Search Results (301)

The growing demand for portable and wireless electronic devices, along with the necessity to reduce reliance on non-renewable energy sources, has driven the need for energy harvesting materials. Nanocomposites, combining a polymeric matrix and a high-performance dielectric ceramic phase, are a promising solution. In such systems, the design of a hybrid matrix–filler interface is critical for achieving desired properties. Here, nanocomposites (NCs) were prepared by adding various amounts of hydrothermally synthesized BaTiO₃ (BT) nanoparticles (NPs) to polydimethysiloxane (PDMS). To investigate hybrid interfaces, NPs were used either bare or surface-functionalized with two silanes, 3-glycidyloxypropyltrimethoxysilane (GPTMS) or 2-[acetoxy(polyethyleneoxy)propyl]triethoxysilane (APEOPTES). NC films (80–100 μm thick) were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), and thermogravimetric analysis (TGA). Dielectric properties and breakdown strength (E_BD) were measured, and the theoretical volumetric energy density was calculated as a function of the filler loading and functionalization. The results demonstrate that hybrid interface design is pivotal for enhancing dielectric performance in NCs. APEOPTES-functionalized NPs significantly improved the dielectric response at a low filler loading (3.5%vol.), increasing permittivity from 2.8 to 7.5, E_BD from 33.8 to 42.1 kV/mm and energy density from 30 to >100 mJ/cm³. These findings underscore that designing hybrid interfaces through NP functionalization provides an effective strategy to achieve superior dielectric performance in PDMS-based NCs, retaining the advantages of the elastomeric matrix by reducing the amount of ceramic fillers. Full article

Reliability and safety of high-voltage transmission lines are essential for stable and continuous operation of a power system. Environmental factors such as pressure, temperature, surface contamination, humidity, etc., significantly affect the dielectric strength of air, often causing unpredictable voltage breakdowns. This research presents a novel machine learning-based predictive framework that integrates Paschen’s Law with simulated and empirical data to estimate the breakdown voltage $\left(V_{bk}\right)$ of transmission lines in various environmental conditions. The main contribution is to demonstrate that data-driven prediction of breakdown voltage $\left(V_{bk}\right)$ using a hybrid machine learning model is in agreement with physical discharge theory. The model achieved root mean square error (RMSE) of 5.2% and mean absolute error (MAE) of 3.5% when validated against field data. Despite the randomness of avalanche breakdown, model predictions strongly match experimental measurements. This approach enables early detection of insulation stress, real-time monitoring, and optimises maintenance scheduling to reduce outages, costs, and safety risks. Its robustness is confirmed experimentally. Overall, this work advances the prediction of avalanche breakdown behaviour using machine learning. Full article

An increasing number of different types of dielectric liquids are appearing on the market. This is undoubtedly related to sustainable development goals. This paper presents comparative studies of the lightning impulse breakdown voltage (LIBV) of six dielectric liquids with different chemical compositions: naphthenic uninhibited mineral oil (UMO), naphthenic inhibited mineral oil (IMO), natural ester (NE), synthetic ester (SE), bio-based hydrocarbon (BIO), and an inhibited liquid produced using gas-to-liquids technology (GTL). Tests were conducted in a point-to-sphere electrode configuration with a 5 mm thick pressboard barrier placed between them. This configuration was designed to more closely replicate the actual configuration found in transformers, where the oil channels are separated by pressboard barriers. Tests were performed for two inter-electrode gap distances of 25 mm and 40 mm, and for both lightning impulse voltage polarities. The pressboard barrier was placed so that the distance between point electrode and the barrier was always the same (10 mm). Measurements were performed using the step method. Before measurements began, the pressboard barrier was impregnated with the dielectric liquid being tested. The obtained measurement results were compared with previous studies conducted by the authors, which used a similar electrode system but without the pressboard barrier. The results confirmed that inserting the pressboard barrier between the electrodes effectively inhibits development of discharges and significantly increases the electrical strength of the entire insulation system. Full article

Understanding the role of carrier traps in the determination of dielectric breakdown of polymer nanocomposite would yield a novel method for the estimation of breakdown strength of the material. In this study, we propose a novel approach to predict the DC breakdown strength of polyethylene (PE) and its nanocomposite at room temperature via the bipolar charge transport (BCT) model based on trap energy estimated from isothermal surface potential decay (ISPD). Test specimens of polyethylene (PE) and its nanocomposites, with a thickness of 110 μm, were fabricated using the hot-pressing method by incorporating 20 nm SiO₂ particles as fillers. The distribution of carrier traps within these specimens was subsequently determined through ISPD measurements. The intrinsic breakdown strength of the sample was derived from the determined trap energy levels, by which the breakdown strength was predicted through the BCT model. Experimental DC breakdown tests were conducted on the specimens to validate the accuracy of the predictions. The results indicated that the DC breakdown strength predicted theoretically was in good agreement with that measured from the experiment. Such a prediction method provides a possible way to employ a non-destructive test to evaluate the DC breakdown strength of polymer nanocomposite. Full article

Silicone rubber from decommissioned composite insulators has become one of the major environmental challenges in the power industry due to its non-degradable nature. Therefore, the recycling and reuse of silicone rubber are of great environmental and economic significance. In this work, a method for preparing silica microspheres based on stepwise pyrolysis combined with post-treatment particle size fractionation is proposed. First, highly spherical silica microspheres were obtained by stepwise pyrolysis. Subsequently, glass fiber membrane filtration and aga-rose gel electrophoresis were employed as post-treatment methods to achieve particle size fractionation and enhanced uniformity. The results indicate that the post-treated silica microspheres exhibit high uniformity, high sphericity, and good dispersibility. This method significantly improves the structural uniformity and microscopic characteristics of the microspheres, making them promising high-value fillers for epoxy resin insulation modification. Comparative analysis with commercial nanosilica used as epoxy fillers shows that the recycled and fractionated silica microspheres achieve comparable improvements in breakdown strength and dielectric performance, confirming their potential for recycling and reuse in high-voltage insulation and electronic packaging applications. Full article

Overhead transmission lines have long relied on cross-linked polyethylene (XLPE) insulation. The production of XLPE insulation requires silane cross-linking, which generates by-products, consumes high energy, and results in poor recyclability-retired XLPE insulation can only be disposed of through incineration or landfilling. Additionally, its high density leads to increased cable weight and sag, reducing the service life of the cables. Therefore, there is an urgent need to develop recyclable and lightweight insulation materials. In this study, recyclable polypropylene (PP) was used as a substitute for XLPE. Hollow glass microspheres (HGM) were incorporated to reduce weight, and hydrogenated styrene-ethylene-butylene-styrene block copolymer (SEBS) was added for toughening, thereby constructing a PP/HGM/SEBS ternary composite system. The results show that the introduction of HGM into the PP matrix effectively reduces the material density, decreasing from 0.890 g/cm³ (pure PP) to 0.757 g/cm³—a reduction of 15%. With the addition of SEBS, the mechanical properties of the composite are significantly improved: the tensile strength increases from 14.94 MPa (PP/HGM) to 32.40 MPa, and the elongation at break jumps sharply from 72.02% to 671.22%, achieving the synergistic optimization of “weight reduction” and “strengthening-toughening”. Electrical performance tests indicate that the PP/HGM/SEBS composite exhibits a volume resistivity of 1.66 × 10¹² Ω·m, a characteristic breakdown strength of 108.6 kV/mm, a low dielectric loss tangent of 2.76 × 10⁻⁴, and a dielectric constant of 2.24. It achieves density reduction while maintaining low dielectric loss and high insulation strength, verifying its feasibility for application in lightweight insulation scenarios of overhead transmission lines. Full article

Crosslinked polyethylene (XLPE) has been the cornerstone material in the power industry for insulating high-voltage cables due to its exceptional properties, including reduced dielectric loss, high dielectric constant and thermal conductivity, and excellent resistance to electrical stress. In the current study, in order to further enhance the electrical and mechanical properties of XLPE’s various types of nanofillers such as metal oxides, boron nitride nanosheets of nanosilica and graphene oxide are incorporated into the XLPE matrix. These nanoparticles promote the occurrence of numerous trap sites, even at modest concentrations, due to their extensive interfacial regions, which affect crucial characteristics including breakdown voltage strength, electrical tree growth, structural defects, space charge accumulation, and thermal aging. The present review summarizes the effects of nanoparticles on the dielectric performance of XLPE. At the same time, the current advancements in the development of a new generation of recyclable insulation materials are briefly discussed. Full article

Failures are sometimes attributed to the deterioration of insulating oil, with contamination by cellulose particles. Such contamination lowers the dielectric strength of the oil. This study investigates the effect of cellulose contamination on the impulse breakdown voltage of transformer oil and evaluates the potential of nanofluids as a remediation strategy. A controlled amount of cellulose particles is added and dispersed into mineral oil at a concentration of 0.02 g/L to simulate a contaminated oil sample. Titanium dioxide (TiO₂) and aluminum oxide (Al₂O₃) nanoparticles are then dispersed into the contaminated oil at concentrations of 0.02 and 0.04 g/L. Impulse breakdown voltage is measured under both positive and negative polarities using electrode gaps of 1 mm and 2.5 mm, while dielectric permittivity is also measured to assess polarization effects. The influence of nanoparticle type and concentration is analyzed considering relaxation time and electron scavenging mechanisms. The results show that cellulose contamination markedly reduces dielectric strength, whereas the addition of nanoparticles effectively restores and, in several cases, enhances the insulating properties beyond those of uncontaminated oil. Full article

Polymer dielectrics offer outstanding advantages for high-power energy storage applications, such as high breakdown strength (E_b) and efficiency (η), while both decrease rapidly at elevated temperature (>150 °C). Although several strategies including nanocomposites and crosslinking have been evaluated to enhance E_b and heat resistance, the discharged energy density (U_d) of polymer dielectrics is still limited by the low dielectric constant (K). Herein, we have implemented a blending strategy by utilizing hydrogen bonding interactions between molecular chains for polyetherimide (PEI) and poly(ester ether urethane) (PEEU). Both the experimental and computational simulation results reveal that the blending can contribute to the increased molecular chain spacing and control the charge transport by destroying the conjugated structure to broaden bandgap and induce deep traps, improving the K and E_b simultaneously. As a result, the blend film achieves an unprecedented U_d of 5.50 with the η above 90% at 200 °C. Furthermore, it exhibits stable performances during ultralong 10⁵ charge–discharge cycles in harsh environments (250 MV/m and 200 °C). This work opens a new avenue to scalable high Ud all-polymer dielectric for high-temperature applications and promotes the understanding of the dielectric behavior of polymer blend films. Full article

High-efficiency, lead-free dielectrics are sought for pulsed-power capacitors, yet pristine Bi_0.5Na_0.5TiO₃ (BNT) suffers from large remanence, high coercivity, and limited breakdown strength. Here, we report (1 − x)Bi_0.5Na_0.5Ti_0.97Nb_0.03O₃-xSr_0.85Ba_0.15Ta_0.5+0.02xAl_0.5−0.02xO₃ (BNTNb–SBTA, x = 0–0.15) ceramics synthesized via solid-state reaction, achieving enhanced relaxor ferroelectric behavior through multi-cation substitution at A- and B-sites. X-ray diffraction confirms a pure perovskite solid solution, while scanning electron microscopy reveals grain refinement, suppressing oxygen vacancies and boosting the breakdown strength. Raman and dielectric analyses evidence strengthened relaxor behavior, accompanied by loop slimming and a systematic rise in breakdown strength. The composition x = 0.10 achieves the best trade-off, delivering W_rec = 3.357 J cm⁻³ and η = 90.5% at E_b = 240 kV cm⁻¹. Robust operational stability is demonstrated with small variations of W_rec/η over 0.1–200 Hz, 25–175 °C, and 10⁶ cycles. Pulsed tests show fast discharge (∼26 ns) with W_d = 0.826 J cm⁻³ at ∼90% efficiency under moderate fields. These results indicate that synergistic A/B-site disorder (Sr/Ba on A-site; Ta/Al with Nb on B-site), combined with microstructural densification, effectively minimizes P_r while elevating E_b, enabling high-efficiency energy storage under practical operating conditions. Full article

The investigation of environmentally friendly, Pb-free ceramic dielectric materials with excellent energy storage capability represents a fundamental yet challenging research direction for the development of next-generation high-power capacitors. In this study, linear dielectric Ca_0.7La_0.2(Mg_1/3Nb_2/3)O₃ was added into [0.65BaTiO₃–0.35(Na_0.5Bi_0.5)TiO₃] to form a solid solution. The introduction of Ca_0.7La_0.2(Mg_1/3Nb_2/3)O₃ modified the crystal structure, enhanced insulation performance and breakdown strength, and reduced hysteresis loss. These improvements collectively contributed to higher energy storage density and efficiency (η). The ceramic pellet with the optimal 10 mol% Ca_0.7La_0.2(Mg_1/3Nb_2/3)O₃ demonstrated a higher retrievable energy density (~3.40 J cm⁻³) and efficiency (~81%) at a breakdown strength of 340 kV cm⁻¹ compared to BaTiO₃-based ferroelectric ceramics. The sample also exhibited good stability across a temperature range of 30–90 °C and a frequency range of 0.5–300 Hz. Thus, the as-prepared ceramics sample exhibited significant potential for pulsed power device applications. Full article

(Bi_0.5Na_0.5)TiO₃-based lead-free ferroelectric ceramics are among the most extensively researched energy storage materials today. In this paper, (1 − x)Bi_0.46Sr_0.06Na_0.5TiO_3−xCaTiO₃ ceramics were synthesized through a solid-phase sintering method by synergistically adjusting CaTiO₃ components after introducing Sr²⁺ at the A-site. The XRD patterns revealed that all samples formed a single perovskite solid solution, with the 111 and 200 peaks shifting to higher levels as the CaTiO₃ increased, indicating a gradual decrease in cell volume. The SEM images exhibited dense crystals without any apparent porosity, which were formed by the different components of the ceramics. Through energy storage, dielectric, and charge–discharge performance tests, it was found that with a 10%mol CaTiO₃ addition, the samples obtained a maximum breakdown field strength of 260 kV/cm and corresponding saturation polarization strength of 32.80 μC/cm² and thereby exhibited a reversible energy storage density valued 3.52 J/cm³. In addition, the dielectric constant varied by less than 10% within the temperature range of 63.7 °C to 132.7 °C and presented good frequency (10–250 Hz) stability at 180 kV/cm. Moreover, the ceramics demonstrated a maximum current density reaching 349.58 A/cm² and a maximum power density of 18.90 MW/cm³ for their charge–discharge performance, all of which makes them suitable for pulse system applications. Full article

The impregnation and curing process of dry bushing requires the epoxy material for bushing to have a good process performance. In addition, the actual operating conditions of dry bushing put forward high requirements on the dielectric properties of the epoxy material. Amine accelerators can not only improve the technological properties of epoxy materials such as gel time and curing exothermic temperature rise by regulating the reaction rate of epoxy resin and anhydride curing agent, but also optimize the dielectric properties of epoxy materials by regulating the crosslinking density of epoxy materials. However, there are many types of amine accelerators, and the effects of amine accelerators with different nucleophilicity on epoxy materials vary greatly. In this paper, four kinds of amine accelerators with different nucleophilic ability were selected to study the influence of the nucleophilic ability of amine accelerators on the process and dielectric properties of epoxy materials. The results show that the stronger the nucleophilicity of the amine accelerator, the shorter the gel time of the epoxy mixture and the higher the exothermic temperature rise during curing, indicating a poorer processing performance. However, stronger nucleophilicity also endows the epoxy material with superior dielectric properties. Among them, the strong nucleophilic ability of TEA shortens the gel time of the material by 50% and increases the curing exothermic temperature rise by 55.3% compared with the weak nucleophilic ability of the DET epoxy system; the dielectric constant and dielectric loss of the material are reduced by 8.3% and 39.5%, respectively, and the breakdown strength is improved by 11.4%. This paper reveals the contradictory relationship between the process and dielectric performance of epoxy materials triggered by the difference in the nucleophilic ability of amine accelerators, and it also provides a new research idea for the improvement of the process and in the dielectric performance of epoxy materials for dry bushing. Full article

As a critical component in high-voltage cable accessories, ethylene-propylene-diene monomer (EPDM) reinforced insulation faces severe issues of surface discharge and bulk breakdown at the insulation interface. To enhance the electrical resistance of EPDM bulk and insulation interfaces, the 4-allyloxy-2-hydroxybenzophenone was employed as a voltage stabilizer to modify EPDM. A systematic study was conducted on the influence of the voltage stabilizer on the DC breakdown strength of EPDM, the anti-migration properties of the voltage stabilizer, and its effect on the surface breakdown voltage of EPDM. Additionally, pressure and surface breakdown test setups were designed. The results indicate that the DC breakdown strength of EPDM decreases with increasing external pressure, and this decline is more pronounced in EPDM modified with the voltage stabilizer. Surface breakdown experiments demonstrate that the voltage stabilizer has a positive effect on improving the surface breakdown voltage of EPDM, with a more significant enhancement observed at the EPDM/XLPE bilayer dielectric interface. Surface potential tests reveal that the grafted voltage stabilizer introduces numerous shallow traps, inhibiting surface charge accumulation and thereby increasing the surface breakdown voltage. Full article

This paper reviews the historical progression of arc-quenching media and examines the unique properties of supercritical carbon dioxide (scCO₂), including its transport characteristics, electrical breakdown resilience, and structural behavior. Through analysis of ionization mechanisms, mean free path, and heat dissipation, scCO₂ emerges as a viable insulating and arc-quenching medium, offering competitive performance and reduced environmental impact. Projected performance metrics for arcing time and dielectric strength show scCO₂’s competitive edge. The limitations of alternative supercritical fluids and the potential benefits of scCO₂ mixtures are discussed. In addition, the paper highlights the development of the first 72 kV scCO₂ AC circuit breaker, marking a significant step toward sustainable high-voltage applications. This work positions scCO₂ as a viable, environmentally friendly alternative to SF₆, with promising implications for future power systems. Full article