Research on the Pressure Characteristics of 550kV Single-Break Self-Blasting Circuit Breaker during the Breaking Process

During the breaking process of the self-blasting circuit breaker, the pressure characteristics greatly affect the action characteristics of the valve and the pressure in the expansion chamber, thus affecting the arc blowing effect. Therefore, a 550kV single-break selfblasting circuit breaker is taken as the research object. Based on the theory of magnetohydrodynamics (MHD), a two-dimensional transient model considering arc radiation is established, and the numerical calculation of the breaking process under two typical breaking conditions with short- circuit current of 63kA and 40kA and arcing time of 12ms is completed. The pressure and temperature distribution in the expansion chamber, and the action characteristics of the valve are obtained. Besides, combined with the test conditions, the 63kA short-circuit current, the pressure and temperature characteristics under short, medium and long arcing conditions are studied, and the valve action time under different conditions is obtained. The results show that the maximum temperature of the arc core region is 33219K at 63kA, which is about 3332K higher than the 40kA condition. The maximum pressure in the expansion chamber is 2.94MPa under the condition of 63kA and 2.36MPa at 40kA. The check valve is mainly affected by the temperature and pressure in expansion chamber side under the two breaking conditions, and the force received on the side of the cylinder is substantially same. The action time of the check valve under 63kA is 0.06ms earlier than the 40kA, and relief valve advance acts 0.05ms. Corresponding to different arcing time, the action time of check valve is 16.38ms, 16.28ms and 16.48ms and the time of relief valve is 17.52ms, 17.42ms and 17.67ms.