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2000, IEEE Transactions on Dielectrics and Electrical Insulation
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2020, IEEE
It is well-known that the high-performance polymeric dielectric films used for high-voltage DC capacitors should have outstanding capabilities in terms of electrical and mechanical properties in order to face harsh operating conditions. Many factors limit the ability of these thin films to face different and growing stresses according to modern electrical requirements. Microstructure properties, additives, impurities, defects formed during manufacturing as well as applied stress types significantly affect the performance of dielectric films and their operational lifetime. This paper presents a comprehensive review of the factors which affect the ageing, degradation and breakdown of metallised polypropylene (PP) capacitors films. The effects of microstructure, surface morphological properties, mechanical properties and defects on the reliability of biaxially oriented polypropylene films (BOPP) are studied. In addition, the phenomena affecting dielectric performance and ageing mechanisms which are induced by electrical, thermal and electrothermal stresses are discussed.
2015, IEEE Transactions on Dielectrics and Electrical Insulation
2010, 2010 10th IEEE International Conference on Solid Dielectrics
2000, IEEE Electrical Insulation Magazine
Revealing the charge transport properties of space grade high insulation materials can benefit the mitigation of electrostatic discharges (ESD) on spacecraft. The charge transport properties of polyimide are investigated by an isothermal surface potential decay (ISPD) experiment under a simulated space environment chamber. After irradiated the sample by an electron gun, the 2-D surface potential distributions are measured by a non-contact potential probe. From the surface potential decay curves, we obtain current density at steady state ISPD. Analyzing the steady state current density against surface potential, we find two regimes. One is Ohmic regime and another is Space Charge Limited Current (SCLC) regime, which are separated at around-950 V with the sample thickness of 27 μm at 298 K. Ohmic resistivity and effective charge carrier mobility are calculated from these two regimes, respectively. In addition, the trap density of polyimide is derived from the SCLC theory, when the sample is charged to high initial surface potential. Index Terms—Charge transport properties, isothermal surface potential decay, Ohmic regime, polyimide, space charge limited current regime.
2008, IEEE Transactions on Dielectrics and Electrical Insulation
2014, Polymer
2008, IEEE Transactions on Dielectrics and Electrical Insulation
Although nanoparticle-modified polymers have tremendous promise in many applications, particularly dielectric energy storage, true nanoscale dispersion is extremely difficult to achieve. In this paper, we carefully engineer various dispersion states of titania nanoparticles in polyvinylidene fluoride and analyze their impact on dielectric behavior and energy storage ability. In particular, we compare nanocomposites prepared using commercially available nanoparticles to those we prepared using in situ and ex situ synthesis of nanoparticles. SEM and TEM studies showed that the in situ case leads to the best dispersion. Interestingly, dielectric permittivity was most influenced by dispersion state where the in situ case showed a higher increase, however, dielectric breakdown and energy storage density were less affected by dispersion and more affected by procedure that minimized residues and impurities. The in situ technique, in particular, showed nanoscale dispersion, low dielectric loss and higher energy storage density. In terms of mechanical behavior, all three cases showed a similar performance in the rubbery region, whereas the impact of dispersion was more pronounced in the glassy region. In fact, the trend was opposite to the dielectric permittivity where nanoscale dispersion resulted in a lower storage modulus likely due to the lower effective mechanical load transfer going to the nanoscale. The results of our study shed some light on the role of dispersion quality and processing techniques in affecting the final dielectric, mechanical and breakdown behavior of TiO2-based polymer nanocomposites.
2000, IEEE Electrical Insulation Magazine
2014, TELKOMNIKA Indonesian Journal of Electrical Engineering
2000, IEEE Transactions on Dielectrics and Electrical Insulation
2009, Electrical Insulation Magazine, IEEE
2000, IEEE Transactions on Nanotechnology
2011, Applied Physics Letters
2009
Abstract This paper investigates the electrical breakdown of a polar fluoropolymer, poly (vinylidene fluoride-hexafluoropropylene) which exhibits an exceptionally high discharged electrical energy density (≫ 25 J/cm 3). It is shown that above room temperature, the breakdown strength decreases with temperature. It is further shown that such a temperature dependence of breakdown strength is consistent with the electromechanical breakdown model by taking into consideration of the plastic deformation of semicrystalline polymers.
2013, Journal of the American Ceramic Society
2007
Amorphous tantalum pentoxide films are currently being studied as a high-k dielectric for high energy-density metal-insulator-metal capacitors. Tantalum pentoxide thin films were prepared through pulsed-dc reactive magnetron sputtering at a high deposition rate (15 Aring/s). The films were amorphous as determined by X-ray and electron diffraction through transmission electron microscopy (TEM) at all sputtering conditions of both low and high ion bombardments unlike other oxides such as zirconium oxide. The structure was also confirmed by electron energy loss spectra using anodized Ta2O5 films as a benchmark. After annealing at 750degC, the films crystallized to the beta-Ta2O5 phase (X-ray analysis). The dielectric constant and loss of the 2 mum-thick films are 21 and 0.3%, respectively, at 1 kHz at room temperature of 25degC. The amorphous films have a Temperature Coefficient of dielectric constant (TCK) of 2.1x10-3ldrC-1, similar to crystalline forms of Ta2O5 namely, alpha-Ta2O5 and beta-Ta2O5. Electrical breakdown field of these amorphous tantalum pentoxide films is as high as 400 MV/m with a corresponding energy density of 14 J/cm3. Electrical breakdown is affected by material crystallinity, which is controlled by annealing. The crystallinity is studied both at bulk level through X-ray diffraction and at the local atomic level through fluctuation electron microscopy (FEM), which is an electron microscopy technique used to study medium range order (MRO) on the length scale of 1-3 nm in apparently diffraction amorphous (TEM and X-ray) materials.
2014, RSC Advances
This review summarizes the current state of polymer composites used as dielectric materials for energy storage. The particular focus is on materials: polymers serving as the matrix, inorganic fillers used to increase the effective dielectric constant, and various recent investigations of functionalization of metal oxide fillers to improve compatibility with polymers. We review the recent literature focused on the dielectric characterization of composites, specifically the measurement of dielectric permittivity and breakdown field strength. Special attention is given to the analysis of the energy density of polymer composite materials and how the functionalization of the inorganic filler affects the energy density of polymer composite dielectric materials.
2007, Materials Science and Engineering: R: Reports
2011, Polymer Composites
2009, Journal of Materials Science-materials in Electronics
Zirconia-P(VDF-TrFE) double-layered laminar composites are experimentally investigated to understand inorganic–organic interfacial effects in composite dielectrics. The DC and AC electrical response of the individual phases were characterized in addition to the zirconia-P(VDF-TrFE) composite. The measured real part of permittivity for the laminar composite is found to be higher than theoretically calculated values using series mixing rules for zirconia and P(VDF-TrFE). Additional polarization of the composite structure can be attributed to either the presence of interfacial polarization of zirconia and P(VDF-TrFE) or modification of polymer. Impedance spectroscopy has shown that dielectric properties of laminar composites are dominated by zirconia thin films in low frequency region. The impedance spectroscopy shows that zirconia blocks charge carrier motion and hence partially contribute towards additional interfacial polarization in the laminar composite. The dielectric response of the laminar composite was also modeled through a Maxwell–Wagner interfacial polarization mechanism, which was found to inadequately describe the polarization response. Equivalent circuit modeling of the composite has revealed an additional interfacial circuit element for the additional polarization, suggesting a structurally modified polymer at the interface.
2012, Applied Physics Letters
Space charge behavior at physical interfaces in cross-linked polyethylene (XLPE) films subjected to a DC field has been investigated as a function of the nature of the interfaces using the pulsed clectro-acoustic technique. Aluminum, gold and carbon black-loaded polyethylene were used as electrodes to investigate space charge build-up in a single dielectric layer. A sandwich structure constituted by two dielectric films of the same nature was used to study the behavior of a charged interface.
Composite technology, where a novel artificial material is fabricated by combining, for example, ceramic and polymer materials in an ordered manner or just by mixing, was earlier used widely for sonar, medical diagnostics, and NDT purposes. However, in recent decades, large numbers of ceramic–polymer composites have been introduced for telecommunication and microelectronic applications. For these purposes, composites of 0–3 connectivity (a three-dimensionally connected polymer phase is loaded with isolated ceramic particles) are the most attractive from the application point of view. Composites of 0–3 connectivity enable flexible forms and very different shapes with very inexpensive fabrication methods including simply mixing and molding. In this brief review, we gather together the research carried out within 0–3 ceramic–polymer composites for microwave substrates, also including embedded capacitor, inductor, or microwave-absorbing performances
2006, IEEE Transactions on Dielectrics and Electrical Insulation
Journal of Electrical Engineering
Space charge behaviour at physical interfaces in cross-linked polyethylene (XLPE) films submitted to DC field has been investigated as a function of the nature of the interfaces using the pulsed electro-acoustic technique. Aluminium, gold and carbon black-loaded polyethylene were used as electrodes to investigate space charge built-up in a single dielectric layer. Charge injection rather than ionic species migration is seen to control space charge distribution in agreement with the storage conditions of the XLPE films. It is shown that the sign and distribution of space charge depend drastically on the nature and polarity of the electrodes
2009, Journal of Physics: Condensed Matter
2011, Microelectronics Reliability
2010, Química Nova
X-ray computed tomography and serial block-face SEM have provided detailed three-dimensional reconstructions of electrical trees for the first time. The application of finite element analysis (FEA) to the analysis of electrical fields in an epoxy block containing a tree is considered. Illustrations are provided by way of a number of case studies. It is shown that the limitations of FEA do not arise from the discrete nature of the meshing: rather uncertainties are more concerned with material properties in high fields on the micrometer scale, the limitations imposed by the pixel size of the imaging technique, and the discrete nature of the image reconstruction technique. For a dynamic model of tree growth space charge dynamics on the same physical scale need also to be modelled. A meshing strategy is used, calibrated against the charge simulation method, to ensure accurate but manageable computations in critical parts of a tree such as branch tips. Examples of field values are given using geometric constructs and low-field material characteristics as illustrative values. The field variation around a conducting tree structure, including the maximum field direction as a branch starts to bifurcate, is determined as an example. These yield values in excess of those expected if space charge movement was considered, but consistent with analytical calculations.
2005, European Polymer Journal
We are interested in the behavior under tension of metal dielectric interfaces and dielectric / dielectric towards the formation of space charges. The material in question is a widely used polyethylene as an insulator in high voltage cables. The space charges are measured by the pulsed electroacoustic technique during the polarization and depolarization. We considered a period for interfaces formed by the contact metal / semiconductor and polyethylene / polyethylene, and the association of two films of polyethylene, (thus obtaining a physical interface between two similar materials ). The results show that the formation and dissipation of space charges depend on the nature of interfaces and a 'physical' interface is not a barrier to the transport of charges.
2008, Journal of Polymer Science Part B: Polymer Physics
2000, IEEE Transactions on Dielectrics and Electrical Insulation
1997, IEEE Transactions on Dielectrics and Electrical Insulation
2015, IEEE Transactions on Dielectrics and Electrical Insulation
2000, IEEE Transactions on Dielectrics and Electrical Insulation
2010, IEEE Transactions on Dielectrics and Electrical Insulation
Polymeric insulating materials with excellent electrical properties are widely used in electrical power equipment. These materials are degraded, however, when they are subjected to partial discharge (PD) with different polymeric materials possessing different levels of PD resistance. In this study the PD characteristics and degradation caused by PD are analysed and compared for four different polymers – poly(ether sulphone) (PES), poly(ethylene terephthalate) (PET), poly(propylene) (PP) and low-density poly(ethylene) (LDPE). An artificial void is created in each of the polymer samples and electrically stressed above PD inception voltage (PDIV) for 4 h. The simulated electric field distribution inside the void for each of the polymer materials at the respective PDIVs is modelled using COMSOL to validate the experimental results. Little work has correlated void PD characteristics with material degradation induced by PD across a range of different polymers and subsequently categorised them according to their PD resistances. This study therefore presents a comparative study of the N– Q patterns of PD pulses (a plot of the number of discharges against the measure of apparent charge), PD repetition rate and the chemical and morphological changes occurring on the void surfaces for each type of polymer. The results show that the PD resistance of these four polymers can be categorised in a decreasing order according to the following sequence: LDPE, PP, PET and PES with LDPE being most resistant to PD and PES the least resistant.
The reliability of low-voltage inverter-fed motors is highly dependent on the inception of partial discharges. The effect of impulsive waveform parameters must be investigated to predict the repetitive partial discharge inception voltage (RPDIV) and define test procedures that can indicate properly the behavior in service of the insulation system. This paper focuses on the RPDIV of magnet wires using twisted pairs subjected to repetitive unipolar impulsive voltage waveforms. The effects of supply frequency (5 to 200 kHz) at pressure levels that are typical for aircraft (20 to 100 kPa) is examined. Results show that RPDIV steadily decreases with frequency up to 100 kHz where it reaches a plateau. This behavior is explained as an effect of the oscillations that inevitably exist in the applied voltage waveform. Therefore, a conservative estimate of the RPDIV could be achieved by raising the supply frequency well above the operation frequency. In the experiments, the RPDIV is decreasing linearly with pressure. If this behavior could be confirmed for other insulation systems, the design of systems working at pressures typical of aircraft would result relatively easy.
Journal of Electrostatics
In this paper, the effect of electrode materials on the formation of the interfacial charge between two dielectrics has been investigated. A sandwich structure constituted by two dielectric films: Low Density Polyethylene (LDPE) and Fluorinated Ethylene Propylene (FEP), was subjected to high DC electric stresses for extended periods of time and space charge measurements were taken using the pulsed electro acoustic (PEA) technique. Aluminum, gold, and carbon black-loaded polyethylene were used as electrodes to investigate the charging behavior of the electrode/dielectric and dielectric/dielectric interfaces. The time dependence of the space charge distribution was subsequently recorded at room temperature under field (polarization) and short circuit conditions (depolarization). Experimental results demonstrated that a charge injected process took place in all cases. However it is shown that the sign and the amount of interfacial charge depend strongly on the nature and the polarity o...