Electrical treeing behaviours in cross‐linked polyethylene cables after thermal ageing

Abstract

Long‐term thermal ageing might have impacts on the physicochemical properties of cross‐linked polyethene (XLPE) cables, thereby influencing their electrical behaviours, such as electrical treeing initiation and growth. The main objective of this work is to report the effects of thermal ageing on the electrical treeing behaviours (initiation and growth) in XLPE cable insulation. For this purpose, the electrical treeing initiation and growth test were performed in accelerated thermal samples. In addition, Differential Scanning Calorimetry and Fourier Transform Infrared Spectroscopy were utilised to investigate corresponding changes in the microstructures of materials. In addition, a correlation was established between electrical treeing behaviours and physicochemical properties during the thermal ageing process. Test results indicate that the thermal ageing process should be divided into three phases, and the re‐crystallisation reaction is considered the primary reason for the increase of average electrical tree initiation voltage (AETIV). Furthermore, the thermal ageing index Xc is correlated to AETIV and the propagation rate of the electrical tree. As equivalent relationships have been established between the relative decrease value w of indexes AETIV, the propagating rate and Xc, this method can be employed to predict the changing pattern of electrical treeing initiation voltage and the propagating rate in future research.

Dynamic Cross-Linked Polyethylene Networks with High Energy Storage and Electrical Damage Self-Healability

“…By using needle tip discharge, the material underwent tree-like voids to form electrical tree (Figure 5a). 52 After 4 h of thermal self-healing, as shown in Figure 5b, the dimension of the main branch decreased, and the small electric tree completely healed, which was comparable to the healing performance of the same sized electrical tree branch in the epoxy resin that was previously reported by the Li group. 17 This indicates that the migration rate of polymer chains increases at the self-healing temperature, and dynamic exchange of free hydroxyl groups and ester bonds from polymer chains repairs these microdefects (Figure 5c).…”

“…Self-healing dielectric polymers not only possess a certain degree of self-healing capability toward mechanical damage but also, more significantly, exhibit comparable self-healing performance in response to electrical damage, with their electrical properties essentially retained after the repair process. By using needle tip discharge, the material underwent tree-like voids to form electrical tree (Figure a) . After 4 h of thermal self-healing, as shown in Figure b, the dimension of the main branch decreased, and the small electric tree completely healed, which was comparable to the healing performance of the same sized electrical tree branch in the epoxy resin that was previously reported by the Li group .…”

Effect and mechanism analysis of matrix resin type on thermal aging characteristics of semi‐conductive shielding material for high voltage cable

“…In recent years, many scholars have conducted a lot of research on the aging of insulation layer of high voltage cable 7–12 . Li et al studied the effect of thermal aging on the crystal structure in the insulation layer of 110 kV cross‐linked polyethylene (XLPE) cable.…”

Effect of nucleating agents on the electrical properties of cross‐linked polyethylene under tensile stress

“…Long-term exposure to external mechanical stress can lead to problems such as sheath rupture and insulation deformation, causing cable failures [3,4]. Moreover, external mechanical stress can damage the aggregated structure of the insulation material, accelerate the growth of electrical trees in the insulation material, and seriously threaten the reliability of cable operation [5,6].…”