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Insulator (electricity)

About: Insulator (electricity) is a research topic. Over the lifetime, 15941 publications have been published within this topic receiving 108950 citations. The topic is also known as: electrical insulator.


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Journal ArticleDOI
TL;DR: Low voltage operation minimizes Joule heating effects that have limited previous systems, opening up the possibility for new biological applications of iDEP.
Abstract: Insulator-based dielectrophoresis (iDEP) is a very promising technique for sorting microparticles based on their electrical properties. The need for microfabricated electrode arrays is eliminated by using constrictions in a microchannel to induce large electric field gradients. In this work, micro-milling is used to build devices with three-dimensional features that exhibit very large constriction ratios. These three-dimensional insulator-based dielectrophoresis (3DiDEP) devices allow for trapping microparticles at average electric fields one order of magnitude lower than two-dimensional designs with the same footprint. Low voltage operation minimizes Joule heating effects that have limited previous systems, opening up the possibility for new biological applications of iDEP.

87 citations

Journal ArticleDOI
01 Sep 1971
TL;DR: In this paper, the influence of a number of parameters, such as surface conductivity, overall length, leakage-path length and profile on insulator flashover is discussed, and the effect of voltage waveshape is shown that direct voltage gives flashover at the lowest peak stress for a given pollution severity.
Abstract: High-voltage insulators may flashover at working voltage when polluted and wet. Pollution is deposited by various forces, of which aerodynamic ones are shown to be usually the most important. Theories to explain the pollution-flashover process are described. The performance of insulators in a polluted environment may be assessed by tests in natural conditions, or by the use of artificial methods, which are critically examined. The influence of a number of parameters, such as surface conductivity, overall length, leakage-path length and profile on insulator flashover is discussed. Studies of the effect of voltage waveshape show that direct voltage gives flashover at the lowest peak stress for a given pollution severity. Pollution flashover can be prevented by washing or greasing or by employing oil-bath or resistive-glazed insulators or special insulator assemblies. The advantages and disadvantages of these remedies are outlined. An analysis of the behaviour of polluted surge diverters and insulators with special functions introduces extra problems which are discussed. Organic insulating materials are degraded by tracking or erosion, but insulators using these materials have advantages, especially for ultra-high-voltage systems. An important aspect of the pollution problem which needs further study is the measurement of the site-pollution severity, so as to classify insulation requirements, and several methods of measurement are described.

87 citations

Journal Article
TL;DR: In this article, a model for predicting the flashover voltage of ice-covered insulators energized with ac voltage is presented, taking into account the variation of ice surface conductivity as a function of freezing water conductivity.
Abstract: A model for predicting the flashover voltage of ice-covered insulators energized with ac voltage is presented in this paper. The model takes into account the variation of ice surface conductivity as a function of freezing water conductivity. The effects of the length of the arc on its own characteristics, as well as the ac arc reignition condition, were determined in a laboratory investigation using triangular ice samples. The model is applied to a short string of 5 IEEE standard insulator units. There is an excellent concordance between the 50% flashover voltage calculated from the mathematical model and the experimental results.

87 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the effects of permanent dipoles on insulator surfaces on the electrical properties of organic thin-film transistors, and they found that the field effect mobility of pentacene thin-filtered transistors increases by a factor of approximately 20 for insulators with an electron-withdrawing group.
Abstract: In order to investigate the effects of permanent dipoles on insulator surfaces on the electrical properties of organic thin-film transistors, the authors fabricated insulators with various self-assembled monolayers and similar surface energies. Surprisingly, they found that the field-effect mobility of pentacene thin-film transistors increases by a factor of approximately 20 for insulators with an electron-withdrawing group. This remarkable increase in the field-effect mobility is due to the increase in the hole density of the insulator surface that arises from the increased band bending of the insulator/semiconductor interface.

87 citations

Journal ArticleDOI
TL;DR: In this article, the electrical discharge characteristics of SF6 are discussed theoretically in relation to the field dependence of the ionization coefficient a and the electron attachment coefficient, and a simple theoretical formulation of breakdown or corona inception voltages of gaps in SF6 is derived.
Abstract: The electrical discharge characteristics of SF6 are discussed theoretically in relation to the field dependence of the ionization coefficient a and the electron attachment coefficient The results are compared with the characteristics of air. A simple theoretical formulation of breakdown or corona inception voltages of gaps in SF6 is derived. The formulation has been examined by experiments on several electrode configurations. At low pressures of less than 4 atm, the agreement of the theoretical and the experimental results is fairly good. The breakdown voltage decreases from the theoretical estimation at higher pressure.

86 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023368
2022892
2021224
2020478
2019561
2018629