Failure Analysis of the Top Hoop of the Disconnector in a 750 kV Substation

Abstract

This paper takes the cracking event of the top hoop of the disconnector in a 750 kV substation as an example, through visual inspection, material analysis, metallographic inspection, SEM, EDS and other test methods, analyzes the reasons for the breakage of the hoop and proposes improvement measures. The results show that the metallographic structure and mechanical properties of the sample hoop castings are poor, and there are local original casting defects such as cracks, pores and porosity. During the operation, the original defects of the discontinuous parts of the structure are further expanded under the action of stress, which eventually leads to the fracture of the hoop.t.