Analysis for calculation method of shielding flashover rate on common-tower double transmission line

Based on the EGM (electric geometry method), some problems when calculating the ratio of exposure arc to exposure arc and shielding arc, exposure arc projection, striking distance coefficient, shielding failure flashover rate etc are analyzed and discussed. It points out that the general maximum striking distance formula is not appropriate for some conditions. Calculating shielding failure flashover rate by current density probability function is proposed; It also suggested that three phase conductors use corresponding striking distance coefficient with the conductor height.