The improved dielectric properties of natural ester oil by using ZnO and TiO2 nanoparticles

Abstract

A transformer is one of the most important devices in a power system. It is used for changing the voltage levels in an electrical system. Its lifetime depends on the heat exchange in the liquid insulation from the core and copper winding inside the transformer. Mineral oil is a widely used liquid insulation that causes problems when it contaminates the surrounding environment because it decomposes slowly. This research is intended to improve properties of a natural oil to replace mineral oil in power transformers. The currents study provides the results of tests on breakdown strength, flash point, fire point, and viscosity of the natural esters in soybean ester and palm esters mixed with nanoparticles. Titanium dioxide (TiO 2 ) and Zinc oxide (ZnO) nanoparticles were used in the investigation. Different quantities of nanoparticles were tested ranging from 0.01g/l‑0.2 g/l. ASTM D1816, ASTM D93 and ASTM D2196 standard methods were used for testing breakdown strength, flash and fire points, and viscosity, respectively. The results indicated that the breakdown strength increased significantly when both TiO2 and ZnO nanoparticles were added to natural oil. The flash and fire points of two types natural oil had higher values than mineral oil. The addition of nanoparticles into the oil had no effect on its flash and fire points. The viscosity of natural oil had lower values than mineral oil. Dielectric properties can be improved by adding a suitable volume fraction of nanoparticles. However, the other properties must be considered before using a natural ester in the field.