Porcelain suspension insulator for OHTL: A comparative study of new and used insulators using 3D-CT

The 3D-CT technique, which is a non-destructive method, is used to verify the use of porcelain insulators for overhead transmission lines (OHTL). 3D-CT techniques are often used to detect defects such as cracks in automotive parts or in the medical field. The results of the 3D-CT technique applied to porcelain insulators indicate a clear difference in the size and distribution of pores between new and used porcelain insulators. The most significant difference is the degradation rate of the porcelain insulator. In the case of the used product, the largest pore size of 24 mm
²
was found in the cement part exposed to the external environment; however, no pore was found in the new product. In addition, for the used porcelain insulator, 18 mm
²
pores were found in the pin head part, which is a part where stress is concentrated; however, few small pores were found at the same position in the new porcelain insulator. Based on the size and distribution of the pores, the areas where the deterioration was the most rapid were identified. The pore area of the cement at the bottom of the cap was five times larger than that at the top when compared to the total area of the cement. This study confirms the size and distribution of defects occurring in the insulator based on aging and provides insight into the long-term reliability and life prediction of insulators.