STUDY OF LONG AIR INSULATION BREAKDOWN IN 500 kV INSULATOR STRING DUE TO LIGHTNING

Abstract

This study presents the simulation results of air insulation breakdown between two electrodes of the insulator string on a 500 kV line under the impact of lightning impulse voltage using EMTP software. Lightning impulses with different shapes and amplitudes striking at different positions on the conductor on a 600 m pole were considered.

The simulation results show that the value of air insulation breakdown voltage between two electrodes of the insulator string depends nonlinearly on the lightning impulse shape as well as the strike position on a 600 m pole, especially with lightning impulses with large front slopes. This should be noted when calculating the line clearance to avoid discharge between the two ends of the insulator string when the internal overvoltage is low. From the simulation results, the expression showing the dependence relationship between the breakdown voltage and the distance between the two electrodes of the insulator string has been given