Electrical aging of extruded dielectric cables: a physical model

Crine, J.‐P.; Dang, C.; Parpal, J.-L.

doi:10.1109/elinsl.1996.549428

Cited by 4 publications

(1 citation statement)

References 22 publications

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“…Many works on XLPE use sections of cable as samples to perform their study [6][7][8][9][10][11][12]. There are also several papers that try to describe the behaviour of the cable insulating layer when it is degraded by thermal treatment [13,14], by treeing formation [15] or by electrical stress [16].…”

Section: Introductionmentioning

confidence: 99%

TSDC study of XLPE recrystallization effects in the melting range of temperatures

Diego¹,

Belana²,

Orrit³

et al. 2006

J. Phys. D: Appl. Phys.

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The electrical properties of crosslinked polyethylene (XLPE), employed in mid-voltage cable insulation are studied using thermally stimulated depolarization currents (TSDC), differential scanning calorimetry (DSC) and x-ray diffraction. A complex heteropolar peak appears by TSDC between 50 and 110 °C, with a maximum at 105 °C. These measurements reveal that there is an optimal polarization temperature (Tpo) around 90 °C. For this polarization temperature, the measured discharge peak area is maximum. Although the presence of a Tpo is common in the study of relaxations by TSDC, in this case one would expect a monotonic decrease in the TSDC response with increasing polarization temperatures due to the decrease in the total crystalline fraction. In this paper, TSDC curves obtained under several conditions are interpreted in terms of recrystallization processes in XLPE during the polarization stage, if the sample is polarized in the melting temperature range. In this case, the recrystallization of a fraction of the material molten at this temperature promotes the formation of more stable and defect-free crystals. The presence of recrystallization processes is detected by DSC and confirmed by x-ray diffractometry. TSDC measurements have been performed with samples polarized at several temperatures (Tp) cooling from the melt or heating from room temperature. Also, TSDC results are obtained with previous annealing or with several cooling rates. These results allow us to infer that crystalline material grown from recrystallization processes that take place in the polarization stage attains a particularly stable polarization. Possible microscopical causes of this effect are discussed.

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