Design of Grading Ring for Composite Cross-arm in 500 kV Single-Circuit Transmission Tower

In this paper, a three-dimensional electric field simulation model of the composite cross-arm in a 500 kV single-circuit transmission tower was established which includes the tower, the composite cross-arm, the composite pulling insulators, the bundled conductors, the grading rings, and the shielding rings. The electric field distribution around the transmission tower is calculated based on the finite element method (FEM). The electric field distributions with and without the grading rings and the shielding rings are compared. Based on the calculation results, the measures to optimize the electric field distribution are put forwards which are useful in the design of transmission lines.