Two cases of explosion in high-voltage cable joints: Fault evolution deduction and combustion physical modeling analysis

Abstract

High-voltage cable joints are critical components that connect cable sections, playing a vital role in cable circuits. However, their specific location and complex installation and maintenance requirements make them vulnerable points in cable circuits. In recent years, there has been a significant increase in breakdowns and explosions in high-voltage cable joints, and it is essential to examine the diverse outcomes resulting from these explosion incidents. This paper conducts an analysis of two incidents of breakdown and explosion in 220 kV integral prefabricated cable joints that occurred on the same cable circuit. Initially, the short-circuit breakdown processes of the two faulty cable joints are deduced through the disassembly inspection. Subsequently, fluid field simulations of the breakdown locations in the faulty joints are performed using finite element simulation software to analyze the impact of breakdown in different areas on the combustion situation of the faulty joints. The results indicate that for integral prefabricated cable joints with insulating flange, there are different discharge paths inside, leading to diverse failure outcomes. The faulty joint experiencing explosion at the insulating flange exhibit intense combustion due to strong air flow.The faulty joint experiencing explosion at the copper protective shell weld, there is limited airflow, and the non-combustible byproducts generated during combustion cover the surface of the integral prefabricated component, preventing further combustion of the cable joint. Lastly, this paper proposes corresponding improvement measures to minimize losses and hazards caused by cable joint explosions, providing references and recommendations for the production and construction of high-voltage cable joints.