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Journal articles on the topic 'Electrical transformer'
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1
Kefalas, Themistoklis D., and Antonios Kladas. "Reduction of Power Grid Losses by Using Energy Efficient Distribution Transformers." Materials Science Forum 721 (June 2012): 269–74. http://dx.doi.org/10.4028/www.scientific.net/msf.721.269.
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The importance of distribution transformer no-load loss on the operation of modern electrical grids is often underestimated. Internationally, distribution transformer no-load loss constitutes nearly 25% of the transmission and distribution losses of electrical grids. The losses in European Union distribution transformers are estimated at about 33 TWh/year whereas, reactive power and harmonic losses add a further 5 TWh/year. In the Greek electrical grid the no-load losses of 140,000 distribution transformers are estimated at about 490 GWh/year. This paper has two goals the first one is to illustrate the significance of distribution transformer no-load loss in periods of high electric energy cost and the second goal is the presentation of a novel numerical methodology for wound core transformers no-load loss analysis, enabling to determine the economically and technically optimum transformer for every use.
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EL-KHATIB, AHMED M. "ELECTRICAL WELDING TRANSFORMER DESIGN." ERJ. Engineering Research Journal 23, no. 1 (January 1, 2000): 165–90. http://dx.doi.org/10.21608/erjm.2000.71204.
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Ziomek, Waldemar. "Transformer Electrical Insulation [Editorial]." IEEE Transactions on Dielectrics and Electrical Insulation 19, no. 6 (December 2012): 1841–42. http://dx.doi.org/10.1109/tdei.2012.6396938.
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Florkowski, Marek, Jakub Furgał, Maciej Kuniewski, and Piotr Pająk. "Overvoltage Impact on Internal Insulation Systems of Transformers in Electrical Networks with Vacuum Circuit Breakers." Energies 13, no. 23 (December 2, 2020): 6380. http://dx.doi.org/10.3390/en13236380.
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Vacuum circuit breakers are increasingly used as switching apparatus in electric power systems. The vacuum circuit breakers (VCBs) have very good operating properties. VCBs are characterized by specific physical phenomena that affect overvoltage exposure of the insulation systems of other devices. The most important phenomena are the ability to chop the current before the natural zero crossing, the ability to switch off high-frequency currents, and the rapid increase in dielectric strength recovery. One of the devices connected directly to vacuum circuit breakers is the distribution transformer. Overvoltages generated in electrical systems during switching off the transformers are a source of internal overvoltages in the windings. The analysis of the exposure of transformers operating in electrical networks equipped with vacuum circuit breakers is of great importance because of the impact on the insulation systems of switching overvoltages (SO). These types of overvoltages can be characterized by high maximum values and atypical waveforms, depending on the phenomena in the circuit breaker chambers, system configuration, parameters of electrical devices, and overvoltage protection. Overvoltages that stress the internal insulation systems are the result of the windings response to overvoltages at transformer terminals. This article presents an analysis of overvoltages that stress the transformer insulation systems, which occur while switching off transformers in systems with vacuum circuit breakers. The analysis was based on the results of laboratory measurements of switching overvoltages at transformer terminals and inside the winding, in a model medium-voltage electrical network with a vacuum circuit breaker.
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Xiang, Dong, and Fei Yu. "Characteristic Analysis of Ship Transformer Magnetizing Inrush Current and its Suppression Method." Advanced Materials Research 1070-1072 (December 2014): 1154–58. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.1154.
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Medium voltage in the electric power system of ship typically is powered by a large capacity transformer for low voltage electrical apparatus. When switching on, the primary side of transformer will produce very large current, which would endanger the safe operation of power for ships. The mechanism and characteristics of magnetizing inrush current is analyzed when the transformer switches with no load. We think that the reason caused magnetizing inrush current is transformers saturation. Pre-excitation is presented through a small volume transformer magnetizing method of suppressing the inrush current of transformer and validated by simulation and experiment.
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Hanus, Oleksii, and Kostiantyn Starkov. "STUDY OF THE NATURE OF OVERVOLTAGES IN THE ELECTRICAL NETWORK ARISING FROM VOLTAGE TRANSFORMERS." Bulletin of the National Technical University "KhPI". Series: Energy: Reliability and Energy Efficiency, no. 1 (2) (July 2, 2021): 28–36. http://dx.doi.org/10.20998/2224-0349.2021.01.05.
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A non-linear dynamic mathematical model of voltage transformer has been considered and overvoltages arising on the elements of voltage transformer equivalent circuit during transient processes have been investigated. The influence of voltage transformer secondary circuit capacitance on overvoltage multiplicity in the primary circuits and the duration of transients has been determined. The advantages of approximation of nonlinearity of voltage transformers by hyperbolic sine are used. Mathematical expressions determining the nature of changes in the forced and free components of the transient process in an electrical network with a voltage transformer have been obtained. It is shown that with the increase of the electric network capacitance the duration of the transition process damping increases and the frequency of the forced oscillations and the level of overvoltage decrease. It is proved that even small, in comparison with the primary nominal sinusoidal voltage, aperiodic components of the voltage transient process can lead to significant overvoltages during voltage transformer outages. It has been substantiated that both the secondary resistance and the switching torque influence the overvoltage multiplicity arising in the primary winding of voltage transformers. It is shown that the closed secondary winding worsens the disconnection process of non-linear inductance of voltage transformers. The values to which overvoltages increase in this case are determined. According to the results of calculations it is determined that with open secondary winding of voltage transformers the duration of transient process significantly increases. It has been found that the decrease of frequency of forced oscillations, which occurs in this case, is accompanied by an increase of currents in the primary winding of the voltage transformer, which is dangerous in terms of thermal stability of the winding insulation. It is shown, that closing the secondary winding of voltage transformers leads to significant reduction of transient damping time. It is suggested that this algorithm can be used to provide a rapid breakdown (suppression) of ferroresonant processes. The effectiveness of such a measure of stopping of ferroresonance processes as short-term shunting of secondary winding of voltage transformers has been investigated. The correlation of parameters of electric networks (capacity of busbar sections, nonlinearity of characteristics of voltage transformers, disconnection torque, etc.) at which ferroresonance process may occur and consideration of which may allow, in terms of prevention of ferroresonance processes, to identify substations (electric networks) that require more detailed research has been determined. The results of analytical studies were tested in the electric networks of JSC "Kharkivoblenergo" and used in the electricity distribution system for the selection of specific voltage transformers for certain configurations of electrical networks.
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Gong, Chen Bin, Qing Hao Wang, Gang Chen, En Lu Wang, Tian Shu Hai, Xin Yu Li, Bo Li, Xue Wang, Chen Yang Liu, and Qi Dong Zhao. "Research on Harm of Harmonics on Electrical Equipment." Advanced Materials Research 986-987 (July 2014): 1846–49. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1846.
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Through the analysis of harmonics caused by transformer, capacitor, electromagnetic voltage transformer and other accident, harmonics is an important indicator of power quality, which has been included in the “pollution" of power grid is found. In order to understand the harmonic, this paper from the concept of quality of electric energy, and then gradually extended to the field of harmonics. This paper firstly introduces the various reasons and equipment may produce harmonic, Secondly, illustrate harm of harmonic to operation of transformers, capacitors, electromagnetic voltage transformers and other electrical equipment, let more people know and understand the relevant knowledge of the harmonic, In order to save technical force and provide scientific basis for future effective harmonic.
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Abdikulova, Z. K., and E. O. Zhaparov. "СALCULATION AND CHOICE OF ELECTRIC CHART OF SUBSTATION OF THE КENTAU TRANSFORMER PLANT." BULLETIN Series of Physics & Mathematical Sciences 70, no. 2 (June 30, 2020): 141–48. http://dx.doi.org/10.51889/2020-2.1728-7901.21.
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Electric supply system in enterprises must provide with electrical supply continuity and reliability as in normal and accidental regimes, quality electro energetic, production efficiency, so in connection with these in the article there have been analyzed work regimes of substations, studied electrical net scheme for Kentau Transformer Plant’s substation, calculated plant’s loads and short circuit currents and on the base of the calculated results curried out inspection for the chosen equipment. The number of connections, reliability of power supply and prospects for development are the determining factors for choosing the electrical scheme of high-voltage switchgears. You also need to take into account the need to conduct audits and tests of switches without interruption. In our case, we have four connections: two communication lines with electrical systems and two transformers. The distribution devices of the substation of the Kentau transformer plant are connected to the transformers according to a block scheme. Electrical installations are connected to the network transformer unit or receive backup power from another substation, since in case of failure of one network, both transformers can not work with the rest of the network. Based on this, measures are proposed for the reconstruction of the substation, with the replacement of the block diagram of the switchgear with the circuit for connecting the power transformer to the switchgear by a bus bridge. Offered measurements on reconstruction of the substation by replacing block scheme of switchgears to scheme of power transformer connection with DD bus bridge. Worked out main modernization problems of the substation switchgear, done calculation and selection of distributing bus bars for arranging switchgear.
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Maximov, Serguei, Manuel A. Corona-Sánchez, Juan C. Olivares-Galvan, Enrique Melgoza-Vazquez, Rafael Escarela-Perez, and Victor M. Jimenez-Mondragon. "Mathematical Calculation of Stray Losses in Transformer Tanks with a Stainless Steel Insert." Mathematics 9, no. 2 (January 18, 2021): 184. http://dx.doi.org/10.3390/math9020184.
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At present it is claimed that all electrical energy systems operate with high values of efficiency and reliability. In electric power systems (EPS), electrical power and distribution transformers are responsible for transferring the electrical energy from power stations up to the load centers. Consequently, it is mandatory to design transformers that possess the highest efficiency and reliability possible. Considerable power losses and hotspots may exist in the bushing region of a transformer, where conductors pass through the tank. Most transformer tanks are made of low-carbon steel, for economical reasons, causing the induction of high eddy currents in the bushing regions. Using a non-magnetic insert in the transformer tank can reduce the eddy currents in the region and as a consequence avoid overheating. In this work, analytical formulations were developed to calculate the magnetic field distribution and the stray losses in the transformer region where bushings are mounted, considering a stainless steel insert (SSI) in the transformer tank. Previously, this problem had only been tackled with numerical models. Several cases were analyzed considering different non-magnetic insert sizes. Additionally, a numerical study using a two dimensional (2D) finite element (FE) axisymmetric model was carried out in order to validate the analytical results. The solved cases show a great concordance between models, obtaining relative errors between the solutions of less than two percent.
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Bulucea, Cornelia A., Doru A. Nicola, Nikos E. Mastorakis, and Carmen A. Bulucea. "Three-phase power transformer modelling in AC/DC traction substations." MATEC Web of Conferences 292 (2019): 01006. http://dx.doi.org/10.1051/matecconf/201929201006.
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Three-phase power transformer is one of the most important elements in the electric power systems, and it plays a significant role in terms of energy savings. Since the efficiency standards can be expressed in terms of electrical efficiency, in an attempt to improve the transformer efficiency, in this study an enhancement of three-phase power transformer modelling with space phasors is presented. There are established the equations with space phasors of the three-phase transformer with symmetrical compact core. This equations system can be used to analyze the dynamic regimes of three-phase transformers. In this paper have been analyzed some aspects of three-phase power transformer operation in a AC/DC traction substation.
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Kulesz, Barbara. "RECTIFIER TRANSFORMERS IN ELECTRIC TRACTION SUBSTATIONS ‐ DIFFERENT DESIGNS." TRANSPORT 20, no. 2 (April 20, 2005): 66–72. http://dx.doi.org/10.3846/16484142.2005.9637998.
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Electric traction in Poland is supplied with dc voltage which is obtained from the power grid via traction substations equipped with transformers and rectifiers. The paper gives the results of the investigation of different designs of these transformer‐rectfier sets ‐ namely, 12‐ and 24‐pulse systems. The comparison of electrical quantities such as ripple content, harmonic content of supply current and output voltage and utilisation of transformer secondary windings is provided.
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CAZACU, Emil, Laurentiu-Marius DUMITRAN, and Lucian PETRESCU. "EVALUAREA SOLICITĂRILOR TERMICE ȘI A DURATEI DE VIAȚĂ A TRANSFORMATOARELOR DE DISTRIBUȚIE AFLATE ÎN REGIM PERIODIC NESINUSOIDAL." "ACTUALITĂŢI ŞI PERSPECTIVE ÎN DOMENIUL MAŞINILOR ELECTRICE (ELECTRIC MACHINES, MATERIALS AND DRIVES - PRESENT AND TRENDS)" 2020, no. 1 (February 10, 2021): 1–13. http://dx.doi.org/10.36801/apme.2020.1.7.
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Electrical transformers are some of the most important equipment in the entire electricity distribution chain. Their operation with optimal values of the parameters (electrical, thermal and mechanical) ensures the continuous supply of consumers. The modern electrical loads of power distribution transformers are often nonlinear and generate several power quality problems, especially the distortion of the waveform of the current that flows through the windings of the transformer. This generates additional stresses (electrical and thermal) of the various components of the transformer (originally designed to operate in pure sinusoidal mode) which can cause abnormal (faulty) operation of the transformer and ultimately reducing its life (estimated by the manufacturer for permanent sinusoidal regime). In order to prevent or diminish the negative effects of the nonsinusoidal regime on the transformer, a deliberate limitation (reduction) of its maximum load is performed. The procedure is known as transformer derating. Its main aim is to establish the most appropriate declassification factors (denomination), resulting from the correlation of the nominal and constructive data of the transformer with the power quality parameters, measured in its secondary part (usually, these are the current distortion level and the corresponding spectrum harmonic). This paper analyzes qualitatively and quantitatively these aspects and proposes a downgrading procedure for in-service transformers which it illustrates in a case study.
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Melnikova, O. S., M. V. Prusakov, and A. A. Zholobov. "Study of the effect of cellulose fibers on the electrical strength of transformer oil." Vestnik IGEU, no. 4 (August 31, 2020): 23–33. http://dx.doi.org/10.17588/2072-2672.2020.4.023-033.
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The electrical strength of transformer oil is the first parameter in transformer insulation tests. Such tests are carried out in a standard discharger according to the values of breakdown voltage. An abrupt decrease in electrical strength occurs when oil is contaminated with mechanical impurities. The greatest influence on the electric field is exerted by highly conductive cellulose fibers. The field between the electrodes may be severely distorted bya «bridge» of such fibers. At the same time, the influence of such particles is not taken into account in the tests. The problem is to experimentally determine the effect of such impurities on the breakdown strength. Thereby, this research poses and solves the problem of determining the dielectric strength of transformer oil in a standard discharger in the presence of cellulose fibers.To simulate electric field strengths, the ANSYS software package has been used. The basis of the 3D model was a standard measuring cell for determining breakdown voltage, which takes into account the boundary conditions in the form of a cube in which the electrode system is located, and the values of the electric field strength in the center of the electrode system.The electric field tension between the electrodes has been calculated, taking into account the influence of increased conductivity of cellulose fibers. It has been found that the electrical strength of oil gaps of moistened fibers with a length of more than 200 μm is significantly reduced, which is not taken into account when testing transformer oil for breakdown in a standard cell. This leads to inaccuracy in determining the electric strength of transformer oil in existing equipment.The results of the study can be used by operational services to improve the assessment of the quality of transformer oil used in power transformers as insulation. The results also can be used to study the mechanisms of electrophysical processes occurring in liquid dielectrics in the presence of fibers.
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Liu, Guo Bin, Ning Wang, Qing Hao Wang, Tian Shu Hai, Chuan Zong Zhao, Gui Bin Hu, Hong Zhi Jiao, Chuan Bing Bi, and Hui Yan Cao. "Chromatographic Analysis of Oil-Based Electrical Equipment Discharge Failure." Applied Mechanics and Materials 602-605 (August 2014): 2953–57. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.2953.
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Discharge of failure was the fault type are likely to occur in transformers, bushings, transformers, and the extent of damage to the equipment is a serious and direct impact on the stable operation of the system, first introduced the principle and gas chromatographic analysis its test methods, then gas chromatography equipment discharge failure is how to judge the conduct described. Through the analysis of transformer oil chromatographic method can be found as early as possible transformers and other equipment inside the existence of latent failures, thus chromatography is to oversee and guarantee the safe operation of an important means of transformer.
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Braña, L., A. Costa, and R. Lopes. "Development of a power transformer model for high-frequency transient phenomena." Renewable Energy and Power Quality Journal 19 (September 2021): 217–21. http://dx.doi.org/10.24084/repqj19.260.
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In recent years, the proliferation of distributed renewable energy sources and the application of new rules for the exploitation of electrical networks imposed by the markets have dictated increasingly demanding operating conditions for electric power transformers, creating new challenges in their exploration and conservation. Transformers that, in addition to the transmission lines, are certainly the most important and critical element of any electrical energy system. Adequate models are necessary to accurately describe transformer behavior and internal response when submitted to different external requests imposed by the network, particularly during transient phenomena, as well as, to properly assess system vulnerabilities and network optimization. This effort is being carried out today by several research groups in the world, namely from Cigré and IEEE. In this work, a transformer model to be integrated into a timedomain equivalent circuit is developed and discussed. Results obtained with this model are compared with measurements obtained by the Cigré JWG A2/C4.52 in a power transformer used as a reference for the working group.
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Saha, T. K., M. Darveniza, D. J. T. Hill, and T. T. Le. "Electrical and chemical diagnostics of transformers insulation. A. Aged transformer samples." IEEE Transactions on Power Delivery 12, no. 4 (1997): 1547–54. http://dx.doi.org/10.1109/61.634174.
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Denisova, A. R., D. P. Spasov, A. R. Galyautdinova, and V. R. Ivanova. "The study of health and quality of operation of the transformer equipment electrical systems." Power engineering: research, equipment, technology 22, no. 3 (September 8, 2020): 23–35. http://dx.doi.org/10.30724/1998-9903-2020-22-3-23-35.
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Detection of defects at an early stage of their occurrence, especially for power transformers that have worked out the standard term, is an acute problem. This article discusses the possibility of using the system of monitoring, control and diagnosis of transformer equipment (SMUID) electrical systems in conjunction with the automated control system of electrical equipment (ASU ETO) and automated information-measuring system of commercial electricity metering (AIIS KUE) with the use of QR-code, as well as using TeamViewer for the operational elimination of accidents and identify abnormal operation of transformer equipment. Transformer monitoring system is designed for monitoring isolation, recording and analysis of partial discharges, monitoring of technical condition ensuring maximum fault-free service life of transformers. In addition, the introduction of automated diagnostics and electrical equipment is a necessary condition for the introduction of SmartGrid technology in industrial electric networks, contributes to the reduction of capital investments in the renewal of the equipment fleet. The methods currently used do not detect dangerous insulation degradation, are not sensitive to its aging, and in some cases mistakenly assess the isolation condition. The work analyses the operability and quality of the systems under consideration, shows the hierarchical structure of SMUID. By applying the proposed idea with the QR-code, it is possible to speed up the process of searching for information about the current technical state of electrical equipment.
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DeCristofaro, Nicholas. "Links of Science & Technology." MRS Bulletin 23, no. 5 (May 1998): 50–56. http://dx.doi.org/10.1557/s0883769400030451.
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On April 13, 1982, the Duke Power Company energized an experimental pad-mount distribution transformer in Hickory, North Carolina. The transformer, manufactured by General Electric, provided electric power to a local residence. That same month, the Georgia Power Company installed a similar transformer, made by Westinghouse Electric, atop a utility pole in Athens, Georgia. It supplied electricity for the exterior lights at the Westinghouse Newton Bridge Road plant. These devices shown in Figure 1 were unique among the nearly 40 million distribution transformers in service in the United States because their magnetic cores were made from an Fe–B–Si amorphous-metal alloy. This new material, produced by Allied-Signal (formerly Allied Chemical), was capable of magnetizing more efficiently than any electrical steel. By replacing grain-oriented silicon steel in the transformer cores, the amorphous metal reduced the core losses of the transformers by 75%.Although distribution transformers are relatively efficient devices, often operating at efficiencies as high as 99% at full load, they lose a significant amount of energy in their use. Because of the number of units in service, coupled with the fact that the core material is continuously magnetized and demagnetized at line frequency, transformers account for the largest portion of the energy losses on electric power distribution systems. It is estimated that over 50 × 109 kWh are dissipated annually in the United States in the form of distribution transformer core losses. At today's average electricity generating cost of $0.035/kWh, that energy is worth over $1,500 million.
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Zhang, Muxin, Liyan Kang, Bing Cao, Ying Shang, Qiutong Wu, Xinran Liu, Haishan Zhou, and Wenyu Liu. "Research and Application of Transformer-User Identification Technology Based On Fault Diagnosis of Electrical Information Acquisition Equipment." E3S Web of Conferences 136 (2019): 04054. http://dx.doi.org/10.1051/e3sconf/201913604054.
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The line loss rate of power supply enterprises is an important economic and technical index, which directly reflects the lean level of marketing professional management of power supply enterprises. At present, the confusion of transformer-user archives in transformer area is still widespread, which is a key issue in line loss management in power supply enterprises. As the downlink communication channel, low-voltage power line carrier can realize cross-station reading, which brings great difficulties to the identification of transformer-user relation. Because the data of calculating the line loss rate of the transformer area depends on the electrical information acquisition system, the running state of the electrical information acquisition equipment is also one of the important factors affecting the line loss rate of the transformer area. This paper will focus on the fault diagnosis technology of electrical information acquisition equipment, and use it to carry out the identification of transformer-user transformers.
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Alyunov, A. N., O. S. Vyatkina, I. G. Akhmetova, R. D. Pentiuc, and K. E. Sakipov. "Issues on optimization of operating modes of power transformers." E3S Web of Conferences 124 (2019): 02015. http://dx.doi.org/10.1051/e3sconf/201912402015.
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The article presents measure to optimize the operating modes of power transformers in order to minimize losses of electrical energy. The influence of actual voltage and service life of power transformers on electric power losses is shown. It was proposed to determine the economic capacity of power transformers taking into account the indicated factors, as well as taking into account the time of transformer switching on into the electric network and the form of the load schedule.
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Van Cuong, Ngo, and Lidiia I. Kovernikova. "Predicting the influence of the non-sinusoidal network mode on power transformers." E3S Web of Conferences 114 (2019): 04005. http://dx.doi.org/10.1051/e3sconf/201911404005.
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The parameters of electrical network modes often do not meet the requirements of Russian GOST 32144-2013 and the guidelines of Vietnam. In the actual operating conditions while there is the non-sinusoidal mode in electrical networks voltage and current harmonics are present. Harmonics result in overheating and damage of power transformers since they cause additional active power losses. Additional losses lead to the additional heat release, accelerating the process of insulating paper, transformer oil and magnetic structure deterioration consequently shortening the service life of a power transformer. In this regard there arises a need to develop certain scientific methods that would help demonstrate that low power quality, for instance could lead to a decrease in the electrical equipment service life. Currently we see a development of automated systems for continuous monitoring of power quality indices and mode parameters of electrical networks. These systems could be supplemented by characteristics calculating programs that give out a warning upon detection of the adverse influence of voltage and current harmonics on various electrical equipment of both electric power providers and electric power consumers. A software program presented in the article may be used to predict the influence of voltage and current harmonics on power transformers.
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Hasan, Mushtaq I., Adnan A. Ugla, and Hassan S. Kadhim. "Improving the thermal performance of electrical transformers using hybrid mixture of (transformer oil, nanoparticles, and PCM)." Al-Qadisiyah Journal for Engineering Sciences 13, no. 3 (September 30, 2020): 175–82. http://dx.doi.org/10.30772/qjes.v13i3.704.
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In this paper, an experimental electrical distribution transformer was studied and a new technique was proposed to improve the performance of a new mixed cooling consisting of pure transformer oil, paraffin wax and nanoparticles. The experiment was carried out on a small transformer that was done by taking a model with dimensions (15 * 10 * 10) cm to facilitate calculations. Paraffin wax absorbs the heat generated in the transformer due to the smelting process that can be used to cool electrical appliances. Nanoparticles have good thermal properties and lead to increased oil insulation to thermal improvements in transformer oil with dispersal of solid nanoparticles and their effects on transformer cooling. Three types of solid nanoparticles were used in this experiment (Al2O3, TiO2, and Sic) with a different volume concentration (1%, 3%, and 5%) and 4% paraffin wax as a certified added percentage for each process. The obtained results showed that when mixing paraffin wax and solid nanoparticles with transformer oil, the transformer cooling performance is improved by reducing the temperature. The best selected nanoparticles were found to be Sic and the reason for this is that Sic has a higher thermal conductivity compared to (Al2O3 and TiO2). The proposed hybrid oil reduces the temperature by 10 ° C (in the case of PCM and Sic) and it is possible to improve the cooling performance of electrical transformers.
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Malažinskas, Vilius, Renaldas Raišutis, Alfonsas Morkvėnas, Saulius Gudžius, Audrius Jonaitis, Jonas Vaičys, and Gediminas Daukšys. "EVALUATION OF THE INSULATION CONDITION OF HIGH-VOLTAGE TRANSFORMERS BY DETECTING PARTIAL DISCHARGES USING THE ELECTROMAGNETIC WAVE RADIATION METHOD." Materiali in tehnologije 55, no. 2 (April 15, 2021): 253–61. http://dx.doi.org/10.17222/mit.2020.175.
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High-voltage transformers are among the most important elements in an electric-power system. Each one of them is affected by various external factors: overvoltage, partial discharge (PD), overheating, vibrations, etc., which are created by a strong electric field, thermal effect, humidity, impurities, factory defects, dissolved water and gas in oil-type-transformer insulation. These and other factors, caused by the environment, reduce the life of a device. Thus, the evaluation of the device condition is one of the most important factors for a system-safety evaluation, which ensures a reliable and economical electrical-network operation. This work reviews different contact and non-contact methods, used to evaluate the conditions of transformers by measuring the level of PD. The selected method, i.e., the non-contact measurement of electromagnetic-wave radiation was used to evaluate the voltage-transformer status. The experiment was performed at a 110 kV substation. The authors discuss the efficiency of the selected method to evaluate the voltage-transformer insulation condition.
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Bai, Bao Dong, and Chong Li. "Measurement Research on Magnetic Properties of Electrical Steel Sheet under DC Bias Conditions." Advanced Materials Research 383-390 (November 2011): 5017–22. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.5017.
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In order to acquire the magnetic properties parameter of transformer core under DC bias conditions, also to reveal the accurate analysis and judgment on the operating characteristics of transformer under the DC bias, this thesis utilized two Epstein Square devices to proceed the experiment and measurement on magnetization curve of some certain transformer which used the 30ZH120 electrical steel sheet under four different lap ways. This paper provided the measure method of bias magnetic density under laboratory conditions, meanwhile it offered the bias magnetization curve and the loss curve. The measure consequence comparison between the electrical sheet steel and the transformer model showed that direct oblique way lap can be more realistically reflected the magnetization characteristic of transformer which worked in the DC bias conditions. For Large Transformer which was difficult to measure the magnetic properties provided a convenient measurement methods, and offered the experiment facts to the theory study of the DC bias transformers.
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Vinogradov, A. V., A. V. Vinogradova, V. E. Bolshev, M. O. Ward, N. V. Makhiyanova, and L. V. Dolomaniuk. "Justification for creating a mobile complex to assess electric energy loss in power transformers during the operation process." E3S Web of Conferences 124 (2019): 02009. http://dx.doi.org/10.1051/e3sconf/201912402009.
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The paper analyzes the statistical data on the transformers of the Kromsky branch of Oreloblenergo OJSC including the average lifetime of the transformers and no-load losses measured in accordance with the requirements of Russian standard GOST 3484.1. The analysis indicates that the declared passport data differ from the measured data. There is also the analysis of technical solutions to improve the power transformer design including to development of new types of electrical steel used in transformer cores, superconducting materials for winding. The article gives an understanding of the advantages and disadvantages of using these technologies as well as the possible reduction of electrical losses. In conclusion there is the justification for creating the mobile measuring complex to assess electric energy loss in power transformers during operation without disconnecting the load. The paper describes the result achieved using such a mobile measuring complex along with the economic effect of creating the project.
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Gao, You Hua, Guo Wei Liu, Xiao Ming Liu, and Zeng Feng Lai. "Calculation and Analysis of Electrical Field in Valve Side Winding of Converter Transformer." Advanced Materials Research 383-390 (November 2011): 4865–70. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.4865.
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The numerical calculation model with compound insulation of transient electrical field is established. The types of voltage applied on the valve side winding of the converter transformer are complicated and the insulation is more prominent. So the simplied calculation model of the valve side winding of the converter transformer is established. The distribution characteristics of electrical field of the valve side winding of the converter transformer is analyzed and electric field in different electrical conductivity and permittivity are calculated under AC high voltage, DC high voltage, AC superimposed DC voltage, polarity reversal voltage. Under all kinds of high voltages, the maximum electric field strength is calculated and analyzed. Some important influence factors for electrical field distribution are also discussed in this paper.
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Borges, Ciaddy Gina Rodriguez. "Software Development for Transformer Model Supporting Significant Learning Electrical Machines." International Journal of Psychosocial Rehabilitation 24, no. 02 (February 10, 2020): 591–99. http://dx.doi.org/10.37200/ijpr/v24i2/pr200373.
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Hnatov, Andrii, Shchasiana Arhun, Ruslan Bagach, Andrii Nechaus, Valentina Tarasova, Oleksandr Ruchka, Alla Don, and Antons Patlins. "ELECTRICAL POWER UNIT OF THE TRANSFORMER OIL CENTRIFUGAL CLEANING UNIT." Automobile transport, no. 48 (May 29, 2021): 101–12. http://dx.doi.org/10.30977/at.2219-8342.2021.48.0.101.
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Problem. Cleaning transformer oil is one of the important engineering tasks, whose solution is associated with significant material and energy expenditure. Due to the increase in electricity consumption at modern automobile companies (firms, organizations, service stations, etc.), the load on transformer substations increases and the requirements for reliability of electrical and electronic devices become more complicated. This, in turn, leads to the problem of cleaning and recycling of transformer oil. Goal. The goal is the research and development of an efficient unit for centrifugal cleaning of transformer oil with a drive control system that provides automation of the start and braking mode of the drive. Methodology. Analytical methods of research, methods of the theory of electric machines and electric drives are used, as well as the methods of calculating electric circuits. Also, methods of analysis of circuits and control of power electronics devices, principles of operation and methods of control of static converters are used. Results. The structural scheme of the unit for cleaning transformer oil is developed. The calculations of the main elements of the power block of the transformer oil cleaning unit are performed. The block diagram of the voltage converter with frequency f = 50 Hz to alternating voltage with frequency f = 400 Hz is developed. Control circuits of the electric drive of the centrifugal separator are chosen. The analysis of operation of electric drive control circuits is carried out and the principles of their work concerning two components are considered: the regulated rectifier and the inverter. Originality. The scheme of the converter of alternating three-phase current with voltage of 220 V and frequency of 50 Hz, into alternating three-phase current with voltage of 220 V and frequency of 400 Hz is developed. This frequency, in addition to providing the necessary characteristics of the oil separator, allows you to develop a converter device of a relatively small weight and volume, and also provides its high reliability. Practical value. Utilizing the used transformer oil in this way will solve several problems at once. It is possible to reduce the initial production of transformer oil. The issue of waste oil disposal is being resolved leading to the solution of the environmental aspect of this problem. All this will reduce the cost of oil poured into transformers and the operating cost of transformer substations.
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Furgał, Jakub, Maciej Kuniewski, and Piotr Pająk. "Analysis of Internal Overvoltages in Transformer Windings during Transients in Electrical Networks." Energies 13, no. 10 (May 22, 2020): 2644. http://dx.doi.org/10.3390/en13102644.
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Due to the increasing requirements for the reliability of electrical power supply and associated apparatus, it is necessary to provide a detailed analysis of the overvoltage risk of power transformer insulation systems and equipment connected to their terminals. Exposure of transformer windings to overvoltages is the result of the propagation condition of electromagnetic waves in electrical networks and transformer windings. An analysis of transformer winding responses to transients in power systems is of particular importance, especially when protection against surges by typical overvoltage protection systems is applied. The analysis of internal overvoltages in transformers during a typical transient related to switching operations and selected failures is of great importance, particularly to assess the overvoltage exposure of insulation systems in operating conditions. The random nature of overvoltage phenomena in electrical networks implies the usage of computer simulations for the analysis of overvoltage exposures of electrical devices in operation. This article presents the analysis of the impact of transient phenomena in a model of a medium-voltage electrical network during switching operations and ground faults on overvoltages in the internal insulation systems of transformer windings. The basis of the analysis is simulations of overvoltages in the windings, made in the Electromagnetic Transients Program/Alternative Transients Program (EMTP/ATP) using a model with lumped parameters of transformer windings. The analysis covers the impact of the cable line length and the ground fault resistance value on internal overvoltage distributions.
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Hassani, Mahdi, Seyed Siavash Karimi Madahi, Hassan Feshki Farahani, and Hossein Sarabadani. "A New Method to Improve the Voltage Distribution and Electric Field Control for Conceder Bushing." Applied Mechanics and Materials 110-116 (October 2011): 5184–88. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.5184.
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Capacitor bushings are one of the key components in power transformers. Although their price is a negligible part of the total price of the power transformer, their quality has a significant effect on performance and reliability of power transformers. In high voltage capacitor bushings, the intensity of voltage and electric field on bushing abacus is very high. This high intensity is also observed in flange parts. The amount of multi layer insulator among the electrodes or floating plates in capacitor bushing make equi-potential surfaces and reduction of electric field in these areas can greatly improve the capacitor bushing performance. In this paper, we investigate the reduction of field intensity and electrical tension and also improvement in voltage control by displacing floating plates which are in the form of aluminum foils stick to impregnated paper. To calculate the field intensity, we used the MAXWELL software using FEM (Finite element method). Using this new method of placing capacitor core its effect on voltage profile reduction and field electrical tension is shown. Over voltage and pollution effects are also investigate on power transformer bushings.
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Robinson, Michael C., Sara E. Wallace, David C. Woodward, and Gene Engstrom. "US Navy Power Transformer Sizing Requirements Using Probabilistic Analysis." Journal of Ship Production 22, no. 04 (November 1, 2006): 212–18. http://dx.doi.org/10.5957/jsp.2006.22.4.212.
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Sizing power transformers in US Navy ships is an issue that surfaced in the design of a new amphibious assault ship. Previous methods averaged the power output from generators over each transformer and calculated load based on a demand factor curve. This technique is not accurate enough in the contract design stages or for zonal architectures since it artificially averages the electrical loads. The proposed methodology uses a systems engineering approach, applying a probabilistic (Monte Carlo) analysis of the electrical loads at each transformer, based on the electrical load analysis (ELA). This methodology will allow the designer to incorporate risk mitigation into a radial or zonal electrical system design to verify adequacy and reduce cost through probability-based transformer sizing.
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Clavel, E., J. Roudet, and A. Foggia. "Electrical modeling of transformer connecting bars." IEEE Transactions on Magnetics 38, no. 2 (March 2002): 1378–82. http://dx.doi.org/10.1109/20.996028.
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Gafvert, U., A. Jaksts, C. Tornkvist, and L. Walfridsson. "Electrical field distribution in transformer oil." IEEE Transactions on Electrical Insulation 27, no. 3 (June 1992): 647–60. http://dx.doi.org/10.1109/14.142730.
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Priya. K.R, Anu, and Sasilatha T. "Transformer Exchanging with Vacuum Electrical Switch." Indonesian Journal of Electrical Engineering and Computer Science 8, no. 3 (December 1, 2017): 679. http://dx.doi.org/10.11591/ijeecs.v8.i3.pp679-680.
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<p>This paper presents investigation of conceivable transient overvoltage that can be produced amid vacuum electrical switch (VCB) operation at the association purpose of a photovoltaic power plant. Average exchanging occasion that is identified with VCB concerns stimulation and de-empowerment of emptied transformer. Nonetheless, at the common photovoltaic power plant the transformer is sustained by an inverter outfitted with LC (or LCL) channels that are important for constraint of music and swell in voltage and current. From the perspective of exchanging operations, the inductance and capacitance of the LV side associated channel influence the regular recurrence of the transformer, which is reflected by various transient framework reaction amid VCB working. In this article, research facility estimation of overvoltage produced amid dispersion transformer exchanging by methods for VCB is examined. Effect of the LC channel associated at the LV side on the overvoltage concealment was contemplated. EMTP-ATP recreations were directed with a specific end goal to confirm the likelihood of homeless people end by methods for extra arrangement associated RL gag at the transformer medium voltage side.</p>
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Brodov, A. A., M. P. Galkin, B. A. Kornienkov, and B. V. Molotilov. "Amorphous electrical steel for transformer cores." Steel in Translation 45, no. 11 (November 2015): 900–902. http://dx.doi.org/10.3103/s0967091215110054.
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Simons, Philip, and Andries Habraken. "Simulation of Electrical Heating with Multiple Transformers." Advanced Materials Research 39-40 (April 2008): 469–74. http://dx.doi.org/10.4028/www.scientific.net/amr.39-40.469.
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In the simulation package GTM-X two methods are available that approximate the electric potentials in the glass melt in the presence of multiple transformers. Both methods control the grouped electrodes in such a way that power consistency is guaranteed, also for complicated electrode groupings and transformer systems. By power consistency we mean that the total heat release, as calculated from the potentials and currents at the electrodes, matches the power that is released in the volume cells. The first method approximates two scalar potentials; it may violate the constraint that electrical currents are conserved per electrode group. The second method solves for two scalar potentials per electrode group (or transformer); the result is that also this additional constraint can be satisfied. In this article, we discuss these two methods and show results for a model problem.
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Prishchepov, M. A., A. I. Zelenkevich, and V. M. Zbrodyga. "Advanced power transformer with improved parameters for rural electrical networks." Proceedings of the National Academy of Sciences of Belarus. Agrarian Series 59, no. 3 (August 5, 2021): 366–77. http://dx.doi.org/10.29235/1817-7204-2021-59-3-366-377.
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The problem of power quality supply is relevant for rural electrical networks, due to long distance and branching, as well as connection of a large number of single-phase and non-linear loads. Asymmetry of electrical loads causes voltage asymmetry, which adversely affects the operation of all elements of the electrical system, causing additional power losses, reducing the service life of electrical equipment and its economic performance, as well as reliability of operation of individual electrical equipment and power supply system as a whole. Reduction of voltage asymmetry can be ensured by rational construction of electrical network circuit and use of special correcting devices. The authors consider it reasonable to use relatively simple and reliable by design and inexpensive power transformers with a “star - double zigzag with a zero wire” (Y/2Zн) winding connection circuit with a neutral winding connection group. The paper deals with design and processes of converting electrical energy in a transformer. It has been proved that phase EMF of the secondary winding coincides in phase with the same EMF of the primary winding, i.e. the proposed circuit has a neutral windings’ connection group. Results of theoretical studies of transformer operation with an asymmetric and non-linear load are presented. Decrease in voltage asymmetry is due to the neutral sequence components compensation. Decrease of the higher harmonic voltage components level occurs due to the compensation of the higher harmonics multiplied three times. It is theoretically substantiated that transformer will not emit higher harmonic components of zero sequence voltages into the supply network. Experimental studies have confirmed the theoretical conclusions that a transformer with Y/2Zн winding connection circuit allows obtaining the highest level of voltage symmetry with an asymmetric load. In single-phase load mode, the values of voltage unbalance factor in reverse sequence do not exceed 1.7 %, in neutral sequence - 2.9 %. The transformer allows obtaining 1.2-1.5 times lower value of total harmonic components factor at non-linear load, which is the best result among circuits studied. This power transformer is resistant to load effects that distort voltage quality and is capable to provide a high level of symmetry and sinusoidal voltage as well as parallel operation with commercially available transformers. This makes it possible to use it in rural electrical networks to reduce power losses, increase service life and efficiency of electrical equipment, and increase reliability of the power supply system.
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Gutten, Miroslav, Daniel Korenciak, Matej Kucera, Richard Janura, Adam Glowacz, and Eliasz Kantoch. "Frequency and time fault diagnosis methods of power transformers." Measurement Science Review 18, no. 4 (August 1, 2018): 162–67. http://dx.doi.org/10.1515/msr-2018-0023.
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Abstract The authors describe experimental and theoretical analyses of faults of power transformer winding. Faults were caused by mechanical effect of short-circuit currents. Measurements of transformer were carried out in high-voltage laboratory. Frequency and time diagnostic methods (method SFRA - Sweep Frequency Response Analysis, impact test) were used for the analyses. Coils of transformer windings were diagnosed by means of the SFRA method and the time impact test. The analyzed methods had a significant sensitivity to a relatively small deformation of coil. In the analysis a new technique for analyzing the effects of short-circuit currents is introduced. This technique is developed for high-voltage transformers (different types of power). The proposed analyses show that it is necessary to analyze the value of short-circuit current. Short-circuit current represents a danger for the operation of the power transformer. The proposed approach can be used for other types of transformers. Moreover, the presented techniques have a potential application for fault diagnosis of electrical equipment such as: transformers and electrical machines.
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Banchuin, Rawid, and Roungsan Chaisricharoen. "Vector SDE Based Stochastic Analysis of Transformer." ECTI Transactions on Computer and Information Technology (ECTI-CIT) 15, no. 1 (January 5, 2021): 82–107. http://dx.doi.org/10.37936/ecti-cit.2021151.188931.
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In this research, the stochastic behaviours oftransformer have been analysed by using the stochasticdifferential equation approach where both noise in thevoltage source applied to the transformer and the randomvariations in elements and parameters of transformers havebeen considered. The resulting vector stochasticdifferential equations of the transformer have been bothanalytically and numerically solved in the Ito sense wherethe Euler-Maruyama scheme has been adopted fordetermining the numerical solutions which have been theirsample means have been used for verification. With theobtained analytical and numerical solutions, the stochasticproperties of the transformer’s electrical quantities havebeen studied and the influences of noise in the voltagesource and random variations in elements and parametersof transformers to those electrical quantities have beenanalysed. The causes of high and low frequency stochasticvariations of such electrical quantities in both transient andsteady state have been pointed out. Moreover, furtherextension of our stochastic differential equations and therelated mathematical formulations has also been given.
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Gonzalez-Garcia, Carlos, and Jorge Pleite. "Transformer Model in Wide Frequency Bandwidth for Power Electronics Systems." Advances in Power Electronics 2013 (January 28, 2013): 1–8. http://dx.doi.org/10.1155/2013/249146.
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The development of the smart grids leads to new challenges on the power electronics equipment and power transformers. The use of power electronic transformer presents several advantages, but new problems related with the application of high frequency voltage and current components come across. Thus, an accurate knowledge of the transformer behavior in a wide frequency range is mandatory. A novel modeling procedure to relate the transformer physical behavior and its frequency response by means of electrical parameters is presented. Its usability is demonstrated by an example where a power transformer is used as filter and voltage reducer in an AC-DC-AC converter.
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Bulucea, Cornelia A., Constantin Brindusa, Doru A. Nicola, Nikos E. Mastorakis, Carmen A. Bulucea, and Philippe Dondon. "Evaluating through mathematical modelling the power equipment busbars electrodynamic strength under sudden short-circuit conditions." MATEC Web of Conferences 210 (2018): 02004. http://dx.doi.org/10.1051/matecconf/201821002004.
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The electrodynamic strength, as forces acting between the current-carrying electric circuits are exerted as long as the currents exist, and have the tendency of deformation and displacement of the circuits. In short-circuit regimes the strength in electrical equipment becomes severe. For instance, short-circuits highly affect power transformers connected to power transmission lines. The effects are also strong because of mechanical deformations occurring in the power transformer connection part. In line with this idea, in this paper it is made an analytical study upon the a.c. single-phase and a.c. three-phase electric circuits, taking into account the current instantaneous maximum value. The paper also entails numerical simulations of electrodynamic strength in power transformer busbars under short-circuit conditions. MATLAB software, with its specific extensions, enable simulation models to generate the charts of the electrodynamic forces in the power transformer connection bars.
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Kirui, Kemei Peter, David K. Murage, and Peter K. Kihato. "Impacts of Placement of Wind Turbine Generators on IEEE 13 Node Radial Test Feeder In-Line Transformer Fuse-Fuse Protection Coordination." European Journal of Engineering Research and Science 5, no. 6 (June 7, 2020): 665–74. http://dx.doi.org/10.24018/ejers.2020.5.6.1939.
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The ever increasing global demand on the electrical energy has lead to the integration of Distributed Generators (DGs) onto the distribution power systems networks to supplement on the deficiencies on the electrical energy generation capacities. The high penetration levels of DGs on the electrical distribution networks experienced over the past decade calls for the grid operators to periodically and critically asses the impacts brought by the DGs on the distribution network operations. The assessment on the impacts brought by the DGs on the distribution network operations is done by simulating the dynamic response of the network to major disturbances occurring on the network like the faults once the DGs have been connected into it. Connection of Wind Turbine Generators (WTGs) into a conventional electrical energy distribution network has great impacts on the short circuit current levels experienced during a fault and also on the protective devices used in protecting the distribution network equipment namely; the transformers, the overhead distribution lines, the underground cables and the line compensators and the shunt capacitors commonly used/found on the relatively long rural distribution feeders. The main factors which contribute to the impacts brought by the WTGs integration onto a conventional distribution network are: The location of interconnecting the WTG/s into the distribution feeder; The size/s of the WTG/s in terms of their electrical wattage penetrating the distribution network; And the type of the WTG interfacing technology used labeled/classified as, Type I, Type II, Type III and Type IV WTGs. Even though transformers are the simplest and the most reliable devices in an electrical power system, transformer failures can occur due to internal or external conditions that make the transformer incapable of performing its proper functions. Appropriate transformer protection should be used with the objectives of protecting the electrical power system in case of a transformer failure and also to protect the transformer itself from the power system disturbances like the faults. This paper was to investigate the effects of integrating WTGs on a distribution transformer Fuse-Fuse conventional protection coordination scheme. The radial distribution feeder studied was the IEEE 13 node radial test feeder and it was simulated using the Electrical Transient Analysis Program (ETAP) software for distribution transformer Fuse-Fuse protection coordination analysis. The IEEE 13 Node radial test feeder In-line transformer studied is a three-phase step down transformer having a star solidly grounded primary winding supplied at and a star solidly grounded secondary winding feeding power at a voltage of . The increase on the short circuit currents at the In-line transformer nodes due to the WTG integration continuously reduces the time coordination margins between the upstream fuse F633 and the downstream fuse F634 used to protect the transformer.
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Liu, Rushan, Mingpan Xiong, and Deyuan Tian. "Relationship between Damage Rate of High-Voltage Electrical Equipment and Instrumental Seismic Intensity." Advances in Civil Engineering 2021 (January 8, 2021): 1–10. http://dx.doi.org/10.1155/2021/5104214.
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Based on the actual damage data of high-voltage electrical equipment in electric substations in the Wenchuan earthquake, this paper uses the cumulative Gaussian distribution function to describe the relationship between the damage rate of high-voltage electrical equipment and the instrumental seismic intensity. The instrumental seismic intensity at strong motion observation stations in the Wenchuan earthquake is calculated, and the Kriging interpolation method is used to estimate the instrumental seismic intensity at 110 kV and above voltage level substations in Mianyang, Deyang, Guangyuan, and Chengdu of Sichuan Province. A cumulative Gaussian distribution function is then used to fit the damage rate-instrumental seismic intensity relationship curve for six types of high-voltage electrical equipment such as the transformer, circuit breaker, voltage mutual inductor, current mutual inductor, isolating switch, and lightning arrester. The results show that transformers have the highest vulnerability during earthquakes, and they suffered a certain level of damage even under low instrumental intensity. The second most vulnerable equipment is the circuit breaker, followed by the lightning arrester, transformer, and isolating switch, which share a similar vulnerability curve.
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Liu, Rushan, Mingpan Xiong, and Deyuan Tian. "Relationship between Damage Rate of High-Voltage Electrical Equipment and Instrumental Seismic Intensity." Advances in Civil Engineering 2021 (January 8, 2021): 1–10. http://dx.doi.org/10.1155/2021/5104214.
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Based on the actual damage data of high-voltage electrical equipment in electric substations in the Wenchuan earthquake, this paper uses the cumulative Gaussian distribution function to describe the relationship between the damage rate of high-voltage electrical equipment and the instrumental seismic intensity. The instrumental seismic intensity at strong motion observation stations in the Wenchuan earthquake is calculated, and the Kriging interpolation method is used to estimate the instrumental seismic intensity at 110 kV and above voltage level substations in Mianyang, Deyang, Guangyuan, and Chengdu of Sichuan Province. A cumulative Gaussian distribution function is then used to fit the damage rate-instrumental seismic intensity relationship curve for six types of high-voltage electrical equipment such as the transformer, circuit breaker, voltage mutual inductor, current mutual inductor, isolating switch, and lightning arrester. The results show that transformers have the highest vulnerability during earthquakes, and they suffered a certain level of damage even under low instrumental intensity. The second most vulnerable equipment is the circuit breaker, followed by the lightning arrester, transformer, and isolating switch, which share a similar vulnerability curve.
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Kumrey, G. R., and S. K. Mahobia. "STUDY AND DESIGN OF SINGLE PHASE CONVERTER USING OF SINGLE PHASE TRANSFORMER." International Journal of Research -GRANTHAALAYAH 4, no. 8 (August 31, 2016): 46–51. http://dx.doi.org/10.29121/granthaalayah.v4.i8.2016.2562.
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The field of electrical transformer are most important equipment which is use to convert ac voltage or current like lower to higher , higher to lower without change in the frequency . its primary side and secondary side are isolate from each other and it can higher or lower voltage level the apparent value of electrical passive element like inductive , resistive . It use to transfer electrical energy for long distance with higher voltage level .the electrical power transmission,distribution through transformer for factories and home . AC supply can easily generated by a convenient voltage and transformed into much higher voltage for transmission and distribution purpose.
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Banerjee, Mudita, and Anita Khosla. "Mitigation of magnetising inrush current in three–phase power transformer." Indonesian Journal of Electrical Engineering and Computer Science 20, no. 1 (October 1, 2020): 39. http://dx.doi.org/10.11591/ijeecs.v20.i1.pp39-45.
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<span>During energization of no – load transformers, a high and peaky current flow on the primary side which has rich second harmonics. This current is magnetising inrush current and it is generated when transformer core is driven deep into saturation. This current has various disturbances on transformer attribute; reduced life-span, major voltage drop, insulation weakening, electrical and mechanical vibrations in coils, difficulties in protecting relays and all leads to poor power quality of the electric system. This paper presents the analysis and comparison of recent techniques to reduce the magnitude of inrush current during energization of power transformer. The simulation results are provided for Pre – insertion of resistors, Controlled swithing and Pre – fluxing method. The best method is suggested for mitigating inrush current by simulating in MATLAB/SIMULINK environment.</span>
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Lakehal, Abdelaziz, and Fouad Tachi. "Bayesian Duval Triangle Method for Fault Prediction and Assessment of Oil Immersed Transformers." Measurement and Control 50, no. 4 (May 2017): 103–9. http://dx.doi.org/10.1177/0020294017707461.
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Dissolved gas analysis of transformer insulating oil is considered the best indicator of a transformer’s overall condition and is most widely used. In this study, a Bayesian network was developed to predict failures of electrical transformers. The Duval triangle method was used to develop the Bayesian model. The proposed prediction model represents a transformer fault prediction, possible faulty behaviors produced by this transformer (symptoms), along with results of possible dissolved gas analysis. The model essentially captures how possible faults of a transformer can manifest themselves by symptoms (gas proportions). Using our model, it is possible to produce a list of the most likely faults and a list of the most informative gas analysis. Also, the proposed approach helps to eliminate the uncertainty that could exist, regarding the fault nature due to gases trapped in the transformer, or faults that result in more simultaneous gas percentages. The model accurately provides transformer fault diagnosis and prediction ability by calculating the probability of released gases. Furthermore, it predicts failures based on their relationships in the Bayesian network. Finally, we show how the approach works for five distinct electrical transformers of a power plant, by describing the advantages of having available a Bayesian network model based on the Duval triangle method for the fault prediction tasks.
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Orjiewulu, J. C., D. C. Chukwuemeka, C. E. Jesusblessing, and A. Ibrahim. "DESIGN AND IMPLEMENTATION OF AN AUTO-TEMP CONTROL SYSTEM FOR DISTRIBUTION TRANSFORMER." Open Journal of Engineering Science (ISSN: 2734-2115) 1, no. 2 (September 9, 2020): 1–19. http://dx.doi.org/10.52417/ojes.v1i2.142.
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Unreliability and interruptions facing power supply are evidence of the excessive heat generated in power systems, as a result of the inefficiency of oil cooling medium employed in distribution transformers. The design and implementation of a prototype automatic temperature control system is to be employed as a method towards solving the above stated problem of excessive temperature rise in distribution transformers. The prototype design consists of a PIC microcontroller programmed in C language, an LM35 temperature sensor, an electric fan and other diverse electronic component. It operates a mechanism that detects temperature rise in the transformer and automatically turns on the cooling fan at extreme temperature conditions. A 16x2 LCD is employed as the medium for temperature display unit of the transformer. The resulting prototype functions in a way that it has the ability to detect every 1ºC rise and reduction in the temperature of the transformer. Thus, at extreme temperature conditions, the automatic temperature control system diminishes the excessive heat generated in the transformer to the appropriate working temperature condition.
Orjiewulu, J. C. | Department of Electrical Electronics Engineering, University of Benin, Benin City, Edo State, Nigeria.
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Panteleev, V. I., I. S. Kuzmin, A. A. Zavalov, A. V. Tikhonov, and E. V. Umetskaia. "Power quality in power supply systems of mining and processing enterprises in Russia." Proceedings of Irkutsk State Technical University 25, no. 3 (July 6, 2021): 356–68. http://dx.doi.org/10.21285/1814-3520-2021-3-356-368.
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This paper investigates the effect of the load factor of frequency converters and thyristor converters on electrical power quality. Recommendations for reducing the influence of higher harmonics and switching overvoltages on the characteristics of electrical power are provided. Higher harmonics were measured by a PKK57 complex device for controlling electrical parameters and a digital oscilloscope of the Tektronix TDS 2024V type. Impulse switching overvoltages were recorded by an active resistance divider of the DNEK-10 type and the above-mentioned oscilloscope. The obtained data were processed by the Loginom 6.4 software and the methods of mathematical statistics. The lower threshold level of the load factor of frequency converters and thyristor converters was set equal to 0.8, at which the sinusoidal distortion of voltage curves correspond to the RF standard of electrical power quality. The suppression degree of higher harmonics from the 5th to 17th frequency by power transformers with a capacity of 250–6,300 kV. A ranged from 95 to 45%. The use of the ‘transformer–converter–electric receiver’ system as applied to the power supply systems of mining and processing enterprises was substantiated. It was shown that electric motors with a capacity of up to 2,500 kW inclusively require protection against switching overvoltages. Conventional RC-absorbers based on RC-circuits connected to the terminals of electric motors are shown to be highly efficient for protecting electric motors against switching overvoltages. Thus, the quality of electrical power in power supply systems of mining and processing enterprises in Russia can be ensured by frequency converters and thyristor converters with a load factor of 0.8 or greater. Provided that the transformer capacity does not exceed 1,000 kV. A, a more efficient and less expensive ‘transformer–converter–electrical receiver’ system is recommended. Effective protection of electric motors of up to 2,500 kW inclusive can be provided using the proposed conventional RC absorber, which maintains the overvoltage rate at a level not exceeding 1.7.
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Fetisov, Leonid Yu, Dmitry V. Chashin, and Yuri K. Fetisov. "Controllable Inductors and Transformers Based On Ferromagnet-Piezoelectric Heterostructuresformers Based On Ferromagnet-Piezoelectric Heterostructures." Radioelectronics. Nanosystems. Information Technologies. 13, no. 1 (March 27, 2021): 27–38. http://dx.doi.org/10.17725/rensit.2021.13.027.
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The elements of electrical circuits, which inductance L can be tuned electrically (the so-called "inductors"), and transforemers are used in modern electronics, radio engineering and low-power energy for galvanic isolation of circuits and converting voltage amplitudes. In this work, new devices of this type have been manufactured and investigated, using the magnetoelectric effect in ferromagnetic-piezoelectric heterostructures. The inductance of the manufactured inductor is tuned by 400% by a control electric field of up to 10 kV/cm applied to the piezoelectric layer of the structure, and by 1000% by an external magnetic field of up to 10 Oe, acting on the structure. The transformer operates in the range of input voltages of 0-8 V, has a power transfer coefficient of 30% and a voltage transformation ratio of 0-14, tunable by a control magnetic field of up to 80 Oe. Methods for calculating the characteristics of magnetoelectric inductor and transformer are described.