The effect of charge recombination on surface potential decay crossover characteristics of LDPE

Abstract

Bipolar charge injection and transport has been ob served in corona charged low density polyethylene (LDPE) dur ing surface potential decay (SPD) processes. The proposed bipo lar charge transport (BCT) model can well interpret the SPD characteristics, especially the SPD crossover phenomenon. Bipo lar charge transport in materials can result in charge recombina tion (CR). It is evident that CR can affect space charge distribu tions and external current of insulators subjected to electrical stresses. Therefore, it is of interest to investigate the influence of CR on the SPD and crossover behaviors of charged insulating materials. We deal with the SPD properties of corona charged LDPE by the BCT model with a constant charge carrier mobility, including charge trapping/detrapping and CR. The non-linear charge advection-reaction equation in the BCT model is solved by a highly stable and accurate finite difference weighted essentially non-oscillatory (WENO) method with the Strang splitting method. The Poisson's equation is resolved by boundary element method (BEM). The simulation outputs show that the recombination co efficients can affect the space charge and electric field profiles,and recombination rate in the corona charged material. We find that the larger the recombination coefficients are, the higher the threshold initial surface potential for SPD crossover will be.

Electrical Field Distribution along HVDC GIL Spacer in SF 6 /N 2 Gaseous Mixture

“…SF 6 ) [14]. The charge transport process in epoxy spacer volume is mainly controlled by the following equations (19)-(21) [24][25][26]. Note that the epoxy spacer in this numerical model is considered to be clean enough, the surface current due to surface transmission can be ignored since there is no special surface treatment to the spacer [27].…”