Dielectrometry measurements of moisture dynamics in oil-impregnated pressboard

Sheiretov, Yanko; Zahn, M.

doi:10.1109/94.395423

Cited by 47 publications

(7 citation statements)

References 7 publications

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“…1) Temperature Instability A major difference in the properties of transformer oil and paper is that the materials are hydrophobic and hydrophilic, respectively. The temperature change will lead to the migration of moisture between oil and paper through diffusion [15]. Accordingly, a dielectric test may not be able to represent the real condition of the insulation except the temperature is stable and moisture equilibrium between oil and paper has reached.…”

Section: A Nonlinearity In Transformer Pdc Measurementsmentioning

confidence: 99%

Investigation of non-linearity in dielectric response measurements for transformer insulation diagnosis

Ashkezari

Saha

et al. 2011

2011 IEEE PES Innovative Smart Grid Technologies

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Dielectric response measurement is emerging as one of the potential non-destructive tools for transformer insulation diagnosis. Studies have been conducted to derive equivalent circuits for dielectric response of transformer oil/paper insulation system, which are normally based on a linear RC model. However, in practice transformer insulation systems may exhibit nonlinear polarisation behaviour. This paper investigates the nonlinearity of the dielectric response of transformer insulation under high excitation voltages. Polarisation and depolarisation current (PDC) measurement is performed on a distribution transformer under different voltages to study the nonlinearity of its dielectric response. Based on these measurements a nonlinear transformer insulation model is proposed, in which a current controlled voltage source (CCVS) is augmented to the wellknown Debye model to approximate the nonlinear effect.

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Section: A Nonlinearity In Transformer Pdc Measurementsmentioning

confidence: 99%

Investigation of non-linearity in dielectric response measurements for transformer insulation diagnosis

Ashkezari

Saha

et al. 2011

2011 IEEE PES Innovative Smart Grid Technologies

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show abstract

“…In those cases knowledge of the dielectric properties is essential. In other research fields than electrical insulation, the water uptake of materials and their dielectric properties have been also studied [122,123,124,125,126,127,128,129,130,131]. Liquid-solid mixtures [132], such as, brine-saturated rocks and porous media [133,134,135,67,54,136,125,126,137], suspensions in solutions [138,139,140] or liquid crystal in polymer matrices [141,142,143,144,145] have been examined using dielectric spectroscopy technique.…”

Section: Experimental Studies Of Dielectric Systemsmentioning

confidence: 99%

Dielectric mixtures: electrical properties and modeling

Tuncer

Serdyuk

Gubanski

2002

IEEE Trans. Dielect. Electr. Insul.

274

154

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A review of current state of understanding of dielectric mixture properties and approaches to use numerical calculations for their modeling are presented. It is shown that interfacial polarization can yield different non-Debye dielectric responses depending on the properties of the constituents, their concentrations and geometrical arrangements. Future challenges on the subject are also discussed.

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“…The high frequency dielectric permittivity of the impregnated filter in buffer is even greater (ε′ ≈ 6), which means that the aqueous solution gets into the pores, thus increasing the dielectric permittivity of the membrane. It is interesting that ε′ of oil-impregnated transformer paper also increases at low frequencies as the result of water sorption . At low frequencies the apparent dielectric permittivity is much higher for all three cases.…”

Section: Resultsmentioning

confidence: 88%

Biomimetic Membranes with Aqueous Nano Chanels but without Proteins: Impedance of Impregnated Cellulose Ester Filters

Kocherginsky

Lvovich

2010

Langmuir

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Earlier we have shown that many important properties of ionic aqueous channels in biological membranes can be imitated using simple biomimetic membranes. These membranes are composed of mixed cellulose ester-based filters, impregnated with isopropyl myristate or other esters of fatty acids, and can be used for high-throughput drug screening. If the membrane separates two aqueous solutions, combination of relatively hydrophilic polymer support with immobilized carboxylic groups results in the formation of thin aqueous layers covering inner surface of the pores, while the pore volume is filled by lipid-like substances. Because of these aqueous layers biomimetic membranes even without proteins have a cation/anion ion selectivity and specific (per unit of thickness) electrical properties, which are similar to typical properties of biological membranes. Here we describe frequency-dependent impedance of the isopropyl myristate-impregnated biomimetic membranes in the 4-electrode arrangement and present the results as Bode and Nyquist diagrams. When the membranes are placed in deionized water, it is possible to observe three different dispersion processes in the frequency range 0.1 Hz to 30 kHz. Only one dispersion is observed in 5 mM KH(2)PO(4) solution. It is suggested that these three dispersion features are determined by (a) conductivity in aqueous structures/channels, formed near the internal walls of the filter pores at high frequencies, (b) dielectric properties of the whole membrane at medium frequencies, determined by polymer support, aqueous layers and impregnating oil, and, finally, (c) by the processes in hydrated liquid crystal structures formed in pores by impregnating oil in contact with water at low frequencies.

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Dielectrometry measurements of moisture dynamics in oil-impregnated pressboard

Cited by 47 publications

References 7 publications

Investigation of non-linearity in dielectric response measurements for transformer insulation diagnosis

Investigation of non-linearity in dielectric response measurements for transformer insulation diagnosis

Dielectric mixtures: electrical properties and modeling

Biomimetic Membranes with Aqueous Nano Chanels but without Proteins: Impedance of Impregnated Cellulose Ester Filters

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