Determination of the electrical properties of nanoparticle added transformer oils

Power transformers are one of the most important and expensive equipment in the transmission and distribution systems of the energy sector. Although the general structure of power transformers does not change much over time, material-oriented developments continue. The most common insulating fluids used in transformers from the past to the present are petroleum-based mineral oils. These insulating fluids generally undertake the functions of cooling by means of heat transfer and electrical insulating in transformers. Various insulating fluids have recently emerged as alternatives to mineral oil. Although there are a wide variety of insulating fluids in the literature, the most preferred ones after mineral oils are natural esters, synthetic esters, and silicone esters. Each insulating fluid is selected according to the place of use and purpose of use, and development studies continue. In recent years, the determination of properties and performance comparisons of nanoparticle-doped insulating fluids has become a popular topic. In this thesis, it is aimed to improve the electrical insulation and thermal conductivity of the existing oil by adding conductive, semi-conducting and insulating solid particles smaller than 100 nm, called nanoparticles, to the mineral oil used as insulating fluid. These nanoparticles are BN, Al2O3, SiO2, and MgO. The sizes of the preferred nanoparticles are chosen as small as possible. The two-step stabilization method based on mass concentration was used as the mixing method for nanoparticles. Nanoparticle weights were calculated according to the mass concentration, first mechanical mixing was made and then stabilized by the ultrasonic bath. AC breakdown voltage measurement, viscosity determination, and thermal conductivity measurement were performed on the samples. The results obtained as a result of the measurements performed on four different nano-fluids were examined comparatively in terms of their positive/negative properties.