This paper presents an experimental study on the AC breakdown voltages of Refined, Bleached and Deodorized Palm Oil (RBDPO) Olein and Coconut Oil (CO) in the presence of conductive (Iron (II,III) Oxide, Fe3O4), semi-conductive (Copper (II) Oxide, CuO) and insulative (Aluminium Oxide, Al2O3) nanoparticles without and with surfactant. The type of surfactant used in this study was Cetyl Trimethyl Ammonium Bromide (CTAB). The volume concentrations range of Fe3O4, CuO and Al2O3 was varied from 0.001% to 0.05%. Transmission Electron Microscope (TEM) was used to characterize the nanoparticles in RBDPO and CO. AC breakdown voltage tests were carried out for RBDPO and CO of which the AC breakdown voltage at 1% probability was determined based on Weibull distribution. It is found that only Al2O3 can improve the average AC breakdown voltage of RBDPO and CO. The AC breakdown voltages at 1% probability for RBDPO and CO can be improved through introduction of Fe3O4, CuO and Al2O3 at certain volume concentrations. Al2O3 provides the highest enhancement of AC breakdown voltages at 1% probability for RBDPO and CO with the highest percentage of improvement can be up to 52%. CTAB has no clear effect on the improvement of AC breakdown voltages of RBDPO and CO based Fe3O4, CuO and Al2O3 nanofluids.

In this paper, the effect of different types of surfactants on the lightning breakdown voltages of palm oil (PO) and coconut oil (CO) based aluminium oxide (Al2O3) nanofluids is investigated. Three different types of surfactants were used in this study known as cationic (cetyl trimethyl ammonium bromide (CTAB)), anionic (sodium dodecyl sulfate (SDS)) and non-ionic (oleic acid (OA)). The volume percentage concentrations of Al2O3 dispersed into PO and CO were varied from 0.001% to 0.05%. The ratio of surfactant to the nanoparticles was set to 50% from the volume concentration of nanoparticles which equivalent to 1:2. In total, two types of refined, bleached and deodorized palm oil (RBDPO) and one type of CO were examined for lightning breakdown voltage. The test was carried out based on needle-sphere electrodes configuration with 25 mm gap distance. The presence of Al2O3 improves both positive and negative lightning breakdown voltages of RBDPO and CO. Under the positive and negative polarities, the CTAB does provide further improvements on the lightning breakdown voltages of RBDPOA (1st type of samples) and CO at most of the volume of concentration of Al2O3. SDS and OA could also further improve the lightning breakdown voltage of CO at certain volume concentration of Al2O3. On the other hand, the lightning breakdown voltage of RBDPOB based Al2O3 nanofluid (2nd type of samples) does not further improve with the introduction of surfactants. At most of the volume concentration of Al2O3, the introduction of CTAB further increases the times to breakdown and decrease the average streamer velocities of RBDPOA under both polarities. The same finding is observed for CO under positive polarity with CTAB and SDS as well as under negative polarity in the presence of all surfactants. The streamer velocities and times to breakdown patterns of RBDPOB based Al2O3 nanofluid are inconsistent in the presence of all surfactants. It is found that RBDPO and CO based Al2O3 nanofluids have second mode of streamer whereby the streamer velocities are from 1 km s−1 to 1.63 km s−1 regardless with or without surfactants.

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-In this paper, a study is carried out to investigate the dielectric, physical and chemical properties of Palm Oil (PO) and Coconut Oil (CO) under open thermal ageing condition. The type of PO used in this study is Refined Bleached and Deodorized Palm Oil (RBDPO) Olein. The ageing experiment was carried out at 85 °C and 115 °C for 1, 3, 5, 7 and 14 days. Several parameters were measured such as AC breakdown voltage, dielectric dissipation factor, relative permittivity, resistivity, viscosity, moisture and acidity throughout the ageing duration. Based on the study, it is found that there are no significant changes on the AC breakdown voltages and relative permittivities for both RBDPO and CO. At ageing temperature of 115°C, there are clear reduction trends of dielectric dissipation factor for CO and resistivities for most of RBDPO. On the other hand, no clear trends are observed for viscosities, moisture and acidities of RBDPO and CO throughout the ageing duration.

One of the important parameter for insulating fluid is the dielectric properties. With the introduction of vegetable oil as possible alternative fluid for transformers application, it is essential to ensure this type of oil could meet the dielectric properties requirement. In this paper, a study is carried out to investigate the dielectric properties of Palm Oil (PO) and Coconut Oil (CO). The type of PO used in this study is Refined, Bleached and Deodorized Palm Oil (RBDPO) Olein. Several parameters such as AC breakdown voltage, dielectric dissipation factor, relative permittivity and resistivity are examined for both as-received and dried samples. It was found that there are differences on the dielectric dissipation factor and resistivity between RBDPO and CO and the dielectric properties performances of all samples are improved after subjected to the drying procedure.

This paper presents a sealed ageing study of palm oil (PO) and coconut oil (CO) in the presence of insulation paper. The type of PO under study is refined, bleached, and deodorized palm oil (RBDPO) olein. Three different variations of RBDPO and one sample of CO are aged at temperatures of 90 °C, 110 °C, and 130 °C. The properties of RBDPO and CO as well as paper under ageing are then analysed through dielectric and physicochemical measurements. It is found that the effect of ageing is not significant on the alternating current (AC) breakdown voltages and relative permittivities of RBDPO and CO. There is a slight increment trend of the resistivity for CO, while for all of the RBDPO, the resistivity slightly decreases as the ageing progresses. Only CO shows an apparent reduction of the dielectric dissipation factor. Throughout the ageing time, the acidities of all of the RBDPO and CO remain at low level, while the moisture in oils decreases. The tensile index (TI) of the papers for all of the RBDPO and CO retain more than 50% of the TI. A significant increment of the paper ageing rates of all of the RBDPO and CO is observed at an ageing temperature of 130 °C.

This experimental study aims to examine the partial discharge (PD) properties of palm oil and coconut oil (CO) based aluminum oxide (Al2O3) nanofluids with and without surfactants. The type of surfactant used in this study was sodium dodecyl sulfate (SDS). The volume concentrations range of Al2O3 dispersed in oil samples was varied from 0.001% to 0.05%. The ratio of surfactants to nanoparticles was set to 1:2. In total, two different types of refined, bleached and deodorized palm oil (RBDPO) and one type of CO were measured for PD. Mineral oil (MO) was also examined for comparison purpose. PDIV measurements for all samples were carried out based on rising voltage method whereby a needle-sphere electrode configuration with a gap distance of 50 mm was chosen in this study. Al2O3 improves the PDIVs of RBDPO, CO and MO whereby the highest improvements of PDIVs are 34%, 39.3% and 27%. The PD amplitude and repetition rate of RBDPO improve by 38% and 81% while for CO, it can increase up to 65% and 80% respectively. The improvement of PD amplitude and repetition rate for MO are 18% and 95%, regardless with and without SDS. Without SDS, the presence of Al2O3 could cause 26%, 75% and 65% reductions of the average emission of light signals for RBDPOA, RBDPOB and CO with the improvement of PD characteristics but both events do not correlate at the same volume concentration of Al2O3. On the other hand, the average emission of light signal levels of the oils increases with the introduction of SDS. The emission of light signal in MO does not correlate with the PD characteristics improvement either with or without SDS.

This paper presents a high temperature ageing study of refined, bleached, and deodorized palm oil (RBDPO) olein at 170 • C in the presence of air. In total, two types of RBDPO were examined. The physiochemical and dielectric properties of RBDPO were measured and analysed. We found that the moisture and viscosities for both RBDPO increased as the ageing progressed, whereas the acidities fluctuated at very low levels at less than 0.005 mg KOH/g. The ageing on the AC breakdown voltages of both RBDPO were not affected throughout the ageing processes. The dielectric dissipation factors and relative permittivities for both RBDPO increased as the resistivities decreased with the ageing time.