Comparison of arc tracking tests in various aerospace environments

Momentary short-circuit arcs between a polyimide insulated wire with defective insulation and another conductor may cause pyrolization of the insulation resulting in a conductive path capable of sustaining the arc. These sustained arcs may propagate along the wires or to neighboring wires leading to complete failure of the wire bundle. Wire insulation susceptibility to arc tracking may be dependent on its environment. Because of all wire insulation types tested to date arc track, a test procedure has been developed to compact different insulation types with respect to their arc tracking susceptibility. This test procedure is presented along with a comparison of arc tracking in the following three environments: (1) air at atmospheric pressure and 1 gravitational (g) force; (2) vacuum (2.67×10^-3 Pa) and 1 g; and (3) air at atmospheric pressure and microgravity (<0.04 g)