Simulation of the effect of the dielectric thickness on space charges and interfacial charge under high voltage DC

Multilayer polyethylene is a material that is generally employed as insulation for the HVDC isolations. In this paper, the influence of the dielectric thickness on space charge dynamic has been studied. For example, low-density polyethylene (LDPE) and Fluorinated Ethylene Propylene (FEP) sandwiched between two electrodes were subjected to high voltage application for the extended duration of time. What is more, the space charge measurements were taken using a more complex bipolar model which is one-dimensional, taking into account trapping, detrapping, and the recombination in order to determine the charge density and electric field of the sample depending on the thickness. On top of that, the simulation was carried out at two different forms LDPE-FEP and FEP-LDPE. In conclusion, simulation results demonstrated that only the polyethylene layer is charged with the polarity of the electrode with which it is in contact. Besides, bulk fillers of the polyethylene are detected.