Role of solid insulating materials in the flow electrification of power apparatus

High static voltages can be generated as a result of the flow of a low conductivity fluid over a solid surface. While past work has concentrated mainly on the properties and conditions of the fluid component, the fundamental charge generation process was studied in this research emphasizing the role of solid insulating materials. Streaming potential was measured by means of a streaming potential apparatus, under well controlled moisture and temperature conditions as well as oil charging properties. Characterization of solid insulating materials was performed using image analysis, dc conductivity measurement, and time-domain dielectric spectroscopy (TDDS). The results showed a linear relationship between streaming potential and pressure drop as predicted by theory. Statistical analysis indicated that the surface roughness significantly affects the streaming potential in the laminar flow regime, but the dielectric constant has no effect