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Dissertations / Theses on the topic 'Dielectrics. Electric insulators and insulation'
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1
Grove, Nicole R. "Characterization of functionalized polynorbornenes as interlevel dielectrics." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/11204.
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Rux, Lorelynn Mary. "The physical phenomena associated with stator winding insulation condition as detected by the ramped direct high-voltage method." Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-04042004-112949.
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Blanco, Agnes M. Padovani. "Low dielectric constant porous spin-on glass for microelectronic applications." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/11840.
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Liu, Xin. "Partial discharge detection and analysis in low pressure environments." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1155573657.
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Shrestha, Prakash. "Study of the dielectric degradation of XLPE and EPR power cables by switching impulses." Master's thesis, Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-08212008-151448.
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Aboutorabi, Seyed Sadreddin. "Étude des conditions critiques de la propagation de l'arc sur les isolateurs recouverts de glace = Study of critical conditions of arc propagation on ice-covered insulators /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2003. http://theses.uqac.ca.
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Lee, Ethan S. "Dielectric reliability in GaN metal-insulator-semiconductor high electron mobility transistors." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120368.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 73-74).
GaN Metal Insulator Semiconductor High Electron Mobility Transistors (GaN MIS-HEMTs) show excellent promise as high voltage power transistors that can operate efficiently at high temperatures and frequencies. However, current GaN technology faces several obstacles, one of which is Time-Dependent Dielectric Breakdown (TDDB) of the gate dielectric. Under prolonged electrical stress, the gate dielectric suffers a catastrophic breakdown that renders the transistor useless. Understanding the physics behind gate dielectric breakdown and accurately estimating the average time to failure of the dielectric are of critical importance. TDDB is conventionally studied under DC conditions. However, as actual device operation in power circuits involves rapid switching between on and off states, it is important to determine if estimations done from DC stress results are accurate. Due to the rich dynamics of the GaN MIS-HEMT system such as electron trapping and carrier accumulation at the dielectric/AlGaN interface, unaccounted physics might be introduced under AC stress that may cause error in DC estimation. To this end, we characterize TDDB behavior of GaN MIS-HEMTs at both DC stress conditions and more accurate AC stress conditions. We find that TDDB behavior is improved for AC stress compared to DC stress conditions at high stress frequencies. At 100 kHz, the average dielectric breakdown time is twice the average dielectric breakdown time under DC stress conditions. Furthermore, the impact of tensile mechanical stress on TDDB under DC stress is investigated. This is an important concern because of the piezoelectric nature of GaN and the substantial lattice mismatch between Si, GaN and AlGaN that results in high mechanical strain in the active portion of the device. If mechanical stress significantly impacts TDDB, designers will have to work with further constraints to ensure minimal stress across the dielectric. To address this, we have carried out measurements of TDDB under [epsilon] = 0.29% tensile strain. We find that TDDB in both the On-state and Off-state stress conditions are unaffected by this mechanical stress. Through measurements done in this thesis, we gather further insight towards understanding the physics behind TDDB. Through AC stress we find that the dynamics of the GaN MIS-HEMTs prolong dielectric breakdown times. Through mechanical stress we find that modulation of the 2-Dimensional Electron Gas and dielectric bond straining have minimal impact on TDDB.
by Ethan S. Lee.
S.M.
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Ribeiro, Júnior Sebastião. "Desenvolvimento de metodologia para análise de arborescências em materiais dielétricos por contraste de fase de raios X." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/690.
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A ocorrência de arborescências em água (water tree) ou elétrica (electrical tree) é apontada como o principal fenômeno de degradação em isolações sólidas de cabos de distribuição de energia elétrica. A evolução destas arborescências pode levar a camada de isolação à ruptura dielétrica e, como conseqüência, à falha destes equipamentos, com a interrupção do fornecimento de energia elétrica. O entendimento deste fenômeno é necessário para desenvolver métodos de análise e prevenção da ruptura de materiais isolantes. Este trabalho mostra a aplicação da técnica contraste de fase por raios X como metodologia para o estudo das arborescências formadas em materiais isolantes de borracha de propileno etileno (EPR) e polietileno reticulado (XLPE).The water tree or electrical tree occurrence is identified as the main phenomena in the degradation in solid isolations of the electric energy distribution cables. The water tree evolution can lead to dielectric breakdown of the isolation layer and, consequently, to the failure this equipment and the interruption of the electric energy supply. The understanding this phenomenon is necessary for the development analysis methods and to prevent collapse in the polymeric insulation. This work demonstrates the application of X-ray phase contrast technique as a methodology for the study of the water tree and electrical tree in Ethylene propylene rubber (EPR) and crosslinked polyethylene (XLPE).
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Warnock, Shireen M. "Dielectric reliability in high-voltage GaN metal-insulator-semiconductor high electron mobility transistors." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112032.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references.
As the demand for more energy-efficient electronics increases, GaN has emerged as a promising transistor material candidate for high-voltage power management applications. The AlGaN/GaN Metal-Insulator-Semiconductor High Electron Mobility Transistor (MIS-HEMT) constitutes the most suitable device structure for this application as it offers lower gate leakage than its HEMT counterpart. GaN has excellent material properties, but there are still many challenges to overcome before its widespread commercial deployment. Time-dependent dielectric breakdown (TDDB), a catastrophic condition arising after prolonged high-voltage gate stress, is a particularly important concern. This thesis investigates this crucial reliability issue in depth. Using a robust characterization strategy, we have studied not only the dielectric breakdown behavior in GaN MIS-HEMTs but also the evolution of the device subthreshold characteristics in the face of high bias stress. This allows us to work towards understanding on a more physical level the underlying degradation behind dielectric breakdown in order to inform future device lifetime models. We begin by looking at positive gate stress TDDB, a classic condition studied in the silicon CMOS community for many years. In order to understand the impact of TDDB, we must also understand how transient degradation effects such as threshold voltage (VT) shift may impact our results and ensure we can disentangle the permanent degradation associated with TDDB. With the foundational understanding of TDDB we establish under these positive gate stress conditions, we turn our attention to OFF-state stress which is a more relevant stress condition that mimics the most common state of these GaN power switching transistors in power management circuits. In order to develop accurate lifetime models for GaN MIS-HEMTs, we show that much care must be taken to ensure that device lifetime does not become distorted by transient trapping-related degradation effects. It is also crucial to have a physics-based lifetime model that gives confidence in making lifetime projections from data collected in the span of hours to lifetime estimations on the order of many years.
by Shireen Warnock.
Ph. D.
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Tsuchiya, Kenji, Hitoshi Okubo, Tsugunari Ishida, Hidenori Kato, and Katsumi Kato. "Influence of Surface Charges on Impulse Flashover Characteristics of Alumina Dielectrics in Vacuum." IEEE, 2009. http://hdl.handle.net/2237/14600.
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Lednev, Alexander I. (Alexander Igorevich). "Time dependent dielectric breakdown in novel GaN metal-insulator-semiconductor high electron mobility transistors." Thesis, Massachusetts Institute of Technology, 2018. https://hdl.handle.net/1721.1/121628.
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This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 83-84).
Power electronics is expanding as we automate and electrify our households and step into mainstream electric vehicles. Recently, GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) have been increasing in popularity for high voltage power electronics applications because they combine high electron mobility with low gate leakage, increasing efficiency. This comes with the tradeoff of increased reliability concerns to be addressed before the widespread commercialization of GaN MIS-HEMTs. This thesis investigates one failure mechanism found in prototype industrial GaN MIS-HEMTs: time dependent dielectric breakdown (TDDB) of the gate insulator. TDDB occurs when a high electric field causes an accumulation of defects in the gate dielectric, forming a conducting path and rendering the device unusable. This is of major concern in GaN MIS-HEMTs because of their role as switches in high voltage circuits. In this work, we develop testing methodologies to address reticle-to-reticle variations and we estimate the lifetime of novel GaN MIS-HEMTs by performing measurements at different stress levels and temperatures in the ON and OFF-states.
by Alexander I. Lednev.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Tang, Wing-man. "MISiC Schottky-diode hydrogen sensors with different gate insulators." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40987772.
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Bansal, Anurag. "Finite element simulation of mechanical characterization of composite insulators /." Full text open access at:, 1996. http://content.ohsu.edu/u?/etd,221.
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Pietersen, Donovan. "The development of a methodology to compile an insulator pollution severity application map for South Africa." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50475.
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Thesis (MScEng)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: The main objective of this research project was to develop a methodology which can be used to assist in developing an insulator pollution severity application map (INSMAP), more particularly for South Africa. The techniques must be able to assist in determining pollution severity levels. At the inception of this project a phase one insulator pollution severity application map was available; this map was based on an existing corrosion map, climatic maps and dust gauge measurements. The phase one map was conservative and did not highlight localised pollution. To confirm and possibly improve on this map, a phase two map was developed, which was based on feedback from Eskom field personnel via an electronic insulator pollution questionnaire survey (based on IEC 60815 guidelines).Jhe questionnaire was incorrectly completed in most cases due to a lack of understanding by field personnel of environmental pollution and the impact on insulator performance. This resulted in an unrealistic map with exaggerated contamination levels. To confirm the findings of the phase one map, a phase three approach was followed, which was focused on an investigation into pollution measurement techniques and methodologies. Based on the phase one map, a need was identified to confirm by measurements the impact of distance-to-coast. Also, the validity of installing a dust gauge at 3 metres above ground level, while insulators are at a height of 8 to 40 meters, had to be investigated. Two pollution monitoring programmes were established: a distance-to-coast and height-above-ground environmental pollution study. Various test methods are described with a complete testing procedure, descriptive equations and related pollution severity classifications for insulator pollution (DDG and ESDD) and corrosion (CLIMAT and metal specimens). The distance-to-coast test results confirm the phase one map, while the height-aboveground measurements justify the installation of dust gauges at 3 metres above ground level. Good correlations were found for the distance-to-coast study between insulator pollution severity and corrosion rates. From the height-above-ground study, a slight (insignificant) decrease in pollution levels was found for increase in height for insulator pollution and corrosion tests. Recommendations are made on setting up a basic pollution monitoring station. Key words: Insulator pollution, Corrosion, Distance, Height.
AFRIKAANSE OPSOMMING: Die hoofoogmerk van hierdie navorsingprojek was die ontwikkeling van 'n metodiek om 'n isolator besoedelingskaart saam te stel, meer spesifiek vir Suid Afrika. Die tegnieke moet die besoedelingsvlakke en impak-afstand van elke besoedelingvlak aandui. 'n Fase een isolator besoedelingskaart het reeds bestaan by die aanvang van hierdie projek, hierdie kaart was gebaseer op 'n bestaande korrosiekaart. Die fase een kaart was baie konserwatief en het nie lokale besoedeling aangedui nie. Dit was besluit om die fase een kaart te verbeter en 'n fase twee kaart was ontwikkel wat gebaseer was op 'n elektroniese isolator-besoedeling vraelys wat deur Eskom se tegniese veldpersoneel voltooi is. Die vraelys is in baie gevalle verkeerdelik ingevul, as gevolg van 'n gebrek aan die kennis oor besoedeling en die impak daarvan op isolatorprestasie. Dit het tot 'n onrealistise kaart gelei met onakurate besoedelingsvlakke. 'n Fase drie ontwikkeling is begin, waar 'n ondersoek gekyk het na metingstegnieke en metodiek vir besoedelingsmetings. 'n Volledige toetsprosedure, beskrywende vergelykings en besoedelingklassifikasies is ontwikkel vir die isolator-besoedeling (DDG en ESDD) en korrosietoetse (CLIMAT en metaal monsters). Toetsstasie seleksiekriterea vir die geografiese plasing van 'n toetsstasie is vasgestel. Twee toetsprogamme is vasgestel: 'n afstand-van-see en 'n hoogte-bo-grondvlak besoedelingsstudie. Die afstand-van-see studie het 'n impak-afstand vir elke besoedelingsvlak vir beide isolatorbesoedeling en korrosietoetse vasgestel. 'n Goeie korrelasie is vasgestel tussen isolator-besoedeling en korrosievlakke. Vir die hoogte-bo-grondvlak studie was gevind dat daar 'n klein (weglaatbare) vermindering in besoedelingsvlakke met toename in hoogte bo grondvlak vir isolatorbesoedeling- en korrosievlakke onstaan. 'n Goeie korrelasie bestaan tussen isolatorbesoedeling- en korrosievlakke. Aanbevelings word gemaak vir die opstel van 'n basiese besoedelingsmetingstasie. Sleutelwoorde: Isolator besoedeling, Korrosie, Afstand, Hoogte.
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Bandaru, Sreekanth. "Effect of high frequency pulse voltages and high temperature on the lifetime characteristics of magnet wires." Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-05132004-135217.
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Angadi, Santosh Vishwanath Jackson Robert Lloyd. "Hydraulic solenoid valve reliability and modeling study." Auburn, Ala, 2008. http://hdl.handle.net/10415/1491.
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Chen, Gang, and 陈刚. "MIS Schottky-diode hydrogen sensors with different gate insulators or substrates." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49799575.
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Hydrogen, one of the cleanest energies, is very attractive in the near future. However, it could be hazardous to store, transport and use hydrogen gas because leakage can cause explosion if sparks appear. Therefore, it is essential to develop sensors to detect the hydrogen leakage in order to prevent potential accidents. In this research, Metal-Insulator-Semiconductor (MIS) Schottky-diode hydrogen sensors with different gate insulators (Ta2O5, La2O3, LaTiON, and HfTiO) or substrates (Si, SiC, and InGaN/GaN MQW) were prepared in order to study their hydrogen sensing performances.
Firstly, two sensors based on Si and SiC with Ta2O5 as gate insulator were prepared and compared. Owing to high permittivity (~25), good thermal stability and low electrical defects, Ta2O5 was chosen as the insulator. The differences in sensitivity and response time between the two sensors were ascribed to the difference in the surface morphology of Ta2O5 between the SiC sensor (mean surface roughness was 0.39 nm) and its Si counterpart (mean surface roughness was 0.22 nm).
Secondly, due to the high permittivity (~25) and good thermal stability of La2O3, the high permittivity (~20), low interface-state density, and low leakage current of LaTiON, Si sensors with these two dielectrics as gate insulator were developed. The sensitivity of the La2O3 sensor could exceed 7.0 at 150 oC, and the sensor exhibited good hydrogen sensing performance at up to 250 oC. On the other hand, the maximum sensitivity of the LaTiON sensor could reach 2.5 at 100 oC. For the LaTiON sensor, the Poole-Frenkel model controlled the carrier transport at high temperatures (150 ~ 200 oC) while the thermionic emission was the dominant conduction mechanism at lower temperatures (from room temperature to 150 oC). For the La2O3 sensor, the hydrogen reaction kinetics was confirmed, and an activation energy of 10.9 kcal/mol was obtained for this sensor.
Thirdly, the La2O3 gate insulator used in the previous work was applied to make MIS sensor on SiC substrate for higher-temperature applications. Its maximum sensitivity and response time at high temperature (260 oC) are 4.6 and 20 s, respectively. The electrical conduction mechanisms were explained in terms of Fowler-Nordheim tunneling (below 120 oC) and the Poole-Frenkel effect (above 120 oC).
Finally, in order to see whether the unique structure of InGaN/GaN multiple quantum wells (MQWs) can be utilized for the MIS Schottky-diode hydrogen sensor, three sensors were made on InGaN/GaN MQWs substrate, one without gate insulator, one
Finally, in order to see whether the unique structure of InGaN/GaN multiple quantum wells (MQWs) can be utilized for the MIS Schottky-diode hydrogen sensor, three sensors were made on InGaN/GaN MQWs substrate, one without gate insulator, one
In summary, the quality of the gate insulator plays an important part in the performance of the hydrogen sensors. SiC and InGaN/GaN MQW substrates are suitable for high-temperature (from ~200 to ~500 oC) applications while the low-cost sensors based on Si substrate can function well below about 200 oC. Hydrogen sensors with these high-k materials (Ta2O5, La2O3, LaTiON, and HfTiO) as gate insulator can produce good electrical characteristics, high sensitivity, and fast response.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
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Tang, Wing-man, and 鄧詠雯. "MISiC Schottky-diode hydrogen sensors with different gate insulators." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40987772.
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Tsuchiya, Kenji, Hitoshi Okubo, Tsugunari Ishida, Naoki Hayakawa, and Hiroki Kojima. "Development Process of Impulse Surface Flashover on Alumina Dielectrics in Vacuum." IEEE, 2011. http://hdl.handle.net/2237/20729.
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Kalbitz, René. "Stability of polarization in organic ferroelectric metal-insulator-semiconductor structures." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5727/.
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Organic thin film transistors (TFT) are an attractive option for low cost electronic applications and may be used for active matrix displays and for RFID applications. To extend the range of applications there is a need to develop and optimise the performance of non-volatile memory devices that are compatible with the solution-processing fabrication procedures used in plastic electronics. A possible candidate is an organic TFT incorporating the ferroelectric co-polymer poly(vinylidenefluoride-trifluoroethylene)(P(VDF-TrFE)) as the gate insulator. Dielectric measurements have been carried out on all-organic metal-insulator-semiconductor structures with the ferroelectric polymer poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) as the gate insu-lator. The capacitance spectra of MIS devices, were measured under different biases, showing the effect of charge accumulation and depletion on the Maxwell-Wagner peak. The position and height of this peak clearly indicates the lack of stable depletion behavior and the decrease of mobility when increasing the depletion zone width, i.e. upon moving into the P3HT bulk. The lack of stable depletion was further investigated with capacitance-voltage (C-V) measurements. When the structure was driven into depletion, C-V plots showed a positive flat-band voltage shift, arising from the change in polarization state of the ferroelectric insulator. When biased into accumulation, the polarization was reversed. It is shown that the two polarization states are stable i.e. no depolarization occurs below the coercive field. However, negative charge trapped at the semiconductor-insulator interface during the depletion cycle masks the negative shift in flat-band voltage expected during the sweep to accumulation voltages. The measured output characteristics of the studied ferroelectric-field-effect transistors confirmed the results of the C-V plots. Furthermore, the results indicated a trapping of electrons at the positively charged surfaces of the ferroelectrically polarized P(VDF-TrFE) crystallites near the insulator/semiconductor in-terface during the first poling cycles. The study of the MIS structure by means of thermally stimulated current (TSC) revealed further evidence for the stability of the polarization under depletion voltages. It was shown, that the lack of stable depletion behavior is caused by the compensation of the orientational polarization by fixed electrons at the interface and not by the depolarization of the insulator, as proposed in several publications. The above results suggest a performance improvement of non-volatile memory devices by the optimization of the interface.Organische Transistoren sind besonders geeignet für die Herstellung verschiedener preisgünstiger, elektronischer Anwendungen, wie zum Beispiel Radio-Frequenz-Identifikations-Anhänger (RFID). Für die Erweiterung dieser Anwendung ist es notwendig die Funktion von organischen Speicherelementen weiter zu verbessern. Das ferroelektrische Polymer Poly(vinylidene-Fluoride-Trifluoroethylene) (P(VDF-TrFE)) eignet sich besonders gut als remanent polarisierbarer Isolator in Dünnschich-Speicherelementen. Um Schalt- und Polarisationsverhalten solcher Speicherelemente zu untersuchen, wurden P(VDF-TrFE)-Kondensatoren und Metall-Halbleiter-Isolator-Proben sowie ferroelektrische Feld-Effekt-Transistoren (Fe-FET) aus dem Halbleiter Poly(3-Hexylthiophene) (P3HT) und P(VDF-TrFE) hergestellt und dielektrisch untersucht. Die Charakterisierung der MIS-Strukturen mittels spannungsabhängiger Kapazitätsspektren machte deutlich, dass es nicht möglich ist, einen stabilen Verarmungzustand (Aus-Zustand) zu realisieren. Kapazität-Spannungs-Messungen (C-V) an MIS-Proben mit uni/bi-polaren Spannungszyklen zeigten eine stabile ferroelektrische Polarisation des P(VDF-TrFE)-Films. Eine Depolarisation des Isolators durch den Mangel an Minoritäts-Ladungsträgern konnte als Grund für die Instabilität des Verarmungs-Zustandes ausgeschlossen werden. Die C-V-Kurven wiesen vielmehr auf die Existenz fixierter, negativer Ladungsträger an der Grenzfläche hin. Zusammenfassend kann festgestellt werden: die Ursache der Ladungsträgerinstabilitäten in organischen ferroelektrischen Speicherelementen ist auf die Kompensation der ferroelektrischen Orientierungspolarisation durch "getrappte"(fixierte) negative Ladungsträger zurückzuführen. Dieses Ergebnis liefert nun eine Grundlage für die Optimierung der Isolator/Halbleiter-Grenzfläche mit dem Ziel, die Zahl der Fallenzustände zu minimieren. Auf diesem Wege könnte die Stabilität des Speicherzustandes in organischen Dünnschichtspeicherelementen deutlich verbessert werden.
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Que, Weiguo. "Electric Field and Voltage Distributions along Non-ceramic Insulators." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1037387155.
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Lee, Sang-Bin. "Sensorless stator winding temperature estimation for induction machines." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/14719.
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Benwell, Andrew L. "Flashover prevention on polystyrene high voltage insulators in a vacuum." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5018.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 18, 2008) Includes bibliographical references.
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Kleinhans, Kevin. "Investigation into possible mechanisms of light pollution flashover of 275kv transmission lines as a cause of unknown outages." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1071.
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Tang, Wing-man, and 鄧詠雯. "Development of high-quality gate insulators to improve the performanceof MISiC Schottky-diode hydrogen sensors." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29736754.
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Elbuzedi, Mohamed. "Material study and properties of polymers used in composite high voltage insulators." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/17749.
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Thesis (MSc)--University of Stellenbosch, 2007.ENGLISH ABSTRACT: Silicone rubber, particularly poly(dimethylsiloxane) (PDMS), has been increasingly used in the manufacture of outdoor high voltage insulators in the recent years. PDMS offers several advantages that make it suitable for outdoor use, such as low weight, a hydrophobic surface, stability, and excellent performance in heavily polluted environments. PDMS surfaces can, however, become progressively hydrophilic due to surface oxidation caused by corona discharge, UV radiation and acid rain. In this study, PDMS samples of controlled formulations as well as six commercial insulator materials four PDMS based and two ethylene propylene diene monomer (EPDM) based were exposed to various accelerated weathering conditions for various periods of time in order to track changes in the material over time. The ageing regimes developed and used to simulate the potential surface degradation that may occur during in-service usage included needle corona and French corona ageing, thermal ageing, UV-B irradiation (up to 8000 hours) and acid rain (up to 200 days). Both the chemical and physical changes in the materials were monitored using a wide range of analytical techniques, including: static contact angle measurements (SCA), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), gas chromatography (GC), gas chromatography/mass spectroscopy (GC/MS), size-exclusion chromatography (SEC), Fourier-transform infrared photoacoustic spectroscopy (FTIR-PAS) and slow positron beam techniques (PAS). A low molecular weight (LMW) uncrosslinked PDMS model compound was used to further study the chemical effects of corona exposure on PDMS materials. PDMS showed far better performance than EPDM, in terms of resistance to the various ageing regimes and “hydrophobicity recovery”.
AFRIKAANSE OPSOMMING: Silikoonrubber, spesifiek polidimetielsiloksaan (PDMS), is gedurende die afgelope paar jaar toenemend gebruik in die vervaardiging van buitelughoogspanningisolators. PDMS het baie voordele vir gebruik in elektriese isolators soos ‘n laer massa, ʼn hidrofobiese oppervlak, stabiliteit en uitstekende werking in hoogsbesoedelde omgewings. Die hidrofobiese oppervlakte kan egter gelydelik hidrofilies word weens oppervlakoksidasie as gevolg van korona-ontlading, UV-bestraling en suurreën. In hierdie studie is PDMS monsters van verskillende samestellings sowel as ses kommersiële isolators (vier PDMS en twee etileenpropileenrubber (EPDM)) blootgestel aan verskillende versnelde weersomstandighede vir verskillende periodes om die veranderinge in die materiale te monitor. Die verskillende materiale is gerangskik volgens hulle werking oor ‘n periode van tyd. Dit het ook ‘n geleentheid gebied om die eienskappe van die verskillende samestellings te bestudeer. Die tegnieke wat ontwikkel is om die moontlike oppervlakdegradasie te simuleer, het naald-korona, “French” korona, UVB-bestraling (tot 8000 uur) en suurreën (tot 200 dae) ingesluit. Beide die chemiese en die fisiese veranderinge in die materiale is gemonitor met behulp van verskeie tegnieke soos statiese kontakhoekbepaling, optiese mikroskopie, skandeerelektronmikroskopie, energieverspreidingsspektroskopie, gaschromatografie, grootte-uitsluitingschromatografie, foto-akoestiese Fouriertransforminfrarooi (PASFTIR) en stadige-positronspektroskopie (PAS). ʼn Lae molekulêre massa PDMS modelverbinding is gebruik om die chemiese effek van korona te bestudeer. Die PDMS materiale het baie beter vertoon teenoor die EPDM materiale in terme van hulle herstel van hidrofobisiteit.
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Chen, Jue. "Shielding characteristics of a commercial 19-inch rack-based cabinet." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Chen_09007dcc803e6a55.pdf.
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Thesis (M.S.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed February 5, 2008) Includes bibliographical references (p. 82).
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Yousefi, Darani Shahrokh. "Control and Automation of a Heat Shrink Tubing Process." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699928/.
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Heat shrink tubing is used to insulate wire conductors, protect wires, and to create cable entry seals in wire harnessing industries. Performing this sensitive process manually is time consuming, the results are strongly dependent on the operator’s expertise, and the process presents safety concerns. Alternatively, automating the process minimizes the operators’ direct interaction, decreases the production cost over the long term, and improves quantitative and qualitative production indicators dramatically. This thesis introduces the automation of a heat shrink tubing prototype machine that benefits the wire harnessing industry. The prototype consists of an instrumented heat chamber on a linear positioning system, and is fitted with two heat guns. The chamber design allows for the directing of hot air from the heat guns onto the wire harness uniformly through radially-distributed channels. The linear positioning system is designed to move the heat chamber along the wire harness as the proper shrinkage temperature level is reached. Heat exposure time as a major factor in the heat shrink tubing process can be governed by controlling the linear speed of the heat chamber. A control unit manages the actuator position continuously by measuring the chamber’s speed and temperature. A model-based design approach is followed to design and test the controller, and MATLAB/Simulink is used as the simulation environment. A programmable logic controller is selected as the controller implementation platform. The control unit performance is examined and its responses follow the simulation results with adequate accuracy.
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Yu, Defen. "Study of electric discharge and space charge formation phenomena in the air gaps of an ice-covered insulator using an icicle/ice-covered plate electrode system = Étude des processus des décharges électriques et formation de charges d'espace dans les intervalles d'air d'un isolateur recouvert de glace à l'aide d'une configuration d'électrodes glaçon/plaque recouverte de glace /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2007. http://theses.uqac.ca.
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Thèse (D.Eng.) -- Université du Québec à Chicoutimi, 2007.La p. de t. porte en outre: Thèse présentée à l'Université du Québec à Chicoutimi comme exigence partielle du doctorat en ingénierie. CaQQUQ Bibliogr.: f. 222-239. Document électronique également accessible en format PDF. CaQQUQ
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Ndiaye, Ibrahima. "Approche physique du développement de streamers positifs sur une surface de glace = Développement of positive streamers along an ice surface : a physical approach /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2007. http://theses.uqac.ca.
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Thèse (D.Eng.) -- Université du Québec à Chicoutimi, 2007.La p. de t. porte en outre: Thèse présentée à l'Université du Québec à Chicoutimi comme exigence partielle du doctorat en ingénierie. CaQQUQ Bibliogr.: f. 222-237. Document électronique également accessible en format PDF. CaQQUQ
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Tallam, Rangarajan M. "Current-based sensorless detection of stator winding turn faults in induction machines." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/13429.
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Mouton, Gerton Nicolaas Jacobus. "An evaluation of different material line insulators under high voltage AC and bipolar DC excitation in a marine polluted environment." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71940.
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Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The worldwide increase in the popularity of high voltage direct current (HVDC) power transmission application has led to questions regarding the performance of high voltage alternating current (HVAC) insulators when energized under HVDC excitation. These questions have led researchers conduct numerous research projects worldwide. A particular question NamPower (the power utility in Namibia) has faced is: how do these insulators perform and age when energized under HVDC excitation in heavily polluted environments? This question was only partly answered by some insulator ageing tests conducted under laboratory conditions for HVDC excitation. However, the natural ageing tests on insulators, which are preferred, have to date been confined predominantly to HVAC excitation voltages. Thus, this research was initiated to investigate the natural ageing performance of insulators under both HVAC and HVDC excitations, when subjected to harsh marine pollution environments. This research project involved performance and ageing tests on three identical sets of line insulators made from different insulator materials, energised under HVAC and both polarities HVDC excitations respectively. The tests were conducted at Koeberg insulator pollution test station (KIPTS), which is a natural marine pollution insulator test station located near Cape Town, along the west coast of South Africa, approximately 50 m from the sea. The set of insulators consisted of EPDM silicone alloy rubber, HTV silicone rubber, RTV silicone rubber coated porcelain, Porcelain and Glass insulators. The HVAC excitation voltage was chosen as 12.7 kV r.m.s. phase-to-ground and it was decided to use a HVDC excitation voltage equal to this value. The research results showed that the insulators made from HTV silicone rubber performed better than the insulators made from EPDM silicone alloy rubber under all excitation voltages. It is also showed that RTV silicone rubber coated porcelain insulators performed better than Glass and Porcelain insulators under all excitation voltages.
AFRIKAANSE OPSOMMING: Die wêreld wye toename in gewildheid van hoë spanning gelyk stroom (HSGS) krag transmisie aplikasie het gelei na vrae oor die effektieweteit van hoë spanning wissel stroom (HSWS) insolators in HSGS aplikasies. Hierdie vrae het gelei na baie navorsings projekte. Een vraag waarmee NamPower (die krag voorsienings maatskapy in Namibia) gekonfronteer was, was hoe gaan die insolators wat onderworpe is aan ’n HSGS toevoer reageer in ’n baie besoedelde omgewing. Hierdie vraag was slegs gedeeltelik beantwoord deur verouderings toetse op insolators wat gedoen is in ’n labaratorium met ’n HSGS toevoer. Inteendeel, die meeste natuurlike verouderings toetse op insolators, soos verkies, is meestal gedoen met ’n HSWS toevoer. Om hierdie rede was hierdie navorsing begin om natuurlike verouderings toetse te doen op insolators onderworpe beide aan HSWS en HSGS toevoere binne ’n marien besoedelde omgewing. Hierdie navorsings projek gaan oor prestering en verouderings toetse op drie, identiese, transmissie lyn insolator stelle, wat onderskeidelik onderworpe was aan HSWS en beide polariteite HSGS toevoere. Die toetse was gedoen by Koeberg insolator besoedeling toets stasie (KIBTS) wat naby Kaapstad geleë is langs die weskus van Suid Africa omtrent 50 m van die see. ’n Stel toets insolators bestaan uit EPDM silikon allooi rubber, HTV silikon rubber, RTV silikon rubber bedekte porselein, Porselein en Glas insolators. Die HSWS waarde waarmee die insolators getoets was, was 12.7 kV w.g.k., fase-na-grond, en dit was besluit om ’n HSGS waarde gelyk aan hierdie spannings waarde te gebruik. Die navorsings resultate wys dat insolators wat gemaak is met HTV silikon rubber presteer beter as insolators wat met EPDM silikon allooi rubber gemaak is onder al die verskillende toevoere. Dit wys ook dat RTV silikon rubber bedekte porselein presteer beter as Porselein en Glas insolators onder al die verskillende toevoere.
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Jasiūnas, Kęstutis. "Aukštosios įtampos įrenginių kombinuotosios izoliacijos kokybės ir resurso tyrimai." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050720_125308-92689.
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Aim of the work 1. To analyze the methods used for the quality and resource assessment of complex insulation; 2. To develop the models for the assessment and analysis of polarization features, dielectric parameters and moisture content in oil- paper insulation; 3. To develop the method for the assessment of moisture quantity by measuring the polarization characteristics; 4. To analyze the impact of water quantity on dielectric parameters of transformer insulation; 5. To classify the quality criteria of oil-paper insulation; 6. To identify the tendencies in variation of insulation’s dielectric parameters and moisture quantity; 7. To implement the developed models and methods in the electricity industry of Lithuania for the assessment of the transformers’ insulation quality and resource.
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Zhang, Zhikuan. "A novel MOSFET's with source/drain on insulator /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202002%20ZHANG.
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Borrill, Leslie (Leslie David). "Non-destructive testing of capless porcelain line post insulators to detect internal defects." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53525.
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Thesis (MScEng)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: This project relates to the unexplained failure of 33kV porcelain line post insulators in ESKOM's Southern Region. An initial investigation suggested that the failures could probably be due to a combination of internal manufacturing flaws and the effects of lightning. The failures all occurred in insulators based on a new design that uses a metal spindle for mechanical attachment to a power line structure embedded in the insulator base. This thesis investigates the non-destructive detection of internal flaws in porcelain line post insulators. The research was structured as follows: • The examination of the manufacturing process and materials used to determine the cause, location and nature of internal flaws. • An electrical field simulation study to verify whether a void in the sulphur cement will experience discharge activity when exposed to systeni nominal voltage or lightning potential. • The identification of non-destructive techniques (NDT) that are potentially viable for determining the presence of insulator internal flaws. • The design of NDT experiments for X-ray, partial discharge (PD) detection and ultrasonic testing. These experiments were evaluated for their effectiveness in determining the presence of internal flaws and their usefulness as a quality control measure in the insulator manufacturing process. The main findings are: The major cause of insulator internal flaws is the fast setting sulphur cement used for cementing the metal spindle (mechanical attachment) to the porcelain body of the insulator. The field simulation study shows that a discharge in a 3mm diameter spherical void on the insulator's axis of symmetry will occur if the insulator is exposed to lightning potential. High energy X-raying is an effective technique for exposing the location, nature, size and number of flaws in the insulator, but is impractical due to the high Xraying cost and over-utilisation of the only high energy X-ray facility in the RSA. The PD experiment was effective in revealing the presence of internal flaws, but the location, nature, size and number of flaws cannot be determined. The experiment is time consuming and is therefore not suitable for quality control in the insulator manufacturing process. A preliminary investigation into the suitability of ultrasonic testing techniques encountered major technical difficulties. Further investigation into the use of ultrasonic 3D imaging techniques is recommended.
AFRIKAANSE OPSOMMING: Hierdie projek hou verband met die onverklaarbare faling van 33kV porselein staaftipe isolators in ESKOM se Suidelike Streek. 'n Aanvanklike ondersoek het daarop gedui dat die falings veroorsaak is deur 'n kombinasie van interne vervaardigingsfoute en die effek van weerlig. Die falings het almal plaasgeving op isolators waarvan die vashegtingsbout direk in die porselein versink is. Die doel van hierdie navorsingsprojek is om nie-vernietigende toetsmetodes (NVT) te ondersoek, teneinde interne foute in die tipe isolators op te spoor. Die tesis is soos volg gestruktureer: • Die ondersoek van die vervaardigingsproses en die materiale wat gebruik word, ten einde die oorsaak, posisie en aard van hierdie foute vas te stel. • 'n Simulasie van die elektriese veld om vas te stelof 'n holte in die swaelsement ontladings salondervind onder die invloed van nominale spanning en weerlig. • Die indentifisering van nie-vernietignde toetsmetodes wat gebruik kan word om die teenwoordigheid van interne foute te bepaal. • Die ontwerp van NVT eksperimente vir X-straal, gedeeltelike ontlading ("PD") deteksie en ultrasoniese toetsing. Hierdie eksperimente is geëvalueer om hul effektiwiteit om die teenwoordigheid van interne foute vas te stel, asook hul nuttigheid as 'n kwaliteitsbeheermaatreël in die iso latorvervaardigingsproses. Die hoofbevindinge is: Die hoofoorsaak van die interne foute is die vinnig-stollende swael-sement wat gebruik word om die metaalinsetsel aan die porselein te heg. Die veldsimulasies het getoon dat 'n ontlading in 'n 3mm sferiese holte op die isolator se simmetrie-as sal plaasvind as die isolator aan weerligpotensiaal onderwerp word. Hoë-energie-X-strale is 'n effektiewe tegniek om die posisie, aard, grootte en aantal foute in die isolator vas te stel. Dit is egter onprakties as gevolg van die hoë koste en oorbenutting van die enigste hoë-energie-X-straal-fasiliteit in die RSA. Die ontladingsdeteksie eksperiment was effektief om die teenwoordigheid van interne foute aan te dui, maar die posisie, aard; grootte en getal foute kan nie bepaal word nie. Die eksperiment is tydrowend en is daarom nie geskik vir kwaliteitsbeheer van die isolatorvervaardigingsproses nie. 'n Voorlopige ondersoek na die geskiktheid van ultrasoniese toetsmetodes het groot tegniese stuikelblokke opgelewer. Verdere ondersoek van die gebruik van ultrasoniese 3D-beeldtegnieke word aanbeveel.
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Abraham, Berhane Teclesenbet. "Degradation and recovery of polydimethylsiloxane (PDMS) based composites used as high voltage insulators." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49902.
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Thesis (MSc)--Stellenbosch University, 2004.ENGLISH ABSTRACT: Polydimethylsiloxane (PDMS) compounds are utilized in outdoor high voltage insulation due to their low weight, vandalism resistance, better anti-contamination performance and their superior hydrophobic nature. Under severe environmental conditions and over prolonged service time, however, the hydrophobic surface can gradually become hydrophilic and then recover with adequate resting period. In this study, room temperature vulcanized (RTV) PDMS samples were prepared with different formulations and then exposed to corona discharge to evaluate its effect. The influence of different additives, such as different types and amount of fillers and additionally added low molar mass silicone oils, on the hydrophobicity recovery of the material was investigated. The effects of two types of corona treatment were also evaluated. Hydrophobicity recovery of corona and UV-C aged PDMS samples was evaluated by means of static contact angle measurements. Positron annihilation spectroscopy (PAS) gave important information on the micro structural change after corona treatment of RTV PDMS as well as naturally aged high temperature vulcanized (HTV) PDMS samples. The different formulations of the RTV PDMS samples and the effect of the additives were studied with this technique. The formation of a thin, highly crosslinked inorganic silica-like (SiOx) layer was confirmed even at the early stage of degradation. It was also possible to estimate the thickness of the silica-like layer formed during corona exposure that is responsible for the loss and recovery of hydrophobicity. The surface hardness and hydrophilicity change of PDMS samples due to corona treatment were studied simultaneously with force distance measurements by atomic force microscopy (AFM). The adhesive force calculated from the pull-off force-distance curves showed that the adhesive force between the probe and the sample decreased with increasing corona treatment time, indicating hydrophobicity recovery. In addition to this, the increase in hardness after corona exposure provides indirect evidence of the formation of a silica-like layer. In all cases the hydrophilicity and the surface hardness of the PDMS samples increased directly after corona treatment and recovered with time. Two types of FTIR spectroscopy were used to analyse the surface of the polymer.
AFRIKAANSE OPSOMMINGS: Polidimetielsiloksaan (PDMS) word in buitelug hoogspanninginsulasie gebruik as gevolg van sy lae massa, weerstand teen vandalisme, verbeterde anti-kontaminasie werkverrigting en superieure hidrofobiese karakter. Die hidrofobiese oppervlakte kan egter gelydelik hidrofillies word onder uiterste omgewingsomstandighede en oor langdurige dienstyd. PDMS materiaal herstel egter nadat dit genoeg rustyd toegelaat is. Kamertemperatuur-gevulkaniseerde (KTV) PDMS met verskillende formulasies is in hierdie studie voorberei, aan korona ontlading blootgestel, geëvalueer en vergelyk. Die invloed van bymiddels soos verskillende tipes en hoeveelhede vuiler, asook addisionele lae molekulêre massa silikoonolie, op die herstel van hidrofobisiteit van die materiaal is ondersoek. Twee verskillende metodes van korona behandeling is ook geëvalueer. Die herstel van hidrofobisiteit van korona en UV-C verouderde PDMS monsters is met statiese kontakhoekmeting geëvalueer. Positronvernietigingspektroskopie (PVS) is 'n kragtige tegniek wat belangrike inligting oor die mikrostrukturele verandering van korona behandelde van KTV PDMS sowel as natuurlik-verouderde hoë temperatuur gevulkaniseerde (HTV) PDMS monsters gee. Die verskillende formulasies van die KTV PDMS monsters, sowel as die effek van die vullers, is met behulp van hierdie tegniek ondersoek. Die vorming van 'n dun, hoogskruisgebinde, anorganiese silika-agtige (SiOx) laag op die PDMS oppervlak, selfs tydens die vroeë stadium van degradasie, is bevestig. Dit was ook moontlik om die dikte van die silika-agtige laag wat gedurende die korona blootstelling gevorm het, en wat verantwoordelik is vir die verlies aan hidrofobisiteit, te bepaal. Die oppervlakhardheid en hidrofilisiteit verandering van PDMS monsters as gevolg van korona behandeling, was gelyktydig met krag-afstand metings deur middel van atoomkragmikroskopie (AKM) bestudeer. Die kleefkrag, soos bereken van aftrek kragafstandkurwes, dui daarop dat kleefkragte tussen die taster en die monster afneem met toenemende korona behandelingstyd, wat beduidend is op die herstel van hidrofobisiteit. Daarbenewens is die toename van oppervlakhardheid na korona blootstelling "n indirekte bewys van die formasie van 'n silika-agtige laag. In alle gevalle het die hidrofilisiteit en die oppervlakhardheid van die PDMS monsters toegeneem direk na afloop van korona behandeling en gevolglik herstel met tyd. Twee tipes IR spektroskopie metodes is gebruik vir die chemiese-oppervlak analises
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Schwardt, Wilhelm Heinrich. "Insulator pollution monitoring device : development, calibration and field evaluation." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50372.
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Thesis (MScEng)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: The calibration and field evaluation of an Insulator Pollution Monitoring Relay (IPMR) were the main aims of this research programme. A repeatable artificial wetting test method was developed after several modifications were made to the steam system, test chamber and the test routine. The IPMR was successfully calibrated with insulators that were artificially polluted according to the solid layer method. Linear and polynomial relationships were determined after curve-fitting techniques were performed on the results. The calibration showed that the IPMR is capable as a device relating the maximum conductivity during artificial wetting to the ESDD, a severity classification parameter. The IPMR was successfully used in a salt fog chamber to determine if the device is capable to evaluate the severity of an instantaneous pollution event. The IPMR was successfully installed at a natural pollution test site along the Cape west coast. The conductivity measurements with natural wetting showed good correlation to flashovers experienced. A rule of thumb, developed to indicate a possible risk of flashover, was based on observations made on the relationship between humidity and surface conductivity. The measured IPMR data was successfully applied to quantify the site severity according to the conductivity measurement with natural wetting. This calculated severity value could be used in the assessment of flashover probability of high voltage insulators.
AFRIKAANSE OPSOMMING: Die hoofdoel van die tesis was die kalibrasie en veldtoetse van 'n isolatorbesoedelingsmonitor (IPMR). 'n Herhaalbare nagebootste benatting-toetsmetode is ontwikkel na veranderings aan die stoomstelsel, toetsruimte en die toetsproses. Die IPMR is suksesvol gekalibreer met isolators wat besoedel was met 'n nagebootste besoedeling volgens die "solid layer method". Liniêre sowel as kwadratiese verwantskappe is ontwikkel na krommepassings op die resultate uitgevoer was. Die kalibrasie het gewys dat die IPMR in staat is om die maksimum geleidingsvermoë wat d.m.v. nagebootste benatting verkry is, met die ESDD, 'n besoedelingsklassifikasie, kan vergelyk. Die apparaat is ook suksesvol gebruik tydens soutmistoetse om te bepaal of dit in staat is om 'n skielike besoedelingsgebeurtenis te kan meet. Na die afhandeling van laboratorium werk is die apparaat by 'n natuurlike isolator besoedeling-toetsstasie langs die Kaapse weskus geïnstalleer. Die geleidingsvermoë metings met natuurlike benatting het goeie korrelasie getoon met isolator oorvonkings. 'n Skattingsmetode wat ontwikkel is om moontlike oorvonkings te voorspel, is gebaseer op waarnemings wat gemaak is van die humiditeit sowel as die oppervlakte geleidingsvermoë. Die IPMR se geleidingsvermoë metings met natuurlike benatting is aangewend om die besoedelingsgraad van die gebied te bepaal. Die bepaalde besoedelingsgraad kan verder gebruik word om die waarskynlikheid van die oorvonking van isolators vas te stel.
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Phillips, Lyndal. "Analysis of polychlorinated biphenyls in transformer oil /." View thesis, 2002. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20031222.095244/index.html.
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Thesis (M.Sc.) (Hons.) -- University of Western Sydney, 2002.A thesis submitted to the University of Western Sydney in fulfillment of the requirements for admission to the [degree of] Masters of Science (Honours). Bibliography : leaves 156-163.
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Farzaneh-Dehkordi, Jalil. "Experimental study and mathematical modeling of flashover of EHV insulators covered with ice." Thèse, Chicoutimi : [Rimouski : Université du Québec à Chicoutimi ;. Université du Québec à Rimouski], 2003. http://theses.uqac.ca.
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Thèse (M.Eng.) -- Université du Québec à Chicoutimi, programme extensionné a l'Université du Québec à Rimouski, 2004.Bibliogr.: f. 97-104. Document électronique également accessible en format PDF. CaQCU
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Akram, Shakeel. "High temperature and high electrical resistance multilayer polyimide nanodielectrics for electric motors insulation." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS028.
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Dans cette thèse, les films multicouches PI / nanocomposites ont été préparés selon un processus de synthèse optimisé. Les échantillons synthétisés ont été caractérisés expérimentalement et par simulations. Tout d'abord, le mécanisme de dégradation des échantillons a été exploré à l'aide d’un générateur d’impulsions. La constante diélectrique, les pertes diélectriques, la rigidité diélectrique, le courant de conduction, la charge d'espace et le courant thermo-stimulé (CTS), ont été étudiées. Ensuite, les niveaux de piège ont été calculés à l'aide des données de déclin de la charge totale et de CTS. Enfin, des modèles 3D de multicouches PI / nanocomposites basés sur les conditions aux limites obtenues à partir d'images SEM / TEM ont été construits dans COMSOL Multiphysics. Ces modèles décrivent l'impact de la dispersion des nanoparticules sur l'amplification du champ électrique. Nos résultats démontrent moins d’agglomération de nanoparticules dans les multicouches et une diminution des charges d’espace et du champ électrique interne. Ainsi, l’utilisation d’isolations multicouches devraient permettre une meilleure fiabilité des moteurs électriquesIn this thesis, the multilayer PI/nanocomposite films were prepared using an optimized synthesis process. The synthesized samples are characterized by experiments and simulations. First, the samples degradation mechanism was explored using pulse power source. Second, dielectric constant, dielectric loss, insulation lifetime, dielectric strength, conduction current, space charge and thermal stimulated current (TSC) were investigated. Third, trap levels were calculated using total charge decay data and TSC data. In the end, multilayer PI/nanocomposite 3D models based on actual boundary conditions obtained from SEM/TEM images of synthesized samples were constructed in COMSOL Multiphysics software. The impact of nanoparticle dispersion on the electric field enhancement is explicitly described in this model. Our results demonstrate that the chances of nanoparticles agglomeration are reduced by using multilayer structure. In consequence, less space charge and low electrical fields are observed in multilayer films. Using multilayer insulations would ensure reliable operation for electric motors and increase its lifetime
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Van, der Merwe Neil. "An investigation into the qualities of new and field aged cycloaliphatic epoxide insulation in the Republic of South Africa." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51613.
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Thesis (M.Ing.)--University of Stellenbosch, 2000.ENGLISH ABSTRACT: The application of cycloaliphatic epoxide (CE) insulation in the Republic of South Africa is investigated within this thesis. There was a request from industry to evaluate the product and indicate its suitability for application within the various geographic and climatic zones typical of the RSA. An extensive survey was conducted into the historic origins of the material, and the experiences of international utilities applying the insulation medium in respect of polluted conditions. The properties of the Automatic Pressure Gelation (APG) CE insulator manufacturing process are discussed with reference to the manufacture of glass and porcelain insulation, and typical areas for concern are discussed with reference to insulators found to deviate from specification. Typical insulators were obtained from the manufacturers and utilities associated with the product, and were subjected to electrical, material and visual examination tests. The electrical tests included AC wet and dry, lightning impulse, clean fog, salt fog, mould release resiliency and the IEC 1109 voltage test. The material tests included the identification of the epoxide systems in use in the RSA, ultraviolet radiation aging simulation, water hydrolysis and salt deposit density tests. The main findings are: • CE insulation is sensitive to marine pollution and continuous-wetting pollution types. • The use of CE insulation is promoted in respect of inland and medium industrial pollution types. • Class B pin-type CE insulation is prone to partial discharge related failures. • Surface roughening on the insulator surfaces leads to reduced AC wet flashover voltages and increased pollution catch. Additionally: • A comprehensive aging hypothesis was developed detailing three independent aging stages/modes applying to CE insulation. • A hypothesis was developed for a new evaluation method for documenting changes on insulator surfaces due to the action of aging mechanisms: The Surface Area Index.
AFRIKAANSE OPSOMMING: Die aanwending van sikloalifatiese epoksied (SE) isolasie in die Republiek Van Suid Afrika word in hierdie skripsie ondersoek. Hierdie ondersoek is geloods op versoek van die elektrisiteitsbedryf om die toepaslike aanwending van die produk onder die verskeie heersende streeksweersomstandighede binne die RSA te evalueer. Breedvoerige navorsing is gedoen om die geskiedkundige oorsprong van die materiaal vas te stel, sowel as om die prestasie daarvan as insulasiemiddel te boekstaaf. Daar is veral gelet op die prestasie van die materiaal onder besoedelende omstandighede en ondervinding wat opgedoen is deur intemasionale ondememings. Die eienskappe van die automatiese drukjelvormings-vervaardigingsproses (APG) word behandel met verwysing na die maak van glas en porselein insulators. Tipiese probleemareas word bespreek van insulators wat afwyk van spesifikasie af. Verteenwoordigende isolators is vanaf vervaardigers en ondememings verkry wat met die produk bemoei is. Hulle is blootgestel aan elektriese, materiaal en visuele toetse. Die elektriese toetse het die volgende behels: nat en droog wisselstroom, skoon waterdamp, sout waterdamp en die IEe 1109 spanningstoets. Die effek van die verlies van die anti-kleefmiddel (gebruik tydens die gietproses) as gevolg van veroudering is ook in detail behandel. Die materiaaltoetse het ingesluit: die uitkenning van die epoksied stelsels in gebruik in die RSA, gesimuleerde veroudering deur ultravioletligbestraling, water hidroliese en soutlaag digtheids toetse. Die hoofbevindings is: • SE isolasie word bemvloed deur seelug besoedeling sowel as volgehoue benatting. Die gebruik van SE isolasie word voorgestel vir binnelandse gebruik sowel as in gebiede met mediumvlak nywerheidsbesoedeling. • Klas B pen-tipe SE isolasie is geneig tot deelontladings wat dan tot faling lei. • Oppervlakvergroffing lei tot In verminderde wisselstroom orvonksspanning onder nat toestande sowel as verhoogde vangs van besoedeling. Bykomend hiertoe is: • 'n breedvoerige SE verouderingshipotese ontwikkel wat drie onafhanklike stadia en modusse van die verouderingsproses uitgewys het. • 'n hipotese ontwikkel vir In nuwe evaluasiemetode om die verandering in die isolatoroppervlak as gevolg van veroudering te dokumenteer: Oppervlakte- Area Indeks (SAl).
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Shifidi, S. K. "Modelling and performance evaluation of an HV impulse test arrangement with HVDC bias." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2722.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.ENGLISH ABSTRACT: From a systems operation and design perspective, it is important to understand the behaviour of HVDC system insulation when presented with high voltage transients, such as induced by lightning and switching operations. Therefore, this thesis investigates the design, operation and performance of a circuit arrangement that can be used in high voltage laboratories to generate impulse voltage waveforms superimposed on a dc bias voltage. The circuit arrangement consists of an impulse generator and a dc source that supplies continuous dc voltage to stress the test object, which can be any type of insulator, i.e. composite, porcelain, glass, gap arrangements, etc. The composite waveform obtained from the test arrangement is used experimentally to investigate the impulse flashover of insulators. For modelling and analysis purposes, the test circuit was transformed to a Laplace equivalent in order to derive the applicable nodal voltage equations. After substitution of circuit parameter values, the voltage equations are then transformed to time domain equations that predict the time-domain behaviour of the circuit. To validate this mathematical approach, the voltage waveforms obtained with this mathematical model is compared with the waveforms measured under laboratory conditions and also with waveforms simulated with HSPICE software. These comparisons are performed using graphical representations. Good correlation was obtained and the results are presented in this thesis. The final stage of this thesis discusses the application of the designed test arrangement for flashover and withstands tests on a silicon rubber insulator. The determination of the flashover values is done by using the existing statistical methods. The insulator was tested under dry conditions and also under polluted wet conditions for both positive and negative impulses compared to the DC bias voltage polarity. The results show that the dc bias voltage does not affect the total voltage flashover of the insulator significantly. It was also observed that wetting affects the flashover for negative impulse more severely, while the influence of wetting is minimal with positive impulse voltages
AFRIKAANSE OPSOMMING: Vanuit ‘n stelselbedryf en ontwerp perspektief, is dit is belangrik om die gedrag van HSGS stelsels te verstaan wanneer dit onderwerp word aan hoogspanning oorgangsverskynsels soos veroorsaak deur weerlig en skakeloperasies. Daarom ondersoek hierdie tesis die ontwerp, werking en werkverrigting van ‘n stroombaanopstelling wat gebruik kan word in hoogspanningslaboratoriums om impulsspannings gesuperponeer op gelykspanning voorspannings op te wek. Die stroombaan bestaan uit ’n impulsgenerator en ‘n gs-bron wat die langdurige gs-spanning voorsien aan die toetsvoorwerp, wat enige tipe isolator kan wees. bv. porselein, glas, gapings, ens. Die saamgestelde golfvorm wat met die toetsopstelling verkry word, is eksperimenteel gebruik om die impulsoorvonking van isolators te ondersoek. Vir die doel van modellering and analise, is die stroombaan na ‘n Laplace ekwivalent getransformeer om die toepaslike knooppunt spanningsvergelykings af te lei. Na substitusie van die stroombaan parameter waardes, word die spanningsvergelykings getransformeer na die tydgebied vergelykings wat die tydgebied gedrag van die stroombaan voorspel. Om die wiskundige benadering te toets, word die spanningsgolfvorms wat met die wiskundige model voorspel word, vergelyk met golfvorms wat onder laboratorium toestande gemeet is en ook met golfvorms wat met HSPICE programmatuur gesimuleer is. Hierdie vergelykings word gedoen met behulp van grafiese voorstellings. Goeie korrelasie is verkry en die resultate word in die tesis gegee. Die finale stadium van hierdie tesis bespreek die toepassing van die ontwerpte toetsopstelling vir oorvonk- en weerstaantoetse op ‘n silikonrubber isolator. Die bepaling van die oorvonkwaardes word gedoen deur bestaande statistiese metodes te gebruik. Die isolator is onder droë en nat besoedelde toestande gedoen, vir beide positiewe sowel as negatiewe impulse met verwysing na die GS voorspan spanning. Die resultate toon dat die gsvoorspanning nie die oorvonkspanning van die isolator beïnvloed nie. Dit is ook waargeneem dat die benatting die oorvonking neer beïnvloed met ‘n negatiewe impuls terwyl die invloed minimaal is met positiewe impulsspannings.
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Sankar, Sandrawattie. "Correlation of microstructural, magnetic, and transport properties of composite metal-insulator films /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p9963657.
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Vosloo, Wallace L. (Wallace Lockwood). "A comparison of the performance of high-voltage insulator materials in a severely polluted coastal environment." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52625.
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Thesis (PhD)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: The main aim of this research programme was to compare the relative performance of different insulator materials used in South Africa when subjected to a severe marine pollution environment. A test programme and procedure, test facility and instrumentation were established. Some novel instrumentation and monitoring equipment were developed and built specifically for this research programme, supported by data analysing software programs. In order to compare material performance only, all non-material design variables between the test insulators had to be removed (e.g. creepage distance, connecting length, inter-shed spacing, profile, etc.). To achieve this some of the test insulators had to be specially manufactured. Leakage current, electrical discharge activity, climatic and environmental data was collected successfully over a one-year test period, starting with new test insulators. The peak and energy values of the leakage current were identified as the two main parameters needed to describe the leakage current activity on the test insulators. A correlation was found between the climatic and environmental data and the leakage current data, and it was found that the leakage current can be determined successfully from some of the climatic and environmental parameters monitored by using multiple regression techniques. Surface conductivity and energy were found to be the best parameters to show the maximum and continuous interaction of the insulator material surface with the electrolytic pollution layer. A natural ageing and pollution test procedure was developed, which has become a South African standard and is gaining international acceptance. A model and hypothesis are proposed to describe the electrical discharge activity that takes place on the test insulators and explain the difference in leakage current performance of the various materials. Keywords: Insulator, Pollution, High Voltage, Leakage current, Material performance.
AFRIKAANSE OPSOMMING: Die hoofdoel van hierdie navorsingsprogram was om die relatiewe prestasie van verskillende isolatormateriale wat in Suid-Afrika gebruik word te vergelyk in 'n swaar besoedelde marine omgewing. 'n Toetsprogram en prosedure, toets fasiliteit en instrumentasie is gevestig. 'n Paar nuwe instrumente en moniteer toerusting is ontwikkel en gebou spesifiek vir hierdie navorsingsprogram, gesteun deur data analise sagteware programme. Ten einde slegs materiaalprestasie te vergelyk, moes alle nie-materiaal ontwerpsveranderlikes tussen die toetsisolators verwyder word (bv. kruipafstand, konnekteer lengte, tussen-skerm spasiëring, profiel, ens.). Om dit reg te kry moes sommige van die toetsisolators spesiaal vervaardig word. Lekstroom, elektriese ontladingsaktiwiteit, klimaat en omgewingsdata is suksesvol versameloor 'n een-jaar toetsperiode, beginnende met nuwe toets isolators. Die piek en energie waardes van die lekstroom is identifiseer as die twee hoof parameters wat nodig is om die lekstroomaktiwiteit op die toetsisolators te beskryf. 'n Korrelasie is gevind tussen die klimaat- en omgewingsdata en die lekstroom data, en dit is gevind dat die lekstroom data suksesvol bepaal kan word van sekere van die klimaat- en omgewingsparameters wat gemoniteer is deur veelvoudige regressie tegnieke te gebruik. Oppervlakskonduktiwiteit en energie is gevind die beste parameters te wees om die maksimum en kontinue interaksie van die isolatormateriaaloppervlak met die elektrolitiese besoedelingslaag aan te toon. 'n Natuurlike veroudering en besoedeling toetsprosedure is ontwikkel, wat 'n Suid-Afrikaanse standaard geword het en besig is om internastionale aanvaarding te wen. 'n Model en hipotese word voorgestelom die elektriese ontladingsaktiwiteit wat op die toetsisolators plaasvind te beskryf en om die verskil in lekstroomprestasie van die verskeie materiale te verduidelik. S/eufelwoorde: Isolator, Besoedeling, Hoog Spanning, Leek stroom, Materiaal prestasie.
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Dallaire, Marc-André. "Contournement en courant continu et alternatif des isolateurs givrés, précontaminés ou propres /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1992. http://theses.uqac.ca.
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Barahmand, Sohrab. "Tension minimale de contournement des isolateurs givrés en région de fonte /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1985. http://theses.uqac.ca.
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Tavakoli, Zaniani Changiz. "Dynamic modeling of AC arc development on ice surfaces = Modélisation dynamique du développement de l'arc électrique à la surface de la glace en courant alternatif /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2004. http://theses.uqac.ca.
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Guerrero, Olivera Tatiana. "Étude expérimentale du contournement des isolateurs recouverts de glace sous tensions de foudre et de manoeuvre /." Thèse, Chicoutimi : [Rimouski : Université du Québec à Chicoutimi ;. Université du Québec à Rimouski], 2004. http://theses.uqac.ca.
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Thèse (M.Eng.) -- Université du Québec à Chicoutimi, programme extensionné à l'Université du Québec à Rimouski, 2004.Bibliogr.: f. 147-150. Document électronique également accessible en format PDF. CaQCU
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Kim, Namsu. "Fabrication and characterization of thin-film encapsulation for organic electronics." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31772.
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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Samuel Graham; Committee Member: Bernard Kippelen; Committee Member: David McDowell; Committee Member: Sankar Nair; Committee Member: Suresh Sitaraman. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Meghnefi, Fethi. "Étude temporelle et fréquentielle du courant de fuite des isolateurs de poste recouverts de glace en vue du développement d'un système de surveillance et de prédiction en temps réel du contournement électrique /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2007. http://theses.uqac.ca.
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Thèse (D.Eng.) -- Université du Québec à Chicoutimi, 2007.La p. de t. porte en outre: Thèse présentée à l'Université du Québec à Chicoutimi comme exigence partielle du doctorat en ingénierie. CaQQUQ Bibliogr.: f. 235-244. Document électronique également accessible en format PDF. CaQQUQ