The calculation model of the shielding failure trip-out rate of double-circuit transmission line on the same tower

Electric geometry method(EGM) was used to calculate the shielding failure trip-out rate of double-circuit transmission line on the same tower in the thesis, with striking distance factor β that conforms to the height of tower changes being introduced and the lightning current obtained when the exposure arc was 0 being considered the strongest shielding failure current. Next analysis was made of effects of various factors like the ground inclined angle, tower structure and so forth on shielding failure trip-out rate of each phase conductor. Finally the calculation results showed as follows: the shielding failure trip-out rate increased first then decreased as the ground inclined angle increased; the shielding failure trip-out rate decreased as the horizontal interval between double shielding wires increased; the complicated relation between shielding failure trip-out rate and tower structure of each phase conductor indicated a respective calculation and analysis rather than a total shielding failure trip-out rate.