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Investigation on thermal ageing impact on dielectric properties of natural ester oil
Published in Springer Verlag
2019
Volume: 101
   
Issue: 3
Pages: 1007 - 1018
Abstract
Ester oils are evolving as next-generation transformer insulants, and it is essential to understand their characteristic variation upon thermal ageing. Corona inception voltage reduces with thermally aged ester oil under AC and DC voltages. The UHF signal generated due to corona discharge activity has energy content in the range 0.4–4 GHz. The magnitude and energy content of the UHF signal formed due to corona activity increases with thermally aged oil. Ionic mobility studies are carried out to understand the impact of thermal ageing on polarization and depolarization current, ion concentration, and ionic radius formed in the oil. Thermal ageing of ester oil leads to an increase in the ionic mobility of oil samples along with an increment in the ionic concentration. The conductivity of oil is observed to increase with ageing, accompanied by a reduction in ionic radii. The effect of voltage stress shows enhanced conductivity for thermally aged oil samples. Dielectric response spectroscopy exhibits higher loss and permittivity values for thermally aged oils. The physicochemical analysis shows a gain in viscosity, moisture content and turbidity, and a marginal loss in thermal conductivity due to the formation of new molecular species. UV analysis exhibits a significant redshift in the oil sample aged at a higher temperature. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
About the journal
JournalData powered by TypesetElectrical Engineering
PublisherData powered by TypesetSpringer Verlag
ISSN09487921
Open AccessNo
Concepts (16)
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    Depolarization
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    Dielectric properties
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    ELECTRIC CORONA
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    Esters
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    Solid solutions
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    Thermal aging
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    Uhf devices
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    CORONA INCEPTION VOLTAGE
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    Dielectric response
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    Enhanced conductivity
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    Ionic concentrations
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    IONIC MOBILITY
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    NATURAL ESTERS
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    PHYSICO-CHEMICAL ANALYSIS
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    POLARIZATION AND DEPOLARIZATION CURRENTS
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    Thermal conductivity