Analysis and improvement measures for the fracture of closing spring in a ±500kv converter station

This study comprehensively analyzed and researched the problem of spring breakage in the closing of the 5071C phase circuit breaker at a ± 500kV converter station. Through a series of scientific experimental methods such as macroscopic inspection, size measurement, chemical composition analysis, hardness testing, metallographic examination, magnetic particle testing, macroscopic morphology testing of fracture surface, scanning electron microscopy testing, and energy spectrum testing, the root cause of spring fracture was identified. The results indicate that the surface of the spring gradually corrodes and forms corrosion pits during operation. The corrosion pits result in a decrease in the stress crosssection of the spring, and under external force, the spring cracks along the pit position, ultimately leading to fracture. This study provides valuable reference information for the design, manufacturing, use, and maintenance of circuit breakers, which can help further improve the stability and reliability of power systems.