Composite crossarm for distribution lines

Abstract

Currently, porcelain, epoxy, silicone or glass insulators are used for the insulation of high voltage overhead power lines, which are fixed to the steel structure of the pole. The presented solution is a glass-fiber reinforced composite insulating structure serving as a dielectric crossarm in high voltage power lines. The essence is a solution assembled using components made of composite materials supplemented by steel elements, which exhibits lower weight compared to all-steel solutions and achieves sufficient insulation properties. The solution also includes the additional possibility of using smaller additional ceramic or composite insulators. The individual components are made of suitable materials with regard to their mechanical and electrical stresses and functions throughout the structure. The paper describes the design of a numerical model that simulates the behaviour of the insulator structure, both mechanically and electrically. The investigated characteristics of the materials are described and the final dielectric and mechanical design verification of the crossarm is presented. The electrical tests were done at several materials (polyurethanes and epoxy). The test results of lightning pulse voltage bring no significant differences between materials. Final HV tests for polyurethanes (decision for PU due to the technology) crossarms were performed at final products with good flashover results. The mechanical tests verified the numerical model, which accurately indicates the positions of the failure of the composites under mechanical loading. This phenomenon was observed in every calculation in which contacts were used, especially between steel and composite parts. This is then used as a safety margin for manufacturing, the effect of material aging and climatic effects on the material of the proposed crossarm. The material characterization of several polyurethanes and epoxy variants was investigated using high voltage test methods and mechanical verificatio...