scholarly journals Time-Dependent Electric Field Distribution in Layered Paper-Oil Insulation

2019 ◽  
pp. 58-63 ◽  
Author(s):  
Gunnar Håkonseth ◽  
Erling Ildstad
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Electric Fields ◽  
Current Density ◽  
Test Object ◽  
Dielectric Response ◽  
Electric Field Distribution ◽  
Time Dependent ◽  
Polarization Current ◽  
Dependent Polarization

Layered paper–oil insulation is used in several types of HVDC equipment. In order to better understand breakdown mechanisms and optimize the design, it is important to understand the electric field distribution in the insulation. In the present work, a test object with such insulation has been modeled as a series connection of oil and impregnated paper. The permittivity, conductivity, and the dielectric response function has been measured for impregnated paper and oil separately and used as parameters in a dielectric response model for the layered insulation system. A system of differential equations has been established describing the voltages across each material, i.e. across each layer of the test object. These equations have been solved considering a DC step voltage across the whole test object. Based on this, the time-dependent electric field in each material as well as the time-dependent polarization current density in the test object have been calculated. The calculated polarization current density was found to agree well with the measured polarization current density of the test object. This indicates that application of dielectric response theory gives a good estimate of the time-dependent electric field distribution in layered insulation systems. The results show that 90 % of the change from initial values to steady-state values for the electric fields has occurred within the first 35 minutes after the voltage step. This applies to the electric fields in both of the materials of the examined test object at a temperature of 323 K.

scholarly journals Analysis of Electric Field and Current Density for Different Electrode Configuration of XLPE Insulation

2018 ◽  
Vol 7 (3.36) ◽  
pp. 127 ◽  
Author(s):  
Nishanthi Sunthrasakaran ◽  
Nor Akmal Mohd Jamail ◽  
Qamarul Ezani Kamarudin ◽  
Sujeetha Gunabalan
Keyword(s):  
Electric Field ◽  
Power System ◽  
Field Distribution ◽  
High Voltage ◽  
Current Density ◽  
Electric Field Distribution ◽  
Electrical Power ◽  
High Electric Field ◽  
Electrode Configuration ◽  
Maximum Electric Field

The most important aspect influencing the circumstance and characteristics of electrical discharges is the distribution of electric field in the gap of electrodes. The study of discharge performance requires details on the variation of maximum electric field around the electrode. In electrical power system, the insulation of high voltage power system usually subjected with high electric field. The high electric field causes the degradation performance of insulation and electrical breakdown start to occur. Generally, the standard sphere gaps widely used for protective device in electrical power equipment. This project is study about the electric field distribution and current density for different electrode configuration with XLPE barrier. Hence, the different electrode configuration influences the electric field distribution. This project mainly involves the simulation in order to evaluate the maximum electric field for different electrode configuration. Finite Element Method (FEM) software has been used in this project to perform the simulation. This project also discusses the breakdown characteristics of the XLPE. The accurate evaluation of electric field distribution and maximum electric field is an essential for the determination of discharge behavior of high voltage apparatus and components. The degree of uniformity is very low for pointed rod-plane when compared to other two electrode configurations. The non- uniform electric distribution creates electrical stress within the surface of dielectric barrier. As a conclusion, when the gap distance between the electrodes increase the electric field decrease.  

scholarly journals On the question of using solid electrodes in the electrolysis of cryolite-alumina melts. Part 3. Electric field distribution on the electrodes

2021 ◽  
Vol 25 (2) ◽  
pp. 235-251
Author(s):  
E. S. Gorlanov ◽  
A. A. Polyakov
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Edge Effect ◽  
Current Density ◽  
Molten Salts ◽  
Functional Relationship ◽  
Electric Field Distribution ◽  
Chemical Inhomogeneity ◽  
Electrolytic Process ◽  
Solid Electrodes

The aim of this work is to identify the theoretical limitations of molten salts electrolysis using solid electrodes to overcome these limitations in practice. We applied the theory of electric field distribution on the electrodes in aqueous solutions to predict the distribution of current density and potential on the polycrystalline surface of electrodes in molten salts. By combining the theoretical background of the current density distribution with the basic laws of potential formation on the surface of the electrodes, we determined and validated the sequence of numerical studies of electrolytic processes in the pole gap. The application of the method allowed the characteristics of the current concentration edge effect at the periphery of smooth electrodes and the distribution of current density and potential on the heterogeneous electrode surface to be determined. The functional relationship and development of the electrolysis parameters on the smooth and rough surfaces of electrodes were established by the different scenario simulations of their interaction. It was shown that it is possible to reduce the nonuniformity of the current and potential distribution on the initially rough surface of electrodes with an increase in the cathode polarisation, alumina concentration optimisation and melt circulation. It is, nonetheless, evident that with prolonged electrolysis, physical and chemical inhomogeneity can develop, nullifying all attempts to stabilise the process. We theoretically established a relationship between the edge effect and roughness and the distribution of the current density and potential on solid electrodes, which can act as a primary and generalising reason for their increased consumption, passivation and electrolytic process destabilisation in standard and low-melting electrolytes. This functional relationship can form a basis for developing the methods of flattening the electric field distribution over the anodes and cathodes area and, therefore, stabilising the electrolytic process. Literature overview, laboratory tests and theoretical calculations allowed the organising principle of a stable electrolytic process to be formulated -the combined application of elliptical electrodes and the electrochemical micro-borating of the cathodes. Practical verification of this assumption is one direction for further theoretical and laboratory research.

scholarly journals Nonperturbative Kinetic Description of Electron-Hole Excitations in Graphene in a Time Dependent Electric Field of Arbitrary Polarization

Particles ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 208-230 ◽  
Author(s):  
Stanislav A. Smolyansky ◽  
Anatolii D. Panferov ◽  
David B. Blaschke ◽  
Narine T. Gevorgyan
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Kinetic Equations ◽  
Nonlinear Effects ◽  
Two Dimensions ◽  
Time Dependent ◽  
Polarization Current ◽  
Kinetic Description ◽  
Orthogonal Direction ◽  
Electron Hole

On the basis of the well-known kinetic description of e − e + vacuum pair creation in strong electromagnetic fields in D = 3 + 1 QED we construct a nonperturbative kinetic approach to electron-hole excitations in graphene under the action of strong, time-dependent electric fields. We start from the simplest model of low-energy excitations around the Dirac points in the Brillouin zone. The corresponding kinetic equations are analyzed by nonperturbative analytical and numerical methods that allow to avoid difficulties characteristic for the perturbation theory. We consider different models for external fields acting in both, one and two dimensions. In the latter case we discuss the nonlinear interaction of the orthogonal currents in graphene which plays the role of an active nonlinear medium. In particular, this allows to govern the current in one direction by means of the electric field acting in the orthogonal direction. Investigating the polarization current we detected the existence of high frequency damped oscillations in a constant external electric field. When the electric field is abruptly turned off residual inertial oscillations of the polarization current are obtained. Further nonlinear effects are discussed.

Study on Electric Field Characteristics of Converter Transformer on Valve Side Winding

2011 ◽  
Vol 130-134 ◽  
pp. 1413-1417
Author(s):  
You Hua Gao ◽  
Guo Wei Liu ◽  
Yan Bin Li ◽  
You Feng Gao
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Electric Fields ◽  
High Voltage ◽  
Electric Field Distribution ◽  
Influence Factors ◽  
Calculation Model ◽  
Dc Voltage ◽  
Voltage Polarity ◽  
Transient Electric Field

Numerical calculation model with compound insulation of transient electric field is given. The insulation is more prominent due to complication for voltage applied on valve side winding of the converter transformer. So the simplied structure for electric calculation on the valve side winding of the converter transformer is established. The electric field distribution characteristics on the valve side winding of the converter transformer is analyzed and electric fields in different resistivity and permittivity are calculated under AC high voltage, DC high voltage, AC superimposed DC voltage, polarity reversal voltage. The maximum electric field intensity is calculated and analyzed under kinds of high voltage. Some important influence factors for electric field distribution are also discussed in this paper.

scholarly journals Electric Field Distribution Analysis of Blood Cancer as a Potential Blood Cancer Therapy

2021 ◽  
Vol 22 (2) ◽  
pp. 127
Author(s):  
Miftakhul Firdhaus ◽  
Ulya Farahdina ◽  
Vinda Zakiyatuz Zulfa ◽  
Endarko Endarko ◽  
Agus Rubiyanto ◽  
...  
Keyword(s):  
Cancer Therapy ◽  
Electric Field ◽  
Field Distribution ◽  
Electric Fields ◽  
B Lymphocyte ◽  
Electric Field Distribution ◽  
Input Voltage ◽  
Electrochemical Process ◽  
Distribution Analysis ◽  
Blood Cancer

Blood cancer causes a significant increase in the concentration of Leukocytes, which can be broken down through dielectrophoresis and electrochemical procedures. Therefore, the electric field plays an important role in the migration of leukocytes to high voltage areas. This is because different electrode arrangements produce varying electric field distributions. Furthermore, this study applied finite element methods to generate electric fields when electrodes with an AC voltage were applied to blood placed in a chamber. Therefore, in this study, variations of mediums and electrode arrangements were investigated, which led to the recommendation of 3 models. The objective was to investigate electrode arrangements that produce optimal electric field distribution for the three models to exhibit a booster of electric field distribution. The maximum electric field is generated close to the electrode (Z=2 mm and Z=92 mm) for any material (i.e. normal blood, B lymphocyte, and T lymphocyte) with values of 22.6 V/m and 23.47 V/m, 22.85 V/m and 22.97 V/m, and 24.88 V/m and 25.01 V/m. Based on principle, lymphocytes in the blood result in positive dielectrophoresis, since they migrate to a higher electric field close to the electrode, with enough input voltage to turn the electrochemical process on the leukocytes into electric current. Furthermore, this study provides new perspectives and ideas, which have not been revealed in previous studies on blood cancer therapy using the electric field of Ag electrode in blood cancer distribution.Keywords: blood cancer, dielectrophoresis, electric field, voltage, electrochemical, and cancer therapy.

scholarly journals Analytical and Experimental Studies on the Application of a Series of Treatment Chambers for Escherichia coli Inactivation by Pulsed Electric Fields

2020 ◽  
Vol 10 (12) ◽  
pp. 4071
Author(s):  
Khanit Matra ◽  
Pattakorn Buppan ◽  
Boonchai Techaumnat
Keyword(s):  
Escherichia Coli ◽  
Electric Field ◽  
Field Distribution ◽  
Electric Fields ◽  
Temperature Rise ◽  
Electric Field Distribution ◽  
Pulsed Electric Fields ◽  
Maximum Temperature ◽  
Liquid Media ◽  
Flowing Liquid

The paper investigated studies on the application of pulsed electric fields for the treatment of liquid media in a continuous manner in a co-field treatment chamber with elliptic insulator profiles. The electric field distribution and the temperature rise in the treatment chamber were evaluated via the finite element method. A non-uniform electric field was found at the elliptical insulator edges, while the electric field distribution on the insulator surface was rather uniform. The maximum temperature rise in the liquid media was located slightly behind the elliptic insulator due to the accumulated heat in the flowing liquid media. In the optimized treatment chamber, the average electric field intensity could be as high as 12.21 kV/cm at the moderate voltage at 7.5 kV. As a strategy to improve the inactivation while limiting the temperature rise, a series of treatment chambers was verified by experiments under the conditions of 7.5 kV, a 2.5% duty cycle, and 250 Hz. It was found that an increase in the treatment units could increase the inactivation efficiency for Escherichia coli. The average log reduction could be improved from 1.82 to 2.39 when the number of treatment units was increased from 1 to 5, respectively.

scholarly journals Conductivity Characterization of Insulation and Its Effects on the Calculation of the Electric Field Distribution in HVDC Cables

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Shili Liu ◽  
Wei Wei ◽  
Tao Liu ◽  
Zhaoyu Hui ◽  
Yuhua Hang ◽  
...  
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Electric Fields ◽  
Electric Field Distribution ◽  
Coincidence Degree ◽  
Insulating Materials ◽  
High Voltage Direct Current ◽  
Different Temperatures ◽  
Materials Used

The calculation of an electric field distribution provides the basis for the structural design of the insulation, and an accurate characterization of conductivity as a function of temperature and electric field forms an important basis for the simulation of the electric field distribution in HVDC (high-voltage direct current) cables. However, the conductivity functions that describe the insulating materials used for HVDC cables in different studies are different, and very little has been reported regarding how to choose the most accurate function. In this work, the conductivity of insulating materials used for HVDC cables is characterized, and the effects of the conductivity characterization on the simulation of the electric field in HVDC cables are studied. First, eight common conductivity functions are compared qualitatively. Then, the conductivities of XLPE for different temperatures and electric fields are measured, and a data fitting technique is used to analyze the coincidence degree between different functions and the test results. Finally, the steady-state electric field distributions of HVDC cables for different temperature gradients are simulated in COMSOL Multiphysics. The results show that the sum of the square of the relative errors of the fitting when using the original functions is larger than that achieved when using the logarithmic form of the functions. The deviations in the electric field caused by taking the logarithm of different functions are smaller.

scholarly journals Resolution of electric field distribution and conductivity in a non-uniform electric field: A teaching proposal

2021 ◽  
pp. 1-9
Author(s):  
Mustafa Erol ◽  
İldahan Özdeyiş Çolak
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Field Distribution ◽  
Electric Fields ◽  
Path Length ◽  
Electric Field Distribution ◽  
Specific Conductivity ◽  
Uniform Electric Field ◽  
Field Lines

This work offers an alternative teaching proposal for the instruction of challenging concepts of electric field distribution and specific conductivity in a non-uniform electric field. Specifically, electric field lines are initially plotted and later on the relation between the electric potential difference and electric field strength is validated.  Additionally, on a selected electric field line, electric field strength versus path length and also conductivity versus path length are plotted to comprehend and teach exceedingly difficult concepts of uniform and non-uniform electric fields. In order to accomplish those tasks, a basic conducting sheet, that is simply a wet cardboard, is designed as a part of the apparatus together with a dc power supply, a multi meter and connecting cables. The established method is interesting in the sense that designed the conducting wet cardboard is novel, very practical, beneficial and minimal costing, hence the approach offers physics educators fresh teaching routes and opportunities to clarify the puzzling concepts of electrical field and conductivity.

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