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Applied voltage frequency dependence of partial discharges in electrical trees
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. (ETK)
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
2009 (English)In: Proceedings of the 21st Nordic Insulation Symposium, Göteborg, Sweden, 2009, 2009Conference paper, Published paper (Refereed)
Abstract [en]

 

In this paper the growth of electrical trees in a needleplane electrode arrangement is investigated. Electrical trees are grown in epoxy samples by applying a sinusoidal voltage of 16 kV peak and 17 kV peak. Electrical tree growth is followed under a stereo microscope in real time. As soon as an electrical tree reaches a specific length or shape the aging sequence ends and the partial discharge activity from the trees is investigated at a fixed voltage with frequencies varying between 0.1 to 100 Hz. The frequency dependence of the partial discharge is investigated and related to the different stage and forms of the electrical tree.

Place, publisher, year, edition, pages
2009.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-31433OAI: oai:DiVA.org:kth-31433DiVA: diva2:403912
Note
QC 20110315 Available from: 2011-03-15 Created: 2011-03-15 Last updated: 2011-03-15Bibliographically approved
In thesis
1. Dielectric properties of poly(ethyelene-co-butyl acrylate) filled with Alumina nanoparticles
Open this publication in new window or tab >>Dielectric properties of poly(ethyelene-co-butyl acrylate) filled with Alumina nanoparticles
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In this work dielectric properties of the poly(ethylene-co-butyl acrylate)filled with alumina nanoparticles are evaluated. These nanocomposite materialswere manufactured at the department of Fibre and Polymer Technology,KTH.This study is limited to the properties of general importance for the AC applications.The dielectric permittivity of the nanocomposite materials wasstudied as a function of filler size, filler content, coating, temperature and airhumidity used for conditioning of the samples. The ultimate goal with thisproject is to describe the influence of material composition, temperature andair humidity on the dielectric properties and model these dependencies.In this thesis the experimental setup for voltage endurance testing of thenanocomposites, namely studying applied voltage frequency dependence ofpartial discharges in electrical trees, with a possibility of following electricaltreeing optically, was developed and described.The dielectric spectroscopy measurements were performed on thoroughly driednanocomposites - so-called dry DS study. It was shown that the experimentaldata can be fitted with Havriliak-Negami approximation, which justifiesthe correctness of the measurement results. It has been shown that addingnanoparticles to the EBA matrix changes the low frequency dispersion significantlyfor the dried samples. It was also indicated that the particle coatingused has very low impact on the resulting permittivity of the thoroughly driedsamples. From the dry DS studies it was suggested that the main cause ofthe scattering in data between the dry samples is most likely the influenceof the material inhomogeneity and possibly the moisture absorption. Thisleads to a possibility of using dielectric spectroscopy as a tool for probing thedispersion of nanoparticles in the polymer matrix.The dielectric spectroscopy measurements were also carried out on the nanocompositesconditioned in the environments with different humidity levels of air inorder to study the influence of absorbed water on the dielectric permittivity- so-called wet DS study. From the wet study it was shown that for the wetsamples the amplitude of the loss peak is defined by the filler size, filler contentand coating used; while its position in frequency domain is determinedby the coating and the humidity level used for conditioning.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011
Series
Trita-EE, ISSN 1653-5146 ; 2011:017
Keyword
nanocomposites, poly(ethylene-co-butyl acrylate), EBA, alumina, dielectric permittivity, absorbed water, humidity, temperature, dielectric spectroscopy, partial discharge, electrical treeing
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-31407 (URN)978-91-7415-900-4 (ISBN)
Presentation
2011-03-25, Seminarierummet, KTH, Teknikringen 33, Stockholm, 10:15 (English)
Opponent
Supervisors
Note
QC 20110315Available from: 2011-03-15 Created: 2011-03-14 Last updated: 2011-03-15Bibliographically approved

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