Reclamation of Synthetic Ester Dielectric Liquids by Pressure and Gravity Percolation Methods

The tremendous demand for electricity requires higher operating voltages, which in turn impose great stress on the transformer insulation system. Condition-based maintenance and liquid decontamination are activities for assessing the risks and extending the service life of such systems. It is therefore important to explore the reclamation of the new biodegradable liquids. It is known that adsorbent-based reclamation is a prominent approach to treating insulating liquids. The present article provides the results of an experimental study on the reclamation of two low-pour-point synthetic ester fluids and a typical synthetic ester liquid using magnesium silicate-based adsorbents. The experimental results also include mineral insulating oil for a baseline reference. All four of these liquids were subjected to accelerated aging under open beaker conditions in the presence of cellulose. The aged liquids were then regenerated by pressure and gravity percolations with two magnesium silicate-based adsorbents. Physicochemical and electrical characterizations were conducted on both the feed and the filtrate. It is inferred that magnesium silicate-based adsorbents have some potential for the reclamation of synthetic esters by removing the polar compounds that evolved with the liquid’s service life.