Study of Surface Resistivity of an Epoxy/Gas Interface versus Electric Field and Relative Humidity

Abstract

International audienceSurface resistivity of solid insulators is usuallydetermined by measuring the current induced when an electricfield tangential to the surface is applied. This classical methodcan become questionable when the electric field is raised. In fact,a current may also flow above the interface through the humidgas, in addition to currents flowing at the interface and below theinterface within the solid bulk. This paper presents anexperimental study of the variation of the surface resistivityversus electric field and relative humidity RH of the surroundinggas. The results show that in dry gas (RH < 1%) and for anelectric field up 8 kV/mm, the surface gets no specific propertiescompared to the volume. However, in humid gas (1% < RH <10%), a decrease of the net surface resistivity (by subtracting thecurrent above and below the interface) is detected