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Journal articles on the topic 'Winding insulation'
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1
Szucs, Aron, Zlatko Kolondzovski, Jan Westerlund, and Juha Vahala. "Diamond enriched lamination and winding insulation for electrical machines." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, no. 4 (July 1, 2019): 1245–52. http://dx.doi.org/10.1108/compel-10-2018-0397.
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Purpose The thermal management of electrical insulations poses a challenge in electrical devices as electrical insulators are also thermal insulators. Diamond is the best solid electrical insulator and thermal conductor. This can lead to a paradigm change for electrical machine winding and lamination insulation design and thermal management. The paper introduces these techniques and discusses its effect for the design of electrical machines and its potential consequences for electromagnetic analysis, for example, in multi-physics modelling. The diamond winding insulation is patent-pending, but the diamond enriched lamination insulation is published for the benefit of the scientific community. Design/methodology/approach The windings of electrical machines are insulated to avoid contact between the coil and other conductive components, for example, the stator core. The principle of using mica tape and resin impregnation has not changed for a century and is well established to produce main insulation on a complex conductor shape and size. These insulations have poor heat-conducting properties. Similarly, the insulation of laminated steel sheets comprising the stator and rotor restrict heat flow. Diamond-based insulation provides a new path. Increased thermal conductivity means reduced temperature rise and the reduced thermal time constants in multi-physics simulations and system analysis. Findings The largest benefit of a diamond-based core insulation is in electrical machines in which the losses are conducted axially to the coolant. These are machines with radial ducts and effective cooling in the end regions. The main benefit will be in reducing the number of radial ducts that positively affect the size, production costs and the copper losses of the machine. The increased thermal conductivity of the diamond insulation system will reduce the thermal constants noticeably. These will affect system behavior and the corresponding simulation methods. Originality/value Diamond insulation can lead to a paradigm change for electrical machine winding and lamination insulation design and thermal management. It might also lead to new modeling requirements in system analysis.
2
Goscinski, Przemyslaw, and Zbigniew Nadolny. "Heat transfer coefficient α of insulation liquid used in power transformers, based on measurements." ITM Web of Conferences 19 (2018): 01016. http://dx.doi.org/10.1051/itmconf/20181901016.
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Proper work of the power transformer is determined by many factors. One of them is relatively low operating temperature of the transformer. Too high temperature has many negative consequences, such as fast aging process of the insulation system. The temperature depends on the load of transmission line, losses and heat exchange in transformer. Heat exchange depends on heat transfer factor α of insulation liquid, which is a component of insulation system of transformer. This factor depends on many factors: the type of insulation liquid, the length of the heating element (windings), temperature, winding surface heat load, the winding position (vertical, horizontal), place on the winding (upper, middle or bottom part). The article presents the results of the measurement of heat transfer factor α as a function of type of insulation liquid, winding surface heat load, and place on the windings. The results will be used by designers and operators of power transformers.
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Kiselev, V. I., T. O. Vakhromeeva, and A. I. Fedyanin. "Increasing reliability of traction electric motors of diesel locomotives taking into account thermophysical parameters of insulation and armature winding conductors." RUSSIAN RAILWAY SCIENCE JOURNAL 81, no. 3 (September 6, 2022): 213–20. http://dx.doi.org/10.21780/2223-9731-2022-81-3-213-220.
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Introduction. The issue of ensuring the operable state of the DC traction motor is relevant due to its large-scale use on diesel locomotives, including modern powerful motors, operating on lines with increased train masses. At present, a rather difficult situation has developed in the locomotive industry with the failure of diesel locomotive traction electric motors due to a decrease in the insulation resistance of the armature windings of the electric motors and their subsequent breakdowns: up to 28 % of the total number of failures of electric motors are due to breakdown of the hull insulation and interturn short circuit of the armature and 13 % of cases are due to reduction in the resistance of the insulating material.Materials and methods. The paper considers the main directions of scientific research on the causes of insulation integrity failure, which lead to unscheduled repairs of traction motors. The theoretical substantiation of the root causes of insulation destruction is based on the importance of taking into account the coefficients of thermal linear expansion of copper and its insulating materials. In order to study thermodynamic processes in the winding of a traction motor, a computational finite element model of a winding coil laid in the groove of the armature core has been developed. The winding model is represented separately by a conductor and insulation, between which contact conditions are specified. The conductor of the calculation model heats up to 120 °C from the current flow. Mathematical apparatus embedded in the MSC calculation program, Patran – Nastran, made it possible to evaluate the deformation of the conductor relative to the insulation as a result of a linear increment due to thermal expansion.Results. With the help of mathematical modelling and based on the results of finite element analysis, the confirmation of the theoretical justification is clearly shown. The difference in elongation during heating of the motor armature conductor and insulation, obtained by mathematical modelling, is 0.6 mm and is significant for the winding (consisting of a conductor and insulation), which is usually considered as a single whole body.Discussion and conclusion. The obtained result shows the need for more detailed studies to select the technology for the insulation of the DC traction motor. The use of insulating materials for the armature winding with coefficients of thermal linear expansion equal to the coefficient of thermal expansion of the copper conductors of the winding will improve the reliability of traction electric motors of diesel locomotives in operation.
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Kumar, Mahendar, Z. A. Memon, M. A. Uqaili, and Mazhar H. Baloch. "An Experimental Insulation Testing Investigation of 210 MW Generator." International Journal of Energy Optimization and Engineering 7, no. 4 (October 2018): 68–91. http://dx.doi.org/10.4018/ijeoe.2018100104.
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This article describes how a drastic failure of a machine is caused by insulation collapse which results heavy interruption as well as losses. The stable operation of a generator mainly depends upon the stator winding insulation. In past, various testing and repairing techniques have been applied in order to analyze the insulation life. However, in this context, a complete stator windings insulation analysis have been carried out by testing and monitoring techniques such as insulation resistance, di-electric absorption ratio, polarization index before repair and after rehabilitation work, ac & dc high voltage, dc resistance test of winding coils, as well as surface potential test, no-load test and short circuit test. It basically reflected the insulation life of stator winding and helped to take remedial measures. This research techniques will pave the way to overcome such failure in machine and recommended the interval based tests for safety purpose.
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Leonov, A. P., and A. Supueva. "PROVIDING A MINIMUM DEFECTIVENESS OF INTER-TURN INSULATION AT THE MANUFACTURING STAGE AND DURING THE EXPLOITATION." Resource-Efficient Technologies, no. 1 (October 12, 2022): 1–9. http://dx.doi.org/10.18799/24056529/2022/1/320.
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The reliability of a low-voltage asynchronous electric motor is primarily determined by the reliability of the stator winding insulation. Common reasons for the failure of the insulation system are the unsatisfactory quality of the enameled wires and electrical insulating materials used for imperfection and violation of the technological process of winding and insulating work, and the discrepancy between operating modes. In the vast majority of cases, failures occur due to damage to the inter-turn insulation as the weakest element. This causes the need to study the insulation system resistance to the formation of defects. The results of assessing the stability of the insulation of winding wires to defect formation are obtained, taking into account the features of the operational loads characteristic of frequency-controlled drives with pulse-width modulation of the output voltage and the influence of the inter-turn insulation defectiveness level on its reliability indicators is also studied. The authors have developed the measures to reduce the defectiveness of inter-turn insulation at the manufacturing stage and during operation. This will ensure a minimum level of insulation defects and increase the resource of asynchronous electric motors by reducing the number of failures.
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Poliakov, M. O., and V. V. Vasylevskyi. "Method for assessing unevenness of cellulose insulation layers aging of power transformers winding." Electrical Engineering & Electromechanics, no. 5 (September 6, 2022): 47–54. http://dx.doi.org/10.20998/2074-272x.2022.5.08.
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Introduction. Improving the methods of estimating the insulation aging of the oil-immersed power transformer windings is an urgent task for transformer condition monitoring systems. The scientific novelty of the work is to take into account the uneven distribution of temperature and humidity along the vertical axis of the winding in modeling the aging of insulation and to develop methods for determining the conditions under which the aging rate of insulation in the intermediate layer will exceed aging rate in the hottest layer. The purpose of the work is to evaluate the wear unevenness of cellulose insulation based on modeling the distribution of temperature and humidity along the vertical axis of the power transformer winding. Methods. The transformer winding is mentally divided into horizontal layers of equal height, the reduction of service life is calculated in parallel for all horizontal layers. Layer with the maximum degree of aging for the entire period of operation and storage of the transformer is recognized as determining the reduction in the service life of the insulation of the transformer as a whole. A model of the interaction of winding layers is developed, with determination of temperatures, humidity, relative rate of aging of each layer due to temperature and humidity as a function of traditional design parameters such as load, cooling temperature, heat capacity and thermal resistance of transformer. The index of exceeding the aging rate by the layered method in comparison with this rate for the hottest layer is offered. The method of genetic algorithms determines the conditions for obtaining the maximum value of this index. Results. A computer model has been developed to predict the aging of the cellulose insulation of transformer windings. According to the proposed method, a layer with significantly shorter insulation aging time (in the example, time reduced by 39.18 %) than for the upper layer was determined, which confirms the feasibility of layer-by-layer monitoring and modeling of insulation aging processes of power oil-immersed transformer windings.
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Kashin, A. I., and A. E. Nemirovsky. "Analysis of depolymerization of insulating compositions of electric motor windings based on ultrasonic radiation." Vestnik MGTU 24, no. 4 (December 30, 2021): 361–71. http://dx.doi.org/10.21443/1560-9278-2021-24-4-361-371.
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This work is a continuation of the fundamental study on implementing an innovative method of repairing electric motors using ultrasound. A study of the method of dismantling windings based on ultrasound has been carried out for the purpose of energy efficiency, environmental friendliness and less time spent on the repair cycle of electric motors in terms of removing the stator winding. The investigated dismantling method is optimal for a number of technical issues in comparison with the existing methods for dismantling electric motor windings. In the work, the main focus is on the material of the winding insulation. Lacquer and compound types of insulation of industrial electric motors, which are the main ones everywhere, have been analyzed. The analysis of the impregnating electrical insulating compositions of the stator windings of electric motors and the influence of ultrasound on them during dismantling of the windings of electric motors at different levels of influence of forcing factors: duration and power of ultrasonic action, concentration and temperature of the working solution. The applied mathematical software systems for calculation and modeling guarantee the reliability and rationality of the results of the experiments obtained during the work. A system of equations has been modeled and models of the effect of useful factors relative to each other have been constructed, the results obtained have been optimized and the optimal parameters of both varnish and compound insulation systems have been identified. The optimal parameters of the investigated types of insulation show encouraging results on many important points: duration, energy consumption, environmental friendliness.
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Nemirovsky, A. E., and A. I. Kashin. "Investigation of the effect of ultrasonic radiation on varnished and compounded impregnating compositions with an innovative method of dismantling electric motor windings." Vestnik MGTU 23, no. 4 (December 30, 2020): 354–63. http://dx.doi.org/10.21443/1560-9278-2020-23-4-354-363.
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For the purposes of energy efficiency, ecology and less time for the cycle of repairing electric motors in the part of the excavation of the stator winding, an innovative method for dismantling ultrasound-based windings has been investigated. From a technical point of view the method has shown to be more optimal in comparison with existing methods of removing the winding. The paper is a continuation of fundamental research on the development of an innovative method of repairing electric motors. It is in this article that the main emphasis is placed on the material from which the insulation of windings is made. Lacquer and compound insulations have been considered being the main types of insulation of industrial electric motors in our country. The analysis of impregnating electrical insulation compositions of motor stator windings has been carried out; the ultrasound effect during the dismantling of motor windings at different levels of influencing factors has been studied, namely duration and power of ultrasonic action, concentration and temperature of the working solution. The validity of the scientific results obtained in the work is confirmed by the correctness of the applied mathematical apparatus and the methods of mathematical modeling, the convergence of the results of numerical modeling and full-scale experiments. A system of equations has been simulated and models of the effect of useful factors relative to each other have been built, the results obtained have been optimized during the experiment and the optimal parameters of both lacquer and compound insulation systems have been identified. The optimal parameters of the types of insulation under study have shown encouraging results on many important points compared to the existing ones: duration, energy consumption, and environmental friendliness. The validity of the conclusions regarding the adequacy of the mathematical models used has been confirmed by the results of experimental studies conducted in the framework of this work of the process of depolymerization of the electric motors' stator windings.
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Ren, Hongtao, and Jianfeng Chen. "Study on lightning impulse voltage distribution and Transfer Overvoltage of 500kV transformer." Journal of Physics: Conference Series 2260, no. 1 (April 1, 2022): 012013. http://dx.doi.org/10.1088/1742-6596/2260/1/012013.
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Abstract Lightning shock wave acts on transformer, and the electromagnetic field in transformer winding is very complex. Due to the electromagnetic oscillation inside the winding, overvoltage will be produced on the main insulation or longitudinal insulation of the transformer, and the potential gradient at the end of the winding is very large, so that the insulation of the transformer is broken down. Therefore, the impact resistance of insulation should be considered in the insulation design of transformer. The amplitude and distribution of overvoltage in transformer winding will affect the selection of insulation material and insulation structure. At the same time, the analysis of transient overvoltage in transformer winding can also provide a theoretical basis for lightning warning system of power system. In order to understand the distribution of transient overvoltage in transformer winding, this paper analyzes the models of cake winding by computer simulation.
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Chumack, Vadim, Mykhailo Kovalenko, Oksana Tymoshchuk, Andrii Stulishenko, and Yevhen Ihnatiuk. "Design of a multilink system for calculating high-frequency processes in electric machines with mesh windings." Eastern-European Journal of Enterprise Technologies 3, no. 8 (123) (June 30, 2023): 54–63. http://dx.doi.org/10.15587/1729-4061.2023.282375.
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This study considers the design of a multi-link high-frequency circuit for calculating defective and defect-free insulation of mesh windings in order to increase the operational reliability of general-purpose electric machines. The object of research is mesh windings of electric machines. The problem to be solved: increasing the operational reliability of electric machines with general-purpose mesh windings by analyzing and modeling defects. The research results make it possible to model defects for the analysis of the state of insulation of electric machines with mesh windings. Special attention in the research was paid to induction motors with a worn-out resource, in particular, 4A80A4 UZ engine. The analysis includes phase-to-body capacitance, winding inductance, eddy current impedance, and winding impedance. Under the WN mode, a decrease in the impedance of the winding section from 3 % to the short-circuit mode was simulated; accordingly, the resonance frequencies for each case of 3 % were determined – 73990 Hz, short-circuit – 74450 Hz, as well as the corresponding input impedances 8938.7 and 8082.5. The corresponding voltage resonances and current resonances were also determined. Appropriate results were also given for the WG scheme. The results reported here relate to the design of the scheme and the research on the defects of the mesh winding. This contributes to the analysis of the state of insulation of mesh windings. The numerical data (resonant frequencies and input impedances) allow a better understanding of the behavior of windings in different states and degrees of defects. Given the research findings, it is possible to better identify and analyze potential defects in mesh windings, which in turn contributes to increasing the reliability of electric machines. The results of this study could be used in the field of diagnosis, service, and maintenance of electric machines with mesh windings
11
Wu, Qian, Yizhuo Hu, Ming Dong, Bo Song, Changjie Xia, Boning Yu, Zhibin Zhang, and Yang Liu. "Optimization of Transformer Winding Deformation Assessment Criterion Considering Insulation Aging and Moisture Content." Energies 13, no. 24 (December 8, 2020): 6491. http://dx.doi.org/10.3390/en13246491.
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Frequency response analysis is widely used to diagnose transformer winding deformation faults due to its high sensitivity, strong anti-interference capability, and equipment portability, but the results of frequency response analysis can be affected by insulation aging and moisture in the transformer, leading to errors in the diagnosis of winding deformation faults. Currently, there is no effective method to prevent such errors. This paper focuses on optimizing the criterion for diagnosing winding deformations when insulation aging and moisture are present. First, the winding frequency response curves of oil-paper insulation were determined by combining insulation aging and moisture tests of the oil-paper insulation with frequency response simulations of the transformer winding. Next, the winding deformation criterion predicting the likelihood and extent of errors diagnosing transformer winding deformations due to the insulation aging and moisture content is discussed. Finally, the corresponding criterion optimization method is proposed. The corresponding results show that insulation aging and moisture can lead to errors when using the correlation coefficient R criterion to diagnose the transformer winding deformations. Moreover, the possibility of winding deformation errors caused by the change of insulation state can be reduced by introducing the corresponding auxiliary criterion through comparing the capacitance change rate based on the frequency response method and that based on the dielectric spectrum method.
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Kuchynskyi, K. A., and O. H. Kensytsky. "Thermomechanical loads of powerful turbogenerator stator winding insulation in the presence of water cooling defects." Electrical Engineering & Electromechanics, no. 4 (June 27, 2023): 75–82. http://dx.doi.org/10.20998/2074-272x.2023.4.11.
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Introduction. An analysis of incidents linked to power units’ emergency disconnecting from network as a result of turbogenerators’ malfunction on the NPP of Ukraine is conducted. It is identified, that the reason of the majority of incidents is an insufficient reliability of the stator winding’s direct cooling system. Problem. The most problematic point in winding for today is the frontal parts, where, while cooling is reduced, there are not only thermal, but also thermomechanical loadings on an insulation appearing. The level of these loading depends on structural design of frontal parts and a character of violation of coolant agent circulation in a bar. In some cases they can exceed limit values. The spread and the quality of research on this issue for today are insufficient. Goal. The aim of the completed research is to determine the thermomechanical loading of insulation of stator winding bar in a powerful turbogenerator with a direct liquid cooling under condition when coolant circulation is malfunctioned. Methodology. A complex mathematical model of thermomechanical processes in an insulation of stator winding bar of a powerful turbogenerator is developed. It takes into account the real geometry of the winding bar, variable thermal loading of core elements in radial and axial directions, as well as ways of fixation of slot and frontal winding parts. Studies of thermomechanical processes in an insulation of stator winding bar of turbogenerator are conducted. Results. Values of mechanical displacement and stress for the different modes of malfunction are obtained. Areas of bar, where mechanical loading may exceed the boundaries of mechanical durability of material of insulation of stator winding are identified. With decline of coolant liquid consumption the radial displacement and stress in the winding insulation bar in the area, where the bar exits from the slot are increasing along with that the values of radial stress of insulation of the winding bar in places of frontal parts’ fixation exceed limit values. Practical significance. The offered mathematical models allow to realize calculation experiments and can be used in practice for development and validation of diagnostic systems, analysis, design and investigation of emergency situations during exploitation of turbogenerators on power stations of Ukraine.
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Nuriddinov, Sardor, Bobomurod Avazov, Fozil Hasanov, and Yulduz Rakhmonova. "Analysis of the causes of traction electric failures of electric cargo cars operated on railways of the Republic of Uzbekistan." E3S Web of Conferences 264 (2021): 05041. http://dx.doi.org/10.1051/e3sconf/202126405041.
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In this article, it is considered to analyze the reliability of TEM (traction electric machine) of electric locomotives of the railways of the Republic of Uzbekistan. To determine the damage, the most expedient and effective method will be to extend the life of the insulation by encapsulating local damage using impregnating materials and heat radiation. Over the past ten years, a stable tendency for insulation breakdown and turn-to-turn closure of the armature winding of the NB-514 type has been maintained in Unitary Enterprise (UE) “O'ztemiryo'lmashta'mir.” In this regard, a hypothesis was put forward that insulation breakdowns and turn-to-turn short-circuit of the armature winding most often occur due to intense heat and mass exchange processes in the insulation of the frontal parts of their windings with open section heads.
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Manusov, V. Z., D. O. Kriukov, and A. V. Semenov. "Computational and experimental study of air-core HTS transformer electrothermal behaviour at current limiting mode." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 1 (February 1, 2021): 155. http://dx.doi.org/10.11591/ijece.v11i1.pp155-162.
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The paper provides the results of the experimental and computational study of the processes occurring in high temperature superconducting transformer windings while secondary winding is short-circuited. The obtained mathematical simulation matches closely with the experimental results. The temperature variation curves for superconducting windings were analysed, and conclusions were made on the necessity of changes in HTS transformer design, namely the necessity of windings heat-insulation from each other and adding a high-resistance coating material for HTS wire in HTS transformer primary winding.
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Li, Min, Wei Yao, Xin Gao, and Yan Ren. "Temperature simulation of oil-immersed transformerbased on fluid-thermal coupling." Journal of Physics: Conference Series 2503, no. 1 (May 1, 2023): 012060. http://dx.doi.org/10.1088/1742-6596/2503/1/012060.
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Abstract The main components of the transformer face overheating and insulation aging caused by electromagnetic losses, which affect their service life. This paper analyzes an oil-immersed transformer with a rated voltage of 800kV based on heat transfer and fluid dynamics principles. The temperature distribution is carried out by magnetic-thermal coupling simulation. The influence of insulation oil flow rate on temperature is analyzed in the thermal field calculation, and the overall temperature rise of transformer and insulating oil is obtained. It turned out that the highest hot spot of the transformer occurs in the low-voltage winding, and the flow speed of insulation oil between the winding is the fastest.
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Andreev, A. M., A. I. Tadzhibaev, A. Sh Azizov, A. M. Kostelov, A. A. Stepanov, G. A. Nazarov, and S. A. Ivanov. "Ensuring the reliability of turbogenerators on the basis of the control of discharge processes in the stator winding insulation." Safety and Reliability of Power Industry 15, no. 3 (November 14, 2022): 199–204. http://dx.doi.org/10.24223/1999-5555-2022-15-3-199-204.
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Issues related to the reliability of the electrical insulation system of high-load powerful turbogenerators with indirect gas cooling are considered and analyzed. The mechanisms of aging of the main components (main insulation, slot filling elements) of the insulation system under operating conditions exposed to electrical and thermal fields, and mechanical forces are studied. Modern ideas about the mechanisms of aging of main insulation and slot filling elements under the action of internal and external impacts (slot and spark discharges) are analyzed. The degradation of insulating materials during operation begins, first of all, in a weak local area of the main insulation, characterized by a large number of technological defects (cavities filled with gas), in which internal partial discharges occur. However, thermosetting insulation of high-voltage electrical machines can function normally throughout its lifetime in the presence of rather intense internal discharges. At the same time, no service life deterioration is observed due to the specific properties of modern main insulation, which contains a mica barrier. The greatest danger is posed by slot partial discharges (SPD) and vibration spark discharges (VS) that occur in the slot area of the stator winding. To reduce the intensity of these discharge processes, it is necessary to optimize the design of the anti-corona coating. On the basis of the performed analysis, a scheme was developed of the aging of the electrical insulation system of the stator winding of air-cooled turbogenerators. Based on the results of prototype tests, an estimated assessment of the "lifetime" of the electrical insulation system of the stator winding, developed using promising electrical insulating materials, was carried out.
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Yashchenko, Sergey, and Dmitry Luchko. "The dependence of the air permeability of glass-mica tapes on the technology of production." Energy Systems 7, no. 3 (December 20, 2022): 63–69. http://dx.doi.org/10.34031/es.2022.3.007.
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The main part of technological processes in almost all industries, including those related to transportation, processing of mineral raw materials, cannot be implemented without the use of electric motors. The high reliability of these machines ensures trouble-free operation and guarantees the safety of people in these industries. The reliability indicators of electric machines depend on the insulation condition of the windings, which is largely determined by the saturation of the winding cavities with the impregnating compound that penetrated them during impregnation. Various manufacturing technologies of mica-containing electrical insulating tapes used as case insulation of coils of traction electric motors (TED) are considered. The main reasons for the failure of traction engines are presented. The existing types of insulation, their possible composition, features and applications are described. A brief description of the main methods of manufacturing electrical insulating mica-containing tapes is given, an assessment of the strengths and weaknesses of each of the technologies are presented. The methods of testing the initial semi-finished tapes and finished insulation are described.
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Quan, Yu Sheng, Dai Juan Wang, Guang Chen, and Zong Cheng Zhang. "Study on the Methodology of Diagnosis for Transformer Winding Insulation Defects." Applied Mechanics and Materials 521 (February 2014): 375–78. http://dx.doi.org/10.4028/www.scientific.net/amm.521.375.
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Power transformer is the important equipment in power system, once the occurrence of faults may bring serious harm to power grid, and even cause great losses. This paper proposes a transformer winding insulation defect detection method. The method only uses the impulse voltage test. It can obtain the diagnosis signal source which contains a lot of harmonic. This paper can judge the insulation defects in the location according to compare the extreme value distribution of every winding voltage and currents correlation coefficient .and can determine the coordinate values. The method does not need large or complex additional equipment, can realize the detection and diagnosis of transformer winding insulation defect location. It is image, intuitive, convenient and practical. This paper studies the insulation defects and the severity of transformer winding, puts forward the method for changing winding current and voltage detection winding insulation defects. And it uses a large number of experiments to verify the insulated and reliability of transformer winding according to different position, different types of insulation defects.
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Kolesnikov, Stanislav, and Andrey Leonov. "RELIABILITY PROBLEMS OF FREQUENCY-CONTROLLED ELECTRIC MOTORS." Electrical and data processing facilities and systems 18, no. 1 (2022): 33–62. http://dx.doi.org/10.17122/1999-5458-2022-18-1-33-62.
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Relevance Widespread use of semiconductor frequency converters is due to the significant advantages of this technology: smoothness and accuracy of controlling the speed and torque of the electric motor, smooth start and stop; increased energy efficiency; the possibility of remote monitoring, etc. The accumulated operational experience has shown an increased failure rate of stator winding insulation of asynchronous motors operating with pulsed power. The presence of high-frequency overvoltages in the inverter signal can lead to the appearance of partial discharges even in the low-voltage motors windings. It’s leading to accelerated degradation of electrical insulation and premature breakdown. Over the past three decades, a significant amount of information has been accumulated in the technical literature: high-frequency transient models have been created; partialdischarge and corona-resistant test methods have been developed; the most important voltage parameters determining the intensity of insulation aging have been determined; regulatory documentation for testing and selection of insulation systems have been developed. Analysis and systematization of existing results are necessary to determine the directions of further research in the subject. Аim of research Identification of new solutions and trends of insulation reliability windings of lowvoltage electric machines when powered by modulated voltage. Research methods Bibliographic analysis, methods of statistical data processing. Results Analysis of the most relevant works on the reliability of low-voltage winding insulation systems in frequency electric drive systems is carried out, a bibliographic list of these works is given. The main results concerning the overvoltages simulation, insulation testing methods, studying the aging mechanisms of winding polymer insulation with pulsed power supply, determining the characteristics of emerging discharges are shown. The ways of further development aimed at modeling overvoltages, taking into account high-frequency effects, increasing the volume of experiments to estimate the insulation lifetime, studying the conditions for the occurrence of partial discharges, creating a common approach to insulation testing are determined.
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Quan, Yu Sheng, Bo Yi, Guang Chen, and Zi Sen Ning. "Research on the Effect of Lightning Oscillatory Wave to Transformer Winding Turn-to-Turn Insulation Fault." Advanced Materials Research 805-806 (September 2013): 855–58. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.855.
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This paper has studied the effect of lightning oscillatory wave on transformer winding insulation fault and finds that lightning oscillatory wave can not directly cause the breakdown of turn-to-turn insulation. Even 200 times lightning oscillatory wave applied on turn-to-turn insulation, the breakdown voltage of turn-to-turn winding almost does not change. On the basis of analysis and research about the distribution and function of lightning oscillatory wave, this paper presents that lightning oscillatory wave does not directly cause the breakdown of turn-to-turn insulation, but acts on turn-to-turn insulation in the form of strong electromagnetic force. Due to the vibration and deformation of the winding, it will cause damage to the insulation and lead to inter-turn short circuit or insulation breakdown. Lightning oscillatory wave also has cumulative effect on transformer winding inter-turn insulation.
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Jiang, Hong-Chun, Yu-Ling He, Gui-Ji Tang, and Ming-Xing Xu. "A Comprehensive Analysis on Transient Electromagnetic Force Behavior of Stator Windings in Turbo-Generator." Mathematical Problems in Engineering 2018 (October 22, 2018): 1–16. http://dx.doi.org/10.1155/2018/4189609.
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This paper presents a comprehensive analysis on the transient electromagnetic force behavior of the stator windings in a QFSN-600-2YHG type turbo-generator. Different from other studies, this paper investigates not only the distribution regularities of the resultant force and the force density, but also the force harmonic characteristics, and the mechanical responses which will cause sensitive impact on the insulation wearing. The whole work is generally based on a proposed simplified model and the 3D finite element coupling calculation. The simplified model contains two parts. The first part is the theoretical model that employs the approximate solution of the image current to obtain the analytic formula of the electromagnetic force on the end windings conveniently. The second part is the FEA model that employs only the end windings and one-tenth of the stator core to save the calculating memory and, meanwhile, obtain the qualified electromagnetic force as well as the mechanical response. It is shown that the nose-top, the connection point between the line part and the end part, and the middle of the involute are the three most dangerous positions of the end winding to sustain serious insulation wearing. Moreover, the winding, which endures the maximum mechanical response, is neither always consistent with the one that has the largest resultant electromagnetic force nor directly in accordance with the winding that affords the most intensive electromagnetic force density. The findings in this paper will be beneficial for the insulation monitoring and the manufacturing improvement on the stator windings.
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Pu, Ziheng, Xinyun Yu, Yaoqiang Wang, Hao Liu, and Zihao Feng. "Inter-Turn Breakdown Fault Analysis and Winding Structure Optimisation of Winding of Dry-Type Transformers in Wind Farms." Energies 16, no. 4 (February 17, 2023): 2012. http://dx.doi.org/10.3390/en16042012.
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To address the problem of winding turn-to-turn breakdown faults in 35 kV dry-type transformers in wind farms under overvoltage conditions, this paper establishes a simulation model based on the structural dimensions and material parameters of the transformer windings. The winding distribution parameters were calculated using the finite element method. The transient processes inside the high-voltage coil were calculated by constructing a multi-conductor transmission line model (MTL) that took into account the influence of the secondary winding. The voltage distribution of the winding was analysed for both lightning shock and extra-fast transient overvoltage conditions. The simulation results show that the maximum overvoltage between turns of the transformer winding under lightning shock is 5.282 kV; the maximum overvoltage between turns of the winding under very fast transient overvoltage is 11.6 kV, which occurs between the first 2–3 layers of the section, close to the insulation breakdown margin. On this basis, the transformer winding structure was optimised and the maximum inter-turn overvoltage after optimisation was 9.104 kV, reducing the likelihood of insulation breakdown by 24.1%. Finally, the accuracy of the winding structure optimisation simulation study was verified by testing the transformer’s impulse voltage before and after optimisation, providing a reference for the stable operation of 35 kV dry-type transformers in wind farm practical applications.
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Silwal, Bishal, and Peter Sergeant. "Thermally Induced Mechanical Stress in the Stator Windings of Electrical Machines." Energies 11, no. 8 (August 14, 2018): 2113. http://dx.doi.org/10.3390/en11082113.
Full textAbstract:
The lifetime of an electrical machine mainly depends on the thermal overloading. Modern day applications of electrical machines on one hand require compact machines with high power density, while on the other hand force electrical machines to undergo frequent temperature cycling. Until recently, in the case of electrical machines, the main factor related to the degradation of the winding insulation was thought to be the thermal oxidization of the insulation materials. It has now been revealed that thermal overloading can also induce mechanical stress in the windings of electrical machines, which over time could lead to fatigue and degradation. In this paper, a comprehensive study of the thermally induced mechanical stress in the windings of an electrical machine is presented. The study is performed using combined thermo-mechanical models. The numerical results are validated by experiments on a segmented stator winding set-up.
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Florkowski, Marek, Barbara Florkowska, and Pawel Zydron. "Partial Discharges in Insulating Systems of Low Voltage Electric Motors Fed by Power Electronics—Twisted-Pair Samples Evaluation." Energies 12, no. 5 (February 26, 2019): 768. http://dx.doi.org/10.3390/en12050768.
Full textAbstract:
Power electronics switching devices currently represent the dominant technology for supplying low voltage (LV) electric motors. The fast switching processes exert a different class of stress on dielectric insulating materials than standard sinusoidal excitations. Such stresses result in an increase in the dynamic activity of the working electric field, which in turn lead to an increased likelihood of partial discharges (PD). The stator design of low voltage motor is often in form of random-wound windings, where the magnet wires (copper or aluminum round wires coated with thin layer of insulation) form a common system of coils with not precisely defined mutual position of particular turns, resulting in various turn-to-turn and coil-to-coil voltage distributions. Pulse Width Modulated (PWM) voltage waveforms from modern electronic inverters are characterized by very short rise times and presence of repetitively occurring overvoltages that can significantly stress the insulation of feeding cables and motors. These factors influence the inception and dynamics of PD and processes of space charge accumulation in electrical insulation. In this paper investigations performed on round magnet wire twisted-pair samples representing LV motor random-wound winding elements are presented. Special attention was afforded to the twist configurations, observed breakdown voltage and PD activity. To describe the field conditions for the formation of PD in the turn-to-turn insulation system, the results of numerical simulations of electric field distributions for winding wires with different diameters, modeled using the COMSOL program, were analyzed. PD created in the insulating systems of model twisted-pair systems were registered and analyzed using the phase resolved partial discharge analysis (PRPDA) method.
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Ibragimov, Matkarim, Dilmurod Akbarov, and Iroda Tadjibekova. "Investigation of asynchronous electric motor winding in heating mode and drying mode to prevent moisture." E3S Web of Conferences 365 (2023): 04019. http://dx.doi.org/10.1051/e3sconf/202336504019.
Full textAbstract:
Asynchronous motors are used in many agricultural industries. Agricultural production is a production with high humidity. As noted above, one of the main reasons for the failure of electric motors in agricultural installations during prolonged downtime is the insulation breakdown due to its dampness. Moistening the winding insulation will degrade the dielectric performance of the insulation. If the electric motor is often switched on and the total operating time per day is at least 4 - 6 hours in rooms with high humidity but without ammonia vapors, then dangerous waterlogging of the windings does not occur. Preheating the windings for an electric motor with a power of 3 kW, to maintain the state of the insulation resistance at a level safe for switching on, can be provided with a power of 12 W.
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Liu, Hongwen, Ke Wang, Qing Yang, Lu Yin, and Jisheng Huang. "On-Line Detection of Voltage Transformer Insulation Defects Using the Low-Frequency Oscillation Amplitude and Duration of a Zero Sequence Voltage." Energies 12, no. 4 (February 15, 2019): 619. http://dx.doi.org/10.3390/en12040619.
Full textAbstract:
The insulation degradation of a voltage transformer winding is not easy to find, but it may ultimately cause the transformer to explode, leading to accidents such as phase-to-phase short circuits. At present, power transformers, lightning arresters, and other equipment have on-line methods to detect the insulation state. However, there is no mature method for the on-line monitoring of voltage transformer winding insulation. In this study, a small current disturbance method based on a zero-sequence loop is proposed. The characteristic parameters of the low-frequency oscillation of zero-sequence voltage after a disturbance are used to evaluate the insulation state of the winding and detect faults. Theoretical modeling, simulation tests, and field tests show that when the insulation resistance of the voltage transformer winding is in the range 0–40 kΩ, a low frequency oscillation of about 10 Hz can be detected on the zero-sequence voltage, and its amplitude and duration are proportional to the degree of damage to the insulation. This can hence be used as a criterion for the on-line detection of voltage transformer winding insulation defects.
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Gayfutdinov, A., Anatoliy Plastun, and Mikhail Baranov. "Radiation-Resistant Valve-Inductor-Type Motor as a Part of Technological Installation for Recycling Nuclear Industrial Waste." Applied Mechanics and Materials 698 (December 2014): 111–15. http://dx.doi.org/10.4028/www.scientific.net/amm.698.111.
Full textAbstract:
Induction motors with conventional organic insulation are used at technological plants designed for recycling nuclear fuel waste of nuclear power stations. In the nuclear radiation environment, the service life of these asynchronous motors does not typically exceed 3-4 months as the winding insulation is destructed being exposed to nuclear radiation. This results in costs increase. To prolong the motor service life and reduce the costs, a valve-inductor-type motor is being developed for this application field due to a simple construction of the stator windings and the feasibility of using non-organic insulation.
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Baboraik, Abdulrahman, and Alexander Usachev. "New model of explanation for phase angle pattern of online partial discharge measurement in winding insulation of turbine generator." Journal of Electrical Engineering 72, no. 1 (February 1, 2021): 66–77. http://dx.doi.org/10.2478/jee-2021-0010.
Full textAbstract:
Abstract On-line partial discharge (PD) measurement in electrical insulation of the turbine generator (TG) is an essential approach to control the quality of insulation and to avoid any undesired shutdowns of TG. Although in the last few decades the number of research in PD on-line monitoring methods in the stator winding of TG has increased significantly, it is still not clear yet why PD only appears at certain phase angles of the AC cycle in the phase resolved partial discharge (PRPD) pattern. Moreover, there is not yet any clarification on how the winding configuration of stator may affect PD phase angle pattern. For this reason, this work examines detailed study of the impact of the winding diagram on PD occurrence in the stator winding of real turbine generator class TVF-60-2 (60 MW, 10.5 KV). In addition, a computer simulation of various sizes of ellipsoidal cavities from 0.1 to 2.5 mm between conductor bar and stator core were carried out by using Laplaces equation in Finite Element Analysis (FEA) software ComSol to investigate the relation between the cavity size and coefficient of electric field. As a result of that, the phase angle of PD occurrence in the stator winding will highly depend on the configuration of bars connection, and the computer simulation has helped identifying the PD inception voltage and applied voltage of various ellipsoidal defects size. These two results have helped proposing an initial new theoretical model of explanation the relationship between voltage distributions and phase angle of PD occurrence to determine the degradation level of insulation caused by ellipsoidal defects in the insulation bars of the stator winding which can be used for stator windings of TG rated 6 kV and higher. This model is the initial step to develop a further comprehensive model of explanation for PRPD patterns which will consider all other types of defects as well as the space charge effects from the previous PD.
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Selema, Ahmed, Mohamed N. Ibrahim, and Peter Sergeant. "Electrical Machines Winding Technology: Latest Advancements for Transportation Electrification." Machines 10, no. 7 (July 12, 2022): 563. http://dx.doi.org/10.3390/machines10070563.
Full textAbstract:
The ever-increasing demand for higher-power dense electrical machines has resulted in different electrical, mechanical, and thermal stresses, which can eventually cause machine failure. For this reason, the management of stresses and losses must be thoughtfully investigated to have a highly reliable electrical machine. The literature agrees that winding losses are the dominant loss mechanism in many electrical machines. However, statements vary on how to mitigate these losses along with the aforementioned stresses. To avoid winding failure, a study of the various winding topologies would allow for a better consideration of the challenges and limitations in the performance of different electrical machines. To this aim, this paper introduces a comprehensive review for different winding topologies. Many reported cases in the literature are summarized and compared. Moreover, the utilization of additive manufacturing (AM) in the production of the machine windings is presented, showing a high level of maturity of this emerging technology. Finally, different challenges facing the design of machine windings are introduced including the AC high frequency losses, thermal management, mechanical and acoustic problems, insulation aging, automated production, and winding manufacturability.
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Chumak, V., O. Timoshuk, Е. Monakhov, А. Vishnevsky, and А. Stulishenko. "FREQUENCY CHARACTERISTICS OF ELECTRICAL MACHINES WITH A MESH WINDING DURING HEAT-AND-MOISTURE AGING." POWER ENGINEERING: economics, technique, ecology, no. 1 (October 11, 2021): 59–66. http://dx.doi.org/10.20535/1813-5420.1.2021.242164.
Full textAbstract:
Operation of an electric drive with damages in power electric circuit of the motor stator results in asymmetry
of the motor phase current charge, increase of heating losses in certain phases, occurrence of variable components of electromagnetic torque and consumed power. An electric motor stator winding consists of a number of stator bars and overhang connections. Due to the complicated winding structure and the steel core, the attenuation and distortion of a pulse transmitted through the winding are complicated, and frequency-dependent. A low voltage impulse method and digital analysis techniques to determine the frequency characteristics of the winding are described. The frequency characteristics of electric motor stator windings are discussed in some detail. The analysis presented in this chapter could be applied to other rotating machines such as low voltage motors. An experiment of damping of electric motor wilding was conducted. Changes in frequency characteristics after the cycle are shown. In this article an analysis of the frequency characteristics of low-voltage electric machines with mush-wound windings, taking into account the processes of successive destruction of the insulation structure by the influence of heat-wet cycles. It is shown that the frequency characteristics can be generalized by the parameter of the state of isolation in the conditions of periodic monitoring of the quality of insulation during regulatory audits. It is proved that the frequency characteristics taken in idle and short-circuit modes have diagnostic features of the level of insulation destruction during humidification, which consist of shifting the characteristics of extremes into the region of lower frequencies, as well as reducing the area under the curve between the minimum and maximum extrema of the characteristic.
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Grabko, Volodymyr, Stanislav Tkachenko, and Oleksandr Palaniuk. "Determination of temperature distribution on windings of oil transformer based on the laws of heat transfer." ScienceRise, no. 5 (October 29, 2021): 3–13. http://dx.doi.org/10.21303/2313-8416.2021.002140.
Full textAbstract:
Object of research: development of a technology for determining the temperature of the winding of a power oil transformer, in particular, the analysis of thermal processes in the winding of a power transformer during short-term overloads, taking into account the influence of the environment.
Investigated problem: temperature distribution in the winding of a power oil transformer taking into account short-term load surges in the problem of assessing the residual life of the insulation of the transformer winding by temperature aging. The calculation of the temperature distribution in the winding was carried out using the passport data and characteristics of the power oil transformer, including the winding, transformer oil, load currents.
Main scientific results: a mathematical model was calculated, with the help of which the results of temperature distribution in the transformer winding were obtained during short-term load surges or constant work with an increased load. According to the presented model, the analysis of the cooling time of the transformer winding after short-term overloads is carried out. Comparing the results obtained on the simulation model with the known results of experimental studies of the temperature distribution in the winding of a power transformer, the adequacy of the mathematical model is proved. It is shown that the use of the laws of heat transfer in a homogeneous plate to analyze the temperature distribution in the transformer winding is not wrong, but requires clarifications and simplifications.
The area of practical use of the research results: enterprises of the machine-building industry and energy companies specializing in the production and operation of transformer equipment. Innovative technological product: simulation model of heat distribution in a transformer winding, which can take into account the load of the transformer, the effect of the environment on the insulation of the transformer windings.
An innovative technological product: a method for diagnosing the duration of the non-failure operation of a transformer, which makes it possible to ensure trouble-free operation and save money for the repair of transformer equipment.
Scope of application of the innovative technological product: design and development of diagnostic systems for windings of power oil transformers
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Decner, Adam, Marcin Baranski, Tomasz Jarek, and Sebastian Berhausen. "Methods of Diagnosing the Insulation of Electric Machines Windings." Energies 15, no. 22 (November 12, 2022): 8465. http://dx.doi.org/10.3390/en15228465.
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The presented article concerns issues related to the diagnostics of the technical condition of the insulation of electrical machines. It discusses the importance of the operational supervision, maintenance and diagnostics of electrical machine insulation systems. The structure of the insulation system is presented and known solutions for making winding insulation are described. The negative impact of conditions and various exposures on the technical condition of the insulation system is described. Special attention is focused on the review of available diagnostic methods for insulating systems of electrical machines. These methods have been arranged in a systematic order according to the type of tests to be carried out.
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Li, Yan, Yang Li, Yin Jun Guan, and Tian Yuan Li. "Calculation of Capacitance and Inductance Parameters of Transformer Winding under very Fast Transient Overvoltage." Advanced Materials Research 986-987 (July 2014): 702–5. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.702.
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The distributed parameters of transformer windings are indispensable in analyzing the transients particularly caused by the very fast transients which occur at the time of disconnecting switch operations in GIS. Winding insulation structure and the safe and stable operation of the transformer are determined by the accuracy of the calculation. In this paper, finite element method (FEM) is used to model and simulate the electromagnetic field calculation of winding capacitance and inductance parameters. The simulation calculation results are consistent with the experimental measurements on a transformer model, which verifies this method is feasible.
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Kulkarni, Sandhya, and Dr Archana Thosar. "Performance Analysis of Permanent Magnet Synchronous Machine due to Winding Failures." International Journal of Electrical and Electronics Research 9, no. 3 (September 30, 2021): 76–83. http://dx.doi.org/10.37391/ijeer.0903081.
Full textAbstract:
The paper describes winding failures in Permanent Magnet Synchronous Motor (PMSM) which are preferred in Electric Vehicles. Drive can be designed with fault tolerance to continue to operate under occurrence of faults. Winding insulation failure is responsible for some of the most serious faults. A method for detecting open circuit of winding, short circuit of winding or turn to turn short circuit in winding may result as a failure of winding insulation is presented. Further a technique for continued post-fault operation of the drive is discussed based upon mathematical model. The detection method operates in real time without the use of additional sensors and is sensitive enough to detect the presence of an air-gap between turns.
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Cizeron, Antoine, Javier Ojeda, Eric Labouré, and Olivier Béthoux. "Prediction of PWM-Induced Current Ripple in Subdivided Stator Windings Using Admittance Analysis." Energies 12, no. 23 (November 21, 2019): 4418. http://dx.doi.org/10.3390/en12234418.
Full textAbstract:
Subdividing stator winding is a way to lower the DC link voltage value in electric drives and reduce the stress on motor insulation. Coupled windings sharing the same stator teeth are modelled in order to evaluate the link between voltages disparities and current ripple. This paper provides an assessment of current ripple rise in the subdivided windings compared to ordinary topologies through the use of a basic inductive model. A method for PWM-Induced current ripple and high-frequency loss estimation based on admittance measurements is developed and experimentally validated. The use of this subdivided structure does not induce more than a 10% rise of the PWM-induced current ripple compared to a standard winding structure.
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Quan, Yu Sheng, Zi Sen Ning, Hua Gui Chen, and Bo Yi. "Study on Detection Method of Transformer Winding Insulation Defects Based on Lightning Impulse Test." Advanced Materials Research 805-806 (September 2013): 847–50. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.847.
Full textAbstract:
Lightning impulse test for power transformer is a highly theoretical and empirical analysis tests for insulation assessment attaches great importance to the power transformer. Facing the problems of detection and diagnostic method based on lightning impulse test for power transformers, this paper proposes a new method of diagnosing the winding insulation defects using two groups of voltage and current with the half-wave and full-wave. This method treats parts of the lightning impulse voltage and current as the signal source, constructs recognition criterion which is closely related to the voltage and current, and diagnose transformer winding insulation defects. Whether the insulation damage exists in the transformer winding which has passed the lightning impulse test can also be diagnosed by the method.
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Azizi, D., and A. Gholami. "Optimum Scheme for Insulation System in HV Generator Based on Electromagnetic Analysis." Engineering, Technology & Applied Science Research 1, no. 3 (June 17, 2011): 49–53. http://dx.doi.org/10.48084/etasr.14.
Full textAbstract:
Electrical insulations are one of the basic parts of electrical machinery in any sizes and characteristics. Focusing on insulating, studies on the operation of industrial-electrical machinery came to the fact that the most important part of a machine is the Stator. This fact reveals the requirement for inspection of the electrical machine insulation along with the electromagnetic tensions. Therefore with respect to insulation system improvement of stator, the HV generator can be optimized. Dielectric parameters such as insulation thickness, spacing, material types, geometry of winding and slot are major design consideration. A very powerful method available to analyze electromagnetic performance is Finite Element Method (FEM) which is used in this paper. The analysis of various stator coil and slot configurations are used to design the better dielectric system to reduce electrical stresses in order to increase the power of generator in the same volume of core. These processes of optimization have been done according the proposed algorithm. In this algorithm the technical constraints have been considered. This paper describes the process used to perform classical design and improvement analysis of stator slot’s insulation with respect to objective function and constraints.
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Plutecki, Zbigniew, and Sławomir Szymaniec. "An analysis of the influence of microclimate on partial discharge activity in emissions of electric machines in the conditions of industrial operation – own research." Archives of Electrical Engineering 62, no. 4 (December 1, 2013): 629–48. http://dx.doi.org/10.2478/aee-2013-0050.
Full textAbstract:
Abstract The article presents the results of diagnostic measurements of partial discharge signal propagation from the winding insulation in electrical machinery, which were performed using an on-line method. This paper describes the results of experiments and the acquired experience in the monitoring of winding insulation in high power and high voltage electrical machines which are important in industrial production processes. The authors show the measurement techniques employed in their research. Representative measurement results are presented along with their analysis. The authors use an SKF monitoring systems to measure: vibrations, temperature, and humidity, as major factors affecting partial discharge activity in the from winding insulation of electrical machines.
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Andreev, A. M., A. Sh Azizov, I. A. Andreev, A. N. Smirnov, A. A. Stepanov, and G. A. Nazarov. "Particularities of measuring partial discharges in stator windings insulation systems of high-voltage electrical machines." Safety and Reliability of Power Industry 14, no. 1 (May 4, 2021): 61–68. http://dx.doi.org/10.24223/1999-5555-2021-14-1-61-68.
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The purpose of the article is to provide potential tools that can make a significant contribution to the identification of partial discharges (PD). Different types of partial discharges occur in stator winding insulation and a few partial discharges may occur simultaneously. Internal partial discharges are electrical discharges that occur in voids in the insulation of the stator winding. In typical stator insulation systems that use epoxy bonded mica tapes, insulation degradation due to internal partial discharges is usually slow (many years or decades). External partial discharges (slot PD and surface PD in the end-winding) are more dangerous and lead to the destruction of the insulation in a short time (several months or years). Therefore, the identification of insulation defects is essential. The analysis of existing methods for identification of defects in the insulation of high-voltage electrical machines using the results of measuring the partial discharges characteristics is carried out. The advantages and disadvantages of each of the groups of identification methods are characterized. It is shown that among the models of knowledge representation in solving problems of diagnostics of insulation systems for high-voltage electrical machines, identification methods, including field tests using training samples, are among the most suitable ones. It is noted that detection of insulation defects and their identification cannot be carried out only by direct measurements of PD characteristics and other dielectric parameters (electrical resistance, dielectric loss, polarization index). For this, special computing programs based on pattern recognition methods should be used. Results are presented of identification of technological defects in the insulation of the stator winding at the stage of factory testing, obtained using the PD identification method developed by the authors
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Zamudio-Ramirez, Israel, Roque Alfredo Osornio-Rios, Miguel Trejo-Hernandez, Rene de Jesus Romero-Troncoso, and Jose Alfonso Antonino-Daviu. "Smart-Sensors to Estimate Insulation Health in Induction Motors via Analysis of Stray Flux." Energies 12, no. 9 (May 1, 2019): 1658. http://dx.doi.org/10.3390/en12091658.
Full textAbstract:
Induction motors (IMs) are essential components in industrial applications. These motors have to perform numerous tasks under a wide variety of conditions, which affects performance and reliability and gradually brings faults and efficiency losses over time. Nowadays, the industrial sector demands the necessary integration of smart-sensors to effectively diagnose faults in these kinds of motors before faults can occur. One of the most frequent causes of failure in IMs is the degradation of turn insulation in windings. If this anomaly is present, an electric motor can keep working with apparent normality, but factors such as the efficiency of energy consumption and mechanical reliability may be reduced considerably. Furthermore, if not detected at an early stage, this degradation could lead to the breakdown of the insulation system, which could in turn cause catastrophic and irreversible failure to the electrical machine. This paper proposes a novel methodology and its application in a smart-sensor to detect and estimate the healthiness of the winding insulation in IMs. This methodology relies on the analysis of the external magnetic field captured by a coil sensor by applying suitable time-frequency decomposition (TFD) tools. The discrete wavelet transform (DWT) is used to decompose the signal into different approximation and detail coefficients as a pre-processing stage to isolate the studied fault. Then, due to the importance of diagnosing stator winding insulation faults during motor operation at an early stage, this proposal introduces an indicator based on wavelet entropy (WE), a single parameter capable of performing an efficient diagnosis. A smart-sensor is able to estimate winding insulation degradation in IMs using two inexpensive, reliable, and noninvasive primary sensors: a coil sensor and an E-type thermocouple sensor. The utility of these sensors is demonstrated through the results obtained from analyzing six similar IMs with differently induced severity faults.
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Jiang, Hong-Chun, Yu-Ling He, Gui-Ji Tang, and Xing-Hua Yuan. "Electromagnetic Force and Mechanical Response of Turbo-Generator End Winding under Electromechanical Faults." Mathematical Problems in Engineering 2021 (December 23, 2021): 1–19. http://dx.doi.org/10.1155/2021/9064254.
Full textAbstract:
This paper comparatively studies the electromagnetic force and mechanical response of the end winding before and after 3 kinds of typical electromechanical faults in turbo-generator. The analytical expression of electromagnetic force of end winding is derived under the composite fault of static eccentricity and rotor interturn short circuit. Meanwhile, the three-dimensional transient finite element simulation is carried on, and the frequency composition and amplitude variation characteristics of the radial, axial, and tangential electromagnetic force are analyzed for the end windings under static eccentricity, rotor interturn short circuit, and composite fault. Therefore, it provides a reference for the vibration wear detection and electromagnetic force control of the end winding. Moreover, the maximum stress and deformation of different positions on the end involute are obtained. And the three-directional vibration acceleration characteristics of the end winding are further analyzed. Finally, the distribution law of winding fatigue failure and vibration wear is acquired, which lays a foundation for the reverse suppression of end winding fatigue failure and insulation wear.
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Duan, Xiaomu, Tong Zhao, Jinxin Liu, Li Zhang, and Liang Zou. "Analysis of Winding Vibration Characteristics of Power Transformers Based on the Finite-Element Method." Energies 11, no. 9 (September 11, 2018): 2404. http://dx.doi.org/10.3390/en11092404.
Full textAbstract:
The winding is the core component of a transformer, and the technology used to diagnose its current state directly affects the operation and maintenance of the transformer. The mechanical vibration characteristics of a dry-type transformer winding are studied in this paper. A short-circuit test was performed on an SCB10-1000/10 dry-type transformer, and the vibration signal at the surface was measured. Based on actual experimental conditions, a vibration-simulation model of the transformer was established using COMSOL Multiphysics software. A multiphysics coupling simulation of the circuit, magnetic field, and solid mechanics of the transformer was performed on this model. The simulation results were compared with measured data to verify the validity of the simulation model. The simulation model for a transformer operating under normal conditions was then used to develop simulation models of transformer-winding looseness, winding deformation, and winding-insulation failure, and the winding fault vibration characteristics were analyzed. The results provide a basis for detecting and analyzing the mechanical state of transformer windings.
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Pambudi, Setio. "Analisa Kinerja Operasional dan Temperature Terhadap Life Time Transformator 370 MVA." Jurnal Indonesia Sosial Teknologi 4, no. 1 (January 27, 2023): 91–101. http://dx.doi.org/10.36418/jist.v4i1.572.
Full textAbstract:
Transformers are very important electrical equipment in the electricity system. Transformers function to increase and decrease the voltage of the electrical assembly system and distribution system. With the temperature conditions in Indonesia, the average temperature in the power plant uses transformer insulation oil cooling. The loading on the power plant transformer always changes depending on the load management center. At the time of loading, there will be current flowing into the transformer coil resulting in increased transformer temperature. Too hot temperatures will cause damage to the transformer insulation and will result in a reduction in the useful life of the transformer itself. This research is carried out observation and analysis by knowing the performance of the transformer in the duration of 24 hours of normal operation by comparing the effect of operating temperature when the load changes, environmental temperature and hotspot temperature. The change in temperature increase that occurs in the transformer is influenced by several factors, including the individual transformer and the temperature of the environment where the transformer is operated. The individual temperature of the transformer is caused by the amount of loading borne by the transformer so that the current flowing in the transformer winding will be higher, the current that continues to increase will cause the transformer winding. A very high temperature in the winding will cause damage to the insulation and the temperature rise can change the insulating properties of the transformer oil which results in the value of the insulating oil decreasing and the decrease in the ability of the insulation level affects the useful life of the transformer. Another factor of increasing transformer temperature is from ambient temperature. With the conditions under which the transformer is operated and the tropical climate conditions in Indonesia which are quite high, this can cause an increase in transformer temperature.
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Li, Tao, Xiaoping Du, Xuewu Sun, and Yuanyuan Song. "Study on the Method of Calculating Temperature Rise of Transformer." E3S Web of Conferences 179 (2020): 01027. http://dx.doi.org/10.1051/e3sconf/202017901027.
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The internal temperature of the transformer is a key parameter to measure the thermal state of the transformer. The service life of the transformer generally depends on the life of the insulating material, and high temperature is the main reason why cause insulation aging, this paper studies the temperature rise of transformer winding hot spot temperature for the key, using the neural network forecasting method, forecasts transformer winding hot spot temperature change rule, calculate the transformer internal temperature rise, provide the temperature of the scientific basis for the safe operation of the transformer.
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Ait-Amar, Sonia, Rania Saoudi, and Gabriel Vélu. "Thermal Aging Study of an Anodized Aluminum Strip Wire for Winding and High Temperature Use." Energies 15, no. 15 (July 24, 2022): 5362. http://dx.doi.org/10.3390/en15155362.
Full textAbstract:
Electrical machines are commonly used in industries and transport and are manufactured with enameled wire coils with polymer insulation. In extreme conditions, as in aeronautics and aerospace, where temperatures exceed 280 °C, the organic insulation deteriorates and it is necessary to find another way to insulate winding wires, in order to ensure a longer life duration of the insulation system and a better operating reliability of electric motors in these environments. Ceramics are more resistant to high temperatures than polymers and the proposed study focuses on the temperature dependence of the dielectric properties of anodized aluminum strips for use in high-temperature electrical machine windings. Different dielectric parameters are measured during thermal constraint. The purpose is to determine the temperature index of the anodized strip and propose a thermal stress life model.
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Quan, Yu Sheng, Dai Juan Wang, Hua Gui Chen, and Zong Cheng Zhang. "Study on the Methodology of Detection for Transformer Winding Insulation Defects Based on Impulse Test." Advanced Materials Research 805-806 (September 2013): 863–66. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.863.
Full textAbstract:
A methodology of diagnosing the winding insulation defect according to data of transient voltage and current from the impulse voltage test is put forward in this paper. Lightning impulse test for transformer is divided into half-wave and full-wave at the moment. According to the full voltage and reduced voltage at two pressure processes. The transient voltage and current from the impulse voltage test can be divided into Series of harmonics. The insulation defect is diagnosed by dividing impulse voltage and current into series of harmonic and structuring discriminant function according to the longitudinal ratio method and cross ratio method for the corresponding period of harmonic voltage and current. The methodology is also applicable to diagnose whether there are insulation damage in the windings those have passed the lightning impulse test.
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Chae, Yoon Seok, Ji Hyung Kim, Huu Luong Quach, Yong Soo Yoon, and Ho Min Kim. "Electromagnetic characteristic analysis of a REBCO magnet with a current bypass/distribution winding technique under an asynchronous rotating magnetic field." Superconductor Science and Technology 35, no. 4 (March 7, 2022): 045017. http://dx.doi.org/10.1088/1361-6668/ac455f.
Full textAbstract:
Abstract Generally, high-temperature superconducting rotating machines (HTSRMs) are considered synchronous machines. If the output of the HTSRM fluctuates based on frequent changes in the electrical or mechanical loads, there is the concern that an asynchronous rotating magnetic field (RMF) is applied from the stationary copper armature winding to the high-temperature superconducting (HTS) field winding in the rotary. This may act as a magnetic disturbance to the HTS field magnet, resulting in permanent damage. To enhance the reliability of HTS magnets in wind power and electric propulsion applications, winding methods with current bypass/distribution characteristics, such as no-insulation (NI) and metal-insulation (MI), have attracted scholarly attention because of their high thermal and electrical stabilities, resulting in their self-stabilizing and protective performances. To verify the feasibility of the NI and MI winding techniques for wind power generators, the basic characteristics under a time-varying magnetic field must be studied, contrary to HTS magnet applications under a time-static magnetic field. Therefore, the electromagnetic characteristics of rare-earth barium copper oxide (REBCO) magnets applied with NI and MI winding technologies were compared and analyzed in this study, considering the magnetically transient situations in which an asynchronous RMF is applied to REBCO magnets. In addition, we developed a characteristic evaluation device similar to a synchronous rotating machine to generate the unsynchronized RMF. Moreover, various basic tests were performed to target the small racetrack-type field windings. The critical current, n-value, terminal voltage, and center magnetic field are investigated under various values of the frequency and current amplitude of the three-phase armature winding, and their behaviors are discussed in detail based on the characteristic resistances of the two test magnets.
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Pothukuchi, Harish Kalyan Ram, Peter Fuchs, and Clara Schuecker. "Analysis of the critical stresses in high-voltage composite winding insulations under thermal loads." Journal of Composite Materials 54, no. 15 (November 21, 2019): 2073–84. http://dx.doi.org/10.1177/0021998319887779.
Full textAbstract:
Stator bars are the critical components in generators with respect to their lifespan. The winding insulation may be susceptible to damage under excessive alternating temperature loads incurred by a high number of start–stop cycles and heavy overloads. The differences in thermal expansion between the different components in the multi-layered winding insulation lead to thermal stresses. This work deals with the thermo-mechanical characterisation of the individual constituents of the winding insulation and the finite element model of a stator bar, based on the material data obtained from the tests that enable the identification of the thermal stresses leading to delamination over thermal cycles. The out-of-plane and the interfacial shear stress are found to be in the critical range with respect to the relatively low cohesive strength of the included individual mica layers.
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Li, Quanwu, Manfeng Dou, Bo Tan, Haitao Zhang, and Dongdong Zhao. "Electromagnetic-Thermal Integrated Design Optimization for Hypersonic Vehicle Short-Time Duty PM Brushless DC Motor." International Journal of Aerospace Engineering 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/9725416.
Full textAbstract:
High reliability is required for the permanent magnet brushless DC motor (PM-BLDCM) in an electrical pump of hypersonic vehicle. The PM-BLDCM is a short-time duty motor with high-power-density. Since thermal equilibrium is not reached for the PM-BLDCM, the temperature distribution is not uniform and there is a risk of local overheating. The winding is a main heat source and its insulation is thermally sensitive, so reducing the winding temperature rise is the key to the improvement of the reliability. In order to reduce the winding temperature rise, an electromagnetic-thermal integrated design optimization method is proposed. The method is based on electromagnetic analysis and thermal transient analysis. The requirements and constraints of electromagnetic and thermal design are considered in this method. The split ratio and the maximum flux density in stator lamination, which are highly relevant to the windings temperature rise, are optimized analytically. The analytical results are verified by finite element analysis (FEA) and experiments. The maximum error between the analytical and the FEA results is 4%. The errors between the analytical and measured windings temperature rise are less than 8%. It can be proved that the method can obtain the optimal design accurately to reduce the winding temperature rise.
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Changjiang, Zheng, Wang Qian, Wang Huai, Shen Zhan, and Claus Leth Bak. "Electrical Stress on the Medium Voltage Medium Frequency Transformer." Energies 14, no. 16 (August 19, 2021): 5136. http://dx.doi.org/10.3390/en14165136.
Full textAbstract:
This paper proposes an equivalent circuit model to obtain the transient electrical stress quantitatively in medium voltage medium frequency transformers in modern power electronics. To verify this model, transient simulation is performed on a 1.5 kV/1 kHz transformer, revealing voltage overshoot quantitatively between turns and layers of the transformer’s HV winding. Effects of rise time of the input pulse voltage, stray capacitance of the winding insulation, and their interactions on the voltage overshot magnitude are presented. With these results, we propose limiting the voltage overshoot and, thereafter, enhancing medium voltage medium frequency transformer’s insulation capability, which throws light on the transformer’s insulation design. Additionally, guidance on the future studies on aging and endurance lifetime of the medium voltage medium frequency transformer’s insulation could be given.