LAUSR

To analyze the changes in microscopic morphology of the pressboard under surface partial discharge conditions, some methods such as enhancement, denoising, segmentation, optimization, edge detection, expansion, and corrosion were used to process scanning electron microscope images of the pressboard, so as to extract the fiber width, hole size, and surface roughness. Experiments show that after different thermal aging times, the trends to change in the microscopic morphology of insulation pressboard under partial discharge are different; the microscopic morphology of the pressboard is changed by the breaking of the chemical bonds in the internal structure of the fiber. At a degree of polymerization of 500, the insulation life is only about half of its original value: at this time, the corresponding fiber width is 91.1% of the unaged pressboard fiber width, and the corresponding roughness is 0.162. At a degree of polymerization of 250, the insulation pressboard is nearing the end of its life: at this time, the corresponding fiber width is 79.2% of that of the unaged pressboard, and the corresponding roughness is 0.225.Graphical Abstract