Space Charge and Trap Distributions and Charge Dynamic Migration Characteristics in Polypropylene under Strong Electric Field

Abstract

Space charge accumulation in polypropylene will accelerate aging of the material and lead to the degradation of its insulation performance. Here, space charge distribution, current conduction characteristics, thermally stimulated depolarization current (TSDC), and surface potential decay (SPD) characteristics of polypropylene (PP) under a strong electric field were measured and analyzed, and the bulk trap and surface trap parameters were extracted. Further, the charge dynamic transport physical processes and characteristics under strong electric field were studied. Experimental results show that the charge accumulation amount in PP under the action of a negative polarity electric field is higher than that of a positive polarity electric field, by about one order of magnitude. There are two obvious charge density peaks on the PP surface, which are 2.60 and 3.66×1020·eV -1 ·m -3 V. The simulation results show that with the extension of the applied voltage time, the injected charges by the electrode gradually migrate to the bulk of the material and eventually the positive and negative charges are offset at the middle position. The local electric field caused by the accumulation of interfacial charges will weaken the original electric field, resulting in the distortion of the internal electric field.

Space Charge Characteristics and Breakdown Properties of Nanostructured SiO2/PP Composites

“…The gradual accumulation of space charge distorts the electric field applied to polypropylene, thereby reducing its electrical strength and potentially causing insulation breakdown in severe cases [25]. The accumulation of space charge in PP accelerates insulation aging and even breakdown, posing safety hazards in cable operations [26][27][28]. Thus, space charge accumulation poses a significant challenge and detrimentally affects the long-term reliability of PP cable operation.…”