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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.


Papers
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Journal ArticleDOI
01 Jul 2001
TL;DR: In this article, the dielectric behavior of polluted porcelain insulators is investigated by means of experimental tests and simulation methods, which leads to the identification of the arc constants.
Abstract: The dielectric behaviour of polluted porcelain insulators is investigated by means of experimental tests and simulation methods. The elaboration of the experimental results, using well known mathematical models of polluted insulators, leads to the identification of the arc constants. It was found out that the arc constants are independent of the insulator type and of the experimental pollution procedure (salt fog or solid layer cool fog method). This allows the formulation of a generalised simulation model of polluted insulators. The critical parameters for the flashover (voltage, current and gradient) are computed by means of the developed model, using only the geometric dimensions of the insulator, the pollution severity and the arc constants. Different types of porcelain insulators are investigated and the variation of the critical parameters upon the density of the pollution layer is determined. The influence of the geometrical dimensions and of the shape of the insulator to the critical parameters is also investigated. Furthermore, analytical relations are defined, between the computed critical parameters and the salt deposit density as well as the dimensions, the shape and the type of the insulator.

78 citations

Journal ArticleDOI
TL;DR: In this paper, the authors show that the classical interpretation of the potential decay in terms of the injection of the deposited charge into the volume of the insulator does not account for their results, which can be explained by the effect of slow volume polarization alone.
Abstract: Surface potential decay after charge deposition by corona or contact has been studied for epoxy samples and compared with polarization measurements. We show that the classical interpretation of the potential decay in terms of the injection of the deposited charge into the volume of the insulator does not account for our results, which can be explained by the effect of slow volume polarization alone. The return potential phenomenon also finds a satisfactory interpretation using this model. The polarization processes involved are the same as for absorption currents. Hence the model may apply to a large variety of other insulating materials.

78 citations

Patent
10 Jun 1998
TL;DR: In this article, a dielectric-wall linear accelerator is improved by a highvoltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators.
Abstract: A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

77 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed an iterative computer simulation of the self-consistent charge transport in bulk alumina samples during electron beam irradiation, based on a new flight-drift model (FDM).
Abstract: Dielectric breakdown is the main cause of insulator degradation. Breakdown strength strongly depends on materials microstructure (grain size, grain boundaries nature,…) [Liebault, J., Vallayer, J., Goeuriot, D., Treheux D., Thevenot, F., How the trapping of charges can explain the dielectrics breakdown performance of alumina ceramics, J. Eur. Ceram. Soc., 2001, 21, 389–397; Si Ahmed, A., Kansy, J., Zarbout, K., Moya, G., Liebault, J., Goeuriot, D., Microstructural origin of the dielectric breakdown strength in alumina: a study by positron lifetime spectroscopy, J. Eur. Ceram. Soc., 2005, 25, 2813–2816]. The experimental study of these materials behaviour towards charge injection was performed by the scanning electron microscopy mirror effect (SEMME) method. It allows to measure the amount of injected charges finally trapped in the insulator. In order to explain the experimental results, we developed an iterative computer simulation of the self-consistent charge transport in bulk alumina samples during electron beam irradiation, based on a new flight-drift model (FDM). Ballistic and drift electron and hole transport as well as their recombination, trapping and detrapping (due to temperature and electric field) are taken into account. As a main result the time dependent secondary electron emission rate and the spatial distributions of currents, charges, field and potential are obtained. The analysis of these two kinds of results allowed us to identify the effect of the microstructure on the behaviour of the injected charges in the insulator and then to propose some mechanisms depending on the temperature leading to a good dielectric breakdown resistance. Indeed, at room temperature a huge localisation of charges limits further injection into the sample that permits to delay breakdown. On the other hand, when the temperature increases, the efficiency of the charge spreading behaviour is improved, leading to a higher dielectric breakdown strength.

77 citations

Journal ArticleDOI
Z. Guan1, R. Zhang1
TL;DR: In this article, the relationship between the reignition and recovery conditions of an AC arc was analyzed based on the alternating character of an arc on the polluted surface, and a formula expressing the resistance of the pollution layer on the insulator was derived.
Abstract: The phenomena and the propagation processes of DC and AC arcs on the surface of polluted insulators were observed and investigated by means of a high-speed camera. Time-resolved photographs indicate that there is an obvious distinction between DC and AC flashover processes. Based on the alternating character of an AC arc on the polluted surface, the relationship between its reignition and recovery conditions is analyzed. The most important factor is the recovery rather than the reignition condition. A formula expressing the resistance of the pollution layer on the insulator is derived. From this, the flashover voltage of a polluted insulator of complex shape can be calculated. A computer program has been developed to calculate the flashover under both DC and AC. Some arc phenomena, such as arc bridging between the sheds or ribs of insulators, the drift of the arc from the insulator surface, and the number of arcs in series before flashover, are taken into account. Much experimentation has been done to determine the flashover voltages of polluted insulators with complex shapes under both DC and AC. Experimental data are in good agreement with the calculated results. >

77 citations


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