Investigation on charge transport processes in liquid dielectrics on the basis of high-purity paraffins
Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
Final Report Abstract
In the following, the results of the project are summarized, so that future research can be based on the project ULFI: For scientific investigation of the electrical conductivity of dielectric liquids, the use of electrodes made from stainless steel is not recommended. It seems better to use a coating with a material with properly defined parameters, such as gold. By the coating, the influence of defects in the surface, that was observed at stainless steel, can be reduced. - When the first seconds after a polarity reversal are to be investigated, voltage sources with automatic polarity reversal can not be used, as they are way to slow. It is recommended to use high voltage amplifiers to produce fast and precise voltage ramps or polarity reversals. - The maximum of the current, that can be observed after a polarity reversal is of high scientific interrest. To explain this maximum, three different explanations can be found in literatur. Hence it is necessary to perform further research with defined parameter studies to get more information about that effect. For this maybe the use of field measurements by the electrooptic Kerr-effect or the measurement of space charges by the Pulsed Electro-Acoustic method (PEA) can be helpful. - The use of pure paraffin as a research object to investigate the electrical conductivity of dielectric liquids seems quite promising as the physical and chemical behavior of the paraffins can be understood well. - It could be shown, that by the use of acids (n-nonan-acid in n-dodecane), the electrical conductivity can be influenced as expected, but needs further investigation to understand the influence totally. The use of salts instead of acids was not sucessful. - Considering the modelling and simulation of the conductivity of dielectric liquids, existing models sucessfully could be used and improved. But also in this field, more research and work is necessary to completely understand and model the conductivity of dielectric liquids.
Publications
- Influence of the Electrode Surface Roughness on the Electrical Conductivity of Pure Paraffin. 20th IEEE International Conference on Dielectric Liquids (ICDL) 2019
C. Dotterweich, F. Dax, M.H. Zink, J. Popp, T. E.M. Staab, G. Sextl, F. Berger
(See online at https://doi.org/10.1109/ICDL.2019.8796663) - Influence of Impurities on the Electrical Conductivity in Paraffinic Model Oil. VDE-Fachtagung Hochspannungstechnik 2020
C. Dotterweich, H.-P. Öftering, M.H. Zink, J. Popp, T. E.M. Staab, G. Sextl, F. Berger
