Electric fields on edges of anisotropic dielectric materials

1989 ◽  
Vol 25 (17) ◽  
pp. 1185 ◽  
Author(s):  
T. Miyata ◽  
T. Takeda ◽  
T. Kuwahara
Keyword(s):  
Electric Fields ◽  
Dielectric Materials ◽  
Anisotropic Dielectric

scholarly journals Using contactless methods of diagnostics of high electric fields

2019 ◽  
Vol 21 (4) ◽  
pp. 123-133
Author(s):  
A. V. Golenischev-Kutuzov ◽  
D. A. Ivanov ◽  
A. A. Potapov ◽  
V. I. Krotov
Keyword(s):  
Electric Fields ◽  
High Voltage ◽  
Optical Sensors ◽  
Electric Power Industry ◽  
Dielectric Materials ◽  
Partial Discharges ◽  
Contact Method ◽  
Diagnostic Device ◽  
Measuring Device ◽  
Remote Diagnostics

In the electric power industry of Russia and abroad, special attention is paid to the problem of an increase in the number of accidents caused by damage to high-voltage insulators in high-voltage equipment. An analysis of emergencies at substations and open switchgears [1- 2, 4] was carried out, which showed that in most cases the causes of damage to high-voltage insulators are natural aging in an applied electric field, overvoltage, and the presence of initial defects in the manufacture of high-voltage insulators. Based on this fact, we developed various methods of non-contact diagnostics of high-voltage insulators in order to identify defects at an early stage of their development. Particular attention was paid to the method of partial discharges because the characteristics of partial discharges provide information on the parameters of defects. The article describes a set of non-contact methods for remote diagnostics of high-voltage insulators; a two-channel method for remote diagnostics of the operating state of high-voltage insulators, based on the registration of partial discharges by electromagnetic and acoustic sensors; a device that allows visual inspection and the search for faulty high-voltage equipment; remote non-contact method for recording electric fields of high tension of industrial frequency, as well as their spatial orientation based on the electro-optical effect. We developed a mock-up of a portable diagnostic device for implementing research methods for high-voltage dielectric elements to diagnose their technical condition using the described complex of non-contact methods. The measuring device as part of a portable diagnostic device consists of a set of sensors for collecting diagnostic information detected by electromagnetic, acoustic and electro-optical sensors and a voltage phase signal applied to the studied highvoltage insulator. The simultaneous use of several sensors at once made it possible to increase the accuracy of localization of partial discharges in high-voltage insulators. Visualization of diagnostic results is possible at the control room in the form of amplitude-phase, frequencyphase and amplitude-frequency diagrams of the distribution of characteristics of partial discharges and on a portable device in the form of radiation intensity from the selected sensor. A portable diagnostic device made it possible in laboratory conditions to study electrophysical processes in various dielectric materials and products under the influence of strong alternating electric fields. A study was made of the features of defects on the rod and the terminal-terminal contact, a diagram of the electrophysical processes accompanying the emission of partial discharges was constructed, and the causes of their occurrence were established.

Flexible cyclic-olefin with enhanced dipolar relaxation for harsh condition electrification

2021 ◽  
Vol 118 (45) ◽  
pp. e2115367118
Author(s):  
Chao Wu ◽  
Ajinkya A. Deshmukh ◽  
Omer Yassin ◽  
Jierui Zhou ◽  
Abdullah Alamri ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Dielectric Constant ◽  
Electric Fields ◽  
High Efficiency ◽  
Dielectric Materials ◽  
Organic Polymer ◽  
Dipolar Relaxation ◽  
High Electric Fields ◽  
High Dielectric ◽  
Harsh Condition

Flexible large bandgap dielectric materials exhibiting ultra-fast charging-discharging rates are key components for electrification under extremely high electric fields. A polyoxafluoronorbornene (m-POFNB) with fused five-membered rings separated by alkenes and flexible single bonds as the backbone, rather than conjugated aromatic structure typically for conventional high-temperature polymers, is designed to achieve simultaneously high thermal stability and large bandgap. In addition, an asymmetrically fluorinated aromatic pendant group extended from the fused bicyclic structure of the backbone imparts m-POFNB with enhanced dipolar relaxation and thus high dielectric constant without sacrificing the bandgap. m-POFNB thereby exhibits an unprecedentedly high discharged energy density of 7.44 J/cm3 and high efficiency at 150 °C. This work points to a strategy to break the paradox of mutually exclusive constraints between bandgap, dielectric constant, and thermal stability in the design of all-organic polymer dielectrics for harsh condition electrifications.

scholarly journals Electrical and Magnetodielectric Properties of Magneto-Active Fabrics for Electromagnetic Shielding and Health Monitoring

2020 ◽  
Vol 21 (13) ◽  
pp. 4785
Author(s):  
Madalin Bunoiu ◽  
Eugen Mircea Anitas ◽  
Gabriel Pascu ◽  
Larisa Marina Elisabeth Chirigiu ◽  
Ioan Bica
Keyword(s):  
Electrical Properties ◽  
Electric Fields ◽  
Health Monitoring ◽  
Silicone Oil ◽  
Low Cost ◽  
Relaxation Times ◽  
Dielectric Materials ◽  
Medium Frequency ◽  
Mass Fractions ◽  
Electromagnetic Pollution

An efficient, low-cost and environmental-friendly method to fabricate magneto-active fabrics (MAFs) based on cotton fibers soaked with silicone oil and iron oxide microfibers (mFe) at mass fractions 2 wt.%, 4 wt.% and 8 wt.% is presented. It is shown that mFe induce good magnetic properties in MAFs, which are subsequently used as dielectric materials for capacitor fabrication. The electrical properties of MAFs are investigated in a static magnetic field with intensities of 0 kA/m, 160 kA/m and 320 kA/m, superimposed on a medium-frequency electric field. The influence of mFe on the electrical capacitance and dielectric loss tangent is determined, and it can be observed that the electrical conductivity, dielectric relaxation times and magnetodielectric effects are sensibly influenced by the applied magnetic and electric fields. The results indicate that the MAFs have electrical properties which could be useful for protection against electromagnetic pollution or for health monitoring.

RELAXOR FERROELECTRIC MATERIALS FOR MICROWAVE TUNABLE APPLICATIONS

2012 ◽  
Vol 02 (01) ◽  
pp. 1230002 ◽  
Author(s):  
QIWEI ZHANG ◽  
JIWEI ZHAI ◽  
LING BING KONG
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Electric Fields ◽  
Transition Metal Ions ◽  
Dielectric Materials ◽  
Ferroelectric Materials ◽  
Rare Earth Ions ◽  
Relaxor Behavior ◽  
Dielectric Tunability ◽  
Device Applications

With strong dependences of dielectric constant on external applied electric fields, relaxor barium zirconium titanate ( BaZr x Ti 1-x O 3 or BZT) and barium stannate titanate ( BaSn x Ti 1-x O 3 or BTS), in both bulk ceramic and thin film forms, are increasingly being recognized as potential candidates of microwave tunable materials for device applications. This paper is aimed to review the recent progress in understanding the dielectric properties (such as tunability, dielectric loss and dielectric constant) of these relaxor materials. However, due to their relatively high dielectric constant and loss tangent, pure Ba(Zr,Ti)O3 and Ba(Sn,Ti)O3 do not fully satisfy the requirements of practical device applications. Therefore, various strategies have been developed to improve the dielectric properties of these two groups of relaxor materials. In this paper, we first discussed the dielectric tunability characteristics of pure Ba(Zr,Ti)O3 and Ba(Sn,Ti)O3 and then summarized the strategies that have been used, including (i) small amount acceptor or donor doping (such as rare-earth ions and transition metal ions) and (ii) forming composites with low loss and low dielectric constant microwave dielectric materials (such as MgO , MgTiO3 and so on). At the same time, the relationship between relaxor behavior and dielectric tunability was also discussed.

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