Electrical Tree Growth Research Articles

Improved body and interface properties of EPDM insulation for HVDC cable accessory by grafted voltage stabilizer

As a key component in HVDC cable accessory, EPDM insulation is prone to breakdown both in body and along interface. To improve the comprehensive electrical strength of EPDM, voltage stabilizer 2-propenyl-4,6-dibenzoylresorcinol (ADR) was simultaneously grafted onto macromolecules through free radical reaction on its vinyl during crosslinking of EPDM. After modification, the mechanical strength and thermal stability of EPDM are improved. In terms of body properties, the injection and rapid transfer of space charge under normal electric field are weakened, the volume conductivity is reduced, the breakdown strength is improved and the growth of electrical tree is suppressed. In terms of interface properties, the normal electric field at the EPDM/XLPE interface is weakened, hence reduced potential risk of deterioration initiated from interface. Moreover, the surface conductivity of EPDM is reduced, the charge accumulation and migration along the EPDM/XLPE interface are suppressed, and the interface breakdown strengths under different interface pressures are significantly increased under tangential electric field. Molecular simulations and UV absorption characteristics indicate that the grafted ADR molecules not only introduce charge traps into EPDM, but also absorb the high energy from trapped electrons and consume it through multiple excitations, thus preventing the electron avalanche and subsequent degradation of EPDM.

RETRACTED: Wang et al. Power Cable Status Evaluation Method Based on Electrical Tree Growth and Data Association Rules. Processes 2023, 11, 2900

The journal retracts the article titled “Power Cable Status Evaluation Method Based on Electrical Tree Growth and Data Association Rules” [...]

Study on characteristics of health monitoring and critical warning based on partial discharge signals during the growth of electrical trees

Study on characteristics of health monitoring and critical warning based on partial discharge signals during the growth of electrical trees

Synergic Effects of Biaxial Mechanical Stress on Electrical Tree Growth of Epoxy Resin

Synergic Effects of Biaxial Mechanical Stress on Electrical Tree Growth of Epoxy Resin

Dynamics of high-speed electrical tree growth in electron-irradiated polymethyl methacrylate.

Dielectric materials are foundational to our modern-day communications, defense, and commerce needs. Although dielectric breakdown is a primary cause of failure of these systems, we do not fully understand this process. We analyzed the dielectric breakdown channel propagation dynamics of two distinct types of electrical trees. One type of these electrical trees has not been formally classified. We observed the propagation speed of this electrical tree type to exceed 10 million meters per second. These results identify substantial gaps in the understanding of dielectric breakdown, and filling these gaps is paramount to the design and engineering of dielectric materials that are less susceptible to electrostatic discharge failure.

Enhancing pulse energy-storage performance via strategy of establishing sandwich heterostructure

The effects of sandwich heterostructure on the energy-storage property are still existing some “mess”, detailed and systematic investigation should be carried out. In this work, novel sandwich heterostructure ceramics composed of (Ba0.94Li0.02La0.04)(Mg0.04Ti0.96)O3 and 0.85(Ba0.94Li0.02La0.04)(Mg0.04Ti0.96)O3–0.15NaNbO3 were prepared by film stacking and laminating technology and traditional solid-state sintering, to reveal the relationship between sandwich heterostructure and energy-storage performance. Sandwich heterojunction significantly affects electron-injection, space-charge, build-in electric field (Ei) direction, interlayer-coupling, interface-blocking and clamping effect. Ei direction is adjusted and electric tree growth is restrained. Interface blocking effect mainly occurs when Ei direction is opposite to applied electric field. Comparatively high polarization and tilted polarization-electric field hysteresis loops are obtained. Outstanding recoverable energy-storage density of 5.81 J/cm3 and discharge energy density of 3.99 J/cm3 are gained with current density of 1016.71 A/cm2 and power density of 305.01 MW/cm3. Satisfactory frequency stability, temperature stability and anti-fatigue feature are also achieved. Such sandwich heterostructure design develops a convenient and effective method to enhance energy-storage performance, and related research guides the study of energy-storage performance in multilayer heterostructure.

Electrical Tree Growth in Fiber Reinforced Epoxy Composites for GIS Insulation Rod

Electrical Tree Growth in Fiber Reinforced Epoxy Composites for GIS Insulation Rod

Partial Discharge Activity During Electrical Tree Growth in Epoxy and its Nanocomposites

Partial Discharge Activity During Electrical Tree Growth in Epoxy and its Nanocomposites

Investigations of the Electrical Tree Growth at Different Voltages and Frequencies

Investigations of the Electrical Tree Growth at Different Voltages and Frequencies

Modulating polarization and carrier migration characteristics via constructing sandwich-structured heterojunction interfaces for achieving excellent high-temperature energy storage properties in polymer nanocomposites

Dielectric polymer nanocomposites are ideal choices for electrostatic energy storage due to their high power density and reliability, but they cannot operate efficiently at high temperature. To solve this issue, herein, we designed and developed sandwich-structured montmorillonite (MMT)/polyetherimide (PEI)-(Pb,La)(Zr,Sn,Ti)O3 (PLZST) antiferroelectrics (AFEs)@dopamine (DA)-MMT/PEI nanocomposites. On one hand, compared to current wide-band gap fillers, i.e., TiO2, Al2O3, ZrO2, and MgO, two-dimensional MMT nanosheets possess unique electrically insulating performances along the thickness direction, and thus can effectively stop charges injecting and migrating, causing low conduction loss, and large breakdown strength (Eb). On the other hand, PLZST AFEs with orthorhombic structure can exhibit high maximum electric displacement (Dmax) and small remnant electric displacement (Dr) at high temperature, which is beneficial for achieving large Dmax-Dr in the nanocomposites. In addition, large dielectric constant differences between MMT/PEI and PLZST@DA/PEI layers can inhibit electrical tree growth, resulting in further raised Eb. Finite element simulations on electrical tree evolving confirm experimental breakdown results. The sandwich-structured nanocomposite displays impressive high-temperature (150 °C) capacitive performances possessing meanwhile a high Eb of 5265.9 kV/cm, large discharged energy density (Ue) of 7.1 J/cm3, being about 6 times that of the commercial biaxially oriented polypropylene, and large charge-discharge efficiency (η) of 81.6 %, which exceeds obviously latest polymer and polymer composites in terms of overall energy storage performances. More encouragingly, it displays an ultrahigh power density of 15.63 MW/cm3 and ultrafast discharge rate of 19.2 ns at 150 °C, indicate its excellent application potential in high-temperature pulse power systems.

Excellent energy storage and discharge performances realized in polymer nanocomposites by introducing core-shell antiferroelectric fillers and constructing bilayer interfaces

Polymer composites filled with one or two-dimensional ferroelectrics possess large discharged energy density (Ue), but deliver low efficiency (η) by reason of their high remnant electric displacement (Dr), and require demanding process conditions. To solve these issues, we have proposed Pb,La(Zr,Sn,Ti)O3 (PLZST)@Al2O3 nanoparticles (NPs)/polyimide (PI)-PLZST@Al2O3 NPs/poly(vinylidene fluoride-hexafluoropropylene) P(VDF-HFP) bilayer nanocomposites. PLZST antiferroelectrics exhibit small Dr and high maximum electric displacement (Dmax), and the Al2O3 shell possesses near dielectric constant with P(VDF-HFP) and PI, which can improve the Dmax, increase the breakdown strength (Eb), and refine D-E loops, and simple preparation method of the NPs is beneficial for the industrial production. The bilayer structure combines advantages of PLZST@Al2O3 NPs/PI with slim D-E loops and small Dr, and PLZST@Al2O3/P(VDF-HFP) possessing high Dmax. Besides, large dielectric differences between adjacent layers inhibit electrical tree growth, thus further causing improved Eb, which is confirmed by electrical tree evolving simulations. Consequently, the bilayer nanocomposites display an ultrahigh Ue of 21.89 J/cm3, which surpasses those of currently reported polymer nanocomposites filled with NPs, and large η of 78.2%. More encouragingly, it manifests ultrafast discharge time of 18.8 ns and ultrahigh power density of 28.3 MW/cm3, meaning its great application prospect in pulse power systems.

Effects of Gradient Magnetic Field on Electrical Tree Growth of SiR/Graphene Nanocomposites

In this paper, an unevenly distributed gradient magnetic field is constructed. The electrical tree characteristics in silicone rubber (SiR) under a gradient magnetic field are investigated. The cumulative damage is increased by 365% under Δ1.5 T and by 411% under Δ-1.5 T gradient magnetic field. A modification method based on graphene nanosheet doping is proposed to improve the insulation performance of the SiR under a gradient magnetic field. With the introduction of an appropriate amount of graphene nanoparticles, the damage area of the SiR/Graphene nanocomposites is reduced to 19.9% in the nonmagnetic field, and is reduced to 17.4% and 14.0% under Δ±1.5 T gradient magnetic field respectively. The time to breakdown is extended by 40-84%. The experimental results show that the magnetic field can affect the charge behavior and enhance the electric field near the electrode. The growth of the electrical tree is accelerated due to the enhanced partial discharges. The graphene nanosheets reduce the interface electric field and inhibit the growth of electrical trees by capturing the injected charges.

Characterization of Electrical Tree Initiation and Growth in XLPE Under Harmonic Waveforms

Characterization of Electrical Tree Initiation and Growth in XLPE Under Harmonic Waveforms

Analysis of Discharge Failure Mechanism of IGBT Power Modules

IGBT power modules are usually used as circuit-breaking components in power systems, and are widely used in solid-state DC circuit breakers, hybrid DC circuit breakers, all-electric aircraft, high-speed railways, new energy vehicles, and power transmission systems. In these systems, IGBT power modules are usually faced with extremely harsh working conditions and there is a failure risk. Insulation degradation should be a cause for concern as a potential path of power module failure. In this paper, the discharge phenomena of the IGBT power module were observed based on Intensified Charge Coupled Devices (ICCD), and the triple junctions composed of copper–ceramic–silicone gel inside IGBT were found as the discharge points. Furthermore, the directed bonded copper (DBC) ceramic filled with silicone gel was used as a test sample to study the discharge failure process, including the partial discharge (PD), surface charges, and electric trees. The mechanism of discharge failure is discussed and analyzed. The insulation degradation process is accompanied by phenomena such as severe partial discharge and rapid electric tree growth. This research provides support for the analysis idea and guidance of the research method for the cause of power module failure.

Enhancing high‐temperature breakdown strength of polyetherimide dielectric nanocomposites with MgO nanosheets by inhibiting charge migration

AbstractPolymer‐based dielectric nanocomposites with excellent high‐temperature energy storage performance are highly desirable in advanced electronic and power systems, but it remains a challenge to achieve superior breakdown strength at elevated temperatures. In this work, two‐dimensional (2D) magnesium oxide nanosheets (MgO NSs) are prepared by a hydrothermal method and used as fillers to fabricate MgO NSs/polyetherimide (PEI) dielectric nanocomposites. The effect of MgO NSs addition (1–4 wt%) on breakdown strength of MgO NSs/PEI nanocomposites is studied from 25 to 150°C. As a result, the nanocomposites containing 3 wt% MgO NSs obtain maximum breakdown strength of 538 kV mm−1 at 150°C, which is 25% higher than that of pure PEI and remains 92% of the room‐temperature value, accompany with an excellent discharged energy density of 3.66 J cm−3. The enhancement of breakdown strength could be attributed to the 2D structure and wide band gap (~7.8 eV) of MgO NSs, which act as barriers to suppress the electrical tree growth and create deep traps to capture charge, thus inhibiting the migration of charge carriers and suppressing electrical conduction. This work provides an effective approach for developing high‐temperature polymer‐based dielectric nanocomposites with high breakdown strength and discharged energy density.

Investigation of electrical tree growth characteristics and partial discharge pattern analysis using deep neural network

Investigation of electrical tree growth characteristics and partial discharge pattern analysis using deep neural network

Role of a 3D Nanoskeleton in Hindering Electrical Tree Growth in Nanocomposites: Insights from in Situ Self-Fluorescence Imaging.

Despite the proposal of nanodielectrics in 1994, the impact of nano- and microstructures on composite performance is still not completely understood. A key reason for this knowledge gap is the lack of in situ characterization of micro- and nanoscale structures within materials. In this study, we observed the self-excited fluorescence of a microscale-damaged microchannel inside a composite under the influence of an electric field. Furthermore, we conducted in situ imaging of the internal microstructures and discharge channels in the composite utilizing external laser excitation. The imaging results reveal that the electrical treelike damage in the composites grows with a single channel under the guidance of the nanoskeleton embedded in the matrix, which demonstrates that the three-dimensional (3D) nano-order skeleton hinders the development of electrical trees. Furthermore, we analyzed the nanoskeleton intervention's enhancement mechanism on the insulation properties of the composites. This work aids in the precision imaging-guided structural design of nanodielectrics.

Effect of Crystalline Morphology on Electrical Tree Morphology and Growth Characteristics of PP Insulation: From Mesoscopic to Macroscopic

This paper aims to investigate the effects of crystalline morphology on electrical tree morphology and growth characteristics of isotactic polypropylene (iPP). The crystalline morphology of iPP is adjusted by altering the crystallized temperature, and the mesoscopic electrical treeing in these samples with a thickness of 280 μm is studied. The polarizing microscope images show that an electrical tree is easier to grow along the spherulites boundary and form a bush tree within spherulites. Compared with samples crystallized at a cooling rate of 2.5 °C/min and the isothermal temperature of 132 °C, the spherulite size of the sample crystallized at a cooling rate of 10 °C/min significantly decreases, resulting in an obvious decrease of the accumulated damage area and length of the mesoscopic electrical tree. The macroscopic electrical treeing is also conducted in the iPP samples with different crystalline morphologies with a thickness of 2 mm. There exists a relation between the mesoscopic and macroscopic electrical growth characteristics by using the Pearson correlation coefficient. It is concluded that the reduction of the spherulite size and the spherulite boundary gap limits the partial discharge and the development of an electrical tree in the amorphous region at the spherulite interface, making it easier to form the bush tree and leading to improved resistance to electrical treeing.

Heterogeneous mesoscopic structure modulation enhancing dielectric strength of polypropylene insulation

This paper focuses on the heterogeneous mesoscopic structure modulation enhancing dielectric strength of polypropylene insulation. α-nucleating agents are used to modulate the heterogeneous mesoscopic structure of polypropylene, and Voronoi Network models with similar structures are established to simulate the electric field distribution at the mesoscopic scale. The experimental results show that the addition of an α-nucleating agent effectively diminishes the spherocrystal size and increases its density. The high continuity and wide range electric field distortion caused by the too-large spherocrystal size and too-loose arrangement is thus suppressed. The improvement of electric field uniformity effectively inhibits the frequency and intensity of partial discharge. Compared with pure polypropylene, the partial discharge in polypropylene composite with α-nucleating agents at 0.1 wt% decreased by 2414 times, and its maximum amplitude decreased by 58.3%. The increase in the spherocrystal density also enhances its blocking effect on the electrical tree growth, and the length and width of it are reduced by 88.6% and 89.1%, respectively. The dispersive development of the electrical tree reduces the incidence of penetration channels along the electric field direction. The breakdown strength is therefore increased by approximately 20%. The simulation results demonstrate that the dielectric property difference between the crystal and amorphous regions within polypropylene at the mesoscopic scale is the main reason that triggers the electric field distortion at its interface and further leads to insulating degradation or even failure. In this study, heterogeneous mesoscopic structure modulation is proved to be an efficient means to enhance the dielectric strength of polypropylene insulation.

Electrical degradation dynamics of glass fiber-reinforced epoxy composites considering different fiber orientation

Glass fiber-reinforced epoxy composites (GFREC) have been widely used in the mechanical components of electrical and electronic devices because of its lightweight, high mechanical strength, excellent electrical insulation properties and corrosion resistance. The research on the electrical degradation dynamics of GFREC is of great significance to avoid the failure of electrical insulation system. Herein the composite samples were prepared using vacuum impregnation technique. The electrical degradation morphology and statistical characteristics (electrical tree length, width, expansion coefficient, breakdown probability and breakdown time) were discussed. The results show that the electrical tree will develop towards the fiber side and grow rapidly along the interface in GFREC. The interfacial orientation will affect the growth characteristics of electrical tree. When the angle between the glass fiber and the needle electrode is 45°, the composite material has relatively superior tree propagation resistance performance, lower breakdown probability and higher breakdown time. The effects of electric field distribution on the tree initiation and electrical degradation are discussed, which reveals the relationship between the electrical degradation and the fiber orientations. The electric field-driven tree growth (FDTG) model is used to explain the growth of trees along interfaces with different orientations from the perspective of dynamic electric field distribution.