Pub Date : 2020-06-01DOI: 10.1109/eic47619.2020.9158730
Gavin Jones, N. Frost
Standardized testing methods are generally utilized to assess in service dielectric material aging and over time use of this information allows one to become knowledgeable as to the condition of the motor, and ultimately, when to repair the machine prior to failure. Traditional accelerated aging experiments are performed to evaluate base dielectric materials for properties such as thermal class and the ability to withstand voltage over time. Physical models for dielectric aging have also been developed. Emulators (aka predictive models) are statistical models trained using advanced analytics and machine learning algorithms to capture the input/output relationships of an underlying system or data set. Once trained, the emulator can be used in lieu of the process that generated the training data to rapidly predict outputs for arbitrary input combinations. Emulators can be created of both deterministic physics-based simulation codes and physical or experimental processes. Using a simple physical motor model, the process of building an emulator will be illustrated. This process begins with a design of experiments to select input combinations for the experimental collection of training data from the physical model. The emulator's predictive accuracy can be iteratively improved through an adaptive design process that combines knowledge of the previously conducted experiments with the emulator's ability to assess areas of greatest uncertainty in its predictions. The final validated emulator can be used for sensitivity analyses of inputs on the output(s) of interest, uncertainty propagation, and optimization. Applications of emulators include virtual sensors, predictive maintenance, calibration of physics-based simulation models, and digital twins. Avenues of application for an emulator of a motor model include predictions of motor life and dielectric failure probabilities based on dielectric and insulation material properties.
{"title":"Introduction to Predictive Models for Motor Dielectric Aging","authors":"Gavin Jones, N. Frost","doi":"10.1109/eic47619.2020.9158730","DOIUrl":"https://doi.org/10.1109/eic47619.2020.9158730","url":null,"abstract":"Standardized testing methods are generally utilized to assess in service dielectric material aging and over time use of this information allows one to become knowledgeable as to the condition of the motor, and ultimately, when to repair the machine prior to failure. Traditional accelerated aging experiments are performed to evaluate base dielectric materials for properties such as thermal class and the ability to withstand voltage over time. Physical models for dielectric aging have also been developed. Emulators (aka predictive models) are statistical models trained using advanced analytics and machine learning algorithms to capture the input/output relationships of an underlying system or data set. Once trained, the emulator can be used in lieu of the process that generated the training data to rapidly predict outputs for arbitrary input combinations. Emulators can be created of both deterministic physics-based simulation codes and physical or experimental processes. Using a simple physical motor model, the process of building an emulator will be illustrated. This process begins with a design of experiments to select input combinations for the experimental collection of training data from the physical model. The emulator's predictive accuracy can be iteratively improved through an adaptive design process that combines knowledge of the previously conducted experiments with the emulator's ability to assess areas of greatest uncertainty in its predictions. The final validated emulator can be used for sensitivity analyses of inputs on the output(s) of interest, uncertainty propagation, and optimization. Applications of emulators include virtual sensors, predictive maintenance, calibration of physics-based simulation models, and digital twins. Avenues of application for an emulator of a motor model include predictions of motor life and dielectric failure probabilities based on dielectric and insulation material properties.","PeriodicalId":286019,"journal":{"name":"2020 IEEE Electrical Insulation Conference (EIC)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128149605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.1109/eic47619.2020.9158667
Jeong H. Choi, Ning Guo, T. Damle, Jeffrey Ding, Richard Nguyen, Chanyeop Park, L. Graber
Future all-electric ships will likely be based on a medium voltage direct current (MVDC) architecture to distribute power to its electrical loads. It is essential to investigate the different conditions from conventional terrestrial power systems under which such power systems operate: (a) DC voltage, (b) ungrounded operation, (c) spectrum of power electronic switching harmonics, (d) environmental conditions and type of pollution, as well as (e) required level of resiliency and reliability. The testbed is designed to operate at up to 60 kV DC voltage, ungrounded, with a superimposed ripple voltage, and enable to study the effect of various degrees of surface pollution and the impact of ground faults. The impact of the above-listed factors as preliminary result is studied experimentally through the testbed. Recommendations for new standards for creepage distance specific to MVDC shipboard power system are provided.
{"title":"Testbed to Study the Surface Charge Distribution along DC Standoff Insulators for All-Electric Ships","authors":"Jeong H. Choi, Ning Guo, T. Damle, Jeffrey Ding, Richard Nguyen, Chanyeop Park, L. Graber","doi":"10.1109/eic47619.2020.9158667","DOIUrl":"https://doi.org/10.1109/eic47619.2020.9158667","url":null,"abstract":"Future all-electric ships will likely be based on a medium voltage direct current (MVDC) architecture to distribute power to its electrical loads. It is essential to investigate the different conditions from conventional terrestrial power systems under which such power systems operate: (a) DC voltage, (b) ungrounded operation, (c) spectrum of power electronic switching harmonics, (d) environmental conditions and type of pollution, as well as (e) required level of resiliency and reliability. The testbed is designed to operate at up to 60 kV DC voltage, ungrounded, with a superimposed ripple voltage, and enable to study the effect of various degrees of surface pollution and the impact of ground faults. The impact of the above-listed factors as preliminary result is studied experimentally through the testbed. Recommendations for new standards for creepage distance specific to MVDC shipboard power system are provided.","PeriodicalId":286019,"journal":{"name":"2020 IEEE Electrical Insulation Conference (EIC)","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127302246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.1109/EIC47619.2020.9158661
I. Hosier, P. Lewin, J. Pilgrim, G. Wilson
In order to understand the aging process of paper used in high voltage transformers, transformer grade Kraft paper samples were aged in a fan oven in order to access the full range of DP values from 1100 (new) to∼200 (end of life). The absence of significant oxidation was verified by infrared spectroscopy and the mechanical and dielectric properties were assessed as a function of DP. Whilst the dielectric properties (in the absence of water) were unaffected by aging, the tensile strength was reduced. This confirms studies in the literature which show that most transformer breakdowns occur through mechanical failure of the paper and crucially, provides a mechanism of providing paper samples of known DP for subsequent exposure to oil flow.
{"title":"Effects of aging on the mechanical and dielectric properties of transformer grade Kraft paper","authors":"I. Hosier, P. Lewin, J. Pilgrim, G. Wilson","doi":"10.1109/EIC47619.2020.9158661","DOIUrl":"https://doi.org/10.1109/EIC47619.2020.9158661","url":null,"abstract":"In order to understand the aging process of paper used in high voltage transformers, transformer grade Kraft paper samples were aged in a fan oven in order to access the full range of DP values from 1100 (new) to∼200 (end of life). The absence of significant oxidation was verified by infrared spectroscopy and the mechanical and dielectric properties were assessed as a function of DP. Whilst the dielectric properties (in the absence of water) were unaffected by aging, the tensile strength was reduced. This confirms studies in the literature which show that most transformer breakdowns occur through mechanical failure of the paper and crucially, provides a mechanism of providing paper samples of known DP for subsequent exposure to oil flow.","PeriodicalId":286019,"journal":{"name":"2020 IEEE Electrical Insulation Conference (EIC)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132097198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.1109/EIC47619.2020.9158679
H. Wilhelm, P. Fernandes, C. Steffens, K. Moscon, M. Mattoso, S. Peres, M. Ziliotto, C. Galdeano, Milton M. S. Junior, J. B. F. Neto, T. Marchesan, V. Bender
Dissolved gas analysis (DGA) in insulating oil is performed periodically to access operating conditions of power transformers. DGA results suggest possible incipient faults and maintenance actions for transformer repair. The more information the process gives, the better and cheaper corrective actions can be. To optimize asset management, determine the need for repair in a transformer failure, or choose options for managing operating conditions, an additional tool that allows maintenance engineering to previously identify failure type would be interesting. When an incipient fault occurs, all construction materials involved will be affected and, therefore leave traces in insulating fluid. This paper is a first step in evaluating potential analytical methods to be used in determining the presence of transformers construction materials in insulating fluids due to incipient faults. Insulating oil samples were first contaminated with different transformer construction materials in order to test different analytical techniques to determine the presence of those materials in oil and/or their influence in oil properties. Samples were thermally aged and then tested by different methods to find out contamination effect on physical chemistry properties, such as total acid number, interfacial tension, dielectric loss and others. The presence of added contaminants both soluble as well as particulate material is also investigated. Soluble contamination materials are determined by use chemical analysis techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Gas Chromatography Mass Spectrometry (GC-MS), Inductively Coupled Plasma (ICP), and enhanced DGA. Some nonconventional analysis techniques were also used to evaluate particulate contaminants related added construction materials, such as particles counting, particle quantification index (PQI), and Analytical Ferrography that gives particles nature, shape and size. This work is part of the R&D research project ANEEL PD-222.2017.
{"title":"Power Transformer Fault Characterization Through Oil Contaminants Evaluation","authors":"H. Wilhelm, P. Fernandes, C. Steffens, K. Moscon, M. Mattoso, S. Peres, M. Ziliotto, C. Galdeano, Milton M. S. Junior, J. B. F. Neto, T. Marchesan, V. Bender","doi":"10.1109/EIC47619.2020.9158679","DOIUrl":"https://doi.org/10.1109/EIC47619.2020.9158679","url":null,"abstract":"Dissolved gas analysis (DGA) in insulating oil is performed periodically to access operating conditions of power transformers. DGA results suggest possible incipient faults and maintenance actions for transformer repair. The more information the process gives, the better and cheaper corrective actions can be. To optimize asset management, determine the need for repair in a transformer failure, or choose options for managing operating conditions, an additional tool that allows maintenance engineering to previously identify failure type would be interesting. When an incipient fault occurs, all construction materials involved will be affected and, therefore leave traces in insulating fluid. This paper is a first step in evaluating potential analytical methods to be used in determining the presence of transformers construction materials in insulating fluids due to incipient faults. Insulating oil samples were first contaminated with different transformer construction materials in order to test different analytical techniques to determine the presence of those materials in oil and/or their influence in oil properties. Samples were thermally aged and then tested by different methods to find out contamination effect on physical chemistry properties, such as total acid number, interfacial tension, dielectric loss and others. The presence of added contaminants both soluble as well as particulate material is also investigated. Soluble contamination materials are determined by use chemical analysis techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Gas Chromatography Mass Spectrometry (GC-MS), Inductively Coupled Plasma (ICP), and enhanced DGA. Some nonconventional analysis techniques were also used to evaluate particulate contaminants related added construction materials, such as particles counting, particle quantification index (PQI), and Analytical Ferrography that gives particles nature, shape and size. This work is part of the R&D research project ANEEL PD-222.2017.","PeriodicalId":286019,"journal":{"name":"2020 IEEE Electrical Insulation Conference (EIC)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134312414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.1109/EIC47619.2020.9158573
K. Alewine, H. Penrose
Electrical Signature Analysis (ESA), while not a new technology, has only recently been utilized in identifying and predicting winding failures in wind turbine generators. This novel application of existing technology has been very successful in identifying problems in several models of generators as well as other drive train issues. This paper will present a review of the basic technology utilized and will present the results from testing several hundred turbines including some with supporting documentation from physical inspections and/or predicted failures. This methodology, which can be trended, provides critical reliability information to help plan and prioritize preventative maintenance actions during low production times as well as periodic provide condition reporting on those turbines where continuous monitoring information is not available.
{"title":"Field Experiences Utilizing Electrical Signature Analysis to Detect Winding and Mechanical Problems in Wind Turbine Generators","authors":"K. Alewine, H. Penrose","doi":"10.1109/EIC47619.2020.9158573","DOIUrl":"https://doi.org/10.1109/EIC47619.2020.9158573","url":null,"abstract":"Electrical Signature Analysis (ESA), while not a new technology, has only recently been utilized in identifying and predicting winding failures in wind turbine generators. This novel application of existing technology has been very successful in identifying problems in several models of generators as well as other drive train issues. This paper will present a review of the basic technology utilized and will present the results from testing several hundred turbines including some with supporting documentation from physical inspections and/or predicted failures. This methodology, which can be trended, provides critical reliability information to help plan and prioritize preventative maintenance actions during low production times as well as periodic provide condition reporting on those turbines where continuous monitoring information is not available.","PeriodicalId":286019,"journal":{"name":"2020 IEEE Electrical Insulation Conference (EIC)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132749195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.1109/eic47619.2020.9158706
Xiaojuan Yu, Yue-E Liu, Hua Hou, Baoshan Wang
Since sulfur hexafluoride (SF6) has been subject to various regulations to reduce the emissions, the eco-friendly alternative gases or gas mixtures have attracted considerable attentions for the electric applications in high voltage transmissions and substations. The mixture of fluoronitrile, i.e., heptafluoro-iso-butyronitrile, (CF3)2CFCN, with CO2 is an effective technique as a candidate to replace SF6. However, such a fluoronitrile/CO2 mixture is lack of the self-healing ability unlike SF6 that it recombines quickly after being dissociated by an electric arc or fault. Therefore, it is important to monitor the decomposition products of the fluoronitrile/CO2 mixture for the purpose of insulation failure alert. Mechanisms for the reactions of (CF3)2CFCN with atomic oxygen due to dissociation of CO2 were calculated using the high-level ab initio methods. It is revealed that the reaction of O(3P, 1D) with (CF3)2CFCN proceeds predominantly via the successive C-O addition/elimination pathways and the singlet-triplet intersection to form C3F7 and NCO radicals as the nascent products. Various ketones, i.e., CF2O, CF3C(O)CF3, FC(O)CN, etc., alkanes, i.e., CF4, C2F6, C4F10, C6F14, etc., and alkenes, i.e., C3F6, are produced via the secondary reactions. To mimic the decomposition details after arc breaking, the reactive molecular dynamics simulations were carried out by mean of an extensively optimized reactive force-filed for the C/H/N/O/F system. It was found that the arc decomposition of the fluoronitrile/CO2 mixture produces the NOx (e.g., NO, NO2) species. In the presence of water impurity, some acidic byproducts including HF, FNCO, FCOOH, etc., can be generated. Theoretical calculations provide an a priori method to detect arc failure of the fluoronitrile/CO2 insulation using the characteristic gases and shed new lights on the operation and maintenance of the electric equipment for health and safety measures.
{"title":"Theoretical Investigations on the Decomposition Characteristic Gases of Fluoronitriles/CO2 Mixture After Arc Interruption","authors":"Xiaojuan Yu, Yue-E Liu, Hua Hou, Baoshan Wang","doi":"10.1109/eic47619.2020.9158706","DOIUrl":"https://doi.org/10.1109/eic47619.2020.9158706","url":null,"abstract":"Since sulfur hexafluoride (SF<inf>6</inf>) has been subject to various regulations to reduce the emissions, the eco-friendly alternative gases or gas mixtures have attracted considerable attentions for the electric applications in high voltage transmissions and substations. The mixture of fluoronitrile, i.e., heptafluoro-iso-butyronitrile, (CF<inf>3</inf>)<inf>2</inf>CFCN, with CO<inf>2</inf> is an effective technique as a candidate to replace SF<inf>6</inf>. However, such a fluoronitrile/CO<inf>2</inf> mixture is lack of the self-healing ability unlike SF<inf>6</inf> that it recombines quickly after being dissociated by an electric arc or fault. Therefore, it is important to monitor the decomposition products of the fluoronitrile/CO<inf>2</inf> mixture for the purpose of insulation failure alert. Mechanisms for the reactions of (CF<inf>3</inf>)<inf>2</inf>CFCN with atomic oxygen due to dissociation of CO<inf>2</inf> were calculated using the high-level ab initio methods. It is revealed that the reaction of O(<sup>3</sup>P, <sup>1</sup>D) with (CF<inf>3</inf>)<inf>2</inf>CFCN proceeds predominantly via the successive C-O addition/elimination pathways and the singlet-triplet intersection to form C<inf>3</inf>F<inf>7</inf> and NCO radicals as the nascent products. Various ketones, i.e., CF<inf>2</inf>O, CF<inf>3</inf>C(O)CF<inf>3</inf>, FC(O)CN, etc., alkanes, i.e., CF<inf>4</inf>, C<inf>2</inf>F<inf>6</inf>, C<inf>4</inf>F<inf>10</inf>, C<inf>6</inf>F<inf>14</inf>, etc., and alkenes, i.e., C<inf>3</inf>F<inf>6</inf>, are produced via the secondary reactions. To mimic the decomposition details after arc breaking, the reactive molecular dynamics simulations were carried out by mean of an extensively optimized reactive force-filed for the C/H/N/O/F system. It was found that the arc decomposition of the fluoronitrile/CO<inf>2</inf> mixture produces the NO<inf>x</inf> (e.g., NO, NO<inf>2</inf>) species. In the presence of water impurity, some acidic byproducts including HF, FNCO, FCOOH, etc., can be generated. Theoretical calculations provide an a priori method to detect arc failure of the fluoronitrile/CO<inf>2</inf> insulation using the characteristic gases and shed new lights on the operation and maintenance of the electric equipment for health and safety measures.","PeriodicalId":286019,"journal":{"name":"2020 IEEE Electrical Insulation Conference (EIC)","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132627207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.1109/eic47619.2020.9158738
H. Penrose
Electrical Signature Analysis is the application and analysis of Voltage and Current data collected on electrical machinery systems. The measurements are converted to amplitude modulated Fast Fourier Transforms that can be evaluated for power, machine and powertrain conditions. Electrical and mechanical conditions are determined through their effects on the airgap magnetic field. One of these effects includes the detection of winding shorts. It has been found in variable frequency drive and wind generation applications that stator and rotor interturn stresses can be detected prior to insulation breakdown. The application of the technology in determining these conditions allows for mitigation of the conditions surrounding the winding stress and potential breakdown.
{"title":"Evaluation of Stator and Rotor Interturn Stress with Electrical Signature Analysis in Variable Frequency Drive and Wind Generator Applications","authors":"H. Penrose","doi":"10.1109/eic47619.2020.9158738","DOIUrl":"https://doi.org/10.1109/eic47619.2020.9158738","url":null,"abstract":"Electrical Signature Analysis is the application and analysis of Voltage and Current data collected on electrical machinery systems. The measurements are converted to amplitude modulated Fast Fourier Transforms that can be evaluated for power, machine and powertrain conditions. Electrical and mechanical conditions are determined through their effects on the airgap magnetic field. One of these effects includes the detection of winding shorts. It has been found in variable frequency drive and wind generation applications that stator and rotor interturn stresses can be detected prior to insulation breakdown. The application of the technology in determining these conditions allows for mitigation of the conditions surrounding the winding stress and potential breakdown.","PeriodicalId":286019,"journal":{"name":"2020 IEEE Electrical Insulation Conference (EIC)","volume":"78 3 Pt 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131205889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.1109/EIC47619.2020.9158744
L. Lusuardi, A. Cavallini, V. Madonna, P. Giangrande, M. Galea
Car manufacturers are increasingly working to make the all-electric car a reliable and affordable mobility option for a larger section of the population. However, several issues need to be addressed before achieving this goal. One of the problems is represented by the qualification of the insulation systems employed in electric motors. Unfortunately, the tests to be performed are time consuming and the design of such measurements very often is done by trial and error, further lengthening the validation phase. In addition, since cars are exposed to variable torque and speed operations (especially when driven in city traffic), the stator winding temperature is expected to vary in a wide range. Nevertheless, indications regarding the impact that highly variable temperature conditions play on the insulation reliability are not available, at the moment. In this work, the results of accelerated thermal aging tests using temperature profiles (i.e. variable temperature ageing) are presented and discussed. The experiments are accomplished on simplified insulation systems for electric motor (i.e. specimens) and cycling temperature profiles, ranging between 200°C – 260°C and featuring different thermal gradients, are applied as ageing stress. Finally, the possibility of relying on statistical techniques for improving the quality of prediction, while shortening the testing time, is explored.
{"title":"Unconventional accelerated thermal ageing test for traction electric motors in vehicles","authors":"L. Lusuardi, A. Cavallini, V. Madonna, P. Giangrande, M. Galea","doi":"10.1109/EIC47619.2020.9158744","DOIUrl":"https://doi.org/10.1109/EIC47619.2020.9158744","url":null,"abstract":"Car manufacturers are increasingly working to make the all-electric car a reliable and affordable mobility option for a larger section of the population. However, several issues need to be addressed before achieving this goal. One of the problems is represented by the qualification of the insulation systems employed in electric motors. Unfortunately, the tests to be performed are time consuming and the design of such measurements very often is done by trial and error, further lengthening the validation phase. In addition, since cars are exposed to variable torque and speed operations (especially when driven in city traffic), the stator winding temperature is expected to vary in a wide range. Nevertheless, indications regarding the impact that highly variable temperature conditions play on the insulation reliability are not available, at the moment. In this work, the results of accelerated thermal aging tests using temperature profiles (i.e. variable temperature ageing) are presented and discussed. The experiments are accomplished on simplified insulation systems for electric motor (i.e. specimens) and cycling temperature profiles, ranging between 200°C – 260°C and featuring different thermal gradients, are applied as ageing stress. Finally, the possibility of relying on statistical techniques for improving the quality of prediction, while shortening the testing time, is explored.","PeriodicalId":286019,"journal":{"name":"2020 IEEE Electrical Insulation Conference (EIC)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131039708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.1109/EIC47619.2020.9158695
Emilio Calo, R. Álvarez, Leonardo J. Catalano, Pablo Morcelle del Valle
The aim of this paper is to determine the influence of temperature, moisture content and thermal ageing on the dielectric frequency response of the insulation of a single stator coil. Measurements were made with a single medium voltage coil at different temperatures and percentages of relative humidity, generated inside a climatic chamber. Then, the coil was thermally aged by a current flow, reaching 120 °C, and the test was performed at different stages of ageing. This study presents the influence of temperature, humidity and ageing on the behavior of dielectric frequency response of a stator coil.
{"title":"Dielectric frequency response of a MV stator coil: effect of humidity and thermal ageing","authors":"Emilio Calo, R. Álvarez, Leonardo J. Catalano, Pablo Morcelle del Valle","doi":"10.1109/EIC47619.2020.9158695","DOIUrl":"https://doi.org/10.1109/EIC47619.2020.9158695","url":null,"abstract":"The aim of this paper is to determine the influence of temperature, moisture content and thermal ageing on the dielectric frequency response of the insulation of a single stator coil. Measurements were made with a single medium voltage coil at different temperatures and percentages of relative humidity, generated inside a climatic chamber. Then, the coil was thermally aged by a current flow, reaching 120 °C, and the test was performed at different stages of ageing. This study presents the influence of temperature, humidity and ageing on the behavior of dielectric frequency response of a stator coil.","PeriodicalId":286019,"journal":{"name":"2020 IEEE Electrical Insulation Conference (EIC)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115894917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.1109/EIC47619.2020.9158669
Yi Zhao, Tao Wen, M. Jin, Weijiang Chen, C. Guo, Qiaogen Zhang, Ming Chen
When an external short-circuit fault occurs, the transformer windings will be subjected to short-circuit electromagnetic force, and accidents such as winding tiltiing and buckling will occur, which seriously endangers the operating safety of the power system. At present, a winding in which multiple continuous transposed conductors (CTCs) wound in parallel is widely used in transformers. In order to suppress the circulating current, the transposition structure is generally adopted, and the structure of the winding is changed. This will affect the leakage magnetic field distribution, and then change the distribution of electromagnetic force. In this paper, a type of 110kV transformer adopting transposition structure in the low-voltage (LV) winding is studied, and a parametric modeling method is proposed to describe the transposition process of the wire. The local finite element model (FEM) including the winding transposition structure is constructed by analyzing the superposition change of the magnetic field at the transposition position. The model contains iron core, 16 low-voltage winding disks, 20 medium-voltage (MV) winding disks. The cloud diagram of the leakage magnetic field of the CTCs at the transposition area and the change of the leakage magnetic field along the circumferential were obtained. The research results show that the leakage magnetic field at the transposition changes significantly and the force of the conductor at the transposition is significantly different from that at the non-transposition area.
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