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.

The Effect of the Nonlinearity of the Response of Lipid Membranes to Voltage Perturbations on the Interpretation of Their Electrical Properties. A New Theoretical Description.

Abstract: Our understanding of the electrical properties of cell membranes is derived from experiments where the membrane is exposed to a perturbation (in the form of a time-dependent voltage or current change) and information is extracted from the measured output. The interpretation of such electrical recordings consists in finding an electronic equivalent that would show the same or similar response as the biological system. In general, however, there is no unique circuit configuration, which can explain a single electrical recording and the choice of an electric model for a biological system is based on complementary information (most commonly structural information) of the system investigated. Most of the electrophysiological data on cell membranes address the functional role of protein channels while assuming that the lipid matrix is an insulator with constant capacitance. However, close to their melting transition the lipid bilayers are no inert insulators. Their conductivity and their capacitance are nonlinear functions of both voltage, area and volume density. This has to be considered when interpreting electrical data. Here we show how electric data commonly interpreted as gating currents of proteins and inductance can be explained by the nonlinear dynamics of the lipid matrix itself.

Current, luminosity, and X-ray emission in the early phase of dielectric surface flashover in vacuum

Abstract: With high-speed electrical and optical diagnostics, an attempt is made to elucidate the physical mechanisms leading to surface flashover. The experimental device uses a cable discharge to study self-breakdown along the surface of an insulator in vacuum. Preflashover current, breakdown voltage, luminosity, and soft X-ray emission are measured in temporal correlation with a resolution of 1 ns. The results show a linearly increasing current in the subampere range, and a corresponding linearly increasing luminosity, before an exponential increase of both signals takes over. The linear phase is accompanied by X-ray emission which ceases at the onset of the exponential phase. The strong influence of externally applied magnetic fields on the linear phase points to the existence of free electrons above the surface during the early phase of flashover. A linear current rise without magnetic field and the formation of a current plateau with an insulating magnetic field indicate a saturation of the current amplification mechanism in the early phase. >

Metal particle movement and distribution characteristics under AC voltage and ball-plane electrodes

Abstract: Metal particles, difficult to be eliminated in gas-insulated metal-enclosed switchgear (GIS), can cause GIS discharge and breakdown between electrodes, or flashover on the insulator surface. It influences the development of ultra-high voltage (UHV) projects. Therefore, the work optimised the model of metal particle movement under AC voltage, studying the metal particle movement and distribution characteristics between ball-plane electrodes through experiment and simulation. Under AC voltage, the particle jumps on a small scale on the plane surface. With the increase of voltage, the jump amplitude increases. However, the collision frequency decreases until the particle collides with the ball electrode. When the initial phase angle of power changes, the particle-moving pattern is symmetrical in the angle ranging from 0 to 180°, and from 180 to 360°. The collision frequency changes slightly with the increase of jump amplitude when the angel ranges from 0 to 120°.

Non-Uniform Distribution of Contamination on Composite Insulators in HVDC Transmission Lines

Abstract: In recent years, the air particulate pollutants formed by the combustion of fossil fuels and the emission of industrial waste gases have constantly been produced, and the polluted particles deposit also seriously affects social production and people’s lives. For instance, pollution-induced flashover is seriously threatening the safe operation of the power system, while insulator pollution non-uniformity has great influence on the flashover voltage of insulators. Therefore, in this paper both field contamination experiments of HVDC (High Voltage Direct Current) transmission lines and wind tunnel contamination simulation tests were conducted, and pollution non-uniformity coefficient KT/B, KW/L and KH/M were proposed and obtained. The results showed that the degree of contamination on top surface and leeward side is heavier than that on bottom surface and windward side. Thus, in the DC energized condition, contamination along the string is also non-uniform, and serious pollution occurs mainly in the high voltage terminal. In order to explain the uneven distribution phenomenon along the string, the coupling-physics model of composite insulator string was established and using the finite element method, the electric field around the insulator was simulated. Furthermore, basing on the field charging theory, the value of electric field force on particles around the insulator surface was calculated and the mechanism of non-uniformity along the insulator sting was then explained. The results are very important for guiding insulation design and field anti-pollution works.

Topology optimization and 3D-printing fabrication feasibility of high voltage FGM insulator

Abstract: This paper presents the design method using topology optimization and the fabricating feasibility using Fused Deposition Modeling (FDM) 3D printing technique for Functionally Graded Material (FGM) insulator. The concepts of FGM and topology optimization are primarily introduced. And a topology optimization approach based on COMSOL Multiphisics is proposed. The optimization objective is to uniform the electric field (E-field) inside/along insulator surface for high electrical withstanding strength. As a result, a proper distribution of permittivity inside the insulator is obtained and the maximum value of E is significantly reduced. The higher the upper bound of permittivity is, the better E-field uniformity is. Finally, it is shown that FDM technique has the potential to be applied to fabricating FGM insulator. However, several technical obstacles have to be overcome before industrial application.