Study on the aging characteristics of insulators sheds

As composite insulators have been widely used in power system, the aging of composite insulator has become a threat to safe operation of transmission line. In order to investigate the influence of several aging factors on the sheds of high temperature vulcanized silicone rubber composite insulator, nine pieces of energized sheds on the high voltage end serviced on 500kV transmission lines have been selected as test samples. The salt deposit density (ESDD) and non-soluble deposit density (NSDD) measurements are adopted to measure the contamination accumulation characteristics of composite insulator sheds. In addition, thermally stimulated current (TSC) and hydrophobicity tests are also carried out on the shed samples. It indicates that TSC characteristics have the same tendency with the change of the contamination accumulation characteristics in both sides of one shed, but different from that of hydrophobicity. Combining with the contamination accumulation characteristics, hydrophobicity and TSC characteristics, a conclusion can be drawn that the contamination accumulation and ultraviolet radiation might be the main causes of aging, which are account for the difference of the aging characteristic between the two sides of one shed.