Field-Enhanced Motion of Impurity Particles in Fluid Dielectrics under Linear Conditions

It has been pointed out by several authors that the influence of impurity particles on dielectric phenomena in non-solid dielectrics can be significant in some cases, especially for technical liquids. In order to get information on such impurity influence, a computer-aided study of the motion of a charged spherical particle under general transient conditions, and with unrestricted conductivity and permittivity of both the medium and the particle has been carried out. To verify the model consistency, a set of tests in n-hexane with sphere-plane electrode geometry have been carried out using different experimental techniques, including high-speed-photography, and satisfactory agreement has been observed. On this basis, a model of the low-field conduction process by impurity particles has been developed assuming negligeable interactions between particles. A computer-aided procedure for the evaluation of impurity convection currents under different conditions has been implemented. The results obtained are compared with tests carried out on n-hexane with controlled pollution. Finally, a detailed discussion of the results obtained is given.