Comparison of Transportation Carriers in the Insulating Materials for HVDC Cable Joint

Introduction of Charge Transport Simulation Models That Fully Consider the Ionization Process

“…In a previous study, it was observed that the conductivity of the three materials increased with increasing field strength in experimental tests, but the magnitude of the increase varied for each material. Specifically, EPDM had the smallest increase in conductivity, while LDPE and nano-XLPE had larger increases [21]. It was also observed that the conductivity curves of LDPE and EPDM intersected in the field strength range of 10-20 kV/mm.…”

“…However, it is difficult to determine the value of all these parameters. In the previous experimental work [21,22], our method can successfully separate the injected part and the ionized part of the carriers. This provides another approach to simplify the calculation model for engineering applications relying on the parameters which can be measured.…”

“…The positive ions, negative ions, electrons, and holes produced in this process are involved in the charge transport process and contribute to the bulk current inside the polymer. In fact, from the results of the blocking experiments, it can be seen that the conductivity of the charges generated during the ionization process is close to that of the injected charges [21], and it is generally believed that the ions are large and slow-moving, so it can be judged that the charge generated during the ionization process is still mainly electrons and holes. Based on this we believe that we cannot use the simple term 'ionic current' to characterize the current generated by the charges produced during ionization, since this part of the charges include both ions and electrons and holes.…”

Dynamics of Phonon-Assisted Holes Trapping and Transport over Chemical Defects in Polyethylene

“…The accumulation of space charge distorts the local electric field and generates extra heat, thus facilitating its aging and degradation process. Despite a substantial literature survey focusing on experimental characterizations of the formation and transport of space charge under a variety of conditions including different electric fields, impregnation patterns of the material, aging conditions, and extreme temperatures, − little is known about the details of the electrical behavior of this material, especially at the molecular level. Unveiling the mechanisms of charge trapping and transport in these insulators and how those processes are affected by local physical structures and chemical impurities could contribute to developing materials with improved insulating properties required for high-voltage cables.…”