Failure Analysis of a Plum Blossom Contact Spring in a Circuit Breaker
摘要
The plum blossom contact spring of the circuit breaker in the power supply line of an ultra-supercritical unit broke after about 50,000 h of operation. In this study, various experimental techniques such as macroscopic examination of morphology, metallographic analysis, chemical composition analysis, scanning electron microscopy and hardness analysis were used to analyze the causes and types of fracture of the plum blossom contact spring. The results indicate that the structural unevenness of the contact spring led to an uneven distribution of tightening pressure on the moving contact, resulting in localized overheating and consequent stress relaxation. This is identified as the main cause of the spring breakage.