Influence of size parameters of grading ring on electric field distribution and icing characteristics of 220kV composite insulator

In this paper, numerical simulations using the finite element method (FEM), were performed to study the electric field (E-field) distributions along ice-covered 220 kV composite insulator with different sizes of grading rings at the high voltage (HV) end. Combining with energized ice accretion tests in artificial climate chamber, the influence of size parameters of grading ring on icing characteristics of composite insulator was analyzed. The results show that the ice accretion of composite insulator with grading ring was more uniform than that without grading ring. With the increase of diameter of grading ring, the E-field distribution along the arcing distance becomes more uniform. The change of pipe diameter has no obvious effect on the E-field distribution at the HV end. The increase of height of grading ring could accordingly lift the main position of E-field distortion and thus enhance the E-field intensity along the string. The ice accretion uniformity, situation of shed space bridged by icicle and the variation of ice weight of composite insulator obtain by icing tests were well accordant with the E-field calculation results.