Volt-ampere characteristics of direct-current arc over a contaminated surface

This study focuses on static and dynamic volt-ampere characteristics of direct-current (DC) arc over a pollution layer based on a plane triangular contaminated glass sample. The definitions and solving methods of static and dynamic volt-ampere characteristics of DC arc were proposed. The parameters A and n in E=AI
^-n
and the time constant τ were used to characterize the static and dynamic characteristics of DC arc, respectively. The needed time of an arc to reach a steady state was determined by measuring its volt-ampere characteristics at various moments. These three parameters (A, n and τ) for the arcs over the upper and lower surfaces of the polluted glass sample were measured through measuring the arc voltage and arc current using an oscilloscope. Generally, the parameter A decreases and n increases with time to reach steady values, and the time constant τ of this process tends to increase as the current grows from 0 to 1 A. The necessary DC voltages to maintain similar arc length on upper and lower surfaces were compared.