Study of magnetic properties of mineral oil based nanofluids

Abstract

Transformer is the most important equipment in a power system network. Thermal and electrical stresses are the major cause of concerns for failures in a power transformer. These stresses are sustained by mineral oil (MO) which provides insulation as well as acts as a coolant in the transformer. MO is extensively used in power transformers for insulation purpose since decades. To overcome the thermal and electrical stresses it is important to enhance the insulation properties. This can be possible by suspension of Nano-sized particles in the oil i.e. nanofluids (NFs). NFs have changed the trend in terms of breakdown, moisture saturation capabilities, etc. The generation of leakage flux in the transformer is responsible for the voltage dip on the load side; hence its reduction is important to maintain good voltage regulation and efficiency. This flux also flows through the liquid dielectric of a power transformer. Thus, it is very much important to analyze the magnetic nature of the liquid dielectric and its impact on the leakage flux. To study this phenomenon, two types of oils are considered; MO and MO based NFs (MO-NFs) with Copper oxide (CuO) and Titanium oxide (TiO2) nanoparticles (NPs) dispersed in them. These oil samples are studied for their magnetic nature using vibrating sample magnetometer (VSM). The liquid insulation magnetization for both MO and MO-NFs is plotted with respect to magnetic field strength. The magnetic characteristics of MO based nanofluids (MO-NF) are discussed in the paper.