Theoretical and experimental laws of anodic and cathodic arc duration on break at low electrical level

This work deals with measurements of arc duration on break in electrical switching contacts in a resistive circuit I < 2 A, and V < 50 V. A sensitive device was constructed with 10 ns time resolution and covering the arc time in the range 10 ns-10 ms. For all contact materials tested (Ag, Cu, Pd, Au, Ag Pd, Ag Au, Ag Cu), experimental points of arc duration versus current are grouped around two theoretical curves corresponding respectively to anodic short arcs and cathodic long arcs. The analytical laws of these curves are found to be in good agreement respectively with multi-burst arc operating (T proportional to t sub b exp(I/i sub b )) and multi-site arc operating models (T proportional to t sub s exp(I/i sub s ) exp 2 ). The lifetime and current intensity of the burst (t sub b , i sub b ) and the site (t sub s , i sub s ) are deduced for various contact materials. 10 ref.--AA