Dielectric Breakdown Research Articles

Electro-hyperelasticity with phase field for electric breakdown modeling

In this paper, we systematically derive the phase field model for electric breakdown channel propagation. The model includes electric charge, mass, momentum and energy conservation equations as well as Allen–Cahn type equation which governs the phase field evolution. The medium motion is described by the Godunov–Romenski type hyperelastic model. Electromagnetic part of the model consists of Maxwell’s equations in quasi(electro)stationary approximation including electric charge conservation law. Derivation of the model is based on the Coleman–Noll procedure and Gurtin’s microforces and microstress framework.

Modelling and experimentation of failure modes to obtain safe operating range for improved dielectric elastomer actuation performance

Abstract Dielectric elastomers (DEs) possess high energy density, lightweight, and low response time making them suitable material candidatures for electromechanical transducers (ET). Performance enhancement of ET necessitates escalated electrical load making prone to failure and subsequently hindering reliability and life cycle. Existing models towards failure mitigation focus on mechanical and electrical loads individually with constant relative permittivity, whereas DEs undergoes combined loading and stretch-electrostriction in real-time application. This study aims to identify safe design and operating parameters by addressing various modes of failures under combined loads and stretch-electrostriction. Under combined load, pre-strain emerges as a crucial parameter to reduce EMI, while extensive pre-strain leads to diminish thickness which in turn promotes electrical breakdown of elastomer. The optimized design for DEs exhibit substantial failure suppression at a pre-strain value of 1.7 ( λ pre ) under maximum electrical load of 37.66 MV / m ( E max ). The efficacy of optimized parameters for the failure suppression is verified through an in-house fabricated planar actuator. Operation within the identified range of parameters is observed to enhance the reliability and lifespan of DE-actuators, marking a noteworthy advancement in the field of soft robotics.

COMPUTER SIMULATION OF ELECTRICALLY CONDUCTING PROPERTIES OF MATERIAL FOR PERSONAL PROTECTION EQUIPMENT

The article presents an analysis of production factors that have a harmful effect on the health of workers. It has been established that one of the leading factors is an increased electrostatic field that occurs when a static charge accumulates on the surface of materials. An increased level of the electrostatic field can lead to various negative consequences for workers’ health. For full antistatic protection at work, not only special tools and workplaces are needed, but also special footwear made of conductive materials with high surface resistance, as well as other personal protective equipment. A computer model for simulating the occurrence and development of an electrical breakdown in a protective material for personal protective equipment is described. The model is based on energy concepts of the occurrence and development of a discharge, taking into account the statistical heterogeneity of the material’s electrical conductivity. The process of breakdown development is considered as a special case of the percolation effect and a branching random process. The model makes it possible to find a relationship between the heterogeneity of the material and the threshold of its protective properties.

Effect of moisture on the electric field and breakdown voltage of XLPE cable interconnectors

Dampness in the joint is a common defect of power cables, and the influence of moisture on the performance of the intermediate joint is very important. The electric field distribution of the joint is analyzed by simulation, and the XLPE sample is used as an experimental object to test the breakdown voltage under different damp levels. Simulation results show that in the composite interface outside the main insulation, the electric field at the water film is only 20%–60% of normal. However, the electric field around the water film generally increases, and as the degree of moisture increases, the electric field distortion becomes more serious, which is prone to inducing breakdown accidents. The electric field around the water film outside the conductor has no obvious distortion and will not directly induce accidents. Through the breakdown voltage experiment of the damp XLPE sample, it is found that the average breakdown voltage is 85%–94% of normal, and it decreases with the increase of moisture. The experimental results are consistent with the simulation results. The results can be used to guide the cause analysis of cable intermediate joint accidents.

Enhanced comprehensive energy storage properties of lead-free KNN based ceramics through composition optimization strategy

As one of the most potential lead-free dielectric capacitors in pulsed power systems, K0.5Na0.5NbO3 (KNN)-based ceramic possesses comparatively high dielectric breakdown strength (BDS) due to its particular submicron grains. Nonetheless, it is hard to improve both the energy efficiency η and the recoverable energy density Wrec of potassium sodium niobate ceramic at the same time. Herein, a composition optimization strategy is used, Bi(Li0.5Nb0.5)O3 (BLN) as a second component and NaNbO3 (NN) as a third component are introduced into KNN-based ceramic. It is corroborated that BLN content facilitates the growth of polar nano-regions (PNRs), and then strengthens the relaxation behavior, lows the remnant polarization Pr and upgrades the maximum polarization Pmax value of the ceramic. A transition from ferroelectricity to relaxation ferroelectricity occurred and an ultrahigh Wrec of 10.03 J/cm3 with a η of 64.15 % and the BDS of 1140 kV/cm are gained in KNN-0.100BLN-NN ceramic, Wrec of 8.25 J/cm3, η of 71.26 % and the BDS of 840 kV/cm are obtained in KNN-0.075BLN-NN ceramic. Besides, the KNN-0.075BLN-NN ceramic exists not only fine energy storage properties, but also high hardness and good temperature and frequency stability, confirming it’s a feasible material to be applied in pulsed power systems

Enhanced dielectric breakdown strength and thermal conductivity of silicone gel composites with high-electron-affinity silicon Dioxide/Cationic Polymer/Nano-diamond

Enhanced dielectric breakdown strength and thermal conductivity of silicone gel composites with high-electron-affinity silicon Dioxide/Cationic Polymer/Nano-diamond

Comprehensive properties analysis of epoxy composites synergistically toughened with liquid nitrile rubber and polyethersulfone

In this paper , epoxy resin (EP) composites with different phase structures were prepared by introducing hydroxyl-terminated liquid nitrile rubber (HTBN) and hydroxyl-terminated polyethersulfone (PES) individually or simultaneously into the resin matrix. The results revealed that the rational distribution of phase structure of rigid PES and flexible HTBN can effectively contributed to the enhancement in their mechanical and electrical insulation strengths. The synergistic effect of the two reinforcing fillers granted the optimized ternary composite a tougher structural network, leading to significant improvements of 73.13% and 18.98% in mechanical impact strength and electrical breakdown strength, respectively, compared to the pristine EP. Furthermore, compared to HTBN, PES exhibited inhibited HTBN dielectric interfacial polarization and EP molecular chain segment relaxation, resulting in decreased dielectric constant and loss in the composites. This study provide insights into the dielectric properties and design strategies for the development of resin-based dielectric materials, ensuring their broader applicability.

Defect engineering design and electrical breakdown model improve dielectric properties and reliability of rare-earth doped BaTiO3-based ceramics

The incorporation of rare-earth elements into BaTiO3-based multilayer ceramic capacitors (MLCCs) plays a pivotal role in enhancing the dielectric constant and reliability. In this study, The BaTiO3-based ceramics doped with La and Dy were prepared separately and their dielectric properties and reliability were thoroughly compared. The La-doped sample exhibited a significantly enhanced dielectric constant, which can be attributed to the short-range migration of liberated oxygen vacancies () facilitated by the incorporation of defects -. However, the presence of free in the La-doped sample led to a significant reduction in insulation resistivity during the initial application of the electric field. Microstructural analysis of the failure points resulted in the proposal of an electrical breakdown model, which elucidates the superior breakdown strength observed in the La-doped sample. This study provides novel insights for the development of MLCCs with high dielectric constants and high reliability.

Achieving Ultrahigh Efficiency of Triboelectric Nanogenerator Energy Harvesting Systems via Hybrid Electronic‐Spark Power Management

AbstractSignificant efforts are devoted to optimizing the efficiency of triboelectric energy harvesting systems, particularly through the design of an advanced power management system (PMS) for Triboelectric Nanoenerators (TENGs). A critical aspect of PMS is the design and control of switches. However, existing switches face significant limitations. For spark switches, precise control cannot be achieved, and electronic switches can only operate at voltages below several hundred volts which is limited by the risk of electrical breakdown. To address these limitations, a hybrid electronic‐spark switch power management system (HESS) is proposed. HESS changes the connection of capacitors from parallel to series by deploying a maximum voltage tracking switch components at the peak voltage point, resulting in a much‐elevated voltage level to activate the spark switch. This approach achieves precise control of the spark switch for the first time and significantly reduces the operating voltage of electronic switches. Through simulation and experimental verification, HESS achieves the control at a voltage level of 1.8 kV for spark switch, with an electrical component breakdown voltage of only 450 V. The power density of the HESS is 29.8 mW Hz−1 m−2, which is a new record for electronic switches.

Karakteristik Breakdown Voltage Pada Dielektrik Minyak Mineral dan Minyak Ester Natural

The increasing demand for electrical energy, driven by population growth and industrial development, necessitates efficient and sustainable power distribution systems. Transformers, essential components of these systems, typically use mineral oil for insulation and cooling, despite its environmental drawbacks, such as high carbon emissions and non-biodegradability. In response, natural ester oils have emerged as eco-friendly alternatives. This study aimed to compare the dielectric breakdown voltage characteristics of mineral oil (Diala B) and natural ester oil (FR3) in transformer applications. The testing followed the IEC 60156 standard, focusing on transformers operating at 20 kV, with a minimum breakdown voltage threshold of 30 kV/2.5mm. Both treated and untreated samples were examined.The results indicated that FR3 ester oil exhibited superior dielectric properties, including higher breakdown voltage, flashpoint, and firepoint, as well as lower carbon emissions compared to mineral oil. These findings suggest that natural ester oil has significant potential as a sustainable replacement for mineral oil, particularly in applications where environmental and safety concerns are prioritized.The study recommends further long-term testing under operational conditions to confirm the performance and stability of ester oil in real-world transformer applications. These findings contribute to the growing body of research supporting the transition to more environmentally friendly transformer insulation materials, which could have broad implications for the power industry’s sustainability efforts

High-temperature time-dependent dielectric breakdown of 4H-SiC MOS capacitors

—With the rapid applications of silicon carbide metal–oxide–semiconductor field-effect transistor (SiC MOSFET) power devices, further improving the performance of SiC MOSFET device through enhancing its gate oxide reliability is one of the crucial directions. The density of interface states in a SiC MOSFET is a significant parameter that affects the reliability of the gate oxide layer. In this paper, the SiC MOS capacitors (MOSCAPs) were prepared by the 1250 °C dry oxidation and 1350 °C NO annealing process. Then, we analyzed the mechanisms of the breakdown by two group of ramped experiment. And we still evaluated the reliability of oxide layer via the high-temperature time-dependent dielectric breakdown (TDDB) tests on the prepared MOSCAPs, meanwhile, the temperature effect on the reliability was considered. Furthermore, the E, 1/E, and E models with Weibull plotting were used to calculate the tBD lifetimes and failure analysis was carried on the failed samples finally. The results indicate that: (1) the impact of the generation and accumulation of the traps in the oxide, which is the main mechanisms of device failure; (2) The prediction of lifetime was calculated with three models at different acceleration factors; (3) at high-temperature, although the lower the density of interface states is, the Si epitaxial growth and C cluster will manifest in the oxide surface and lead to the breakdown of SiC MOSCAPs.

Improving the distribution system capability by incorporating ZnO nanoparticles into high-density polyethylene cable materials

This paper introduces a novel insulated cable designed to enhance the distribution system’s capabilities. Accordingly, high-density polyethylene loaded with varying concentrations of zinc oxide (ZnO) nanoparticles (NPs) ranging from 0.0 to 5 wt% was prepared using the melt-blending technique. Zinc oxide (NPs) is synthesized by using sol–gel technique and their microstructure was examined by X-ray diffraction. The new insulated cable, HDPE nanocomposite loaded with 1 wt% of ZnO, demonstrates a 43% reduction in the relative dielectric constant and a 16.5% improvement in breakdown strength compared to pure HDPE. The observed changes in both the dielectric constant and breakdown strength offer several advantages in electrical applications. These benefits include a decrease in feeder current at the same loading level, mitigation of inrush transients during load switching, and a reduction in earth fault current values, particularly in unearthed distribution networks with ungrounded cables. A comparative study is conducted between the conventional insulating cable based on the original material (HDPE) and the new insulated cable incorporating ZnO nanomaterial at a ratio of 1.0 wt% of the total cable mass per unit length. This comparison utilizes data from two actual medium-voltage distribution feeders. Both actual feeders are simulated using the EMTP/ATP package. The obtained results prove the efficacy of the developed material cable (polymer doped with ZnO NPs) compared to the base material. The peak and duration of inrush current can be cut to 77.3% and 67% of their original values, respectively. The earth fault current can be reduced to 56.5% in ungrounded networks, while substation current under the normal operation can be cut to 84.3% with the same load currents.

Simultaneously Enhanced Thermal Conductivity and Dielectric Breakdown Strength in Micro/Nano-BN/Epoxy/PC Multilayer Composites

Simultaneously Enhanced Thermal Conductivity and Dielectric Breakdown Strength in Micro/Nano-BN/Epoxy/PC Multilayer Composites

Exploring the Crystal Structure and Electronic Properties of γ-Al2O3: Machine Learning Drives Future Material Innovations.

For decades, researchers have struggled to determine the precise crystal structure of γ-Al2O3 due to its atomic-level disorder and the challenges associated with obtaining high-purity, high-crystallinity γ-Al2O3 in laboratory settings. This study investigates the crystal structure and electronic properties of γ-Al2O3 coatings under the influence of an external electric field, integrating machine learning with density functional theory (DFT). A potential 160-atom supercell structure was identified from over 600,000 γ-Al2O3 configurations and confirmed through high-resolution transmission electron microscopy and selected area electron diffraction. The findings indicate that γ-Al2O3 deviates from the conventional spinel structure, suggesting that octahedral vacancies can reduce the system's energy. Under an external electric field, the material's band structure and density of states (DOS) undergo significant changes: the bandgap narrows from 3.996 to 0 eV, resulting in metallic behavior, while the projected density of states (PDOS) exhibits peak broadening and splitting of oxygen atom PDOS below the Fermi level. These alterations elucidate the variations in the electrical conductivity of alumina coatings under an electric field. These findings clarify the mechanisms of γ-Al2O3's electronic property modulation and offer insights into its covalent and ionic mixed bonding as a wide-bandgap semiconductor. This discovery is essential for understanding dielectric breakdown in insulating materials.

Synergistic effects in Na0.5Bi0.5TiO3-based thin film through stress field regulation for excellent capacitive energy storage

Thin film dielectric capacitors have attracted significant attention under the current trend of integration and portability in electronic devices. In this work, Na0.5Bi0.5(Fe0.03Ti0.97)O3–SrTiO3 (NBFT–STO) thin films are synthesized via sol–gel method onto flexible Pt/Mica and rigid Pt/Ti/SiO2/Si substrates, respectively to obtain NBFT–STO dielectric capacitors under different local stress fields. Synergistic effects between dielectric polarization and breakdown strength (EBD), as well as dielectric polarization and polarization hysteresis are obtained, with the rigid one exhibiting higher EBD and the flexible one possessing high polarization linearity. Excellent capacitive energy storage performance with Wrec of 28.00 J/cm3 and η of 70.44 % are obtained at 20 kHz for the NBFT–STO thin film onto Pt/Mica. These findings provide a new route to modulate polarization behavior of NBT–based thin film through stress field regulation for capacitive energy storage.

Research on the Inner Surface Discharge of the Insulation Sheath of Electric Locomotive Cable Terminals

Adding an insulating sheath to the exposed metal part of the outer insulation of a roof cable terminal can extend the creepage distance of the leakage current and significantly reduce the probability of pollution flashover on the outer insulation of the equipment. However, during the actual operation of the locomotive, the inner surface of the insulating sheath is discharged, resulting in cable insulation breakdown, the mechanism of which is unclear. This paper establishes a cable terminal–sheath electric field simulation model and studies the interface air gap, the interface with wet pollution, and the distribution of damp pollution on the outer surface and other factors on the electric field distribution of the cable terminal–sheath structure and the interface discharge, revealing the mechanism of discharge on the inner surface of the cable terminal’s insulation sheath. A voltage of 25 kV rms is applied, and the simulation results show that when the outer surface of the cable terminal is clean and there are air gaps and wet dirt on the inner surface, the maximum distortion electric field at the inner surface is 0.8 × 105~3.4 × 105 V/m, and the value of the electric field at this time is not enough to cause a partial discharge; when there is a uniform layer of wet dirt on the outer surface of the cable terminal, the electric field on the inner surface averages 1.5 × 105 V/m, which is about 275% higher than the average electric field when the outer surface is clean; when there is wetting or an air gap on the inner surface at the same time, the maximum aberration electric field on the inner surface is 1.8 × 105~1.9 × 106 V/m. The wetting on the outer surface of the cable terminal strengthens the non-uniformity degree of the distribution of the electric field, and when there is wetting and an air gap on the inner surface, the over-voltage on the cable terminal inevitably leads to a discharge phenomenon in the air gap. This provides a theoretical basis for optimizing the insulation sheath structure to solve the discharge problem.

Ultra-fine nano-crystalline optimize electrostatic energy storage

Grain size pays a crucial role in the properties of ferroelectrics and dielectrics. Reducing the grain size is considered to be an effective mean for enhancing dielectric energy storage. In this work, high recovered energy storage density and efficiency were achieved in three-layered Aurivillius thin films by ultra-fine grain nano-crystalline engineering. The ultra-low remanent polarization can be attributed to the emergence of polar nano-regions due to the disruption of macroscopic continuity of ferroelectric domains by ultra-fine nano-grains. At the same time, all thin films have high dielectric breakdown strength due to the presence of extremely high grain boundary density. Thus, a high recovered energy storage density of 71 J/cm3 and an efficiency of 76% were achieved, and the thin film capacitors show good fatigue endurance and temperature stability. The results suggest that ultra-fine nano-crystalline engineering can expand the application of traditional ferroelectric thin films in energy storage devices.

Preparation of a MIL-125/MoS2/SiO2 Ternary Nanohybrid and Its Smart Electrorheological Behavior.

In this work, a kind of ternary hybrid material, MIL-125/MoS2/SiO2, was prepared by a solvothermal and Stöber method. In this system, MIL-125, as the matrix material, not only furnishes a large specific surface area for MIL-125/MoS2/SiO2, thereby providing a basis for stronger interfacial polarization, but also effectively enhances the antisettlement ability of the electrorheological fluids (ERFs). Different characterizations, such as scanning electron microscopy, transmission electron microscopy, XRD, XPS, FT-IR, BET, electron mapping, etc., were used to analyze the ternary nanohybrid. The ERFs prepared by combining the different advantages of the three materials in the hybrid system were studied by a HAAKE high-speed rotary rheometer. In addition, the combination of MoS2 and SiO2 provides suitable electrical conductivity and dielectric properties for the system to promote the generation of interface polarization, ensuring that the entire system exhibits stronger electrorheological behavior without electrical breakdown and thus obtains higher shear stress.

Improved healability for large‐sized electrical breakdown in thermosetting polythiourethane with excellent mechanical properties and electrical insulation

AbstractReplacing thermoset insulation by healable and recyclable covalent adaptable networks is a promising approach to the sustainable development of electrical and electronic devices. However, the repair performance gifted by dynamic covalent bonds always conflicts with the excellent mechanical properties gifted by stiff cross‐linked networks. In this paper, by introducing dynamic thiocarbamate bonds, polythiourethane (PTU) with excellent mechanical properties and electrical insulation comparable to commercial epoxy resins are successfully developed, which exhibit superior healability and recyclability properties. Sub‐centimeter scale electrical breakdown failures of the PTU samples could be efficiently self‐healed with a healing efficiency up to 90%, while the storage modulus and volume resistivity exceeded 2 GPa and 1016 Ω cm, respectively. Even though the electrical breakdown strength inevitably declined after multiple repair processes, PTU samples could restore their initial excellent insulation performance by simply reprocessing with the efficiency above 95%. Moreover, the efficient healability performance of large‐sized electrical breakdown failures remained after the reprocessing. These outstanding characteristics underscore the tremendous potential of PTU materials as a new generation of sustainable high voltage insulation.

Spectral and optic-metric methods of monitoring parameters of plasma channels caused by discharge currents between metals granules in working liquids

Introduction. Spark-erosion processing of metals and alloys granules in working liquids is the basis of a several technological processes. Efficiency of energy use in them and parameters of the resulting product largely depend on the accuracy of stabilization and regulation of pulse power in each plasma channel between the granules. To achieve this, until now only the voltage and current of the discharge pulses in the entire layer of granules have been controlled. Problem. The measurement methods, which are used, are not effective enough for monitoring the parameters of individual plasma channels and predicting the size distribution of eroded metals particles at the stage of their formation. The aim of the work is to develop a method for determining the volumes of components of plasma channels in layers of metals granules during their spark-erosion treatment to predict the size distribution of eroded metal particles at the stage of their formation, as well as to simplify the method of spectrometric analysis of the elemental composition of substances surrounding plasma channels for the operational prediction of the chemical composition of resulting products. Methodology. A series of experiments were carried out on spark-erosion processing of Al and Ag granules layers in distilled water. Using a digital camera, images of the plasma channels in them were obtained. Based on the theory of pulsed electrical breakdown of liquid dielectrics, an analysis of the components of plasma channels was carried out. Using the specialized ToupView program, the volumes of equivalent ellipsoids of rotation were determined, approximating the halos of colored radiation likely arising from streamers, as well as the spark cores of plasma channels emitting white light. The shades of the resulting radiation were studied for several metals and working liquids. The obtained data were compared with the known results of spectrometric studies for the same elements excited by similar mechanisms. Results. The theory of discharge-pulse systems for spark-erosion processing of granular conductive media has been developed in the direction of new methods for monitoring the parameters of discharge pulses and predicting the chemical composition and size distribution parameters of eroded metal particles at the stage of their production. An optic-metric method has been developed for determining the volumes of halos and cores of plasma channels. A simplified spectral method for determining the chemical composition of erosion particles based on the shade of the resulting radiation was proposed. Originality. The developed new optic-metric method makes it possible to obtain information about almost every plasma channel, which refines predictions of the size distribution of erosion particles. To implement the method, general-purpose hardware and specialized software that is freely available are used. The developed method of simplified spectral analysis of excited atoms makes it possible to make preliminary predictions of the chemical composition of the obtained erosion particles already at the stage of their formation without the use of expensive specialized equipment. Practical significance. The ratio of the volumes of halos and cores of plasma channels between Al and Ag granules in distilled water was measured. An analysis of the emission spectra of plasma channel halos between Al, Ag and Cu granules in distilled water, Fe in ethyl alcohol, Ni-Mn-Ga and Ti-Zr-Ni alloys in liquid nitrogen, and Ti-Zr-Ni in liquid argon was carried out. Based on spectrometry data, the resulting shades of these radiations were substantiated and their description in the RGB system is given. References 56, table 1, figures 4.