Analysis on Stress Corrosion Cracking of Brass Connecting Nut Utilized in Pneumatic Mechanism for 500kV Tank Circuit Breaker

Abstract

Abstract Circuit breaker is an on-load device that can interrupt load or short-circuit current. Recently, failure of component used in circuit breaker occurs frequently, thus the safety and stability of power grids is severely affected. In this paper, the fracture cause of a brass connecting nut of tank circuit breaker for 500 kV substation was investigated by means of macro-morphology inspection, chemical composition analysis, microstructure analysis, fracture morphology analysis, numerical simulation and energy spectrum analysis. The result showed that the fracture of the brass connecting nut was mainly caused by stress corrosion and stress concentration. Meanwhile the poor mechanical properties due to improper manufacture process, accelerated the development of the stress corrosion cracking of the brass connecting nut.