Use of Ester Oil in Power Transformer & Its Various Characteristics Analysis with Convectional Mineral Oil

I have planned to investigate the various characteristics like Dielectric, Overloading, Partial Discharge (PD) etc. of mineral oil and Ester oil filled power transformer. Mineral oil is the most commonly used insulating liquid for transformer applications, and an extensive database of knowledge has been accumulated over the years. Increased environmental, safety performance and economic have led to the consideration of other oils for use as transformer insulating fluids. Esters have been used as dielectric liquids since the invention of oil filled transformers in the late 1980s. Both types of oils tested are commercial products and commonly used in transformers. A Partial discharge (PD) is localized dielectric breakdown of a small portion of a solid or fluid electrical insulation (EI) system under high voltage (HV) stress. The discharge may occur at any point in the insulation system that the electric field strength exceeds the breakdown strength of that portion of the insulation system. In transformers, the insulation system is comprised of the winding insulation material as well as the dielectric fluid. PD can occur in a gaseous (i.e.SF6), liquid (Mineral Oil –Ester Oil) or solid insulating medium (Press board, Craft Paper, Insulation etc). Insulation failures begin with and are characterized by small but detectable releases of energy or Partial Discharge. That means partial discharges are the first indication of insulation breakdown. PD measurements can also provide information about ageing condition of transformers and thus enable conclusions about their lifetime. One of the main factory tests which used for assessing the insulation quality of power transformers is Partial Discharge test. The certainty of Partial Discharge (PD) measurement results can be affected by different factors such as materials used inside the transformer, Dielectric fluid, workmen ship during manufacturing process. The overload capability of Ester fluid is also remarkably higher compare to the mineral oil .An experimental study carried out on a real three phase Power Transformers at manufacturer high-tech test laboratory using modern test equipment . Dielectric tests were carried out on Power Transformer to understand Electrical Properties of Mineral oil and Ester Oil.