Space charge accumulation within polymeric materials has been associated with their accelerated ageing. The measurement of this phenomenon can be used to correlate space charge profiles and their evolution to ageing. In this paper, accumulated charge depletion after long electrical ageing processes has been analyzed following a research trend pointed out in previous works. In order to extend this analysis to several materials, the electrically barely known UHMWPE (Ultra-high molecular-weight polyethylene), mostly used in medical applications, has been compared to well-known XLPE and LDPE. It has been proposed some extremely simple indicators that can be used to know the ageing of a polymeric insulation without incurring in simplifying assumptions and using only the charge profiles obtained directly from the space charge measurements taken by PEA (Pulse Electro Acoustic) method.
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I will be using this blog to interact with you about science news and electrical engineering subjects, expanding on some of the topics in it and posting on some of the ideas related to my researches. This is a great place for you to get to know me and to learn about renewable resources, electricity and HVDC projects.
The use of nanofillers to induce certain changes in electrical properties of polymeric materials, show great interest
for electronic and electrical engineering applications. In this paper, composites of HDPE filled with submicrometric particles of tetragonal BaTiO3 have been prepared. An extraordinary uniform dispersion of the particles was achieved from a first process of mixing by high energy ball milling and subsequent hot pressing. Some electric measurements such as dielectric strength and resistivity were carried out to evaluate the final electrical properties as a function of the processing and the amount of BaTiO3 particles. It was observed how the resistivity decreases when the amount of BaTiO3 increases. Besides, the dielectric strength decreases as the amount of BaTiO3 particles increases. Finally it was observed that as the BaTiO3 content increases the cylindrical-like “conducting channel”, in which the dielectric failure happens, disappears, occurring a dielectric breakdown with a less regular shape.
In order to replace old insulation systems based on oil-paper, other materials, such as low density polyethylene (LDPE), high density polyethylene (HDPE) and specially, crosslinked polyethylene (XLPE), have been used. Characterization of new polymeric materials potentially useful for HVDC power cables is an interesting research topic to work on. In this paper, one material whose previous applications have been far away from power engineering, has been studied: Ultra high molecular weight polyethylene (UHMWPE). Firstly, UHMWPE has been characterized in terms of statistical dielectric strength. Moreover, space charge generation and transport has been analysed in an accelerated electrical ageing experiment in order to compare UHMWPE to other polymeric materials such as XLPE or LDPE. In order to measure space charge profiles, the pulsed electroacoustic (PEA) technique has been applied to polymer sheets withstanding more than 80kV/mm DC for more than 10 days.