Change search
Refine search result
1 - 12 of 12
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Ariza, David
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    On the inception and propagation of streamers along mineral-oil/solid interfaces2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents an experimental study of positive and negativestreamers propagating along mineral-oil/solid interfaces under square highvoltage pulses. The thesis includes the design and construction of anexperimental setup to studying the streamers in a point-plane configurationcapable to detect streamer parameters such as velocity, length, propagationtime, emitted light and charge.The first part of this experimental study is devoted to the analysis of thestreamer inception at mineral-oil/solid interfaces under negative polarity. Thestreamer inception voltage and charge recordings are reported for eachmineral-oil/solid interface. It is found that only solids with a permittivitysimilar to that of mineral oil can influence the streamer inception voltage.Solids with matched permittivity such as LDPE and PTFE increase the inceptionvoltage. The cases with solids with higher permittivity than mineral oil havesimilar inception voltage as the streamer incepted in the liquid bulk withoutsolid. The second part is devoted to studying the propagation of first mode negativestreamers along different mineral-oil/solid interfaces. A comparison of theelectrical and physical properties of the streamers (e.g. charge, length,velocity, etc.) is presented. Solid samples with different chemical compositionand different physical properties are used. The solid samples are anoil-impregnated kraft paper and an low-porosity paper referred to as kraftfibril paper made from cellulosic micro and nano fibrils. Polymeric films madeof low density polyethylene (LDPE), polyethylene terephthalate (PET),polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) are also usedas the solid. Streamers propagating along the liquid/solid interface arecompared with streamers developing in mineral oil without solid. Streamerspropagate longer and faster along solids with low surface roughness, lowporosity and higher electrical permittivity than mineral oil showing aquasi-continuous injection of charge in the early stage of propagation.The third part of the experimental study deals with second mode positivestreamers propagating along mineral-oil/solid interfaces. The inception andpropagation of the streamer are investigated using different mineral-oil/solidinterfaces. Measurements of the streamer velocity, charge, stopping length,propagation time, together with light recordings and shadowgraphs are reported.It is found that the interface can influence the streamer inception voltage,branching, stopping length, velocity, charge and current. Properties of thesolid and of the interface (i.e. surface roughness, permittivity, wettability)are parameters that influence the streamer propagation.

  • 2.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Beccera, Marley
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Methling, Ralf
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gortschakow, Sergey
    Inception of first mode negative streamers at mineral oil-solid interfacesManuscript (preprint) (Other academic)
  • 3.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Becerra, Marley
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Hollertz, R.
    Pitois, Claire
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Measurements of the charge of streamers propagating along transformer oil-solid interfaces2014In: Proceedings of the 2014 IEEE 18th International Conference on Dielectric Liquids, ICDL 2014, IEEE , 2014, p. 6893165-Conference paper (Refereed)
    Abstract [en]

    This paper presents an experimental study of the positive streamer charge in transformer oil and oil-solid interfaces in a point-plane gap (5mm) under impulse voltage 50ns\1800μs (maximum peak voltage 24 kV). The experiment is intended to compare the charge of streamers propagating in transformer oil with and without a solid barrier along their path. The solid barrier constricting the streamer volume consists of two parallel strips of either impregnated pressboard or a polymeric film (PA6) installed at both sides of the point electrode. The maximum cumulative charge of the streamer is found for the case when the impregnated pressboard is used and the minimum cumulative charge for the case of the polymer as a barrier.

  • 4.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Becerra, Marley
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. ABB Corp Res, Stockholm, Sweden.
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pitois, Claire
    On the initiation of negative streamers at mineral oil-solid interfaces2015In: IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP), IEEE conference proceedings, 2015, p. 563-565Conference paper (Refereed)
    Abstract [en]

    This paper reports the probability distribution of negative streamers initiated in mineral oil with and without a solid interface. In addition, the charge injected by conduction currents prior to the streamer inception is presented. Impregnated paper and polymeric films made of PET, PTFE and PVDF are tested as solid materials. Comparison of the conduction charge for the different oil-solid interfaces is presented. It is found that the permittivity of the material used at the solid interface does not influence significantly the condition for streamer initiation in mineral oil. A nonlinear increasing of the charge readings for the impregnated paper, PET and PVDF cases are observed.

  • 5.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Becerra, Marley
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. ABB Corporate Research, Sweden.
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pitois, Claire
    ABB Corporate research .
    Propagation of negative streamers along mineral oil-solid interfaces2015In: Proceedings of the 2015 CEIDP Conference on Electrical insulation and Dielectric phenomena, CEIDP 2015, IEEE conference proceedings, 2015, p. 566-569Conference paper (Refereed)
    Abstract [en]

    This paper introduces an experimental study on the propagation of negative streamers along mineral oil-solid interfaces. A standard type of impregnated paper and different polymeric films (made of PET, PTFE and PVDF) are selected as solid materials immersed in mineral oil. The effect of the solid material on the streamer propagation along the interface formed with transformer oil is studied. Streamer velocities classified as first mode propagation point cathode are reported. Voltage gradient of the streamer channel and its stopping voltage are calculated for all the cases. Comparison of streamer charge and stopping length propagation are reported.  

  • 6.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Becerra, Marley
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Inception of first mode negative streamers at liquid/solid interfacesIn: Journal of Physics D: Applied PhysicsArticle in journal (Refereed)
    Abstract [en]

    This paper presents an experimental study on the inception of first mode negative streamers at different mineral-oil/solid interfaces. This study is performed with a point-plane configuration immersed in mineral oil (point cathode). The mineral-oil/solid interface is done by assembling a solid in an inclined position into the point-plane gap. The solid is in contact (or in the proximity) with the point electrode tip. The tested solids are a kraft paper, a paper made from cellulosic micro and nano fibrils and different polymeric films (low density polyethylene (LDPE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF)). These solids have different relative permittivity and structural composition. It is found that the streamer inception voltage is statistically similar for the cases with solids with higher permittivity than mineral oil. The streamer inception voltage for the case without any solid barrier is also statistically similar to the cases with solids with higher permittivity than mineral oil. It is also found that the inception voltage is higher for streamers initiated at permittivity-matched interfaces (cases with LDPE and PTFE). Additionally, the influence of the spatial limitation with the solid surface to the volume where the streamer initiation process takes is performed with PTFE by varying the distance between the point electrode and the solid surface. It is shown that the streamer inception voltage depends on the distance between the point electrode and the solid surface. Furthermore, It is observed that the streamer inception voltage is also influenced when the distance between the point electrode and the surface of the PTFE is several micrometers (twenty times longer than the penetration depth of the avalanche responsible of streamer initiation). Additionally, it is also shown that a recently-proposed streamer inception criterion is unsuitable to predict the streamer inception conditions close to permittivity matched and mismatched liquid/solid interfaces.

  • 7.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Becerra, Marley
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Second Mode Positive Streamers Propagating Along Mineral-oil/solid InterfacesManuscript (preprint) (Other academic)
    Abstract [en]

    This paper presents an experimental study on second mode positive streamers propagating along mineral-oil/solid interfaces. The inception and propagation of these streamers is investigated with different impregnated solids (low density polyethylene (LDPE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE) polyvinylidene fluoride (PVDF), two papers referred to as kraft paper and a kraft fibril paper, made from cellulosic micro and nano fibrils, a lignin-free paper and a paper with high lignin content referred to as k107 kraft paper). Streamers are initiated in a point-plane configuration under step voltages with 35 ns rise time. The radius of the tip is 2.9 μm and the solid is installed in an inclined position in close contact to the point electrode. Shadowgraphs, charge and light recording of the streamers are reported for each case. Furthermore, estimations of the streamer stopping length, velocity, current and average charge are reported. It is found that the streamer inception is influenced by the solid interface indicating that the inception process is not only conditioned by the field at the tip but also by the interface. A time delay is observed before the initiation of the streamer and probably correlated with the initiation process and formation of the gaseous phase. Additionally, the threshold propagation voltage of the second mode streamers at mineral-oil/solid interfaces is shown to be independent of the interface. It is also shown that the different characteristics of streamers propagating along the tested interfaces cannot be fully explained by the capacitive coupling effect due to permittivity mismatch. Thus, it is suggested that the characteristics of streamers propagating near interfaces is affected by other properties of the solid such as chemical composition, wettability and surface roughness.

  • 8.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Becerra, Marley
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pitois, Claire
    ABB AB Corporate Research.
    First Mode Negative Streamers along Mineral Oil-solid Interfaces2017In: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 24, no 4Article in journal (Refereed)
    Abstract [en]

    This document presents an experimental study on the propagation of first mode negative streamers along mineral oil-solid interfaces. Samples made of an oil impregnated kraft paper and a low-porosity paper made from cellulosic micro and nano fibrils, as well as different polymeric films (low density polyethylene (LDPE), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF)) are used as the solid. A comparison of the length, charge and velocity of streamers for all different mineral oil-solid interfaces is reported. It is shown that streamers propagate longer and faster along mineral oil-solid interfaces with low surface roughness, low porosity and higher electrical permittivity than mineral oil. Those streamers show a quasi-continuous injection of charge in the early stage of their propagation. This quasi-continuous charge injection consists of a sequence of small charge steps separated by few tens of nanoseconds in between. In comparison, the streamers that propagate along surfaces with similar permittivity to the mineral oil have lower injection of charge and higher stopping voltage conditions than streamers propagating free in the liquid without any solid barrier.

  • 9.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Becerra, Marley
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Methling, Ralf
    INP - Leibniz Institute for Plasma Science and Technology.
    Gortchakow, Sergey
    INP Leibniz Institute for Plasma Science and Technology.
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Influence of Paper Properties on Streamers Creepingin Mineral Oil2017In: Proceedings of IEEE International Conference on Dielectric Liquids, ISSN 2153-3725, E-ISSN 2153-3733Article in journal (Refereed)
    Abstract [en]

    This work presents an experimental study ofsecond mode positive streamers propagating along mineral oilpaperinterfaces. A point-plane arrangement immersed inmineral oil with the paper inclined 60 degrees to the planeelectrode is used to create the liquid-solid interface. Kraft paperand a kraft fibril paper, made from cellulosic micro and nanofibrils, with higher density and lower surface roughness are usedas the solid materials. High speed shadowgraphy and chargerecordings are used to compare the propagation of second modepositive streamers along the mineral oil-kraft paper and mineraloil-kraft fibril paper. Streamers creeping along the mineral oilkraftpaper interface propagate mainly into the liquid, with oneor two main filaments. In comparison, the streamers propagatingalong the kraft fibril paper show a strong reduction of thebranching; these streamers consist of a single filament thatpropagates exactly on the solid surface. Streamers along the kraftfibril paper also have longer propagation time than for the casewith kraft paper. Mutual electrostatic shielding betweenfilaments is observed for the streamers creeping on the kraftpaper. An electrostatic analysis of the influence of permittivity,density and surface roughness of the solid in the electricalproperties of the streamer filaments is also performed.

  • 10.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Beccera, Marley
    Pitois, Claire
    KTH.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    First mode negative streamers at mineral oil-solid interfacesManuscript (preprint) (Other academic)
  • 11.
    Ariza, David
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Methling, Ralf
    Gortschakow, Sergey
    Influence of paper properties on streamers creeping in mineral oilManuscript (preprint) (Other academic)
  • 12.
    Hollertz, Rebecca
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Pitois, Claire
    Ariza, David
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Dielectric Response of Kraft Paper from Fibres Modified by Silica Nanoparticles2015In: 2015 IEEE CONFERENCE ON ELECTRICAL INSULATION AND DIELECTRIC PHENOMENA (CEIDP), IEEE conference proceedings, 2015, p. 459-462Conference paper (Refereed)
    Abstract [en]

    Papers have been prepared from fibres that were modified by physical adsorption of silica nanoparticles. Cationic and anionic nanoparticles were adsorbed either directly onto wood fibres or using the layer-by-Iayer (LbL) technique where silica nanoparticles and a polyelectrolyte of opposite charge were adsorbed in consecutive layers. It was shown that it is possible to tailor the dielectric and mechanical properties of kraft paper by utilizing the pH-dependence of the charge density of both the nanoparticles and the polyelectrolyte during the build-up of layers onto wood fibres. With only one layer of cationic silica nanoparticles, 6.0 wt% of nanoparticles were adsorbed at pH 6, leading to almost complete coverage of the wood fibre surface, resulting in a paper with low dielectric losses and improved in-plane tensile properties.

1 - 12 of 12
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf