Mechanism of Increase of Electrostatic Charging Tendency in Insulating Oil for Oil-immersed Transformer

Okabe, S.; Kotoh, Masanori; Tsuchie, Motoo; Amimoto, T.

doi:10.1541/ieejpes.129.229

Cited by 1 publication

(8 citation statements)

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“…ECT values for the same sulfoxide concentration in oil 2 are larger than those in oils 1 and 3. The ECT depends not only on the sulfoxide concentrations but also on the molecular structures and weights of sulfoxide compounds [7]. Thus oil 2 contains lots of sulfide compounds that have profound effect on increasing the ECT compared to oils 1 and 3.…”

Section: Results Of Thermal Aging Testsmentioning

confidence: 99%

“…One of the reasons for this large variance is that these oils contain various kinds of sulfoxide compounds. The increasing effect depends on the type of sulfoxide [7]. The effect of aromatic sulfoxide molecules is not significant compared to straight chain molecules.…”

Section: Properites Of Insulating Oilmentioning

confidence: 89%

“…The high ECT of mineral insulating oil originates in the sulfide compounds that are contained in new oil [7]. Sulfide compounds degenerate into sulfonium ions via sulfoxide compounds.…”

Section: Correlation Between Sulfoxide Concentration and Volume Resismentioning

confidence: 99%

“…Since sulfonic acid is generated by oxidation of sulfoxide, serious deterioration due to oxidation is considered to occur when sulfonic acid is detected. Reverse polarity in the ECT is observed with the addition of sulfonic acid and this effect is transient [7]. Thus monitoring the concentration of sulfonic acid is necessary for evaluating the ECT.…”

Section: Properites Of Insulating Oilmentioning

confidence: 99%

“…The ECT of mineral insulating oil was found to increase by changes of sulfur compounds that are contained as minor components [7]. Sulfide compounds are contained in new oil.…”

Section: Introductionmentioning

confidence: 97%

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Diagnosis on increase in electrostatic charging tendency of mineral insulating oil for power transformers due to aging

Okabe

Kohtoh

Amimoto³

2010

IEEE Trans. Dielect. Electr. Insul.

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Diagnosis on electrostatic charging tendency (ECT) of mineral insulating oil for power transformers has been performed. Increase in the ECT is derived from sulfonium ions, which are generated by sulfoxide compounds and hydrogen ions. Strong correlation between the ECT and the sulfoxide concentration is obtained in a series of thermal aging tests with oxygen and/or copper catalyst. The volume resistivity of oil is used as an alternative indicator for the concentration of hydrogen ion because hydrogen ions increase the electrical conductivity of oil and the sensitivity of conventional property such as total acid value is too low to evaluate the aging deterioration of closed-type transformers. Analysis of oils extracted from 98 actual transformers, whose operating years are between 3 and 46 years, are performed. High ECT values more than 200 pC/ml are detected in some oils and their volume resistivity values are less than 4 x 10 14 Ωcm. Degree of the correlation between the ECT and the sulfoxide concentration is low compared to the result of the thermal aging tests. A diagnostic map with four areas classified using a pair of indicators of volume resistivity and sulfoxide concentration is useful to predict prospective increases in the ECT. Appropriate transformer operation and maintenance including air exposure avoidance of their mineral insulating oils is one of the effective solutions to prevent the ECT from increasing.

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Section: Results Of Thermal Aging Testsmentioning

confidence: 99%

Section: Properites Of Insulating Oilmentioning

confidence: 89%

“…The high ECT of mineral insulating oil originates in the sulfide compounds that are contained in new oil [7]. Sulfide compounds degenerate into sulfonium ions via sulfoxide compounds.…”

Section: Correlation Between Sulfoxide Concentration and Volume Resismentioning

confidence: 99%

Section: Properites Of Insulating Oilmentioning

confidence: 99%

“…The ECT of mineral insulating oil was found to increase by changes of sulfur compounds that are contained as minor components [7]. Sulfide compounds are contained in new oil.…”

Section: Introductionmentioning

confidence: 97%

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