Surface Potential Decay of Negative Corona Charged Epoxy/Al₂O₃ Nanocomposites Degraded by 7.5-MeV Electron Beam

Investigation on space charge and charge trap characteristics of Al–epoxy nanocomposites

“…Studies have indicated that initial fast potential decay is credited to detrapping of charges from shallow traps, and subsequent slower potential decay is ascribed to detrapping from deep traps [15]. The initial surface potential in a negative polarity case is higher than positive polarity over the sample surface for the applied transient voltages under uniform experimental conditions.…”

“…6 and 7, respectively. The trap depth at maximum energy density is treated as a trap centre [15]. The left shift in the trap centre is intuitively thought as the depreciation in trap depth, and it can be correlated with the increment in the decay rate of potential decay curves.…”

Investigation on the digital image correlation and charge trap characteristics of Al/epoxy nanocomposites

“…The density of trapped charges (N(E)) at different energy levels (E) within the bulk of the material with the variation of trap depth (ΔE) [34,35] is expressed by the following equation: amount of energy required for a charge carrier to get liberated from the localized trap site [20]. The trap depth at maximum energy density is treated as a trap centre [36]. Variation in trap centre for positive and negative polarities of the applied DC voltage profiles as a function of filler concentration is shown in figures 10(a) and (b).…”

Global experience of HVDC composite insulators in outdoor and indoor environment

“…The charge dynamics is affected by three activities; namely conduction on the surface along the solid-gas interface, conduction in the bulk of the material and neutralization of surface charges by surrounding ionic carriers [31,32]. Yuan et al [33] studied and analyzed the surface potential decay (SPD) characteristics of virgin and in-service aged HTV-SiR insulator sheds filled with silica and aluminium hydroxide operated at ±500 kV and ±800 kV DC transmission lines in China. The samples from these lines were removed after 10 years and 6 years in service, respectively.…”