Abstract: For the composite transformation of 220 kV portal cement tower, we designed two types of nodes for connection of the middle phase composite crossarm. The first type of middle phase node is a "cat head type", which is divided into upper and lower parts, and the post insulators on both sides of the middle phase are consolidated by bolts. Meanwhile, a pair of boards are extended on both sides of the upper part of node, and connected to the line insulator to form a stable triangular structure composite crossarm. The second type of middle phase node is a "flange butt type", which is divided into three parts. First, specific flanges on both sides of node, and post insulator is integrally formed by glue. Second, a splint is arranged between the two special flanges. The splint not only provides the hanging point for the middle phase conductor, but also adjusts the distance between the cement rods on both sides of the door type cement pole tower. We used WorkBench to analyze the new composite crossarm node in the middle phase of the 220 kV portal cement tower, and obtained the stress distribution of each component. The analysis results show that the design of "flange butt type" node is reasonable and satisfy the stress requirements. Finally, we designed the electrical simulation and experiment for the "flange docking type" node and grading ring. The experimental results show that the mechanical and electrical performance of the "flange butt joint" node is stable and can meet the requirements of the engineering.

Key words: composite crossarm, portal cement tower, new node design, numerical simulation