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An investigation into solid dielectrics

An investigation into solid dielectrics
An investigation into solid dielectrics
Direct measurement techniques for the investigation of electrical processes in solid dielectrics are reviewed and their respective strengths and weaknesses are discussed, particularly the complementary nature of thermally stimulated current measurements. The successful design and construction of a new Thermally Stimulated Discharge Current (TSDC) Spectrometer at the University of Southampton is presented and its correct function validated with experimental measurements of the well known and often characterized synthetic polymers low density polyethylene (LDPE) and polyethylene terephtalate (PET). Results were found to correspond well to published data. First TSDC observations of filled and oil impregnated papers are presented.

The second aspect of this work is the investigation of natural polymer insulation materials,specifically paper for oil-paper insulation systems. For the first time, electrical insulation papers with filler contents up to 50% were investigated. Bentonite and talcum were compared as filler materials and found to have negative and positive effects respectively.

The superior electrical strength of a talcum filled kraft paper was verified, and a series of constructive modifications was undertaken to further maximise its electrical strength at comparable or improved dielectric performance. An increase in electrical breakdown strength of 20% to 30% has been observed, but the substitution of such great amounts of fiber with fillers also lead to a reduction in mechanical strength of the paper. Further trials with chemical additives were conducted to counteract this effect and polyvinyl alcohol and starch were found to enhance the paper strength. Additional trials also comprised sizing agents, guar gum and wet strength agents. Uncharged or slightly charged chemical additives provided best results with regard to dielectric performance. The significance of the trialled paper modifications is judged in light of statistical analysis.
Kleemann, Tobias
7743b53d-b874-42cf-b3c5-2ae2f8c9d87e
Kleemann, Tobias
7743b53d-b874-42cf-b3c5-2ae2f8c9d87e
Lewin, Paul
78b4fc49-1cb3-4db9-ba90-3ae70c0f639e
Swaffield, D.J.
d5828393-2cfb-4f1b-ace4-cd44e0ee5542

(2012) An investigation into solid dielectrics. University of Southampton, Faculty of Physical and Applied Sciences, Doctoral Thesis, 231pp.

Record type: Thesis (Doctoral)

Abstract

Direct measurement techniques for the investigation of electrical processes in solid dielectrics are reviewed and their respective strengths and weaknesses are discussed, particularly the complementary nature of thermally stimulated current measurements. The successful design and construction of a new Thermally Stimulated Discharge Current (TSDC) Spectrometer at the University of Southampton is presented and its correct function validated with experimental measurements of the well known and often characterized synthetic polymers low density polyethylene (LDPE) and polyethylene terephtalate (PET). Results were found to correspond well to published data. First TSDC observations of filled and oil impregnated papers are presented.

The second aspect of this work is the investigation of natural polymer insulation materials,specifically paper for oil-paper insulation systems. For the first time, electrical insulation papers with filler contents up to 50% were investigated. Bentonite and talcum were compared as filler materials and found to have negative and positive effects respectively.

The superior electrical strength of a talcum filled kraft paper was verified, and a series of constructive modifications was undertaken to further maximise its electrical strength at comparable or improved dielectric performance. An increase in electrical breakdown strength of 20% to 30% has been observed, but the substitution of such great amounts of fiber with fillers also lead to a reduction in mechanical strength of the paper. Further trials with chemical additives were conducted to counteract this effect and polyvinyl alcohol and starch were found to enhance the paper strength. Additional trials also comprised sizing agents, guar gum and wet strength agents. Uncharged or slightly charged chemical additives provided best results with regard to dielectric performance. The significance of the trialled paper modifications is judged in light of statistical analysis.

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Published date: July 2012
Organisations: University of Southampton, Electronics & Computer Science

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Local EPrints ID: 346911
URI: http://eprints.soton.ac.uk/id/eprint/346911
PURE UUID: fc4d86c5-26d9-4934-9c9a-609890eef8c5

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Date deposited: 27 Feb 2013 12:09
Last modified: 18 Jul 2017 05:00

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