Hybrid Insulation Research Articles

Polyphosphazene with excellent superhydrophobicity, electrical insulation, flame-retardancy, and mechanical durability for composite insulators

Composite insulator is an important component of the power system which has high requirements for insulating properties, hydrophobicity, long-term reliability, and safety. Aiming to improve the comprehensive performance of composite insulators, we propose a novel composite based on polyphosphazene matrix and inorganic fillers including h-BN, SiO2 and aramid pulp (AF-p). By the synergistic effect of the optimized chemical structure of polyphosphazene and modification by multi-scale hydrophobic electrical insulation fillers, the poly(difluoroalkoxy)phosphazenes (PDFP) composite presents enhanced hydrophobicity with the static water contact angle (WCA) up to 154° and rolling angle (RA) as low as 8°. Benefiting from the multiscale roughness constructed by multi-fillers, the PDFP composite exhibits superior mechanical durability. The contact angle of the sample still exceeds 150° after abrasion by sandpaper (800#) for 1000 cm. Meanwhile, with the addition of hybrid insulation fillers, the Weibull breakdown strength of PDFP/30h-BN/10SiO2-200/6AF-p is improved by 76 % compared to PDFP. Besides, the unique elemental composition of PDFP endows the PDFP composite with excellent flame retardancy with a 55 % limiting oxygen index and V-0 of the UL-94 grade, which guarantees safety for insulator applications. The results confirm the great potential of polyphosphazene for composite insulators.

Study on Preparation and Application Technology of Micro scale New Foam Ceramics for Power Equipment

With the proposal of a new type of power system in China, the new environment-friendly insulating medium micro nano foam ceramic is urgently needed to replace SF6, epoxy resin and other insulating materials in the GIS/GIL key power equipment. The new material technology can prepare: foam ceramic design method. Preparation method of foam ceramics and the functional modulation of micro/nano structures. The electrical performance of the foam ceramics was improved. Achievable: the stable performance of micro/nano structures under the high field strength. Excellent thermal conductivity under high current action. It has local replacement function in insulation material applications such as SF6 and epoxy resin. Detectable: Starting from the electrical performance of the UHV hybrid insulation material system, UHF technology and photo-acoustic spectroscopy technology are applied to the high sensitivity detection of the decomposition products and partial discharges of foam ceramics, focusing on types of fluorocarbon decomposition gases, making use of strong correlation between the decomposition products and the partial discharge detection data, and combining the multi-source data fusion algorithm to achieve the prediction of insulation structure data sequence and online detection of the latent faults for the special GIS/GIL.

Inkjet‐Printed Flexible Thin‐Film Thermal Sensors for Detecting Elevated Temperature Range

All inkjet‐printed thermal sensors are manufactured based on a metal–insulator–metal (MIM) interface or capacitor architecture, for the adapted device size ranging from 16 to 36 mm2 active area. Two different material inks, namely a nanoparticle conductive silver ink and an inorganic‐polymer‐based hybrid insulator ink, are applied layer by layer on a thin flexible polyimide substrate, for developing the printed MIM devices. To ensure the desired electronic conductivity and insulation from the layers, the manufacturing process steps and parameters are tuned, accordingly. The results show that the inkjet‐printed MIM devices could constitute up to 15 μm thickness and demonstrate average detection of a change in electrical capacitance ranging from 20 to 100 pF, when the temperature is varied between 100 and 300 °C. The investigations also summarize that the change in the electrical response is enough to detect an increment of 50 °C. The printed sensors also display high operational stability and repeatability, when subjected to thermal cycling.

Hybrid ceramic insulation made of oxide fiber ceramic matrix composite and paper-based ceramic for hot forming tools

Many modern automotive and aerospace components are heat-formed at temperatures up to 900 °C. Due to the high tool temperature, insulations are employed to reduce the heat loss and the energy consumption of the process. However, current insulation materials for the force flow of these processes still require active counter-cooling. In this study, the performance of a novel hybrid structure with improved insulation capability for such applications was investigated. It consisted of an outer frame made of an oxide fiber composite (OFC) and a paper-based ceramic (PBC) as a filler. The mechanical and thermal properties for both materials were determined and implemented in a finite element model (FEM) to numerically design the layout of a hybrid structure. Experimental load tests in process-oriented conditions validated the simulation results. The hybrid insulation appears promising, as mechanical stability and good insulation capabilities were confirmed.

Thermal insulation capability of nanostructured insulations and their combination as hybrid insulation systems

The applications of insulation materials in buildings and vehicles are more important than ever. Therefore, the application of thermal insulation materials having high-performance heat-blocking properties such as nano-structured insulations like aerogels and graphite polystyrene is essential. In this paper a comprehensive thermal characterization will be presented, executed on two types of fibrous aerogels (slentex, pyrogel) as well as on graphite-expanded polystyrene, to compare their thermal insulation capability. Moreover, their possible sandwich-structured application as hybrid insulation systems was tested, too. The surface analysis of the samples is going to be presented through microscopic and wetting experiments. Thermal conductivity as well as specific heat capacity measurement results of both individual and sandwich structures will be shown. Slentex aerogel has the lowest thermal conductivity and performed best of all. The results of the hybrid structures are promising. The moisture uptake of the pyrogel aerogel is the highest. Based on the measured values theoretical models will be applied for validation, moreover, a face-to-face analysis will also be presented. Furthermore, calculations regarding thermal properties will also be highlighted. Results of both infrared absorption tests and differentiated scanning calorimetry would help the decision makers and it proves the high infrared absorption of graphite polystyrene.

Trend of Sulfur Hexafluoride (SF6) Gas Mixtures and Other Alternatives as Insulation Gas: an Overview

Research works are actively ongoing to seek a solution for reducing the usage of sulfur hexafluoride (SF6) as a gas insulator in high-voltage equipment since it was listed as one of the greenhouse gases under the Kyoto Protocol. However, manufacturers still in favor of using SF6 due to its excellent insulation and arc-quenching properties. One way to reduce SF6 usage is to mix it with other gases or replace it with alternative gas mixtures. The research status of SF6 gas mixtures and other potential substitutes is summarized in this paper. Electrical insulation properties, physical and chemical mechanisms, and environmental considerations, along with the scope and limitations of such mixtures were analyzed. The development prospects of SF6 gas mixtures were forecasted based on their best mixture ratio. Hybrid insulation gases consisting of three compounds (two electronegative gases with one buffer gas) have shown to be an ideal compromise in terms of cost, distinguished low environmental impact, and high dielectric strength. Trifluoroiodomethane (CF3I) offers great advantages among other dielectric gases, since it exerts minimal greenhouse effects, and has a considerable liquefaction temperature and higher dielectric strength. Therefore, the application of CF3I for reducing the usage of SF6 in gas mixtures was highlighted. The fundamental knowledge on the breakdown strength of the gas mixtures and their behavior under different electric fields need to be analyzed before any recommendations can be made.

Electric driving of magnetization dynamics in a hybrid insulator

Established forms of electromagnetic coupling are usually conservative (in insulators) or dissipative (in metals and semiconductors). Here, we point out the possibility of nondissipative electric driving of magnetization dynamics, if the valence electronic states have nontrivial topology in the combined space of crystal momentum and magnetization configuration. We provide a hybrid insulator system to demonstrate that the topology-based nonconservative electrical generalized force is capable of supporting sustained magnetization motion in the presence of Gilbert damping, with quantized and steady energy pumping into magnetization motion from the electric field. We also generalize our results to magnetic textures, and discuss an electric-field-induced Dzyaloshinskii-Moriya interaction which can be nonconservative.

AC Performance of HTV-SR and Its Hybrids Loaded with Nano-/Micro-Silica/ATH Fillers

In the present study, long-term multi-stress aging performance of silicone-based polymeric insulators was investigated for possible use on high-voltage alternating current transmission lines in Pakistan. One neat sample of high-temperature-vulcanized silicone rubber and four silica and alumina trihydrate filled hybrid composites were studied for 5000 h under accelerated multi-stress aging simulating environment of Karachi. Several measurements and diagnostic techniques such as hydrophobicity assessment, leakage current measurement, scanning electron microscopy, Fourier transform infrared spectroscopy, tensile testing and shore-A hardness were deployed to better establish a reliable comparison of resistance-to-aging among the investigated samples. Through extensive analysis of all measured data, it was established that among the investigated five samples, the specimen representing silicone hybrid composite containing 2% nano-silica and 20% micro-silica showed the most superior performance. Expanding grid in Pakistan which has been facing several challenges in terms of pollution-related flashovers maybe made more reliable through use of silicone rubber hybrid insulators.

Análise de desempenho e ciclo de vida de isoladores do sistema de distribuição de energia em ambientes de elevada agressividade

Neste estudo, foi avaliado o sistema de distribuição de energia frente ao desempenho em durabilidade de materiais e seus aspectos ambientais, com relação às análises do ciclo de vida (ACV) de isoladores elétricos de diferentes tecnologias, avaliando ensaios de desempenho individual e os principais impactos gerados sob a perspectiva “de berço ao túmulo”. Inicialmente, para o estudo de desempenho, foram considerados nove isoladores distintos, os quais foram submetidos aos ensaios de névoas limpa (48 h) e salina (360 h), com medidas de hidrofobicidade e de corrente de fuga, além da aplicação de poluentes artificiais. Após a realização dos testes, foram selecionados quatro destes isoladores com os melhores desempenhos, para então realizar os estudos de ACV por meio do software SimaPro 8.3. Pelos resultados de desempenho pode-se inferir que os isoladores que possuíam revestimentos de silicone e obtiveram os menores valores de corrente de fuga durante os ensaios de névoa limpa e salina, indicaram melhores atuações em ambientes agressivos. Já, por intermédio da ACV foram verificados os impactos ambientais dos isoladores de características equivalentes, uma vez que três desses possuíam a porcelana como material principal constituinte. O isolador híbrido de núcleo de resina com fibra de vidro revestido com silicone indicou os menores impactos ambientais devido à sua baixa quantidade de massa em relação aos outros, porém não foi possível verificar a qualidade dos dados implementados nos ICVs.Palavras-chave: Isoladores, rede de distribuição de energia, estudo de desempenho, análise do ciclo de vida, impactos ambientais.

Breakdown path and condition of air-insulated rod–plane gap with polymeric barrier inserted under alternating voltages

In order to improve the insulating performance of air-insulated high voltage electrical apparatuses, solid barriers are always introduced in the interelectrode gaps. The breakdown paths and conditions of air-insulated rod-plane gaps in the range of 2–5 cm under alternating voltages were investigated for three different sizes of polyvinyl chloride barriers inserted at different gap positions. The breakdown processes were observed using two cameras placed in orthogonal directions, and two typical breakdown paths were captured. The statistical results showed that the occurrence probabilities of the two typical breakdown paths were related to the barrier position, but that the breakdown voltages were very similar in all breakdown events. Further, formulae to predict the breakdown voltage were deduced using a linear regression method. The results provide a reference for improving the insulation performance of gas–solid hybrid insulation systems based on the barrier effect as well as for modelling gas discharges in hybrid gaps.

Energy retrofit analysis of cross-laminated timber residential buildings in Seoul, Korea: Insights from a case study of packages

Cross-laminated timber (CLT) is a potential option to achieve reductions in carbon emissions and energy consumption. CLT construction systems are environmentally friendly compared to more energy-intensive materials. In this study, the mid-rise apartments with CLT proposed by ASHRAE 90.1 were analyzed for energy consumption. First, the energy consumption of CLT buildings during heating and cooling was analyzed using four types of insulation. For CLT buildings, the airtightness was approximately 0.61 ac/h, (about 0.2 ac/h lower than that of the steel-frame buildings), suggesting that air-tight performance can reduce energy consumption. Energy-saving technology packages were applied to CLT buildings using rock wool insulation, which showed the highest total energy savings of 82.71 MWh, indicating economically advantageous hybrid-insulation. After the analysis of energy consumption according to the type of insulation, the energy retrofit was applied. Second, five energy-saving packages (including energy-saving, heating and cooling, and renewable energy technologies) were applied to two selected CLT buildings to further study energy consumption and energy efficiency. For CLT building using hybrid insulation, Package 3 reduced the total energy consumption by 14.14%, while for CLT building using rock wool insulation, Package 3 had the highest total energy consumption at 12.81%.

Cardiac pacemakers: a basic review of the history and current technology

In the 60 years since the first human implant of a cardiac pacemaker, tremendous improvements have been made to devices themselves as well as the lead systems. Improvement in battery materials has allowed for production of smaller devices with greater longevity and a vast array of technologies allowing for communication between the device and the operator. Lead wires, typically to as the weakest part of the pacing system, have also seen a metamorphosis as improvements in conductor materials and hybrid insulation have been shown to improve reliability. With the recent development of leadless pacing systems, the downfalls of implantable leads can be avoided. These improvements have allowed a more widespread use of cardiac pacing in veterinary applications since the first reported canine implant in 1967.

Long Range Multilayer Hybrid Plasmonic Waveguide Components and Integrated Circuit

In this work, CMOS compatible hybrid insulator metal insulator (HIMI) planar plasmonic waveguide based components such as, racetrack ring resonator, y-splitter, coupler and dual parabolic profile nano antenna have been proposed and investigated at 1.55 μm operating wavelength for the first time. The proposed components are analyzed at various parametric variations using CST microwave studio. The proposed racetrack ring resonator offers 153.88 nm free spectral range, 0.3232 nm FWHM and 46.57 dB extinction ratio at 0.40 μm radius and 0.49 μm separation length. Y-splitter divides equal power of 46.85% in both output arms and coupler couples till 86.5% power in coupled arm. The dual parabolic profile nano antenna offers a gain, bandwidth and efficiency of 7.99 dB, 203 THz and 84.56 % respectively. Using all the components, HIMI plasmonic integrated circuits have also been designed and investigated for on chip applications. Proposed components work very efficiently in chip scale integrated circuit. This investigation provides groundwork for future chip scale applications.

Design and Performance of Transverse-Type Thin-Film Nano-Thermoelectric Generators

Design methodology and performance of nano thermoelectric generators (nTEGs) using human body heat are investigated for wearable device applications. A transverse type of module suitable for a thin-film thermopile is employed for the nTEGs. It is revealed that the thermal and electrical insulation of the interspace of their modules is an important factor to determine the output power of the nTEGs. A new module structure using insulator/vacuum hybrid insulation with its design methodology that maximizes the output power is developed. Output power of a few milliwatts can be achieved by a wrist-band style mounting of the nTEG module with an optimized design.

Dual-Gate Phototransistor With Perovskite Quantum Dots-PMMA Photosensing Nanocomposite Insulator

Dual-gate InGaZnO thin-film-transistors were fabricated to demonstrate their feasibility as phototransistors by fully exploiting the perovskite quantum dots (QDs) with superior quantum yield. Here, we show that by coupling the top-gate photo sensing polymethyl methacrylate (PMMA)/CsPbBr3 QDs hybrid insulator with the classic SiO2 bottom-gate insulator, the phototransistor can exhibit a combination of excellent detective performance ( $3.75\times 10^{12}$ Jones detectivity and $1\times 10^{3}\text{A}$ /W responsivity) and electrical performance (small 3-V threshold voltage, 0.53-V/decade substhreshold slop, and 0.1-V hysteretic threshold voltage’s shift). Additionally, this dual-gate phototransistor exhibits high stability and accelerated detecting speed ( $ ) due to the inorganic perovskite QDs/PMMA hybrid gate insulator. Our results suggest that in a proper device architecture, perovskite nanomaterials can be promising candidates for cost-effective, high-performance phototransistor.

Hybrid Insulator Metal Insulator Planar Plasmonic Waveguide-Based Components

This is the first report on investigation of CMOS compatible hybrid insulator metal insulator (HIMI) planar plasmonic waveguide-based components. In this letter, a realistic planar HIMI plasmonic waveguide, which offers good balance between propagation length (253 μm) and confinement (38%), has been studied at 1.55-μm operating wavelength for designing various waveguide components. Key components, such as 90°, Sand U-shaped bends, have been investigated and their transmission and loss characteristics have been analyzed at different bend radii. The components exhibit transmittance up to 80% at various bend radii within a confinement area of 0.25×0.04 μm 2 . This investigation could be fruitful in designing plasmonic integrated circuits for chip-scale applications.

Long term performance of vacuum insulation panels in hybrid insulation district heating pipes

This paper presents studies on district heating pipes where a vacuum insulation panel replace the innermost layers of polyurethane around the service pipe. One of the main challenges are their long term performance. Prototypes have been tested both in field in a district heating grid and in laboratory with a constant temperatures. The results indicate that the panels are intact after four years in field. In the laboratory, the pipes have been exposed to a constant temperature of 115°C for over three years without damage to the panels.

The impact of the temperature dependent thermal conductivity of insulating materials on the effective building envelope performance

Constant thermal conductivity values of insulating materials are typically used in building design and assessment. However, the thermal conductivity depends on many factors, such as on the temperature and moisture content. Linear temperature-dependent laws have been occasionally proposed for inorganic fibrous materials such as fiberglass or rock wool that exhibit a decreased thermal conductivity (better performance) at low temperatures. However, the petrochemical-foamed insulating materials such as the polyisocyanurate, have less regular temperature dependent behaviors with a poorer performance at both extremely cold and warm temperatures. This means that the use of constant thermal conductivity values results in actual building envelope performance different from the design predictions, with increasing building energy consumptions, greater risks of condensation issues, and decreased occupants’ comfort. This paper aims to quantify the impact of the temperature dependency of the thermal conductivity in exterior walls and flat roofs. Experimental results over a large temperature range (from −20°C to +60°C) for different insulating materials were used in hygrothermal simulations in both continental and humid temperate climates. Common insulating materials were taken into accounts, such as fiberglass, rock wool, polyisocyanurate, and extruded polystyrene. The increase in the energy fluxes from common building envelopes once the effective thermal conductivity was considered resulted below 10% for walls and as high as 70% for roofs, especially in the cold weather. Finally, a hybrid insulation system constituted by two layers of different materials, i.e. a polyisocyanurate and a rock wool is investigated.

Ceramic and hybrid support insulators for UHVDC systems

The requirements for UHVDC installations in terms of length, mechanical strength, permissible deflection, creepage distance, shed profiles and pollution resistance are still a challenge for all existing technologies and solutions. Based on the positive long time experience with solid core porcelain post insulators and the pollution experience of insulators with silicone housings the fundamental concept of both were used to develop a new type post insulator with inside ceramic core and housing of silicone. The challenge was to provide a reliable and economical solution, which combines the advantages of both technologies. Realising the needs for high strength, low deflection under load for many applications PPC Insulators Austria began the development of hybrid post insulators. The ceramic solid core design provides superior advantages in terms of bending strength, also for torsion load and compression load. The silicone rubber housing allows thinner sheds and greater creepage distances, provides improved long term pollution flashover performance and protects the core from short circuit arc damage. As design for DC hybrid post insulators was chosen upright tapered, uniform and underhung tapered insulators columns stacked of single hybrid insulator sections. The single sections could be varied in core diameter, length, creepage distance, fittings and holepattern. The shed profile used for DC applications was defined according the recommendations given by CIGRE. Selected design tests, electrical and mechanical type tests were conducted according to the relevant parts of IEC standards for composite and ceramic insulators. Also a long term test installation was performed to establish a confidence in this product. The long term test installation has been energized at 725 kV DC and later the voltage was increased to 761 kV DC. The tests have served well in providing final qualification. Beside these voltage tests measurements of ESDD/NSDD, hydrophobicity and also visual inspections were carried out. The mechanical properties were driven from the seismic requirements and have been calculated by finite element modelling of the reactor and its support structure. For post insulators with silicone rubber sheds and with solid core porcelain may be the most stable solution and this type has been adopted in different 800 kV projects. One of the new insulator was chosen for smoothing reactor support for 800 kV DC system in India.

Effect of Porcelain/Polymer Interface on the Microstructure, Insulation Characteristics and Electrical Field Distribution of Hybrid Insulators

Effect of Porcelain/Polymer Interface on the Microstructure, Insulation Characteristics and Electrical Field Distribution of Hybrid Insulators