Study on dimensions of void in GRP rod of composite insulator

As an important part of composite insulator, glass fiber reinforced polymer (GRP) rod needs to bear the main mechanical and keep certain insulation performance. The void in the material is key factor to the performance of GRP rod. The void with larger size could affect the electric field distribution significantly and lead to the “Lantern-like” heating. In this paper, the structure of void in GRP rod is studied by 3D X-ray microscope. It is found that the void dimensions in the GRP rod is generally less than 300μm, but the interconnection of linear hole makes the length of the void increase significantly. For the GRP rod with high porosity, the length of connection hole is hard to be detected directly by the existing technology, but it could be calculated based on the diameter of the hole. Based on the calculation method, the dimensions of void in GRP rod could be inspected by the observation of section using optical microscope.