Radiation properties of [C₄F₇N-CO₂-O₂]-PTFE-Cu mixtures at high temperatures and pressures for high-voltage circuit breakers

Abstract

C4F7N-CO2-O2 is currently considered the most promising replacement for SF6 in high-voltage circuit breakers. During high-current interruption conditions, arc radiation plays a pivotal role in arc modeling and is frequently accompanied by vapors ablated from the electrodes and nozzles. To investigate the influence of ablated vapors on the radiative properties of gas mixtures, net emission coefficients (NECs) for various ratios of C4F7N mixtures and PTFE and Cu vapors are calculated under the assumption of local thermodynamic equilibrium. The NECs for [C4F7N-CO2-O2]-PTFE-Cu mixtures that are obtained are required for radiation modeling and arc simulation in high-voltage circuit breakers. It has been found that neglecting the presence of PTFE vapor does not affect the
NEC at high temperatures. However, the influence of copper vapor on the radiative properties in the high-temperature region becomes apparent at elevated ratios, and self-absorption is more pronounced at very high pressures. Based on these findings, recommendations for choosing NECs for use in modeling that balance accuracy and efficiency are proposed.