We perform a systematic investigation of methods for including radiation transport in arc simulations by analysing both various ways of solving the radiation transfer equation and methods for averaging the absorption coefficient over frequency. We show that the discrete ordinate method (DOM) and the P1 approximation can be used to produce good results: DOM being slightly more accurate and P1 being faster. Furthermore, we demonstrate that it is possible to start from the full absorption spectrum and produce band-averaged absorption coefficients with sufficient accuracy, if the frequencies are grouped not only based on frequency but also based on their magnitude. This makes it possible to introduce radiation transport in arc simulations in a systematic manner, with full control of accuracy. In a follow-up paper, part II, we apply our results to the simulation of several switching arcs, demonstrating the feasibility of self-consistent arc simulations for switching applications.

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An accurate and robust method for radiative heat transfer simulation for arc applications was presented in the previous paper (part I). In this paper a self-consistent mathematical model based on computational fluid dynamics and a rigorous radiative heat transfer model is described. The model is applied to simulate switching arcs in high voltage gas circuit breakers. The accuracy of the model is proven by comparison with experimental data for all arc modes. The ablation-controlled arc model is used to simulate high current PTFE arcs burning in cylindrical tubes. Model accuracy for the lower current arcs is evaluated using experimental data on the axially blown SF6 arc in steady state and arc resistance measurements close to current zero. The complete switching process with the arc going through all three phases is also simulated and compared with the experimental data from an industrial circuit breaker switching test.

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