The effect of organic additives on the breakdown strength of transformer oil

Evangelou, C; Zaky, A. A.; Megahed, I.Y.

doi:10.1088/0022-3727/6/6/103

Cited by 11 publications

(10 citation statements)

References 8 publications

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“…It is also possible to have different optimum concentrations. This somewhat confirms the idea reported by Evangelou et al [7].…”

Section: Discussionsupporting

confidence: 93%

“…Thus, Zaky and Hawley [6] reported that weak concentrations of aromatic additives enhance the breakdown voltage of insulating oils and that there is an optimum concentration of additives that results in a maximum increase of the breakdown strength. Evangelou et al [7] reported that the breakdown voltage varies with the additive concentration in a complex manner. The characteristics obtained for a very wide range of additive concentrations indicated that there could be more than one optimum concentration.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Electronic Scavenger Additives on the AC Dielectric Strength of Transformer Mineral Oil

Khaled

Béroual

2018

Energies

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This paper is devoted to the influence of two types of electronic scavenger additives/compounds, namely, carbon tetrachloride (CCl4) and methyl iodide, which is also called iodomethane (CH3I), on the dielectric strength of transformer mineral oil. The tests are achieved in a sphere-sphere electrodes arrangement under AC voltage according to the IEC 60156 standard. The investigated additive concentrations range from 0 to 600 ppm. The verification of the conformity of the experimental results with normal and Weibull probabilistic distributions as well as the estimation of the breakdown voltage with risk probabilities of 1%, 10%, and 50% are also performed. It is shown that there is an optimum concentration of each type of electronic scavenger compound at which the dielectric strength of the mineral oil is significantly improved (i.e., it reaches a maximum value). This improvement is of 98% with 500 ppm of CH3I and 93% with 200 ppm of CCl4. It is also shown that the breakdown voltage values of all of the investigated samples with and without additives conform to a Weibull distribution but not to a normal distribution. The obtained results are discussed with regard to the possible mechanisms that may be responsible, particularly the two phases of inception and propagation of the streamers.

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“…It is also possible to have different optimum concentrations. This somewhat confirms the idea reported by Evangelou et al [7].…”

Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

The Effect of Electronic Scavenger Additives on the AC Dielectric Strength of Transformer Mineral Oil

Khaled

Béroual

2018

Energies

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“…It has been previously reported that the presence of wear metals, oxygen and moisture are factors that accelerate the kinetics of decomposition (Meshkatoddini, 2008). Increases in the aromatic content of the oil was thought to bring about poorer resistance to oxidation, however this is not always the case (Evangelou et al, 1973). Although results in this study show no significant differences in the activation energies for VO, BHT-B and DBP-B, addition of aromatics in oils, show functional activity in environments deficient in nitrogen and sulfur impurities (Evangelou et al, 1973).…”

Section: Dsc Analysismentioning

confidence: 99%

“…Increases in the aromatic content of the oil was thought to bring about poorer resistance to oxidation, however this is not always the case (Evangelou et al, 1973). Although results in this study show no significant differences in the activation energies for VO, BHT-B and DBP-B, addition of aromatics in oils, show functional activity in environments deficient in nitrogen and sulfur impurities (Evangelou et al, 1973). Hindered phenols are also found to show profound activity under conditions in which oxygen is depleted (Rudnick, 2009).…”

Section: Dsc Analysismentioning

confidence: 99%

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The Determination of Kinetic Parameters of Transformer Oil and its Blends by Thermal Analysis

Dukhi¹,

Bissessur²,

Ngila³

et al. 2012

International Journal of Emerging Electric Power Systems

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The insulation of transformer oil comprise of two practices: paper and dielectric fluid (such as mineral transformer oil). Ageing of these oils occur mainly by thermal, electrical and oxidative stresses. This paper describes the determination of kinetic parameters of a naphthenic based transformer oil and its blends based on the Ozawa, Flynn and Wall (OFW) and Kissinger models using data obtained from thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC), plots. Virgin oil and its blends were analysed from an initial temperature range of 20-25 ºC to 300 ºC at temperature ramps of 1, 2, 4, 6, 8 and 10 ºC min -1 . The OFW method in conjunction with TGA data was used to calculate the apparent decomposition activation energies at each of the selected weight loss (% conversion or α) values. The activation energies at 10% weight loss were found to be 57.0, 63.7 and 69.3 kJ mol -1 for BHT-B (virgin oil-2,6-di-tert-butyl-4-methylphenol blends), DBP-B (virgin oil-2,6-di-tert-butylphenol blends) and VO (virgin transformer oil), respectively. However using this method the activation energy (E a ) of the oils showed no significant difference between virgin oil and its blends. DSC curves revealed that the decomposition reaction was exothermic in nature. From DSC data the activation energy was determined using two separate models: OFW and Kissinger models. Decomposition activation energy obtained from DSC data showed no significant difference when applied to these two models. Dissipation factor tests showed superior results for the blends when compared to those of virgin transformer oil. However, the blends showed substantial reductions in their dielectric breakdown voltage. The implication of the reduced breakdown voltage is that the blends show poorer dielectric strength in comparison to virgin transformer oil.

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Methods for improving the workability of natural ester insulating oils in power transformer applications: A review

Ghani

Muhamad

Noorden

et al. 2018

Electric Power Systems Research

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The effect of organic additives on the breakdown strength of transformer oil

Cited by 11 publications

References 8 publications

The Effect of Electronic Scavenger Additives on the AC Dielectric Strength of Transformer Mineral Oil

The Effect of Electronic Scavenger Additives on the AC Dielectric Strength of Transformer Mineral Oil

The Determination of Kinetic Parameters of Transformer Oil and its Blends by Thermal Analysis

Methods for improving the workability of natural ester insulating oils in power transformer applications: A review

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