The electrical properties of hygroscopic solids

Christie, J.H.; Krenek, Stephan; Woodhead, Ian

doi:10.1016/j.biosystemseng.2008.09.023

Cited by 23 publications

(20 citation statements)

References 62 publications

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“…This is a typical feature of a system of charge carriers hopping within a disordered distribution of sites such as humid cellulose [116]. This behaviour at low frequencies can be explained by an equation in the form of eq (7.6).…”

Section: Effect Of Moisture On Frequency Dependent Ac Conductivitymentioning

confidence: 99%

“…In the presence of an electric field, charges can accumulate at the dead ends of percolation paths (mostly crystalline surfaces) and acts as an ensemble of large dipoles [116]. Once the electric field is removed, these temporary dipoles are relaxing and contribute to depolarisation current.…”

Section: Selecting An Appropriate Modelling Techniquementioning

confidence: 99%

“…In the case of a charge percolation system, there are dead ends of percolation paths. In the presence of an electric field, charges can accumulate in these dead ends and act as a set of large dipoles [116]. The dead ends are not permanent and they have limited lifetimes.…”

Section: Effect Of Moisture On Frequency Domain Dielectric Responsementioning

confidence: 99%

“…FDS presents the response of the material to sinusoidal excitation of varying frequency. A notable fact is that dielectric response of a wide range of solid materials including oil impregnated cellulose [116,[120][121][122][123][124][125], poly-oxymethylene, and porous glass [126] are principally governed by the absorbed moisture. Therefore, dielectric response measurements in time and frequency domains have been significantly increased in use during the past two decades to estimate the moisture content in cellulose based insulation of transformers.…”

Section: Theory Of Dielectric Polarisationmentioning

confidence: 99%

“…Generally, three main polarisation mechanisms can be observed in insulation materials, namely deformation (electron or atomic), ionic and dipolar polarisation. Moreover, some of the insulation materials possess different types of polarisation mechanisms such as interfacial polarisation (space charge polarisation) and hopping charge carrier polarisation [109,[111][112][113][114][115][116].…”

Section: Dielectric Polarisation and Basic Principlesmentioning

confidence: 99%

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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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Section: Effect Of Moisture On Frequency Dependent Ac Conductivitymentioning

confidence: 99%

Section: Selecting An Appropriate Modelling Techniquementioning

confidence: 99%

Section: Effect Of Moisture On Frequency Domain Dielectric Responsementioning

confidence: 99%

Section: Theory Of Dielectric Polarisationmentioning

confidence: 99%

Section: Dielectric Polarisation and Basic Principlesmentioning

confidence: 99%

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Condition monitoring of biodegradable oil filled transformer

Mudiyanselage¹,

Bandara²

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Electronics with and on Paper

2012

Transparent Oxide Electronics

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Hybrid Proton and Electron Transport in Peptide Fibrils

Amit

Appel

Cohen

et al. 2014

Adv Funct Materials

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Protons and electrons are being exploited in different natural charge transfer processes. Both types of charge carriers could be, therefore, responsible for charge transport in biomimetic self‐assembled peptide nanostructures. The relative contribution of each type of charge carrier is studied in the present work for fibrils self‐assembled from amyloid‐β derived peptide molecules, in which two non‐natural thiophene‐based amino acids are included. It is shown that under low humidity conditions both electrons and protons contribute to the conduction, with current ratio of 1:2 respectively, while at higher relative humidity proton transport dominates the conductance. This hybrid conduction behavior leads to a bimodal exponential dependence of the conductance on the relative humidity. Furthermore, in both cases the conductance is shown to be affected by the peptide folding state under the entire relative humidity range. This unique hybrid conductivity behavior makes self‐assembled peptide nanostructures powerful building blocks for the construction of electric devices that could use either or both types of charge carriers for their function.

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The electrical properties of hygroscopic solids

Cited by 23 publications

References 62 publications

Condition monitoring of biodegradable oil filled transformer

Condition monitoring of biodegradable oil filled transformer

Electronics with and on Paper

Hybrid Proton and Electron Transport in Peptide Fibrils

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