The Deduction of Line Surge Arrester Shunting Coefficient at Line Lightning Protection
Lin Miao · 2008
To solve the calculation problem of line surge arrester 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 arrester 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.