulator string it protects by its voltage clamp capability after action, but also shunt lightning current： commonly, 7 %- 10 % lightning current will be shunted through transmission line when lightning strikes directly on top of transmission tower, 6 % -8 % lightning current will be shunted through transmission line when lightning strikes directly on central span of overhead grounding wire, and 70 % - 75 % lightning current will be shunted through ground when lightning shielding failure happens.