Browsing Institutt for elkraftteknikk by Author "Ildstad, Erling"
Now showing items 1-20 of 67
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A Novel Methodology to Monitor Partial Discharges in Microvoids at Solid-Solid Interfaces
Kantar, Emre; Ildstad, Erling (Chapter; Peer reviewed, 2019)The combination of two solid dielectrics increases the risk of partial discharge (PD) activity in microscopic cavities at the solid-solid dielectric interfaces, facilitating interface tracking failures. The main purpose ... -
A stochastic model for contact surfaces at polymer interfaces subjected to an electrical field
Kantar, Emre; Hvidsten, Sverre; Mauseth, Frank; Ildstad, Erling (Journal article; Peer reviewed, 2018)Morphology of the contact area between solid insulation materials ultimately determines the short- and long-term electrical properties of the complete insulation system. The main purpose of this paper is to propose a ... -
AC Breakdown Voltage of 50-Year-Old Service Aged Hydro Power Generator Stator Bars
Aakre, Torstein Grav; Ildstad, Erling (Journal article; Peer reviewed, 2022)Randomly selected generator bars from a 50-year-old Norwegian hydro power generator were examined in this work. Typical non-destructive tests, as partial discharge and dissipation factor measurements were initially performed ... -
AC Electrical Breakdown Strength of Solid Solid Interfaces - A study about the effect of elasticity, pressure and interface conditions
Panagiotopoulos, Dimitrios (Master thesis, 2015)In several electrical insulation components, such as cable connectors, joints and penetrators, various solid insulating materials are usually brought in contact, forming interfaces. The dielectric strength of these ... -
Automation of Testing of Polymer HVDC Cables using Controlled Rapid Voltage Surges.
Karlsen, Thomas (Master thesis, 2007)This report aims to describe the work done in order to develop a solution for automation of failure detection and performance of rapid voltage surges. The automated system was developed with basis in the experimental circuit ... -
Breakdown strength of oil-impregnated paper insulation at DC with superimposed lightning impulse voltage
Birkeland, Andreas (Master thesis, 2021)Før HVDC-kabler med isolasjonssystemer bestående av oljeimpregnert papir installeres utføres fabrikasjonstester, hvorav en av de viktigste prøvene går ut på å påføre DC spenning med overlagret lynimpuls. Denne prøven består ... -
Breakdown strength of solid|solid interface
Hasheminezhad, Seyed Majid; Ildstad, Erling; Nysveen, Arne (Chapter, 2010) -
Breakdown Voltage of Polymeric HVDC Insulation at DC Stress and Superimposed Lightning Impulse Voltages
Ildstad, Erling; Mauseth, Frank; Olsen, Espen Torlei (Peer reviewed; Journal article, 2022)Space charge formation makes it difficult to predict the resulting electric field distribution within HVDC cable insulation. The main purpose of the work presented here has been to experimentally study how the lightning ... -
Challenging Defects of High Voltage Insulation Systems
Ildstad, Erling (Chapter, 2019)The primary function of a high voltage insulation system is to prevent the flow of electric current between oppositely charged conductors, facilitate heat transportation and provide mechanical support throughout a long ... -
Condition Assessment of Generator Bars by Time Domain Dielectric Response Measurements
Fjeldstad, Daniel Ekornrud (Master thesis, 2021)Majoriteten av norske vannkraftgeneratorer har vært i drift i 40 år eller mer. Noe som betyr at de nærmer seg sin forventede levetid. Nye driftsforhold introdusert de siste årene gjør at metoder tilstands vurdering blir ... -
Condition Assessment of Hydro Generator Insulation Using Partial Discharge Measurements
Skattenborg, Regina (Master thesis, 2018)More than half of all hydro generator failures are caused by insulation breakdown. Insulation failures inflict serious damage on the generator and represent significant operating costs for utility companies. One of the ... -
Condition Assessment of Hydro Generator Stator Bar Insulation Examination of PD void activity versus AC voltage magnitude and frequency
Arctander, Stine (Master thesis, 2020)Innføringen av væravhengige fornybare energikilde i det eksisterende nettet vil påvirke det nåværende driftsmønsteret fra strømproduksjon vi kjenner i dag. Når man kombinerer energikilder som sol- og vindkraft med ... -
Condition Assessment of Hydrogenerator Stator Bar Insulation Using Partial Discharge Measurements
Aakre, Torstein Grav; Ildstad, Erling; Hvidsten, Sverre (Chapter, 2018)This paper presents results from laboratory measurements of partial discharge (PD) activity in 50 cm long samples cut from the mainwall section of old hydrogenerator stator bars. All stator bars were manufactured in 1976 ... -
Condition Assessment of Oil Impregnated Paper Transformer Insulation using DC Conduction Measurements.
Bjørneby, Marianne (Master thesis, 2016)The objective of this thesis has been to study how DC conduction measurementscan be used as a diagnostic tool for condition assessment of oil impregnated paper.In this context, the DC conduction measurements were performed ... -
Condition Monitoring of Subsea Connectors - Partial Discharge Detection Using a High Frequency Sensor
Myklatun, Jon Thore (Master thesis, 2014)This thesis discusses possible causes of failure and potential condition indicators that may be used to monitor the condition of the insulation system of a subsea connector. The main focus is to describe how high frequency ... -
Cooling of Buried Power Cables by Using Metallic Pipes as an Alternative to Polymeric Pipes - Comparison of Results from Experiments and Simulations
Beck Sletten, Tord (Master thesis, 2016)It is common to install power cables in polymeric pipes at road crossings and in urban areas where exceptional protection and flexibility is necessary. In such case, the pipe is usually filled with air, which increases the ... -
DC Tangential Electric Breakdown Strength of Silicone Rubber Interfaces under dry, wet and oily conditions
Hammerøy, Ole Andre (Master thesis, 2016)This research work is a part of an on-going project at NTNU/SINTEF-Energy Research aim- ing at developing new criteria for design of compact high voltage subsea connectors. Most high voltage insulation systems consists of ... -
Design av undervanns høyspenningskomponenter
Hoem, Olav Egil (Master thesis, 2007)Med store deler av de lett tilgjengelige petroleumsressursene allerede utvunnet, er man nå i stadig større grad interessert i å utvinne olje og gassfelt som tidligere ble betraktet som økonomisk ulønsomme. En slik trend ... -
Dielectric response and electrical conductivity of mass impregnated HVDC cable insulation
Pettersen, Lars Erik (Master thesis, 2018)The main purpose of this thesis has been to gather data which facilitates design improvements of oil-impregnated paper insulation used in HVDC cables. Conductivities and loss tangents were gathered for this purpose. Several ... -
Dynamic Current Rating of Power Transformers
Kopperud, Trond Ivar (Master thesis, 2021)På grunn av forventet økning i kraftbehov og bruk av fornybare energikilder i fremtiden, er det et press for å undersøke metoder til å øke effektiviteten til eksisterende nettinfrastruktur. Smart grid konsepter slik som ...