Low-Voltage Arc Simulation with Out-Gassing Polymers

Polymer walls and inserts are an important design criterion in low-voltage switching devices. Besides their good insulation properties they are used to influence the switching arc. An important part of the energy dissipated in the arc is absorbed by the walls of the arc chamber. This leads to degradation and evaporation of the polymer and subsequent impact on and interaction with the switching arc. This contribution explains the enhancements of an existing simulation model for the interaction between the low-voltage switching arc and walls composed of polyamide PA 66. This includes a model of plastic ablation, the influence of the plastic vapor on the transport properties of the arc as well as on its radiation. Calculations and comparisons with experimental results show the applicability of the model in arc chambers that are close to reality.