Advanced Characterization Techniques Based on Luminescence in XLPE and Modified XLPE

Abstract

Crosslinked Polyethylene finds application in the insulation of high voltage cables, constituting a high demanding domain in terms of electrical performances. High quality XLPE grades are now produced for insulation under high voltage direct current (HVDC) stress. Luminescence techniques have constituted original techniques along the development of such materials, particularly as regards the role of defects and residues in the behavior of materials in terms of electrical charges stabilization. Luminescence provides a family of extremely sensitive techniques, though limited to substances with unsaturated groups: in materials like XLPE only additives, residues and defects are optically active. After recalling the grounds of luminescence principles in organic materials, we explain the techniques implemented, mainly based on photoluminescence and on an analysis of optical emissions related to charge traps into materials. The main results obtained with the identification of the role of these 'defects' are presented before addressing the knowledge brought by luminescence methods, including electroluminescence, on thermal and electrical ageing aspects of polyethylene materials.

Electronic properties of polyethylene naphthalate as derived from photo-stimulated discharge, luminescence experiments and quantum chemical calculation

“…All the luminescence experiments were realized with a home-made set-up build around a cooled photomultiplier (Hamamatsu R943-02) working in photon counting mode and a cooled CCD camera associated with a grating monochromator for spectra acquisition. An updated description of the set-up is described in [19]. The chamber is designed such as high voltage can be applied, it can sustain secondary vacuum and the sample can be cooled down using liquid nitrogen circulation.…”