Study on the Formation of the Electric Field around Three-phase Insulators in 110kV Transmission Tower and Its Influence on Flashover Voltage

The electric field distribution around the insulator is the main influencing factor of its flashover characteristics. And the electric field distribution of the insulator is affected by the external tower structure and connecting parts. Therefore, there are differences in electric field distribution of the insulators with different tower structures. And the insulator flashover characteristics vary depending on the tower structure and the suspension position of the insulators. In order to study the effect of tower structure on the electric field distribution around the insulator and its effect on flashover voltage, based on COMSOL Multiphysics, the finite element simulations on the electric field distributions around the composite three-phase insulators suspended on the umbrella-shape the drum-shape towers were conducted in this paper. The formation of the electric field distribution around the insulator suspended in the tower and the influence of the tower structure on its electric field distribution were analyzed. In addition, the flashover characteristics test of the composite insulator in the $110\mathrm {k}\mathrm {V}$ transmission line at high altitude area was carried out. The test was under a standard lightning impulse voltage of $1.2/50\mu \mathrm {s}$. Combined with the test results, the relationship between the 50% impulse discharge voltage of the three-phase insulators suspended in the tower and the uneven coefficient of electric field is further analyzed and verified.