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

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