Comparative study of transformer aged oil reclamation by fuller's earth and activated bentonite

In service, transformer oil was subjected to several stresses, especially electrical and thermal aging. These ones cause its deterioration and lead to transformer failure. The effects of aging processes of insulating oil lead to its change or its treatment. One way to treat transformer aged oil is to reclaim it by using the adsorption process. It consists to remove the acid components, water and oxidation products with an adsorbent material. In this paper, experiments have been performed with service aged oil reclaimed in laboratory conditions by two types of adsorbents, namely fuller's earth and activated bentonite. After its treatment, the reclaimed aged oil is submitted to an accelerated thermal aging times in presence of copper and paper. This is done to evaluate the behavior of the two kinds of reclaimed aged oil. A comparison of the fuller's earth reclaimed aged oil properties and that one reclaimed by activated bentonite, is performed to test their adsorbing power. The results obtained in laboratory conditions, indicate that the type of adsorbents is very important for reclamation process.