Simulation Research on Electrode Erosion Characteristics of Miniature Circuit Breaker During Short Circuit Interruption Process

Electrode erosion during short circuit interruption process has great effects on interruption performance and service life of a miniature circuit breaker (MCB). Thus it is of great importance to study characteristics of electrode erosion of MCB. In this article, a mathematic model of electrode erosion was developed, in which state changes, energy balance equation of the interface between arc plasma and electrode, and moving boundary were taken into account. The parameters of arc stagnation time on static contact and arc current were measured, which can be taken as input conditions for the erosion model. Then the temperature distribution, erosion rate, erosion volume and erosion mass were calculated under 3kA short circuit current. The validity of the model was verified by comparing the simulated erosion masses with experimental results. The influences of arc stagnation time and mass fraction of SnO₂ on the erosion mass of electrode were also analyzed under 3kA short circuit current. It is found that with the increase of arc stagnation time from 0.5ms to 1ms, the quality of mass loss increases linearly and the growth rate is approximately 7.06mg/ms. Moreover, for the three electrode materials with different SnO₂ mass fractions, 8%, 10% and 12% respectively, the quality of mass loss increases slightly from 4.5mg to 4.8mg