Concentration dependence of corrosive sulfur on copper-sulfide deposition on insulating paper used for power transformer insulation

Amimoto, T.; Hosokawa, N.; Nagao, E.; Tanimura, Junji; Toyama, S

doi:10.1109/tdei.2009.5293964

Cited by 55 publications

(21 citation statements)

References 6 publications

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“…These diagnostic techniques include fault gas analysis, moisture analysis, dielectric monitoring, UHF sensors, acoustic sensors, off line or on line PD testing, dielectric response measurements, time response dielectric spectroscopy, dielectric discharge method and return voltage measurement, interpretation of measurements, transfer function analysis and expert system diagnostic software. The phenomenon of understanding the ageing of Kraft paper insulation shows that paper degradation is the cause of production of furan based aldehydes or hydrocarbon gases produced in mineral oil which results in change in DP (degree of polymerization) of cellulose in insulating paper or effect of various parameters using electrical, mechanical and chemical techniques is evaluated which are relevant to assess the state of both paper and oil insulation with identifying its effective life [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Thermal degradation of Kraft paper is caused due to increase in operating temperature so this insulating paper is thermally upgraded to neglect the aging by treating it with additional additives which result in formation of a new modified insulating paper such as amine modified Kraft paper, cyan ethylated paper, and carbamate modified paper by chemical modification for better performance and some other alternative oils are used as a substitute to mineral oil like alkyl-naphthalene oil, vegetable oil to increase the life of oil-paper insulation [21][22].…”

Section: Liquid Oil Insulation:-mentioning

confidence: 99%

“…In addition, a product DBDS (Dibenzyl disulfide) found in mineral oil which causes the layering of copper sulphide on cellulose insulating material [9]. This deposit layer on paper increases rate of deterioration of paper.…”

Section: Ageing Effects:-mentioning

confidence: 99%

“…This sulfur is appeared as a compound DBDS (Dibenzyl disulfide) found in mineral oil that causes the deposition of copper sulphide on paper insulating material. When sulphur present in DBDS comes in contact with copper leads to layering of copper-sulphide on insulating paper due to which electric strength of insulation is reduced [9]. Decreasing the DBDS value partially in mineral oil will enhance life span of transformers [10].…”

Section: Dissolved Gas Analysis:-mentioning

confidence: 99%

See 2 more Smart Citations

A Review of Condition Monitoring Assessment of Power Transformers Insulation

Aggarwal¹,

Jindal²,

Singh³

2016

IJAR

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Section: Liquid Oil Insulation:-mentioning

confidence: 99%

Section: Ageing Effects:-mentioning

confidence: 99%

Section: Dissolved Gas Analysis:-mentioning

confidence: 99%

See 1 more Smart Citation

A Review of Condition Monitoring Assessment of Power Transformers Insulation

Aggarwal¹,

Jindal²,

Singh³

2016

IJAR

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“…The current state of the art still suggests conflicting ideas for the chemical reaction mechanism, although there are 3 main events in this complex reaction that are common to most suggested models. First the reaction of DBDS with copper where sulfur is displaced from the oil to the conductor, then copper-sulfur compounds at the conductor are formed and finally there is a displacement of copper to the oil and paper [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Tracking copper sulfide formation in corrosive transformer oil

Amaro

Facciotti

Holt

et al. 2013

2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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Corrosive sulfur in the last decade has been recognized as a major risk to high voltage transformers. An initial study undertaken by CIGRE on copper sulfide in transformer insulation investigated possible sources, i.e. Dibenzyl Disulfide (DBDS), it also looked at possible mitigating techniques, i.e. passivation, environmental influences, i.e. temperature, and improvement to oil corrosion standards, i.e. EN 62535. Although there was significant volume of research undertaken the high voltage industry still felt there is a lack of understanding in the process of copper sulfide formation and long-term effects of mitigation techniques. Hence a new CIGRE transformer working group, A2.40, was created.The identification of techniques with the ability to track the mechanism of copper sulfide (Cu 2 S) formation is fundamental to the current research objectives. The technique suggested in this paper involves the use of X-ray fluorescence (XRF), which is used for elemental analysis, to track the quantity of sulfur in the oil. As the deposits of Cu 2 S form in the conductors and paper insulation the amount of sulfur in the oil decreases. By using a series of laboratory experiments is possible to investigate how the rate of formation of Cu 2 S changes with time, suggesting that there is an initial chemical reaction needed for the Cu 2 S deposits to form. Scanning Electron Microscopy with Energy-dispersive X-ray spectroscopy (SEM-EDX) has been used to investigate the surface of copper at several different stages of the copper sulfide formation. By manipulating variables, i.e. temperature, it is possible to map their influence and provide a more precise risk assessment of transformer with corrosive oil to electrical utility companies. The experimental results suggest the possibility of developing a method to indirectly measure Cu 2 S deposition on conductors and insulation paper by tracking sulfur concentration changes in the transformer oil.

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“…In the past decade a considerable amount of research has been carried out, new corrosive sulfur detection tests and standards have been implemented [2][3][4], mathematical models to predict Cu 2 S deposition rate on paper [5] and mitigating techniques have been developed [6].…”

Section: Introductionmentioning

confidence: 99%

Impact of corrosive sulfur in transformer insulation paper

Amaro

Holt

Facciotti

et al. 2013

2013 IEEE Electrical Insulation Conference (EIC)

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In recent years a significant volume of research has been undertaken in order to understand the latest failures in oil insulated power apparatus due to deposition of copper sulfide on the conductors and in the insulation paper. Dibenzyl Disulfide (DBDS) has been found to be the leading corrosive sulfur compound in the insulation oil. As there are currently no nondestructive techniques available to analyze the degree of damage from sulfur corrosion, electrical plant operators are faced with a choice of either replacing an asset which might still have several years of operational life or keeping a transformer operational with an increased risk of failure. This paper investigates permittivity and loss factor curves of transformer oil impregnated insulation paper, at different corrosive sulfur degradation stages. Three types of transformer conductors are investigated; new, artificially aged and service aged. To increase the understanding of the electrical behavior of Cu 2 S this paper demonstrates how the electrical properties change with moisture content. Dielectric spectroscopy is used to demonstrate some of the electrical changes across a wide frequency range, from 1mHz to 1MHz.

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Concentration dependence of corrosive sulfur on copper-sulfide deposition on insulating paper used for power transformer insulation

Cited by 55 publications

References 6 publications

A Review of Condition Monitoring Assessment of Power Transformers Insulation

A Review of Condition Monitoring Assessment of Power Transformers Insulation

Tracking copper sulfide formation in corrosive transformer oil

Impact of corrosive sulfur in transformer insulation paper

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