Influence of Temperature on Flow Electrification Characteristics of Oil-Pressboard Insulation

In order to investigate the temperature dependence of flow electrification characteristics of oil-paper insulation, an oil-paper tube model with concentric cylindrical electrode geometry was built in laboratory. Experiment study on flow electrification under different types of external electric field was carried using the closed oil circulating system, and the influence law and mechanism of temperature on the flow electrification oil-paper insulation was analyzed. The experiment results demonstrated that the streaming currents increase exponentially with temperature in the absence of an external electric field and under AC electric field. At high flow velocity the streaming currents show high dependence on temperature. The streaming currents show same changing tendency with temperature at different amplitude of applied AC voltage. The streaming currents show peak effect with temperature when the insulation withstand DC voltage and AC superimposed DC voltage. Increase of amplitude of external voltage lead to slightly decrease of peak point temperature. However, increase of the DC component ratio of AC superimposed DC voltage lead to significantly decrease of the peak point temperature and faster decrease speed of streaming current after passing the peak value. The theoretical analysis based on the experiment results demonstrated that the streaming current is decided by the negative ions migration and diffusion in the paper at low temperature, and the streaming current is decided by positive ions convection by oil flow and leakage current at the outer electrode at high temperature. The temperature influences the flow electrification characteristics by affecting the ions migration and diffusion speed and the electric field distribution in the insulation.