Investigation of the aging of line composite insulator sheds

The aging problem of material of composite insulators is one of key issues for power utilities. The most commonly used methods for aging evaluation are observation method, HC water spray classification method and static contact angle method and so on. However, there some subjective factor would be introduced by the operator of those methods. In order to investigate the aging state more objective, the thermally stimulated current (TSC) test has been used in our investigation. In this paper, the investigation on the aging of line composite insulator sheds has been carried out using the static contact angle method and TSC. This paper report the test results for the samples from the 110kV composite insulator sheds after 8 years of field operation. The test samples were prepared from the insulator sheds located in HV, LV and mid-section respectively, and the upside and downside of one shed has also been took care. According to the test, the result of hydrophobicity test is in accordance with the TSC test, and it was found that the aging degree of different sheds in the same line composite insulator is non-uniform. The HV end of the insulator generally has higher aging degree than that of LV end, and the mid-section of sheds aging is the lightest. This result is helpful for the comprehensive evaluation method of composite insulator sheds aging degree.