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 beta 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.