This article deals within the study of the effect of artificial radiations on physical and chemical properties of the crosslinked polyethylene (XLPE) material, widely used for manufacturing high-voltage cables. Within this framework, several experimental tests, using essential characterization techniques, were performed to study XLPE behavior under ultraviolet (UV) aging. Attenuated total reflection Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy were thus carried out to identify the main structure changes of the material before and after exposure to UV. In addition, appearance changes and DC (Direct Current) volume resistivity were evaluated. The obtained results showed that UV radiation has a great effect on the physicochemical properties of XLPE cable insulation.

A contactless method based on energy shift of high‐energy cut‐off of the x‐ray bremsstrahlung, the so‐called Duane Hunt Limit and a conventional low voltage electrical technique (three‐probes technique) is applied on thermal and corona aged silicone rubber (SiR) to measure, respectively, the surface potential, Vs, and the surface resistivity, ρs. The effect of aging on these quantities, representing the dielectric properties, is studied. The results are highly reproducible and highlight a good correlation between Vs and ρs. It was observed that thermal aging combined with electrical aging deteriorates more the electrical properties of the polymer than thermal aging alone. Explanations for electrical characteristics (Vs, ρs) change with aging are supported by attenuated total reflection Fourier transform infrared spectroscopy spectra analysis and a chemical mechanism of aging in three steps (i.e., oxidation‐polycondensation, degradation, and thermal cracking). The surface degradation of the polymer is revealed by images of surface morphology obtained by using scanning electron microscopy (SEM). Roughness is greater for combined thermal and corona aging mode compared to thermal aging alone. In addition, the surface degradation of SiR polymer is confirmed by the loss of its hydrophobicity.

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Under operating conditions effect, insulated power cables can undergo critical degradations. Ultraviolet (UV) radiations are one of the most destructive constraints which affect the properties of the material used for insulation. Because of its good properties, crosslinked polyethylene (XLPE) is widely used in medium voltage (MV) and high voltage (HV) cables insulation. Regardless of its excellent performances, XLPE can degrade when exposed to UV. The objective of this work is to report experimental results concerning the effect of accelerated UV ageing on the properties of XLPE insulation. For this purpose, dielectric characterization, visual observations and scanning electron microscopy (SEM) analysis are performed to assess the extent of ageing. Obtained results show that UV ageing affects greatly the XLPE insulation. So, an evolution in the dielectric properties (dielectric constant, dissipation factor, dielectric loss index and AC volume resistivity), color change and deterioration of surface morphology with ageing time are noticed.

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An experimental investigation of the charging and discharging currents in polypropylene and polystyrene under 1000 V DC stress were presented. The results showed a distinct difference between the charging and discharging currents. As known, the charging current after the DC voltage application decreases rapidly during the first hundred seconds then approached a stabilisation. The discharging current flowing in the opposite direction of the charging current was observed. It was concluded that space charge have formed in the sample. The charging and discharging currents for both the polypropylene and the polystyrene increased with increasing thermal aging time at 80 °C. It was established that the rise in the current depends on the thermal aging time which induces anomalous discharging current flowing in the same direction as the applied field.

This paper deals with the behavior of the crosslinked polyethylene (XLPE) used as high-voltage power cable insulation under ultraviolet (UV) radiations. For this, XLPE samples have been irradiated for 240 h using low-pressure vapor fluorescent lamps. Electrical (surface and volume resistivities), mechanical (tensile strength, elongation at break and surface hardness) and physical (weight loss, water absorption, work of water adhesion and contact angle) tests have been first carried out. Experimental results show that the XLPE characteristics are affected by UV radiation. Indeed, a decline in surface resistivity, mechanical properties, and contact angle, and an increase in the water retention amount and weight loss have been recorded. In order to predict and extrapolate some XLPE properties, a supervised artificial neural network (ANN) trained by Levenberg-Marquardt algorithm has been designed. The collected database is used to train and test the ANN performance. The obtained results show that the proposed ANN algorithm presents good estimation and prediction since the predicted output values agree with the experimental data.