Fault arc effects under vacuum conditions on cable bundles for space applications

A multitude of “arc tracking” tests on cables for space applications has been performed to improve the basic understanding of the phenomena responsible for the fault arc behaviour. The damage caused in a cable bundle develops in a complex system consisting of metallic conductors, insulation materials and arc plasma. Considering the degradation effects, vacuum as one of the applied test parameters, has turned out to be an important test environment. The investigations are based on a new test method, developed to assess the arc tracking properties of cables for space applications and was presented at different NASA Workshops. Tests were conducted with different insulation materials at cables with different AWG´s at 125 V DC and nominal currents. The tests were focused on the environment vacuum, using air only for the purpose of comparison. For some cable types, vacuum has turned out to be a worst-case environmental condition with respect to fault arc effects, such as conductor burn-off, degradation of the insulation of adjacent cables and the extension of the fault arc. This paper aims at presenting these worst case experiments in detail