Behavioural assessment of aged natural ester based nanofluid using statistical technique

Nanofluid (NF) is an emerging class of liquid dielectric used in various high voltage apparatus for the purpose of insulation. In this research, the performance of aged natural ester based NF is studied using statistical analysis. Natural ester extracted from vegetable oil (VO) has the property of better biodegradability and high fire resistance, which makes it suitable to be used as a transformer insulating fluid. For formulating the NF, exfoliated hexagonal boron nitride (Eh-BN) nanoparticle (NP) is dispersed into the VO in specific volume percentage. This study throws light on the various electrical properties such as breakdown voltage (BDV), dielectric dissipation factor (DDF), resistivity and dielectric constant of four types of oils - VO, aged VO, VO-NF and aged VO-NF. The ageing process of the oil is carried out following the open beaker oxidative ageing technique for 500 hours of duration, in the presence of copper catalyst, kraft paper and pressboard. A comparative analysis is carried out among all the four types of oil. Weibull distribution is chosen as it is a very efficient statistical tool and this is plotted for the AC breakdown data to ascertain the probability of failure of the dielectric liquid. By studying the experimental data, it is observed that the VO-NF shows significant enhancement in the dielectric performance with ageing. Furthermore, the Weibull data exhibits that the VO-NF shows higher breakdown voltages as compared to VO at different failure probabilities.