Energy losses from an arc tracking in aeronautic cables in DC circuits

A specific setup was developed to create a fault transient arc between aeronautic cables with current intensity up to 100 A. Electrical measurements were coupled to arc length determination, based on arc fast imaging in order to deduce the shape of the arc and the electrode voltage drop. Using optical sensors the radiation emitted by the arc in the range of wavelength higher than 200 nm (non VUV radiation) was estimated. The cable ablation rate was also deduced in the study. A phenomenological and quantitative analysis was performed by coupling the experimental results with theoretical calculation of net emission and using literature results on arc energy transfer. The results show that for copper cables, about 45% of the input electric energy is transferred to the contacts producing a strong ablation of the cable. Then the radiation part is divided in two contributions having more or less the same ratio (12% each): VUV radiation deposited very near from the arc, and non VUV radiation that may propagate far from the arc. The remaining energy is lost by convection and thermal conduction.