Analysis and verification of strength of 110kV porcelain post insulator

Porcelain post insulators are widely used in power equipment as insulation-supporting structure. The current standard has clear requirement for the overall strength of porcelain post insulators; however, the operation and maintenance data of various operating conditions show that shed damage is a major failure type of porcelain post insulators. At present, strength verification of cantilever beam is employed in the strength design of porcelain post insulator, focusing on the stress on the root of porcelain, with the strength of the shed and the stress between the sheds not taken into account. In this paper, calculation based on the main type of operation failure of 110kV porcelain post insulators shows that the stress between sheds near the root of porcelain brushing is much larger than that on the root of porcelain brushing, which is proved by experimental verification. According to the result, a good explanation of the phenomenon that a large number of porcelain post insulators damage concentrated in the between the sheds of the root of the porcelain brushing is proposed with the optimization of the current design and test criteria of porcelain post insulator.