Search Results (2,369)

The galvanic corrosion and electrical insulation between TC4 Ti-alloy and 304 stainless steel coupled in pipe joints were investigated using the finite element method. The results obtained from polarization were applied as boundary conditions. The simulation incorporated secondary current distribution with chemical species transport and laminar flow. COMSOL modeling provided calculated values that showed good agreement with experimental measurements. The model was utilized to examine the influence of geometric and environmental factors, including insulation resistance, insulation distance, pipe diameter, temperature, and electrolyte concentration, on the galvanic corrosion process. The results indicated that electrical insulation performance significantly affects the corrosion process. Full article

Fracto-emission is the ejection of electrons and positive ions from matter undergoing a mechanical fracture. The creation and propagation of fractures in insulating material can generate an electrical signal that can be detected using a sufficiently fast signal recorder. The theoretical equations related to crack creation/propagation that induce an externally electric signal are detailed for two conditions: with and without an external applied electric voltage. Results from an experiment with no externally applied voltage are presented for fibreglass-reinforced epoxy laminate samples, in which current signals ranging from 50 mA to 100 mA are measured in a time frame of 200 ns. The signal-to-noise ratio is high enough to consider that the signal that was recorded is not a measurement artifact. This method may help to identify and track a crack propagating inside dielectric materials. Full article

This paper examines Connected Smart Green Buildings (CSGBs) in Burnaby, BC, Canada, with a focus on townhouses with one to four bedrooms. The proposed model integrates sustainable materials and smart components such as recycled insulation, Photovoltaic (PV) solar panels, smart meters, and high-efficiency systems. These elements improve energy efficiency and promote sustainability. Operating in island mode, CSGBs can function independently of the grid, providing resilience during power outages and reducing reliance on external energy sources. Real data on electricity, gas, and water consumption are used to optimize load management under isolated conditions. Electric Vehicles (EVs) are also considered in the system. They serve as energy storage devices and, through Vehicle-to-Grid (V2G) technology, can supply power when needed. A hybrid Machine Learning (ML) model combining Long Short-Term Memory (LSTM) and a Convolutional Neural Network (CNN) is proposed to improve the performance. The metrics considered include accuracy, efficiency, emissions, and cost. The performance was compared with several well-known models including Linear Regression (LR), CNN, LSTM, Random Forest (RF), Gradient Boosting (GB), and hybrid LSTM–CNN, and the results show that the proposed model provides the best results. For a four-bedroom Connected Smart Green Townhouse (CSGT), the Mean Absolute Percentage Error (MAPE) is 4.43%, the Root Mean Square Error (RMSE) is 3.49 kWh, the Mean Absolute Error (MAE) is 3.06 kWh, and $R^2$ is 0.81. These results indicate that the proposed model provides robust load optimization, particularly in island mode, and highlight the potential of CSGBs for sustainable urban living. Full article

Most current international standards for qualifying polymer-insulated wires for aircraft applications rely on degradation tests conducted under standard pressure conditions. However, some wires are used in unpressurized areas and therefore need to withstand low-pressure conditions. In the technical literature, there is a shortage of data on this topic. This article focuses on accelerated wet arc tracking tests of insulated wires and evaluates three methods that assess the performance of surface discharges generated during degradation, based on the light emitted, under different pressure conditions in the range of 100 kPa–16 kPa. The experimental results presented in this paper show that the sensitivity of the proposed methods increases with atmospheric pressure, allowing a better quantification of the degradation effects at higher pressures. These results can also help to gain experience and understanding in how commercial optoelectronic sensors can be used to assess the insulation condition by analyzing the light generated by the surface discharges. Full article

High-performance cross-linked polyethylene (XLPE) is currently employed in ultra-high-voltage direct current (UHVDC) cables, with the electrical tree being an important cause of DC cable breakdown. The comparison of XLPE samples under different manufacturing processes can provide a reference for the progress of cable production processes. This paper compares laboratory-prepared XLPE samples (DC-XLPE) with XLPE samples extracted from actual cables (Cable-XLPE) through electrical tree experiments, X-ray diffraction (XRD), and gel permeation chromatography (GPC). The experimental findings indicate that the breakdown time of DC-XLPE increased by nearly 50% compared to Cable-XLPE, with slower electrical tree growth and lower average discharge magnitude observed. Overall, DC-XLPE exhibited superior resistance to DC electrical tree and partial discharge. XRD and GPC analyses revealed minimal differences in crystallinity and grain size between the two types, with the primary distinction being DC-XLPE’s notably higher molecular weight and more concentrated molecular weight distribution. The differences in physicochemical properties may be attributed to more precise and uniform temperature control during the crosslinking process in laboratory settings, as well as a higher removal rate of crosslinking byproducts, ultimately leading to enhanced resistance to electrical tree and partial discharge in DC-XLPE. Full article

Recent advancements in 3D printing technology have enabled the rapid production of complex structures, yet the dielectric performance of 3D printing materials and their potential for manufacturing electrical components remain insufficiently studied. In this study, a capacitor rated at 10 kV with a capacitance of 1 nF was designed and developed for high-voltage applications. During the production of the capacitor, the insulating and conductive parts were fabricated using a 3D printer. While PLA, ABS, ASA, and PETG were employed as insulating materials, aluminum was chosen as the conductive part. Theoretical calculations and the finite element method were used to validate the measured capacitance of the equipment. The performance of the prototype capacitor was analyzed through partial discharge inception voltages (PDIV), dissipation factor (tanδ), and breakdown voltage measurements. Dissipation factor measurements were performed at 2 and 4 kV voltages in the 50–400 Hz frequency range. The performance of employed materials was comparatively analyzed through experimental and simulation results. Finally, the impact of different insulating materials on the dielectric performance of the prototype capacitors was evaluated. Full article

In this paper, a design of vanadium dioxide for dynamic color gamut modulation based on Fano resonance is proposed. This approach facilitates color modulation by manipulating the phase transition state of vanadium dioxide. The device integrates both broadband and narrowband filters, featuring a structure consisting of a top silver mesh, a layer of vanadium dioxide, and a Fabry–Pérot cavity, which allows for effective modulation of the reflectance spectrum. Simulation results demonstrate that when vanadium dioxide is in its insulating state, the maximum reflectivity observed in the device spectrum, reaching 43.1%, appears at 475 nm. Conversely, when vanadium dioxide transitions to its metallic state, the peak wavelength shifts to 688 nm, accompanied by an increased reflectance peak of 59.3%. Analysis of electric field distributions reveals that the intensity caused by surface plasmonic resonance dominates over the excited Fano resonance while vanadium dioxide is in its insulating state, which is the opposite of when vanadium dioxide transitions to its metallic state. This behavior exhibits an excellent dynamic color-tuning capability. Specifically, the phase transition of vanadium dioxide results in a color difference ∆E₂₀₀₀ of up to 36.7, while maintaining good color saturation. This technique holds significant potential for applications such as dynamic color display and anti-counterfeit labeling. Full article

Cross-linked polyethylene (XLPE) is applied in most advanced high-voltage direct-current (HVDC) power cable insulations, which are produced via dicumyl peroxide (DCP) technology. The electrical conductivity of insulation material can be increased by cross-linking byproducts from the DCP process. Hence, currently much attention is being paid to a new process to produce cross-linking byproduct-free XLPE. The cross-linking in situ between ethylene–glycidyl methacrylate copolymer and 1,5-disubtituted pentane via reactive compounding is a substitute for DCP. The reaction potential energy information of the eighteen reaction channels was obtained at the B3LYP/6-311+G(d,p) level. Results demonstrated that epoxy groups and 1,5-disubtituted reactive groups can react in situ to realize the XLPE-based network structure via covalent linking, and epoxy ring openings yielded ester. 1,5-disubtituted pentane played a cross-linker role. The reactivity of the carboxyl group was stronger than that of the sulfydryl or hydroxyl group. The reaction channel RTS1 was more kinetically favorable due to the lower reaction Gibbs energy barrier height of 1.95 eV. The cross-linking network construction of the new XLPE insulation without byproducts opens up the possibility of DCP substitution, which is beneficial to furthering the design of thermoplastic insulation materials for power cables in the future. Full article

Insulating materials can be classified into solid, liquid, and gaseous forms. Solid insulation materials are divided into different types such as organic, inorganic, and polymer types. In electrical circuits, solid insulation materials are generally used as components that provide insulation and mechanical support. In recent years, as a result of developing technologies, the production of participation insulation materials with 3D printing technology has become widespread. Three-dimensional printing technology enables the rapid creation of objects by combining materials based on digital model data. It is important to evaluate the materials produced with 3D printing in terms of insulation coordination. Studies have shown that the electrical breakdown strength of solid dielectrics varies depending on factors such as sample type, thickness, the magnitude of applied voltage, and the temperature of the physical environment. According to IEC-60243 standards, there are various methods to measure the breakdown strength of solid insulators applied to different voltage types. In this study, the behavior of PLA, ABS, ASA, PETG, and PC/ABS materials produced with 3D printing and having the potential to be used as insulation materials when exposed to high voltage within the scope of insulation coordination was investigated. The breakdown strengths of solid insulation materials produced with 3D printing were measured in the high-voltage laboratory within the scope of IEC-60243. Breakdown strength was statistically evaluated with the Weibull distribution. Damage analysis of the breakdowns in the test specimens was examined in detail with ImageJ software. With the comparative analysis, the behaviors of PLA, ABS, ASA, PETG, and PC/ABS solid insulation materials were revealed and their superiority over each other was determined. Full article

The rise in electricity costs for households over the past year has driven significant changes in energy usage patterns, with many residents adopting smarter energy-efficient practices, such as improved indoor insulation and advanced home energy management systems powered by IoT and Digital Twin technologies. These measures not only mitigate rising bills but also ensure optimized thermal comfort and sustainability in typical residential settings. This paper proposes an innovative framework to facilitate the adoption of energy-efficient practices in households by leveraging the integration of Internet of Things technologies with Digital Twins. It introduces a novel approach that exploits standardized parametric 3D models, enabling the efficient simulation and optimization of home energy systems. This design significantly reduces deployment complexity, enhances scalability, and empowers users with real-time insights into energy consumption, indoor conditions, and actionable strategies for sustainable energy management. The results showcase that the proposed method significantly outperforms traditional approaches, achieving a 94% reduction in deployment time and a 98% decrease in memory usage through the use of standardized parametric models and plug-and-play IoT integration. Full article

In order to ensure the long-term reliability and safety of power transformers, it is important to continuously monitor the characteristics of insulating oil, which not only helps in understanding its behavior over time but also ensures the safety of the equipment. The current study analyzes in-service insulating oil with the aim of relating deterioration and changes in the oil with service aging. Insulating oil samples were collected from three power transformers, with a voltage level of 220 kV and 132 kV, installed at a 220 kV substation. Electrical and chemical characteristics were obtained, and the impact of service aging and the relationships among load variation, oil, and winding temperatures with the characteristics were evaluated. Variations in the dielectric dissipation factor and breakdown voltage with service aging were recorded for all transformers, while the moisture content increased with each service year. Among the concentrations of gases present in the insulating oil, carbon monoxide, oxygen, and nitrogen concentrations increased after each service year. The impact of load variation on the breakdown voltage of the 132 kV transformer oil was more prominent than for the 220 kV transformers. The analysis of gas ratios and moisture content identified the degradation of cellulose insulation in all transformers, which was due to the presence of electrical faults. Full article

Aluminum nitride (AlN) with a wide band gap (approximately 6.2 eV) has attractive characteristics, including high thermal conductivity, a high dielectric constant, and good insulating properties, which are suitable for the field of resistive random access memory. AlN thin films were deposited on ITO substrate using the radio-frequency magnetron sputtering technique. Al’s and Au’s top electrodes were deposited on AlN thin films to make a Au/Al/AlN/ITO sandwich structure memristor. The effects of the Al₂O₃ film on the on/off window and voltage characteristics of the device were investigated. The deposition time and nitrogen content in the sputtering atmosphere were changed to adjust the thickness and composition of AlN films, respectively. The possible mechanism of resistive switching was examined via analyses of the electrical resistive switching characteristics, forming voltage, and switching ratio. Full article

Epoxy resin (EP) is an outstanding polymer material known for its low cost, ease of preparation, excellent electrical insulation properties, mechanical strength, and chemical stability. It is widely used in high- and ultra-high-voltage power transmission and transformation equipment. However, as voltage levels continue to increase, EP materials are gradually failing to meet the performance demands of operational environments. Thus, the development of high-performance epoxy resin materials has become crucial. In this study, a combined treatment using plasma and a fluorine-containing coupling agent was employed to fluorinate graphene nanosheets (GNSs), resulting in DFGNSs. Different concentrations of GNSs/DFGNS-modified EP composites were prepared, and their effects on enhancing the surface insulation properties were studied. Tests on surface flashover voltage, surface charge dissipation, trap distribution, and surface resistivity demonstrated that both GNSs and DFGNSs significantly improve the insulation properties of EP materials. Optimal improvement was achieved with a DFGNS content of 0.2 wt%, where the flashover voltage increased by 16.23%. Full article

This paper examines the modeling approaches used to analyze the electric field distribution in high-voltage direct-current gas-insulated systems (HVDC-GISs) used for the acceleration grid power supply (AGPS) of neutral beam injectors (NBIs). A key challenge in this context is the degradation of dielectric performance due to radiation-induced conductivity (RIC), a phenomenon specific to the harsh radioactive environments near fusion reactors. Traditional models for gas conductivity in HVDC-GISs often rely on constant or nonlinear conductivity formulations, which are based on experimental data but fail to capture the effects of external ionizing radiation that triggers RIC. To address this limitation, a more advanced approach, the drift–diffusion recombination (DDR) model, is used, as it more accurately represents gas ionization and the influence of radiation fields. However, this increased accuracy comes at the cost of higher computational complexity. This paper compares the different modeling strategies, discussing their strengths and weaknesses, with a focus on the capabilities in evaluating the charge accumulation and the RIC phenomenon. Full article

Relaxor ferroelectric film capacitors exhibit high power density with ultra-fast charge and discharge rates, making them highly advantageous for consumer electronics and advanced pulse power supplies. The Aurivillius-phase bismuth layered ferroelectric films can effectively achieve a high breakdown electric field due to their unique insulating layer ((Bi₂O₂)²⁺ layer)). However, designing and fabricating Aurivillius-phase bismuth layer relaxor ferroelectric films with optimal energy storage characteristics is challenging due to their inherently stable ferroelectric properties. In this work, lead-free CaBi_4-xLa_xTi₄O₁₅ films were synthesized using the sol–gel technique and a weakly coupled relaxor design. On one hand, the introduction of La³⁺ ions weaken the dipole–dipole interactions, thereby enhancing the relaxor behavior. Alternatively, the expansion of grain size is restricted to enhance the number of grain boundaries, which possess improved insulating properties. This leads to a higher breakdown electric field. The results indicate that CaBi_4-xLa_xTi₄O₁₅ (x = 1.0) films exhibit excellent recoverable energy storage density (70 J/cm³) and high energy efficiency (73%). Moreover, the film exhibited good temperature stability and frequency stability. This study not only identifies a promising material for dielectric film capacitors but also demonstrates that the energy storage capabilities of Aurivillius-phase bismuth layer ferroelectric films can be effectively modulated through a design incorporating weakly coupled relaxor characteristics. Full article