Measurement and simulation analysis of internal pressure in arc chamber of low-voltage molded case circuit breaker

During the arc interruption process, the internal pressure in the arc chamber of a molded-case circuit breaker (MCCB) rises rapidly. In this study, the arc behavior and internal pressure in an MCCB are measured and calculated. First, using computational fluid dynamics, the internal pressure in the arc chamber is computed both with and without a baffle. In the presence of the baffle, it is found that the pressure is similar at various measurement points, whereas without the baffle, obvious differences in pressure are observed. Second, a moving model considering the contact opening process is proposed based on the relationships between the arc positions, arc area, and source terms at a typical point in time. Compared with a fixed arc model, the moving arc model provides a more precise arc distribution and pressure in the arc chamber of an MCCB.