A Three Dimensional CFD Analysis to Investigate the Effect of Ablative Materials and Venting Arrangement on Arc Characteristics in Low Voltage Circuit Breakers

When a low voltage circuit breaker interrupts a fault current, arc plasma is established between the contacts of the breaker. This paper focuses on influence of various polymer vapors like PA66, POM, PTFE, PMMA etc on the arc behavior and effect of venting on pressure distribution. The ablated polymer vapor, which is generated by strong arc radiation, changes the thermodynamic and transport properties of arc plasma. CFD Simulation showed the cooling of the arc plasma and improvement in gas flow. Three different generations (baffled grills, perforated plates, meshed wires) of vents were studied to obtain their pressure drop characteristics. Three dimensional CFD analysis of these vents were carried out by evaluating the porous jump coefficients and vent parameters. The study of the venting arrangement helped in better design of the vents with optimal pressure drop characteristics and deionization of the gases. The commercial computational fluid dynamics package FLUENT is customized to build electromagnetic capabilities for MCB arc extinction chamber. These two factors, ablative polymers and venting, affect and modify the arcing environment improving the overall quenching efficiency of a low-voltage circuit breaker.