Potential distribution computation and structure optimization for composite cross-arms in 750 kV AC transmission line

As composite cross-arm will be used in domestic 750 kV AC transmission line for the first time, careful and meticulous preparatory work is highly needed. Using a three-dimension (3-D) finite-element method (FEM) software, this paper presents computation results of the potential and electric field distribution for composite crossarms in the process of structure optimization. Several optimization programs for composite cross-arm have been studied and the final design is made to omit the suspension insulator string, to increase the length of post insulators and to configure suitable grading and shielding rings based on preliminary design. A set of grading and shielding rings configuration program has been proposed. The comparison between optimized composite cross-arms and 750 kV line composite insulators indicates that composite cross-arms have better potential distribution. The electric tests demonstrate that optimized composite cross-arms have good electrical performance and can meet operation requirements.