A Method for Analysing and Characterizing the Arc Cooling Effect of Different Gases in Strong Axial Flow With SF₆ and Air as Examples

A method of quantifying the abilities of different gases to cool an axis-symmetric arc in strong axial flow is established. It is able to quantitatively account for the contributions of different energy exchange processes, such as convection, conduction, radiation and turbulent mixing, towards arc cooling (i.e., increase of arc resistance) during the current zero period of the interruption process. Applying the method to a decaying SF6 arc and an air arc in a converging-diverging nozzle with the arc current ramped down linearly from 1 kA to zero at a rate of 13.5 A/μs, it is shown that the arc cooling effects of turbulence and radial convection, in terms of the reciprocal of their arc cooling characteristic time (1/τk), keep increasing in SF6 in the last 2 μs before current zero, but remain effectively unchanged in air. The arc cooling index (ACI) defined at 1 μs before current zero is found to be 2.59/μs for SF6 and 0.96/μs for air. The SF6 arc resistance at current zero is approximately 4 times that of air under the arcing conditions used in this study

Further Development of Mathematical Models for Free-Burning Electric Arcs

A mathematical model predicting the electric arc plasma behavior in air and atmospheric pressure is developed. Modeling algorithms are reported for free-burning (rather than wall stabilized) dc-arc parameters, such as the arc radial temperature distribution T(r) , electric field E along the arc column, and arc radius r0 (radius of the electrically conductive zone σ>0 ). Such arcs may have more complex structures than wall-stabilized arcs. Examples of such arcs are electromagnetically rotated arcs, electric arc furnaces (EAFs), and lightning return stroke (LRS). By comparison with experimental data and with more precise calculations, the model was validated practically and theoretically and formed the basis for investigating the behavior of complex electromagnetically convoluted arcs in the process of interrupting direct currents

Electrical Erosion Resistance of Graphene Reinforced Cu-W Circuit Breaker Contact Materials under 5 kA Arc

This work integrates experimental and MD simulation approaches to study the role of graphene in G-Cu-W composites. Arcing tests were conducted on G-Cu-W and Cu-W contact samples under a 5kA peak current. Experimental results show that adding graphene leads to a lower surface roughness of the sample following arcing. MD simulation results indicate that the G-Cu-W model exhibits a smoother surface and fewer lost metal atoms than the Cu-W model due to the protective effect of graphene layer

Electrical Erosion Resistance of Graphene Reinforced Cu-W Circuit Breaker Contact Materials under 5 kA Arc

This work integrates experimental and MD simulation approaches to study the role of graphene in G-Cu-W composites. Arcing tests were conducted on G-Cu-W and Cu-W contact samples under a 5kA peak current. Experimental results show that adding graphene leads to a lower surface roughness of the sample following arcing. MD simulation results indicate that the G-Cu-W model exhibits a smoother surface and fewer lost metal atoms than the Cu-W model due to the protective effect of graphene layer.</jats:p