Blar i SINTEF Open på forfatter "Lundgaard, Lars Esben"
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A novel bench size model coalescer: Dehydration efficiency of AC fields on water-in-crude-oil emulsions
Lesaint, Cedric Michel; Berg, Gunnar; Lundgaard, Lars Esben; Ese, Marit-Helen Glomm (Journal article; Peer reviewed, 2016)We describe herein the design of a small AC electrostatic model coalescer for investigating coalescence efficiency of water in oil emulsions. The function of the model coalescer is tested on emulsions with different water ... -
Absorption of water in silicon gel
Lesaint, Cedric Michel; Babault, Celine; Liland, Knut Brede; Lundgaard, Lars Esben (Chapter; Peer reviewed, 2014)Water is an important enemy of an electric insulation system. Water vapour can be absorbed by electrical insulation materials (liquids or solid) and migrate in between the materials to achieve the same relative humidity ... -
Comparison between synthetic ester and mineral oil impregnated transformer paper aging markers
Liland, Knut Brede; Linhjell, Dag; Lesaint, Cedric Michel; Ese, Marit-Helen Glomm; Lundgaard, Lars Esben; Mavrommatis, Pascal; Stjepanovic, Nenad Miroljub (Proceedings of IEEE International Conference on Dielectric Liquids;, Chapter; Peer reviewed, 2017)For transformers in service, aging markers from cellulose in oil such as furans, water, methanol and acids are measured for diagnostic purposes. The content of these indicators, measured in oil, may therefore vary with ... -
Conduction and Electric Fields in Dielectric Liquids in Needle-to-Plane Gaps
Hestad, Øystein Leif Gurandsrud; Aakre, Torstein Grav; Lundgaard, Lars Esben (Peer reviewed; Journal article, 2024)This paper describes measurements of conduction currents in both neat and commercial insulating liquids. Conduction in thermodynamic equilibrium has been measured by applying a low ac voltage in a uniform field. High-field ... -
Currents in AC stressed liquid insulated needle plane gap
Grav, Torstein; Lundgaard, Lars Esben (Chapter; Peer reviewed, 2014)Currents and space charge phenomena in 8 different dielectric liquids have been investigated for an ac stressed needle plane gap. Applied frequencies ranged from 0.1 Hz to 100 Hz. A high resolution analogue-digital converter ... -
Dielectric Performance of Transformer Liquids–Summary of a CIGRE Study
Lundgaard, Lars Esben; Liu, Qiang; Lesaint, Olivier; Madshaven, Inge (Peer reviewed; Journal article, 2023)This article reviews the functional requirements, dielectric performance, and test standards of insulating liquids from a transformer design perspective. -
Electrocoalescence III : staus and summary report from activities
Lundgaard, Lars Esben; Munkejord, Svend Tollak; Reboud, Jean-Luc; Lesaint, Cedric Michel; Ervik, Åsmund; Ese, Marit-Helen Glomm (SINTEF Energi. Rapport;, Research report, 2016) -
Experimental Study of Clamping Pressure during Step Loading of Power Transformer with and without Prior Energisation
Madshaven, Inge; Enoksen, Henrik; Lundgaard, Lars Esben; Jaufer, Stefan; Krause, Christoph; Prasnikar, Borut; Mjelve, Asgeir (Peer reviewed; Journal article, 2024)The electrification of society, increasing renewable energy sources and mobility charging lead to new loading patterns for power transformers. Dynamic load conditions induce enhanced mechanical stress on the transformers’ ... -
Experimental study of electrocoalescence of water drops in crude oil using near-infrared camera
Hellesø, Svein Magne; Atten, Pierre; Berg, Gunnar; Lundgaard, Lars Esben (Journal article; Peer reviewed, 2015)Results are presented concerning the influence of an applied electric field on the coalescence of a water droplet with a much bigger water drop, both drops being immersed in a crude oil. This original study of electrocoalescence ... -
Field dependent conductivity of n-pentane
Hestad, Øystein Leif Gurandsrud; Linhjell, Dag; Lundgaard, Lars Esben; Samseth, Jarl Ø.; Unge, Mikael (Proceedings of IEEE International Conference on Dielectric Liquids;2017, Chapter; Peer reviewed, 2017)A sensitive differential charge measurement technique was used to measure the conduction current from a sharp needle in a needle plane geometry in n-pentane. The current was measured at voltages up to the threshold for ... -
Field-dependent molecular ionization and excitation energies: Implications for electrically insulating liquids
Davari, Nazanin; Åstrand, Per-Olof; Unge, Mikael; Lundgaard, Lars Esben; Linhjell, Dag (Journal article; Peer reviewed, 2014) -
Influence of fast rise voltage and pressure on partial discharges in liquid embedded power electronics
Abdelmalik, Abdelghaffar Amoka; Nysveen, Arne; Lundgaard, Lars Esben (Peer reviewed; Journal article, 2015) -
The influence of pressboard parallel to the field on AC-breakdown in oil gaps
Lundgaard, Lars Esben; Danielsen, Harald (SINTEF Energi. Rapport;, Research report, 1983) -
Langsgradienter i impregnert elektrisk isolasjon (forsøksresultater)
Lundgaard, Lars Esben; Danielsen, Harald; Hansen, Walter; Nielsen, Hans Jørgen (SINTEF Energi. Rapport;, Research report, 1983) -
Liquid insulation of IGBT modules: Long term chemical compatibility and high voltage endurance testing
Liland, Knut Brede; Lesaint, Cedric Michel; Lundgaard, Lars Esben; Hernes, Magnar; Glomm, Wilhelm (Chapter; Peer reviewed, 2016)To facilitate operation of power electronics for subsea operation at ambient pressure components have to be submerged in a liquid. Equipment and schemes for testing of long term properties have been developed. Several ... -
Partial Discharge Inception in Ceramic Substrates Embedded in Silicone Liquid, Silicone Gel, and Mineral Oil at Fast Voltage Rise and Sinusoidal Voltage
Semenov, Ivan; Aakre, Torstein Grav; Folkestad, Ingrid Gunheim; Smisethjell, Ingrid; Niayesh, Kaveh; Lundgaard, Lars Esben (Peer reviewed; Journal article, 2024)This paper summarizes experiments that were carried out on insulating ceramic substrates and a needle-plane arrangement with the purpose to characterize the inception of partial discharges (PD) in the insulation of ... -
Partial Discharges in Narrow Gaps on Power Electronic Converter
Abdelmalik, Abdelghaffar Amoka; Nysveen, Arne; Lundgaard, Lars Esben (Chapter; Peer reviewed, 2014) -
Pre-breakdown phenomena in hydrocarbon liquids in a point-plane gap under step voltage. Part 2: behaviour under negative polarity and comparison with positive polarity
Lundgaard, Lars Esben; Linhjell, Dag; Hestad, Øystein Leif Gurandsrud; Unge, Michael; Hjortstam, Olof (Journal article; Peer reviewed, 2020)This study addresses the dielectric performance of nonpolar hydrocarbon liquids and mineral oils under negative polarity stress. Stopping length for non-breakdown streamers, breakdown voltages and velocities for various ... -
Prebreakdown phenomena in hydrocarbon liquids in a point-plane gap under step voltage. Part 1: behaviour at positive polarity
Linhjell, Dag; Lundgaard, Lars Esben; Unge, Michael; Hjortstam, Olof (Journal article; Peer reviewed, 2020)This study addresses the dielectric performance of nonpolar hydrocarbon liquids and mineral oils under positive polarity stress. It is of interest to improve knowledge on how functional properties of dielectric liquids ... -
Pressure Dependent Propagation of Positive Streamers in a long Point-Plane Gap in Transformer Oil
Linhjell, Dag; Lundgaard, Lars Esben; Unge, Mikael (Proceedings of IEEE International Conference on Dielectric Liquids;, Chapter; Peer reviewed, 2019)The propagation of positive streamers in a naphtenic transformer oil in an 80 mm point-plane gap has been investigated under an impulse voltage being close to a step voltage and under pressures ranging from 0.1 to 1.7 MPa. ...