Types Of Insulators Research Articles

On the pyrolysis characteristic parameters of four flame-retardant classes of PVC sheathless cable insulation materials

Flame retardant cables are widely used today, while the comparison of thermal degradation behavior between PVC cable insulation materials with different flame-retardant levels has not been extensively studied so far. The thermal degradation behaviors of four flame-retardant and one non-flame-retardant PVC cable insulation materials were studied using thermogravimetric (TG) analysis and a combination of TG-Fourier transform infrared analysis. Generally, TG data differ at the first peaks but are similar at the second peaks for various types of insulation materials. This is because the reaction mechanisms of the first pyrolysis stage vary with the change of flame-retardant level, while the second pyrolysis stage is similar regardless of the flame-retardant level. Besides, the flame-retardant performance level cannot solely be evaluated based on the activation energy of these insulation materials. The coupled Fourier transform infrared spectroscopy (FTIR) shows that during the pyrolysis of flame-retardant PVC insulation materials (ZA-BV, ZB-BV, ZC-BV, and ZR-BV), the amount of the seven major released components, arranged in order from most to least, is C-H bending > H2O > C-H stretching > CO2 > C-H aliphatic bending > CH2 deformation > C-Cl stretching. While for the non-flame-retardant PVC insulation material (BV), the series is CO2 > C-H bending > C-H stretching> H2O > C-H aliphatic bending > CH2 deformation > C-Cl stretching. The reported results provide a basis to evaluate the thermal degradation behavior of typical PVC cable insulation materials at present and can also provide essential data for the numerical simulation of an electrical fire.

Acoustic properties of commercial thermal insulators

Material manufacturers give very limited or no information of the acoustic properties of thermal insulators in broad perspective. The purpose of our study was to compare the acoustic performance of commercially available thermal insulators. Thirteen insulator types produced by several manufacturers were studied. The acoustic performance was determined holistically by measuring six acoustic quantities: sound reduction index of bare insulator, sound reduction index of encapsulated insulator (insulator between two boards), normal incidence sound absorption coefficient, airflow resistivity, dynamic stiffness per unit area, and reduction of impact sound pressure level in a floating floor. All measurements were conducted according to prevailing ISO standards in an experienced test laboratory. The acoustic performance differed significantly between insulator types for each acoustic quantity. The ranges were 1027 dB, 3352 dB, 0.200.78, 3.02700 kPas/m2, 1.5730 MN/m3, and 1536 dB, when the thickness of the insulator was 100 mm. Closed-pore insulator types usually carried worse acoustic properties than open-pore insulator types. Lower thermal conductivity was associated with worse acoustic performance of two acoustic quantities. Insulator manufacturers should consider to better declare the acoustic properties of insulator products, because this knowledge is needed in the acoustic design of building constructions and other applications.

Optical properties of WTe2-a layered topological insulator: A DFT study

To assess its suitability for optoelectronic applications, the structural, electronic, and optical characteristics of a 2H type of layered WTe2 topological insulator have been examined using first principles DFT simulations. We have utilized single to four layers of two-dimensional 2H WTe2 for this purpose. An intriguing behavior has been uncovered in our studies. For 2H WTe2, monolayer to quad layer have distinct values for many optical characteristics such as the real and imaginary parts of the dielectric function, absorption coefficient, refractive index, etc. Our findings show that stacked 2H WTe2 might be useful in the production of optoelectronic devices.

Negative magnetoresistance in antiferromagnetic topological insulating phase of GdxBi2−xTe3−ySey

Antiferromagnetic topological insulators have attracted great attention in the condensed matter physics owing to the fundamental interest in exotic quantum states and topological antiferromagnetic spintronics. Starting with the typical topological insulator of Bi2Te3, we introduced the magnetic order by substituting Gd at the Bi site and tuned the Fermi level by substituting Se at the Te site. That is, we prepared single crystals of GdxBi2−xTe3−ySey with various x (= 0.02 and 0.06) and y (= 0.1, 0.2, 0.5, 0.7, 1.0, and 1.5). The magnetic data revealed an antiferromagnetic order for x = 0.06, and the transport data manifested the charge neutral point at y = 0.7. Combining all these results together, the material with x = 0.06 and y = 0.7 is characterized as an antiferromagnetic topological insulator, where we observed exotic magnetotransport properties such as weak antilocalization and negative longitudinal magnetoresistance that are frequently analyzed as chiral anomalies in Weyl materials.

Techno-Environmental Assessment of Insulation Materials in Saudi Arabia: Integrating Thermal Performance and LCA

Arid and hot regions, like Saudi Arabia, utilize up to 60% of the country’s energy to regulate buildings’ indoor comfort. Energy efficiency is a long-term sustainability measure that is part of the government’s Vision 2030 strategy. A standard method of improving the thermal performance of buildings is through the use of insulation materials. Considering the cooling loads’ requirement and the Global Warming Potential (GWP), the present research evaluated the effectiveness of insulation materials, including extruded polystyrene, expanded polystyrene, rock wool, and glass wool in the hot, arid climate. For this case study, four similar villas facing the cardinal directions were selected from the residential project at Qassim University. HOBO data loggers were used to collect indoor temperature data. Thermal performance and Life Cycle Assessment (LCA) were conducted in accordance with Saudi Building Code-602 (SBC-602). Simulation outputs based on the four cardinal directions were used for assessing the thermal performance and LCA of the different thicknesses and densities of insulation materials. This was done using IESVE and SimaPro, IMPACR2002+, to assess their cooling load and GWP, respectively. The results suggest the potential for using lower insulation thickness for the northern and western façades without violating the SBC. The results obtained the actual thicknesses of the three insulation materials for achieving indoor temperatures in the four cardinal directions and the selection of materials and their densities along with associated GWP. The outputs of the study have been generalized in the form of a performance-based flowchart as a tool for selecting the type and thickness of thermal and environmental insulation in residential buildings in the Qassim region of Saudi Arabia.

SF6 decomposition behaviour under partial discharge of typical insulation defects in gas‐solid insulated valve‐side bushing of converter transformer

AbstractIn this paper we investigated SF6 decomposition behaviour of typical insulation defects in gas‐solid insulated converter transformer valve‐side bushing under partial discharge (PD). Additionally, we compared the results with that of gas insulated switchgear (GIS). The results indicated that SF6 decomposition behaviour varies with the insulation defects type. For metal protrusion defects, the proportion ranking of CO2 and SO2 can be related to whether the needle tip is wrapped with epoxy resin‐impregnated paper (ERIP). The proportion of carbon‐containing products is much higher under contamination defect than under other defects. Moreover, the proportion of carbon‐containing components is higher under flashover condition than under PD condition and is accompanied by the appearance of H2S and CS2. However, the yield of SO2F2 is always low. Compared to negative DC voltages, positive DC voltages have a higher proportion of carbon‐containing components, mainly in the form of more CO2 and less SOF2. Compared to the PD decomposition behaviour of typical insulation defects in GIS, when PD involves ERIP, the proportion of carbon‐containing products, especially CO2, is significant higher, while the proportion of sulphur containing products, especially SO2F2, is lower.

Clothing thermal insulation of infant in stroller relating to evaluation of thermal environment of infant

The clothing thermal insulation for individual clothing ensembles of infant and strollers has been clarified. However, the clothing thermal insulation for the combination of them has not been measured at all. The purpose of this study is to examine the typical values of human factors such as the clothing area factor and clothing thermal insulation of an infant in a stroller. As typical clothing ensembles, seasonal combinations of infant clothing with a stroller were selected. The stroller was treated as part of the infant’s clothing. The clothing area factors were measured by using the photographic method. The clothing thermal insulations were measured by using an infant’s thermal manikin. The typical clothing area factor of an infant in a stroller is 3.67 for summer clothing, 3.75 for mid-season clothing, and 4.19 for winter clothing. The typical clothing thermal insulation of an infant in a stroller is 1.23 clo for summer, 1.39 clo for mid-season, and 1.97 clo for winter. The stroller was shown to significantly affect the body heat balance between the infant and the thermal environment.

Semiconductor–metal transition in Bi2Se3 caused by impurity doping

Doping a typical topological insulator, Bi2Se3, with Ag impurity causes a semiconductor–metal (S-M) transition at 35 K. To deepen the understanding of this phenomenon, structural and transport properties of Ag-doped Bi2Se3 were studied. Single-crystal X-ray diffraction (SC-XRD) showed no structural transitions but slight shrinkage of the lattice, indicating no structural origin of the transition. To better understand electronic properties of Ag-doped Bi2Se3, extended analyses of Hall effect and electric-field effect were carried out. Hall effect measurements revealed that the reduction of resistance was accompanied by increases in not only carrier density but carrier mobility. The field-effect mobility is different for positive and negative gate voltages, indicating that the EF is located at around the bottom of the bulk conduction band (BCB) and that the carrier mobility in the bulk is larger than that at the bottom surface at all temperatures. The pinning of the EF at the BCB is found to be a key issue to induce the S-M transition, because the transition can be caused by depinning of the EF or the crossover between the bulk and the top surface transport.

Energy Performance Assessment of the Container Housing in Subtropical Region of China upon Future Climate Scenarios

Being continuously abandoned in huge amounts year-round by freight industry, shipping containers meet increasing regenerative utility in forms of temporary buildings, small public facilities, etc., especially in fast-developing countries with large populations and high living intensities like China. Although recycled containers have been nicely entitled with green building visions, their characterized inferior thermal properties (low inertia, poor insulation, etc.) when compared to conventional building forms and materials will greatly hinder their energy-saving potential, especially under the serious future extreme climate expectations. It therefore becomes particularly necessary to uncover the actual energy and thermophysical behaviors of the container building typology, upon extreme future climate scenarios targeting zero carbon forms for small-scale and temporary buildings in the upcoming future. In reference to existing data, this study made reasonable predictions of future extreme climate conditions (2050 and 2080), employing the Morphing method, and examined the cooling energy performances of the typical container housing in a subtropical climate through dynamic simulations. The energy-saving effectiveness of key design variables including insulation types, thicknesses, window opening areas and air infiltration rates has been validated and quantitatively revealed for such a building typology among the tested hot summer and warm winter region. Results imply that the additional energy burden brought by future extreme weather conditions cannot be ignored. The heat gains from envelopes and hot air infiltration are both key design factors of cooling energy increments for such building types upon future extreme climates. Compared with expanded pearl- and vermiculite-type insulation materials, thinner (70~90 mm) plastics and mineral wool-type ones have better energy-saving performance and therefore are worth consideration. High air infiltration rates and window openings in eastern or western orientations shall be carefully selected. The research outcomes can provide key references for design decisions made for the energy-efficient and low-carbon design of the container building typology among subtropical zones, or similar climate regions in response to future climate conditions.

Experimental researches of elastomeric materials to stabilize the oscillation of power grid structures

This paper proposes a new type of insulator, has both insulating and damping properties to improve the operational reliability of overhead power lines' structures (OHPL). In order to assess an effectiveness of the new insulator's design have made laboratory tests of a insulator model with different types of elastomer seals, differed of the rubber marks and the type of reinforcement. An experiment consist of two stages: at the first stage an object of study has been exposed to cyclical vibration, at the second – the impact of an impulsively load. Results of the research showed, that the most effective are the elastomeric gasket with a minimum rigidity characteristics without reinforcement. Using insulators with such dampers allows to reduce the first maximum impulse to a support by an average of 20% and reduce the frequency and amplitude characteristics of the system. Based on this was developed a new type of elastomer reinforcing with steel sheet elements in the form of a truncated cone.

Influence of External Surface Radiation Properties on Thermal Performance of Walls——Take a typical office building in Chengdu as an example

In this paper, taking a typical office building in Chengdu as an example, the coupling relationship between the radiation properties (short-wave absorption coefficient and long-wave emission coefficient) of the external surface materials of the wall and the insulation types and the insulation performance is studied by using software simulation method. The results show that the internal insulation wall is beneficial to reduce the heating load while the external insulation wall is beneficial to reduce the cooling load. And the external surface material's radiative properties hardly affect the wall insulation type choice. Still, in the case of Chengdu office buildings, interior insulated walls are more conducive to year-round building energy efficiency. In summer, the radiation characteristics of the outer surface material will affect the choice of the best heat transfer coefficient (U-value) of the wall. When the short-wave radiation absorption coefficient is small, the wall with good insulation performance will appear anti-energy-saving phenomenon. Therefore, it is recommended that the regions with high cooling loads fully consider the influence of the external surface material's radiation properties on the wall's thermal performance in the design of the thermal performance of the wall.

AIR PASSENGER TERMINAL DESIGN IN THE FRAMEWORK OF THE SUSTAINABLE DEVELOPMENT STRATEGY

The construction of new passenger air terminals, reconstruction or expansion of existing ones should take place with a decreasing in the impact on the environment, taking into account the strategy of sustainable development and environmental, social and economic aspects recommended by the Global LEED certification system. The construction sector is beginning to realize that sustainability is key and technology has an important role to play in helping to achieve the Sustainable Development Goals. Building information modeling (BIM) can help achieve all of the Sustainable Development Goals. BIM can impress with its performance. Primarily, BIM realizes this advantage through its ability to facilitate communication and coordination, identify clashes, and reduce costs. The information model of the air passenger terminal contains not only geometric data, but also all energy data and information such as insulation type, opaque enclosure structures, glazed structures, energy sources, climate data, aspects of heating, cooling and ventilation. In this case, engineers can work with building energy model BEM. The design, construction and operation of air passenger terminals must be carried out in accordance with the design dimensions of sustainable terminals, it is necessary to implement modern technological developments, such as intelligent systems, BIM-technologies, ecological and renewable building materials, alternative energy sources.

Исследование радиочастотных характеристик RFID-индикаторов для линейных полимерных изоляторов различного уровня напряжений

The article describes the possibilities of using the digital method of non-destructive testing of polymer linear insulators using RFID technologies. The possibility of installing RFID indicators is being considered not only on specially designed insulators with built-in electrodes, but also on standard insulators currently produced by Russian manufacturers. The location of RFID indicators for installation on polymer linear insulators of the LC type is shown. A comparison of the radiation patterns of RFID indicators installed on polymer insulators with the voltage of 110 and 35 kV is provided, the results obtained are analyzed. Conclusions are drawn about the possibility of using RFID-indication for insulators at different voltage levels for both overhead power lines and contact network insulators.

Study on Intermittent Discharge Characteristics of Typical Solid Insulation Defects in Gas Insulated Switchgear

Study on Intermittent Discharge Characteristics of Typical Solid Insulation Defects in Gas Insulated Switchgear

Investigation of oil level and type of solid insulator on creeping discharges propagating under an ac electric field

The Journal of the National Science Foundation of Sri Lanka publishes the results of research in all aspects of Science and Technology. The journal also has a website at http://www.nsf.gov.lk/. 2021 Impact Factor: 0.682The JNSF provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.Cover :Leatherback (a), green (b - adult & f - hatchling), hawksbill (c) and olive ridley (d) turtles who nest in Sri Lankan beaches, green turtle crawl marks (e) and by-catch of sea turtles in fisheries (c & d)Photo credits: SJ Perera (a & c), WPN Perera (b & e), K Ekaratne (d & f)

Analysis of design and structural features of the external insulation materials of high-voltage devices

In the article, the authors have analysed the design and structural features of various materials for external insulation of high-voltage apparatuses, namely, high-voltage equipment of stations and substations. The operational reliability of the external insulation is determined mainly by the electrical load, which is characterized by the local values of the field strength. The field strength along the insulating cover is distributed very unevenly and has a maximum value near the electrode with high voltage. Electrical isolators are used in all high-voltage apparatus of electrical transmission and distribution circuits to separate the voltage from the ground. The materials used in the development and production of electrical insulators have certain unique characteristics. These materials prevent the free passage of internal electric charges in the material, which makes it practically impossible to conduct an electric current. The ability of a material to prevent electrical conductivity is characterized by its dielectric strength. Polymer insulators allow you to combine high mechanical strength with satisfactory electrical characteristics. In such combined structures, fiberglass rods or cylinders are used as an element that withstands mechanical load. Also, the design of the internal insulation of the capacitor type, impregnated and filled with hardened epoxy resin, allows for particularly precise winding of the synthetic material and the placement of aluminium foils, which provide the capacitive levelling of the graduation and are necessary for the control and formation of the electric field. Such a field is controlled in such a way as to optimize the dimensions, mass and electrical characteristics of the high-voltage apparatus depending on the voltage class and other parameters. The protective polymer coating provides high electrical characteristics of insulators under operating conditions. It is known that during the operation of the high-voltage device, the aging rate of the external insulation is additionally enhanced due to the complex and heterogeneous structure of the insulating cover itself, as well as the influence of the surrounding environment and weather conditions. The main element of external insulation is the supporting insulating cover, in the middle of which the elements of the active part of a certain electrical device are placed. Its basis is usually a glass-epoxy cylinder (this ensures the mechanical stability of the structure), on which ribs made of organosilicon rubber are placed, which in turn ensures the electrical strength of the external insulation.

Predicting novel atomic structure of the lowest-energy Fe n P13–n (n = 0–13) clusters: A new parameter for characterizing chemical stability

A series of novel atomic structure of lowest-energy Fe n P13–n (n = 0–13) clusters via density functional theory (DFT) calculations and an unbiased structure search using Crystal structure AnaLYsis by Particle Swarm Optimization (CALYPSO) code. Our research results show that the global minimum geometry structure of neutral Fe13–n P n (n = 0–6) clusters tend to form cage structures but the lowest-energy Fe13–n P n (n = 7–13) clusters are gradually evolution from a cage structure to a chain shape geometric structure. Their geometric structure should responsible for the raise of binding energy from Fe7P6 to P13 clusters rather than chemical components. This is completely different from a linear relation of the binding energy with chemical components in our previous research for Cu n Zr13–n (n = 3–10) clusters (J. Mol. Liq. 343 117603 (2021)). Hence, in order to characterize the global chemical stability of target cluster, we proposed a new parameter (jyq = η/χ) that the chemical hardness of isolated cluster is used to be divided by its electronegativity. One of the biggest advantages of this parameter is successful coupling the ability of a resistance to redistribution of electrons and the ability to attract electrons from other system (such as atom, molecular or metallic clusters). Moreover, it is found that the P13 cluster shows typical insulator characteristics but the Fe12P1 shows typical conductor characteristics, which phenomena can be attributed to the remarkable delocalized and localized electrons in Fe12P1 and P13, respectively. In terms of nearly-free-electron mode, we also found that the number of electrons on Femi level (N(E F)) are obviously tended to toward a lower value when Fe was replaced gradually with P from Fe13 to P13, and a non-magnetic can be observed in Fe13, Fe2P11, Fe1P12, and P13 that mainly because their perfect symmetrical between spin-up and spin-down of density of states of electrons.

Topological properties of Xene tuned by perpendicular electric field and exchange field in the presence of Rashba spin–orbit coupling

Xene (X=Si, Ge, Sn) is a typical and promising two-dimensional topological insulator with many novel topological properties. Here, we investigate the topological properties of Xene tuned by a perpendicularly applied electric field, exchange field, and Rashba spin–orbit coupling (RSOC) using the tight-binding (TB) method. We show that in the presence of RSOC, the system can be converted from a quantum spin Hall (QSH) insulator into a conventional band insulator (BI) by a weak perpendicular electric field or into a quantum anomalous Hall (QAH) insulator by a weak exchange field. Additionally, a suitable combination of electric and exchange fields can give rise to a valley-polarized metallic (VPM) state. Furthermore, we explore the competition between the electric field and exchange field in tuning the topological states owing to the Rashba coupling effect. When the electric field is stronger than the exchange field, the system tends to be in a topologically trivial BI state; otherwise, it will be a QAH insulator. More intriguingly, for a fixed exchange field and RSOC, as the perpendicular electric field increase continuously from zero, the system undergoes multiphase (e.g. QSH-VPM-BI) transitions. This paves the way for designing multiphase transition devices through external single-field regulation.

Зависимость воздухопроницаемости стеклослюдинитовых лент от технологии их изготовления

The main part of technological processes in almost all industries, including those related to transportation, processing of mineral raw materials, cannot be implemented without the use of electric motors. The high reliability of these machines ensures trouble-free operation and guarantees the safety of people in these industries. The reliability indicators of electric machines depend on the insulation condition of the windings, which is largely determined by the saturation of the winding cavities with the impregnating compound that penetrated them during impregnation. Various manufacturing technologies of mica-containing electrical insulating tapes used as case insulation of coils of traction electric motors (TED) are considered. The main reasons for the failure of traction engines are presented. The existing types of insulation, their possible composition, features and applications are described. A brief description of the main methods of manufacturing electrical insulating mica-containing tapes is given, an assessment of the strengths and weaknesses of each of the technologies are presented. The methods of testing the initial semi-finished tapes and finished insulation are described.

A Numerical Simulation to Select the Optimal Thermal Agents for Building Parts

The use of thermal insulation is one of the most crucial solutions for reducing energy consumption when designing buildings. In this study, we investigate the use of various types of thermal insulation (air, cellulose, fiberglass, mineral wool, polystyrene, and polyurethane foam) to determine the best location when designing. The numerical study is done using ANSYS/FLUENT 16 software and an enthalpy-porosity formalism. According to the study's findings, all heat insulators investigated offer effective insulation, but some of them, like air, have characteristics that make them challenging to employ. The remaining insulators satisfy all requirements for usage as a thermal insulator. Given that it possesses all the necessary characteristics to be used as a thermal insulator, (polystyrene) is one of the most important insulators that are readily available locally. The use of thermal insulation in buildings reduces the need for refrigeration equipment to maintain comfortable conditions, which has a significant negative impact on the environment.