Statistical Investigation of AC Dielectric Strength of Natural Ester Oil-Based Fe₃O₄, Al₂O₃, and SiO₂Nano-Fluids

Abstract

This paper deals with the effects of conductive and insulating nanoparticles at various sizes and concentrations on the ac dielectric strength of natural ester oil, namely, MIDEL 1204. The investigated nanoparticles are conductive (Fe 3 O 4) and two insulating (Al 2 O 3 and SiO 2). The measurements of breakdown voltages are achieved according to IEC 60156 standard. Experimental findings show that the investigated nanoparticles have not a significant influence on insulation performances of natural ester oil as it is the case with mineral oils and synthetic esters. The best improvement does not exceed 7%; it is obtained with Fe 3 O 4 (50nm) at a concentration of 0.4 g/L and Al 2 O 3 (13 nm) at a concentration of 0.05 g/L. In some cases, the addition of nanoparticles even reduces the dielectric strength of natural ester oil. Indeed, a decrease of 15% is observed with SiO 2 at a concentration of 0.05 g/L. The statistical analysis of experimental results is performed using two probabilistic functions, namely, normal and Weibull laws. It is shown that the breakdown voltage values of the investigated nano-liquids generally obey the normal and Weibull distributions. In addition, the breakdown voltage with a risk of 1% and 50% probability is deduced. INDEX TERMS Breakdown, nano-fluids, natural ester, normal distribution, statistical analysis of experimental data, transformer oil, Weibull distribution.

Sustainable, Renewable and Environmental-Friendly Insulation Systems for High Voltages Applications

“…It had been stated that smart fluids formed with few particular nanoparticles (NPs) that smart fluids manufactured with some explicit nanoparticles (NPs) may be adapted to the preference of applications [123][124][125][126]. Numerous investigators studied BDS, viscosity, pour point, thermal features and streamer development in nano-based ester liquids [26,127,128]. A substantial enhancement is observed with the suspension of various types of NPs.…”

Statistical Investigation of Lightning Impulse Breakdown Voltage of Natural and Synthetic Ester Oils-Based Fe3O4, Al2O3and SiO2Nanofluids

“…These probabilistic distributions are the most used to analyze the BDV of dielectrics. The interest in such analyses for the design and maintenance of power apparatus as well as for improving the predictability of insulation performance has been outlined in previous work [10]. Note that in this study one uses the 2-parameter Weibull distribution assuming the location parameter equal to 0 instead 3-parameter Weibull distribution.…”

“…These were supplied by Sigma-Aldrich. Their distribution, composition, shape and size as well as the techniques used for their characterization were described in previous works [9], [10]. The breakdown voltage (BDV) tests were executed under negative lightning impulse, on a test cell of 500 ml volume containing two brass spherical electrodes of 12.5 mm diameter with the electrode gap being 2.50 ± 0.05 mm.…”

“…However, according to recent studies, the addition of some NPs also enhances the AC breakdown voltage (AC-BDV) of insulating liquids and especially that of MO-based Fe 3 O 4 nanofluids [9]. In the case of esters, the AC-BDV can also be improved but to a lesser degree than that of MO [10], [11]. NFs thus appear to be potential substitutes for MO, since they fulfill two of the properties essential for use in HV devices and in particular in power transformers, namely efficient heat transfer and good dielectric performances.…”

“…The polarity effect will not be observed in uniform or quasi-uniform electric fields because of the symmetry of electrode configuration. The aim of this work is to study the LI-BDV of natural ester (NE) and synthetic ester (SE) liquid-based NFs in a sphereto-sphere electrode configuration (i.e., in a quasi-uniform electric field), using the same NPs as in previous work in AC [10], [11]. The main objective of this study is to compare the dielectric withstand in lightning impulse voltages to that measured in AC in our previous work, under the same experimental conditions for the same nanofluids.…”