Measurements of DC resistivity of insulating oils

Zhou, Mu; Wang, Zhongdong; Liu, Q.

doi:10.1109/ichve.2016.7800895

Cited by 6 publications

(2 citation statements)

References 6 publications

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“…Tan δ is usually used as an ageing indicator, since it depends on the polarity of the sample, which increased with the ageing due to the appearance of pollutants in the dielectric liquid. The resistivity of the oil is another essential parameter to assess the transformer insulation condition, based on the fact that its value is sensitive to the oil degradation (Mu, Wang, and Liu 2016). The previous parameters were measured in the same laboratory test, which was carried out at 90 ºC.…”

Section: Chemical and Dielectric Characterisation Of The Aged High-de...mentioning

confidence: 99%

Study on the degradation of the compression strength of spacers made of high-density pressboard used in power transformers under the influence of thermal ageing

Oria

Méndez

Carrascal

et al. 2022

Preprint

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The structural components inside power transformers are commonly made of high-density pressboard, due to its suitable mechanical and dielectric properties. One of these essential components are the spacers used in the windings of transformers, which are subjected to compressive loading during operation. The spacers are immersed in dielectric liquid and subjected to high temperatures and chemical reactions during the lifespan of the transformer, which result in the degradation of their dielectric and mechanical properties. The performance and reliability of the power transformer greatly depends on its mechanical integrity, so it is necessary to understand how the ageing degrades the mechanical response of the high-density pressboard. In this study, spacers made of high-density pressboard were immersed in uninhibited naphthenic oil and aged at 150 ºC for different periods of time. The evolution caused by the thermal ageing over some chemical parameters (acidity and moisture content) and dielectric properties (AC breakdown voltage, dielectric dissipation factor, resistivity and degree of polymerisation) of the oil and the high-density pressboard was studied experimentally. Compressive mechanical tests were performed on samples of the aged high-density pressboard, and the compressive stiffness during the ageing process was related with other chemical and dielectric parameters.

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Section: Chemical and Dielectric Characterisation Of The Aged High-de...mentioning

confidence: 99%

Study on the degradation of the compression strength of spacers made of high-density pressboard used in power transformers under the influence of thermal ageing

Oria

Méndez

Carrascal

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…For instance, Jonathan Hägerbrand conducted measurements of resistivity in transformer insulation liquids [11], while Z. Mu, Z.D. Wang, and Q. Liu measured the DC resistivity of insulating oils [12]. Both studies provide insights into the electrical properties of dielectric fluids and their potential for use in EV battery thermal management.…”

Section: Introductionmentioning

confidence: 99%

Degradation Effects of Base Oils after Thermal and Electrical Aging for EV Thermal Fluid Applications

Tormos,

Bermúdez,

Ruiz

et al. 2023

Lubricants

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This study presents the experimental results of the effects on base oils after thermal and electrical aging to determine key parameters of next-generation fluids for thermal management in electric vehicles. The test fluids selected were a mineral base oil API G-III, an API G-IV Polyalphaolefin (PAO), a diester, and a polyolester, all of which had similar kinematic viscosity (KV100 = 4 cSt). All were initially characterized with measurements of density, viscosity, thermal conductivity, specific heat capacity, breakdown voltage, resistivity, and dissipation factor. They underwent two separate aging processes, one thermal, heating the test fluid at 150 °C for 120 h with a copper strip as a catalyst; and the second one an electrical aging process, with the application of 1000 breakdown voltage discharges. The same properties were measured again after each aging process and compared to the initial ones. It was found that the thermal properties ranged with similar values and did not suffer major changes after the aging processes, unlike electrical properties, which vary between samples and after thermal and electrical stress. The insights gained from this study have implications for both the development of next-generation e-thermal fluids and the future standardization of these fluids for EV thermal management applications. The findings of this study underscore the significance of formulating and selecting a suitable dielectric fluid for EV thermal management. By leveraging the insights provided, researchers and engineers can advance in the development of efficient and reliable e-thermal fluids while working towards future standardization to enhance the performance and safety of EV battery systems.

show abstract

Degradation of the compression strength of spacers made of high-density pressboard used in power transformers under the influence of thermal ageing

et al. 2023

View full text Add to dashboard Cite

The structural components inside power transformers are commonly made of high-density pressboard, due to its suitable mechanical and dielectric properties. Among these components are the spacers used in the windings of transformers, which are subjected to compressive loading during operation. The spacers are immersed in dielectric liquid and subjected to high temperatures and chemical reactions during the lifespan of the transformer, which result in the degradation of their dielectric and mechanical properties. The performance and reliability of the power transformer greatly depends on its mechanical integrity, so it is necessary to understand how ageing degrades the mechanical response of the high-density pressboard. In this study, spacers made of high-density pressboard and pieces of copper conductor were immersed in uninhibited paraffinic oil and aged at 150 °C for different periods of time, trying to realistically represent the process suffered by a power transformer during its whole lifespan. The evolution caused by the thermal ageing over some chemical parameters (acidity and moisture content) and dielectric properties (AC breakdown voltage, dielectric dissipation factor, resistivity and degree of polymerisation) of the oil and the pressboard was studied experimentally. Compressive mechanical tests were performed on samples of the aged high-density pressboard, and the compressive stiffness during the ageing process was related with other chemical and dielectric parameters.

show abstract

Measurements of DC resistivity of insulating oils

Cited by 6 publications

References 6 publications

Study on the degradation of the compression strength of spacers made of high-density pressboard used in power transformers under the influence of thermal ageing

Study on the degradation of the compression strength of spacers made of high-density pressboard used in power transformers under the influence of thermal ageing

Degradation Effects of Base Oils after Thermal and Electrical Aging for EV Thermal Fluid Applications

Degradation of the compression strength of spacers made of high-density pressboard used in power transformers under the influence of thermal ageing

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