Re-examination of the dielectric spectra of epoxy resins: bulk charge transport and interfacial polarization peaks

Chalashkanov, N. M.; Dodd, S.J.; Dissado, L.A.; Fothergill, J.C.

doi:10.1109/tdei.2014.6832281

Cited by 25 publications

(23 citation statements)

References 34 publications

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“…Interestingly, IP is observed in the neat epoxy spectrum, and loss index attains high values. IP has been detected in loss spectra of many polymers due to the presence of additives, impurities and plasticizers [32][33][34][35]. On the other hand, increased values of loss tangent should be related to high values of the dielectric loss ("&), since tan' is defined as the ratio of the imaginary to the real part of dielectric permittivity.…”

Section: Hydration Studiesmentioning

confidence: 99%

Barium ferrite/epoxy resin nanocomposite system: Fabrication, dielectric, magnetic and hydration studies

Kanapitsas¹,

Tsonos²,

Psarras³

et al. 2016

Express Polym. Lett.

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Abstract. Composite systems of epoxy resin and barium ferrite nanoparticles have been prepared, and studied varying the content of the inclusions. Morphology of prepared samples has been examined via scanning electron microscopy and X-ray diffraction spectra, while electrical and magnetic properties were investigated by means of broadband dielectric spectroscopy, and magnetization tests respectively. Finally, water vapor sorption measurements were conducted in order to study the water sorption dynamics of the system. Electron microscopy images revealed the successful fabrication of nanocomposites. Dielectric permittivity increases with filler content, while three relaxation processes were detected in the relative spectra. These processes are attributed to interfacial polarization, glass to rubber transition of the matrix, and re-orientation of polar side groups of the polymer's chain. Magnetization and magnetic saturation increase with magnetic nano-powder content. Nanocomposites absorb a small amount of water, not exceeding 1.7 wt%, regardless filler content, indicating their hydrophobic character.

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Section: Hydration Studiesmentioning

confidence: 99%

Barium ferrite/epoxy resin nanocomposite system: Fabrication, dielectric, magnetic and hydration studies

Kanapitsas¹,

Tsonos²,

Psarras³

et al. 2016

Express Polym. Lett.

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“…The locus of the translation point is given below the master curve and the spectra are normalized with respect to the data obtained at the highest temperature. As previously reported the dielectric spectra exhibits a quasi-dc (QDC) process and a mid-frequency dispersion [17]. The QDC behavior implies that in these conditions charge transport takes place by means of structured paths [21] that are not uniformly distributed spatially.…”

Section: Dielectric Measurementsmentioning

confidence: 93%

“…A threeelectrode configuration was used for the measurements. Further details of the test cell and the measurement equipment used can be found in [17]. …”

Section: Dielectric Measurementsmentioning

confidence: 99%

“…In this work we have used the dielectric measurements presented in [17] to determine that there is a bulk quasi-dc (QDC) transport process that is available to displace charges in a set of flexible epoxy resins. The analysis allows us to determine the conditions of humidity, temperature, and frequency, under which the displacement of the charge will be effective in moving dischargeinjected charge away from electrical tree tips during the half-cycle of an applied voltage.…”

Section: Introductionmentioning

confidence: 99%

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The role of bulk charge transport processes in electrical tree formation and breakdown mechanisms in epoxy resins

Chalashkanov

Dodd

Dissado

et al. 2016

IEEE Trans. Dielect. Electr. Insul.

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Electrical treeing experiments have been conducted at different temperatures and levels of absorbed moisture in Araldite CY1311 epoxy resin samples above their glass transition temperature, i.e. when the resin was in a flexible state. The fractal dimension of the electrical trees obtained and the rate of tree growth were found to depend on the environmental factors: temperature and humidity. It has also been found that at certain levels of temperature and moisture absorbed in the samples, a transition occurs from electrical treeing degradation to breakdown by thermal runaway. Complementary investigations of the dielectric properties of the same epoxy resin system have revealed that a bulk quasi-dc (QDC) charge transport mechanism takes place above the glass transition temperature, and we show that the characteristic features of the dielectric response are related to the shape of the electrical treeing degradation and the transition to thermal breakdown. This is explained qualitatively through the effect of the bulk QDC charge transport process in modifying the local space charge electric field distribution.

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“…DH cluster theory is a linear dielectric response theory, which describes the two distinct classes of relaxation processes associated with bound charge dipole clusters and potentially mobile charge clusters [118,231,232]. The first category describes a cooperative motion (relaxation) of molecular dipoles within a constrained geometrical domain called a cluster followed by the interactive motion between neighbouring clusters.…”

Section: Dh Cluster Modelmentioning

confidence: 99%

Condition monitoring of biodegradable oil filled transformer

Mudiyanselage¹,

Bandara²

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Natural and synthetic ester insulating oils have higher fire points and excellent biodegradable characteristics. Therefore, in order to reduce the adverse environmental impact and to improve the fire safety of transformers, there is an increasing demand for natural and synthetic ester insulating liquids as a transformer insulating oil. However, present understanding on ageing behaviour of ester oil-paper composite insulation system and knowledge on application of existing condition monitoring tools for ester based insulation systems are inadequate. This impedes the cost effective and reliable field applications of ester insulating oils, particularly application of natural esters. To reduce this knowledge gap, series of controlled ageing experiments are performed in this research project to provide a better and comprehensive understanding on ageing behaviour of ester oil-paper insulation systems. Furthermore, applicability of existing chemical and electrical based condition monitoring techniques for ester oil-paper insulation systems is systematically investigated in this research project.In this thesis, ageing behaviour of dry pressboard insulation in mineral and three different ester insulating oils under simulated transformer operating environment is investigated. Moreover, the ageing behaviour of natural ester-pressboard composite insulation in moisture rich environment is also compared with that of mineral oil-pressboard system. Degree of polymerisation of pressboard samples measured at different ageing interval is used in this research to determine the ageing condition of pressboard. Moreover, applicability of oil related diagnostic parameters such as concentration of dissolved furanic compounds, acidity value, Dielectric Dissipation Factor (DDF), viscosity and colour to assess the degree of degradation of both ester and mineral insulating oils is thoroughly investigated in this research project. The potential of FTIR (Fourier Transform Infrared spectroscopy) techniques for characterising the degree of degradation of paper insulation is also discussed in this thesis. In addition, this thesis concentrates on characterisation of the charge dynamic in insulating oil through modelling of their dielectric responses.The comparison of gassing behaviour of ester and mineral insulating oils under two different low temperature faults and low energy electric discharge condition is also presented in this thesis.Dissolved Gas Analysis (DGA) results presented in this thesis depicts that faults gases detected in ester and mineral oil samples subjected to a similar fault are akin in type but quantitatively different. The quantity of fault gases produced in two different natural ester oils is also dissimilar.For example, soy-based natural ester produces a large quantity of ethane (C2H6) under low temperature overheating condition than sunflower oil based natural ester. Therefore, this research project investigates the applicability of well-established DGA interpretation schemes namely Duval II | P a g e triangle, IE...

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Re-examination of the dielectric spectra of epoxy resins: bulk charge transport and interfacial polarization peaks

Cited by 25 publications

References 34 publications

Barium ferrite/epoxy resin nanocomposite system: Fabrication, dielectric, magnetic and hydration studies

Barium ferrite/epoxy resin nanocomposite system: Fabrication, dielectric, magnetic and hydration studies

The role of bulk charge transport processes in electrical tree formation and breakdown mechanisms in epoxy resins

Condition monitoring of biodegradable oil filled transformer

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