Investigation on the Properties of Natural Esters Blended with Mineral Oil and Pyrolysis Oil as Liquid Insulation for High Voltage Transformers

Bakrutheen, M.; Iruthayarajan, M. Willjuice; Kumar, Sunil

doi:10.1007/978-981-10-4852-4_17

Cited by 5 publications

(2 citation statements)

References 17 publications

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“…Studies related to the use of natural ester fluids as an intended replacement of mineral oil in paper oil insulation systems have been conducted and published many times, e.g., in [1]- [3]. Often mentioned problems are the higher viscosity of esters, up to 50 mm 2 •s −1 at 40 • C [4]; higher pour point, −17-−28 • C [5]; higher permittivity, ε r = 3-4 [6]; lower oxidative stability [7]; and higher price of commercially produced esters compared with those of mineral oils. These facts play a critical role in the current deployment of ester fluids in industry.…”

Section: Introductionmentioning

confidence: 99%

Various Aging Processes in a Paper-Natural Ester Insulation System in the Presence of Copper and Moisture

et al. 2020

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This article adds more information to the problem of natural ester use as an electroinsulating fluid in cellulose paper-oil systems, e.g., for use in power transformers. An accelerated thermal aging (120, 140 and 160 • C) of samples consisting of cellulose paper (transformerboard), a treated natural ester (filtered, basic Al 2 O 3 , 0.53% DBPC), a copper plate and moisture was studied. Research was especially focused on the impact of moisture on the aging of the above system. Samples with three different oil moisture levels (80, 143 and 305 ppm water content) were subjected to thermal aging to display the change in a selection of properties (tanδ, acid number, water content). For a study of the polarization effects, broadband dielectric spectroscopy (BDS) was performed to observe the complex permittivity and conductivity dependencies on the temperature and frequency (±30 • C, 0.01-10 7 Hz). Havriliak-Negami (H-N) diagrams were used to further understand the results. The degradation products during thermal aging were recognized by Fourier transform infrared (FT-IR) spectroscopy. Hydrolysis and hydrogenation occurred in the insulating system with a natural ester aged by elevated temperatures, which is in contrast to CO 2 formation in the case of electric aging. The results showed an increase in the acid number, dissipation factor, and number of hydrolysis and hydrogenation products. Furthermore, changes in polarization were observed as a consequence of the thermal aging of paper-natural ester insulation system with the presence of copper and moisture. INDEX TERMS Aging, dielectrics, hydrogenation, hydrolysis, oil insulation, paper-oil insulating system, natural ester, complex permittivity.

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Section: Introductionmentioning

confidence: 99%

Various Aging Processes in a Paper-Natural Ester Insulation System in the Presence of Copper and Moisture

et al. 2020

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“…There are commercial products already used in the transformers [3,4], however, still, several technical problems prevent them from being deployed. Well know are problems with their higher viscosity (a heat transfer issue) [5], high pour point [6], higher permittivity [7], low oxidation stability [8] (a hermetic design is required) and the high price of commercially produced esters, etc. This is also the reason why currently such fluids are deployed in Europe sporadically, mainly in headquarters or showrooms of international corporations or in specially protected areas.…”

Section: Introductionmentioning

confidence: 99%

Development of a Biodegradable Electro-Insulating Liquid and Its Subsequent Modification by Nanoparticles

et al. 2018

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Abstract:The paper is focused on the possibility of replacing petroleum-based oils used as electro-insulating fluids in high voltage machinery. Based on ten years of study the candidate base oil for the central European region is rapeseed (Brassica napus) oil. Numerous studies on the elementary properties of pure natural esters have been published. An advantage of natural ester use is its easy biodegradability, tested according to OECD-301D (Organisation for Economic Co-operation and Development) standard, and compliance with sustainable development visions. A rapeseed oil base has been chosen for its better resistance to degradation in electric fields and its higher oxidation stability. The overall ester properties are not fully competitive with petroleum-based oils and therefore have to be improved. Percolation treatment and oxidation inhibition by a phenolic-type inhibitor is proposed and the resulting final properties are discussed. These resulting fluid properties are further improved using titanium dioxide (TiO 2 ) nanoparticles with a silica surface treatment. This fluid has properties suitable for use in sealed distribution transformers with the advantage of a lower price in comparison with other currently used biodegradable fluids.

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Aging of Electrical Insulating System Based on Organic Ester

Trnka

Totzauer

Mentlík

et al. 2018

2018 IEEE 2nd International Conference on Dielectrics (ICD)

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Investigation on the Properties of Natural Esters Blended with Mineral Oil and Pyrolysis Oil as Liquid Insulation for High Voltage Transformers

Cited by 5 publications

References 17 publications

Various Aging Processes in a Paper-Natural Ester Insulation System in the Presence of Copper and Moisture

Various Aging Processes in a Paper-Natural Ester Insulation System in the Presence of Copper and Moisture

Development of a Biodegradable Electro-Insulating Liquid and Its Subsequent Modification by Nanoparticles

Aging of Electrical Insulating System Based on Organic Ester

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