Measurement of dynamic potential distribution during the propagation of a local arc along a polluted surface

A novel method for measuring the dynamic potential distribution during the propagation of a local arc along a polluted surface is described. In order to study the role of electric stress during the pollution flashover process, a flat polluted glass plate model has been designed. Measuring electrodes made with a strip of aluminum foil were stuck to the bottom of the plate, opposite the side on which the local arc propagated. Using the capacitance between the polluted surface and the measuring probe, which is in series with an additional capacitor, a potential divider was constructed. By means of the dividers and magnetic tape data recorder the dynamic potential distribution, the position of the local arc, and its propagation velocity were measured. The results show that the velocity of arc propagation along a polluted surface is 0.2-1.0 m/s, and the maximum average potential gradient in the pollution layer is 0.5 kV/cm