Model to estimate the trapping parameters of cross‐linked polyethylene cable peelings of different service years and their relationships with dc breakdown strengths

Abstract

In this study, an improved trapping/detrapping model was used to simulate the charge dynamics in cross-linked polyethylene peelings from different-year aged cables. Injection barrier of trapping parameters was estimated by the model fitted to experimental data for each type of sample. Moreover, dc breakdown tests were operated on those samples. It has been found that the dc breakdown strength of inner-layer samples is the lowest in cable sections with thicker insulation layer taken from high-voltage ac (HVAC) 220 kV service condition, whereas for the cable with thinner insulation from HVAC 110 kV, middle-layer samples have worst breakdown performance. This might be explained by the space charge issues under long-term HVAC condition. More importantly, a clear relationship between estimated model parameters, including injection barrier, trap depth and trap density, with the dc breakdown strength in each layer has been reported in this study. High Voltage

New Method for Shallow and Deep Trap Distribution Analysis in Oil Impregnated Insulation Paper Based on the Space Charge Detrapping

“…Charges decay faster from shallow traps than that from deep traps [16,17,32], therefore, the firstorder exponential decay expression of charge detrapping shown above should be changed to double exponential decay expression, as shown in Table 1. In the following, the trap distribution of oil impregnated insulation paper based on the first-order exponential fitting analysis (common method) and the double exponential fitting analysis (improved method) is compared.…”

“…This corresponds to the release of fast charges and slow charges, respectively. As depicted in publication [1,3,16,17], charges trapped in deep traps usually dissipate slowly, while charges that are trapped in shallow traps escape from the traps very shortly. Figure 5 shows the dissipation law of the trapped charges in the sample with new oil and aged oil.…”

“…Ageing could introduce defects (physical and chemical) and lead to the rise of localised states in the material. The localised states is named trap [16,17]. Space charge are determined by the trap distribution [1,[16][17][18][19], which is related to defect in material [20][21][22][23].…”

“…Many researches about the trap distribution characteristics for polyethylene and insulation paper have been conducted [1,[16][17][18][22][23][24][25]. The space charge measurement which is non-destructive is the current popular technology for trap distribution analysis.…”

“…The space charge measurement which is non-destructive is the current popular technology for trap distribution analysis. In [16,17], trap energy level and the trap density of the low density polyethylene (LDPE) and gamma irradiated LDPE were analyzed by a trapping-detrapping model for the shallow and deep trap. It is found that trap parameter changes could reflect the LDPE ageing.…”