Pub Date : 2018-06-01DOI: 10.1109/EIC.2018.8481084
Mojtaba Rostaghi Chalaki, Z. Ahmed, Ian Robinson, J. Klüss
One of the most important parameters to provide safety for personnel and test equipment in high voltage laboratories is a reliable grounding system. The main characteristics of a reliable grounding system include low resistance at low frequency tests (power frequency test) and low potential rise at high frequency tests such as an impulse test. Also, low impedance connections in the test equipment grounding circuits could improve the grounding system's reliability. Therefore, in this paper the reliability of the grounding system is evaluated during routine activities at Mississippi State University's High Voltage Laboratory. For assessment, the ground potential rise was measured at all accessible ground connections for the impulse test system. Also, the effect of moisture variation in the laboratory ground soil layers was studied. In addition, the high frequency response of the laboratory grounding system was measured, and the feasibility of using alternative conductor types for the test equipment grounding circuits was investigated. Results show that several grounding points in the laboratory exhibit high voltage levels (ground potential rise) during impulse testing, which signifies a reduced safety for measuring devices and other equipment in the laboratory. Also, due to the type of grounding soil, its resistivity changes during different seasons throughout the year. Additionally, the harmonic impedance of the grounding system showed resistive behavior for a wide range of frequencies, and using the conductor strips instead of braided wire decreased the test circuit inductance which is a desirable feature from the grounding perspective.
{"title":"Performance Evaluation of High Voltage Laboratory Grounding","authors":"Mojtaba Rostaghi Chalaki, Z. Ahmed, Ian Robinson, J. Klüss","doi":"10.1109/EIC.2018.8481084","DOIUrl":"https://doi.org/10.1109/EIC.2018.8481084","url":null,"abstract":"One of the most important parameters to provide safety for personnel and test equipment in high voltage laboratories is a reliable grounding system. The main characteristics of a reliable grounding system include low resistance at low frequency tests (power frequency test) and low potential rise at high frequency tests such as an impulse test. Also, low impedance connections in the test equipment grounding circuits could improve the grounding system's reliability. Therefore, in this paper the reliability of the grounding system is evaluated during routine activities at Mississippi State University's High Voltage Laboratory. For assessment, the ground potential rise was measured at all accessible ground connections for the impulse test system. Also, the effect of moisture variation in the laboratory ground soil layers was studied. In addition, the high frequency response of the laboratory grounding system was measured, and the feasibility of using alternative conductor types for the test equipment grounding circuits was investigated. Results show that several grounding points in the laboratory exhibit high voltage levels (ground potential rise) during impulse testing, which signifies a reduced safety for measuring devices and other equipment in the laboratory. Also, due to the type of grounding soil, its resistivity changes during different seasons throughout the year. Additionally, the harmonic impedance of the grounding system showed resistive behavior for a wide range of frequencies, and using the conductor strips instead of braided wire decreased the test circuit inductance which is a desirable feature from the grounding perspective.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126423516","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 : 2018-06-01DOI: 10.1109/EIC.2018.8481103
B. Song, M. Ren, Jierui Zhou, M. Dong
Compared with traditional partial discharge(PD) detections, optical PD detection has significant advantages in anti-interference, intrinsic characterization and sensitivity in the particle discharge detection of Gas Insulted Switcher(GIS). Optical PD positioning is an efficient and economical positioning method which has a high practical value. In this paper, a new optical sensor array positioning system, consisted of three Silicon photomultipliers(SiPM) in different planes, is designed to locate the PD source in a distance. As the distance between SiPM and PD source increased, the PD source can be regard as a point light source, and the light illuminate to the SiPM is considered to be parallel light. In this circumstance, the radiant flux illuminating to the SiPM is proportional to the cosine of the angle between SiPM plane normal vector and the parallel light. Thus, we can use these characteristics to find the PD source. First, we verified that the quantitative relationship between SiPM output and the cosine of the angle between SiPM plane normal vector and the parallel light intensity. Second, we established nonlinear equations to find the approximately position of the PD source. The calculation of the equations show that there would be a 1cm acceptable positioning deviation with a 30cm distance between SiPM and PD source. The deviation is caused by reflection, measurement error, and some non-linear factor. Owing to its distinctive positioning mechanism, the optical PD positioning by SiPM has the advantages in sensitivity and low cost comparing with traditional positioning technology On the other hand, the problem of accuracy practical application of the system still need more research effort.
{"title":"A New Optical Method of Partial Discharge Distant Positioning in GIS","authors":"B. Song, M. Ren, Jierui Zhou, M. Dong","doi":"10.1109/EIC.2018.8481103","DOIUrl":"https://doi.org/10.1109/EIC.2018.8481103","url":null,"abstract":"Compared with traditional partial discharge(PD) detections, optical PD detection has significant advantages in anti-interference, intrinsic characterization and sensitivity in the particle discharge detection of Gas Insulted Switcher(GIS). Optical PD positioning is an efficient and economical positioning method which has a high practical value. In this paper, a new optical sensor array positioning system, consisted of three Silicon photomultipliers(SiPM) in different planes, is designed to locate the PD source in a distance. As the distance between SiPM and PD source increased, the PD source can be regard as a point light source, and the light illuminate to the SiPM is considered to be parallel light. In this circumstance, the radiant flux illuminating to the SiPM is proportional to the cosine of the angle between SiPM plane normal vector and the parallel light. Thus, we can use these characteristics to find the PD source. First, we verified that the quantitative relationship between SiPM output and the cosine of the angle between SiPM plane normal vector and the parallel light intensity. Second, we established nonlinear equations to find the approximately position of the PD source. The calculation of the equations show that there would be a 1cm acceptable positioning deviation with a 30cm distance between SiPM and PD source. The deviation is caused by reflection, measurement error, and some non-linear factor. Owing to its distinctive positioning mechanism, the optical PD positioning by SiPM has the advantages in sensitivity and low cost comparing with traditional positioning technology On the other hand, the problem of accuracy practical application of the system still need more research effort.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126551813","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 : 2018-06-01DOI: 10.1109/EIC.2018.8481036
O. W. Iwanusiw, P. Eng.
The principle which allows one to measure voltage ratio and convert this reading to transformer turns ratio sounds very simple. In practice, however, the conversion is influenced by practical issues, such as cores whose permeability and loss changes with applied voltage and causes conversion errors. This is especially troublesome when testing three-phase transformers using single-phase excitation. Three-phase transformers use cores more efficiently than do single-phase transformers, thus the loss and permeability effects are reduced, provided three-phase excitation is employed. The advantages of using three-phase excitation for ratio measurement of three-phase transformers include: * reduced dependence on test voltage. * ability to identify transformer's configuration. * ability to measure directly the ratio and phase shift of phase shifting transformers. * ability to provide additional information regarding the balance of the phases, shorted turns and excessive core loss.
{"title":"The Art and Science of Transformer Ratio Measurement","authors":"O. W. Iwanusiw, P. Eng.","doi":"10.1109/EIC.2018.8481036","DOIUrl":"https://doi.org/10.1109/EIC.2018.8481036","url":null,"abstract":"The principle which allows one to measure voltage ratio and convert this reading to transformer turns ratio sounds very simple. In practice, however, the conversion is influenced by practical issues, such as cores whose permeability and loss changes with applied voltage and causes conversion errors. This is especially troublesome when testing three-phase transformers using single-phase excitation. Three-phase transformers use cores more efficiently than do single-phase transformers, thus the loss and permeability effects are reduced, provided three-phase excitation is employed. The advantages of using three-phase excitation for ratio measurement of three-phase transformers include: * reduced dependence on test voltage. * ability to identify transformer's configuration. * ability to measure directly the ratio and phase shift of phase shifting transformers. * ability to provide additional information regarding the balance of the phases, shorted turns and excessive core loss.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116121544","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 : 2018-06-01DOI: 10.1109/EIC.2018.8481020
O. Diaz, L. Arevalo, Dong Wu
In high voltage equipment like bus terminals and interconnectors, it is common the use of large rounded electrodes to control high electric fields and improve the air insulation strength. A lot of information has been gathered from experimental campaigns during the last decades, where the main task focused on measuring the U50% breakdown voltage for several common electrode arrangements, and based on that, predict the behavior of similar electrode configurations existing in substations, transmission lines, etc. One special case occurs when small conductive protrusions are located on the surface of large electrodes. It has been observed before that the measured U50% is reduced compared with the case of an electrode without protrusions. In the present work, we analyze experimental results regarding the time-to-breakdown in switching impulse tests on large electrodes considering the presence of protrusions. A relation between the time-to-breakdown, the electrode type and the gap length was analyzed comparing different experimental data.
{"title":"Time to Breakdown on Large Electrodes Tested with Positive Switching Impulses","authors":"O. Diaz, L. Arevalo, Dong Wu","doi":"10.1109/EIC.2018.8481020","DOIUrl":"https://doi.org/10.1109/EIC.2018.8481020","url":null,"abstract":"In high voltage equipment like bus terminals and interconnectors, it is common the use of large rounded electrodes to control high electric fields and improve the air insulation strength. A lot of information has been gathered from experimental campaigns during the last decades, where the main task focused on measuring the U50% breakdown voltage for several common electrode arrangements, and based on that, predict the behavior of similar electrode configurations existing in substations, transmission lines, etc. One special case occurs when small conductive protrusions are located on the surface of large electrodes. It has been observed before that the measured U50% is reduced compared with the case of an electrode without protrusions. In the present work, we analyze experimental results regarding the time-to-breakdown in switching impulse tests on large electrodes considering the presence of protrusions. A relation between the time-to-breakdown, the electrode type and the gap length was analyzed comparing different experimental data.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"64 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134391770","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 : 2018-06-01DOI: 10.1109/EIC.2018.8481078
T. Aakre, E. Ildstad, S. Hvidsten
This paper presents results from laboratory measurements of partial discharge (PD) activity in 50 cm long samples cut from the mainwall section of old hydrogenerator stator bars. All stator bars were manufactured in 1976 and samples were taken after 35 years in service from both the low and high voltage sections of the generator, as well as non-energized back-up bars. The PD activity, using a phase resolved (PRPDA) measuring system, was investigated at different test voltages up to 9.6 kV (1.5 U0), frequencies and temperatures in the range 20–155 °C and 0.1-50 Hz, respectively. The service-aged and the unaged reference samples showed a clear difference in voltage frequency dependence. It was, however, not possible to distinguish between service-aged bars from high and low electric stress. The observed frequency and temperature dependences are discussed with respect to theoretical assumptions regarding possible void degradation and surface conductivity.
{"title":"Condition Assessment of Hydrogenerator Stator Bar Insulation Using Partial Discharge Measurements","authors":"T. Aakre, E. Ildstad, S. Hvidsten","doi":"10.1109/EIC.2018.8481078","DOIUrl":"https://doi.org/10.1109/EIC.2018.8481078","url":null,"abstract":"This paper presents results from laboratory measurements of partial discharge (PD) activity in 50 cm long samples cut from the mainwall section of old hydrogenerator stator bars. All stator bars were manufactured in 1976 and samples were taken after 35 years in service from both the low and high voltage sections of the generator, as well as non-energized back-up bars. The PD activity, using a phase resolved (PRPDA) measuring system, was investigated at different test voltages up to 9.6 kV (1.5 U0), frequencies and temperatures in the range 20–155 °C and 0.1-50 Hz, respectively. The service-aged and the unaged reference samples showed a clear difference in voltage frequency dependence. It was, however, not possible to distinguish between service-aged bars from high and low electric stress. The observed frequency and temperature dependences are discussed with respect to theoretical assumptions regarding possible void degradation and surface conductivity.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134505499","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 : 2018-06-01DOI: 10.1109/EIC.2018.8480888
J. Andle, Jonathan P. Murray, David Lane, Tom Cunneen
There is an increasing awareness of the role partial discharge monitoring plays in extending the operational life of electric power assets. For years, high value assets have undergone a periodic, off-line testing regimen; however, these tests are cost-prohibitive for the large numbers of transmission and distribution assets or even the electrical balance of plant equipment at generation facilities. This paper seeks to apply layered processing to extract meaningful information from real-time, on-line partial discharge signals, allowing asset health estimations from a highly reduced data stream consistent with distributed control systems.
{"title":"Ubiquitous, On-Line, Partial Discharge Trending","authors":"J. Andle, Jonathan P. Murray, David Lane, Tom Cunneen","doi":"10.1109/EIC.2018.8480888","DOIUrl":"https://doi.org/10.1109/EIC.2018.8480888","url":null,"abstract":"There is an increasing awareness of the role partial discharge monitoring plays in extending the operational life of electric power assets. For years, high value assets have undergone a periodic, off-line testing regimen; however, these tests are cost-prohibitive for the large numbers of transmission and distribution assets or even the electrical balance of plant equipment at generation facilities. This paper seeks to apply layered processing to extract meaningful information from real-time, on-line partial discharge signals, allowing asset health estimations from a highly reduced data stream consistent with distributed control systems.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134564319","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 : 2018-06-01DOI: 10.1109/EIC.2018.8481126
K. Yamashita, S. Watanuki, T. Miyake, T. Sakoda, Wataru Kawano
Although the demand of reliable power systems and stability of supplying electric power are quite crucial for all of power companies, aging and deterioration of the electric power equipment are ongoing. For this reason, we propose a partial discharge locator (PDL) system. This is possible to locate the cable fault for power cables under the transmission and the distribution systems in operation. In conventional systems, the propagation velocity of a PD pulse must be known for the cable fault detection. However, it likely depends on the deterioration state of the power cable. Thus, PDL uses injection signals only to measure the propagating time instead of obtaining propagation velocity. This implicates the need of communication among two devices in order to make system accurate. In this paper, we first show how the PDL works on-line power cable with time synchronization between two sides and injection trigger for obtaining propagating time. We also provide information of the propagation characteristics of a current pulse which simulates a partial discharge current on branched 22kV XLPE cables.
{"title":"Development of On-Line Partial Discharge Locator for Electric Power Cable","authors":"K. Yamashita, S. Watanuki, T. Miyake, T. Sakoda, Wataru Kawano","doi":"10.1109/EIC.2018.8481126","DOIUrl":"https://doi.org/10.1109/EIC.2018.8481126","url":null,"abstract":"Although the demand of reliable power systems and stability of supplying electric power are quite crucial for all of power companies, aging and deterioration of the electric power equipment are ongoing. For this reason, we propose a partial discharge locator (PDL) system. This is possible to locate the cable fault for power cables under the transmission and the distribution systems in operation. In conventional systems, the propagation velocity of a PD pulse must be known for the cable fault detection. However, it likely depends on the deterioration state of the power cable. Thus, PDL uses injection signals only to measure the propagating time instead of obtaining propagation velocity. This implicates the need of communication among two devices in order to make system accurate. In this paper, we first show how the PDL works on-line power cable with time synchronization between two sides and injection trigger for obtaining propagating time. We also provide information of the propagation characteristics of a current pulse which simulates a partial discharge current on branched 22kV XLPE cables.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126075921","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 : 2018-06-01DOI: 10.1109/EIC.2018.8481058
R. Hussain, V. Hinrichsen
High voltage direct current (HVDC) power transmission is becoming more and more competitive to high voltage alternate current (HVAC) power transmission, especially for bulk power transmission over long distances. For crossing wide metropolitan areas or long distances in the open sea, especially HVDC cable lines are attractive. Regarding the insulation, extruded XLPE HVDC cables offer significant advantages over those with other types of insulation, e.g. oil-paper insulated cables. In addition to higher permissible conductor temperatures also jointing of extruded cables is simpler. Nevertheless, the electric field distribution is much more complex in HVDC insulation systems because it strongly depends on the conductivities of the insulation. Especially the presence of space charges can lead to increased electric field stress up to failure of the device. These challenges require development of new insulating materials that are suitable for HVDC applications. The purpose of this paper is to present the method of Thermally Stimulated Depolarization Currents (TSDC), which allows investigating and evaluating insulating materials. First, the general test procedure of a TSDC measurement is introduced, and then all significant TSDC parameters are described. A test setup has been developed to perform TSDC measurements, which is presented in this paper. Furthermore, the challenges of a TSDC measurement are outlined and solutions are introduced. The investigations are performed on a liquid silicone rubber (LSR) to be used as an insulating material, e.g. for the insulation of a cable joint. In addition, TSDC measurements are performed on LSR samples with different concentrations of nanofillers to evaluate their electrical properties. The final approach is to present the scope of the TSDC method with regard to HVDC applications.
{"title":"Thermally Stimulated Depolarization Currents on Silicone Rubber with Nanofillers","authors":"R. Hussain, V. Hinrichsen","doi":"10.1109/EIC.2018.8481058","DOIUrl":"https://doi.org/10.1109/EIC.2018.8481058","url":null,"abstract":"High voltage direct current (HVDC) power transmission is becoming more and more competitive to high voltage alternate current (HVAC) power transmission, especially for bulk power transmission over long distances. For crossing wide metropolitan areas or long distances in the open sea, especially HVDC cable lines are attractive. Regarding the insulation, extruded XLPE HVDC cables offer significant advantages over those with other types of insulation, e.g. oil-paper insulated cables. In addition to higher permissible conductor temperatures also jointing of extruded cables is simpler. Nevertheless, the electric field distribution is much more complex in HVDC insulation systems because it strongly depends on the conductivities of the insulation. Especially the presence of space charges can lead to increased electric field stress up to failure of the device. These challenges require development of new insulating materials that are suitable for HVDC applications. The purpose of this paper is to present the method of Thermally Stimulated Depolarization Currents (TSDC), which allows investigating and evaluating insulating materials. First, the general test procedure of a TSDC measurement is introduced, and then all significant TSDC parameters are described. A test setup has been developed to perform TSDC measurements, which is presented in this paper. Furthermore, the challenges of a TSDC measurement are outlined and solutions are introduced. The investigations are performed on a liquid silicone rubber (LSR) to be used as an insulating material, e.g. for the insulation of a cable joint. In addition, TSDC measurements are performed on LSR samples with different concentrations of nanofillers to evaluate their electrical properties. The final approach is to present the scope of the TSDC method with regard to HVDC applications.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121653487","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 : 2018-06-01DOI: 10.1109/EIC.2018.8481070
Martin Scheler, M. Rossner, Lukas Reißenweber, F. Berger, U. Prucker, Andreas Hopf
In the field of HVDC bushings, temperature gradients inside the bushing core have more impact on the electric field distribution compared to AC. Furthermore, more experiences are existing in the DC case for the oil-insulation system than for solid-gas. The aim is to study the potential distribution in the bushing core of a solid-gas insulated high voltage bushing at very low frequencies (5 mHz to 100 mHz) under the effect of a temperature gradient. Previous investigations suggest that, after a DC voltage is applied, it takes dozens of hours before a true DC field condition is reached due to the end of all polarization processes in the insulation material. An investigation at very low frequencies is therefore reasonable to determine the temperature behavior of the capacitive-resistive transition. As test object, a single-sided 180 kV bushing core is used (only one end of the core is graded). Five metal foils of the capacitive grading were carried out of the ungraded side of the core, so potential measurements on this foils could be undertaken, and furthermore, the distortion of the electric field by the metal foils is lower compared to a double-sided grading. The test arrangement also allows measurements under different insulation gases with different pressures. Air is used as insulation gas since the test voltages are lower than or equal 30 kV. AC measurements are performed via capacitive sensor. In case of DC, the sensor evaluates the initial magnitude of the discharging process of a charged capacity. The distortion of the field distribution within the bushing core, caused by the influence of the measuring device has no significant impact, because its additional capacitive load is less than 80 pF. Since it is of deterministic nature, its influence can be taken into account. To perform a temperature gradient, the primary conductor is heated until the temperature gradient reached a constant value, and then set under voltage. At the one hand, the temperature and voltage distribution in the bushing core is measured, and on the other hand it is verified with our investigations of the material properties.
{"title":"Potential Distribution in the Bushing Core of a Solid-Gas Insulated High Voltage Bushing in the Very Low Frequency Region Under the Effect of a Temperature Gradient","authors":"Martin Scheler, M. Rossner, Lukas Reißenweber, F. Berger, U. Prucker, Andreas Hopf","doi":"10.1109/EIC.2018.8481070","DOIUrl":"https://doi.org/10.1109/EIC.2018.8481070","url":null,"abstract":"In the field of HVDC bushings, temperature gradients inside the bushing core have more impact on the electric field distribution compared to AC. Furthermore, more experiences are existing in the DC case for the oil-insulation system than for solid-gas. The aim is to study the potential distribution in the bushing core of a solid-gas insulated high voltage bushing at very low frequencies (5 mHz to 100 mHz) under the effect of a temperature gradient. Previous investigations suggest that, after a DC voltage is applied, it takes dozens of hours before a true DC field condition is reached due to the end of all polarization processes in the insulation material. An investigation at very low frequencies is therefore reasonable to determine the temperature behavior of the capacitive-resistive transition. As test object, a single-sided 180 kV bushing core is used (only one end of the core is graded). Five metal foils of the capacitive grading were carried out of the ungraded side of the core, so potential measurements on this foils could be undertaken, and furthermore, the distortion of the electric field by the metal foils is lower compared to a double-sided grading. The test arrangement also allows measurements under different insulation gases with different pressures. Air is used as insulation gas since the test voltages are lower than or equal 30 kV. AC measurements are performed via capacitive sensor. In case of DC, the sensor evaluates the initial magnitude of the discharging process of a charged capacity. The distortion of the field distribution within the bushing core, caused by the influence of the measuring device has no significant impact, because its additional capacitive load is less than 80 pF. Since it is of deterministic nature, its influence can be taken into account. To perform a temperature gradient, the primary conductor is heated until the temperature gradient reached a constant value, and then set under voltage. At the one hand, the temperature and voltage distribution in the bushing core is measured, and on the other hand it is verified with our investigations of the material properties.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128248884","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 : 2018-06-01DOI: 10.1109/EIC.2018.8481088
J. Luksich, A. Sbravati, A. Yerges, K. Rapp, C. Mcshane
This paper reviews the natural ester aging data found in Annex B of IEEE C57.154 and adds new aging data that extends the original aging times. It presents the results from almost 3.5 years of accelerated aging tests, consisting of thermally upgraded Kraft paper in soybean oil and high oleic sunflower oil using both glass and steel aging vessels. Aging temperatures were 150°C, 160 °C, 170°C and 180 °C. Additional aging systems consisting of thermally upgraded Kraft paper in mineral oil were run as reference systems. The paper in mineral oil aged at rates consistent with the IEEE mineral oil unit life equation, sufficing the test validation criteria defined in IEEE C57.100. The natural ester data was consistent between the soybean oil and high oleic sunflower oils as well as between the glass and steel aging systems. The unit life coefficient is recalculated incorporating the new data, confirming the previously adopted values of thermal classes.
{"title":"Sealed Vessel Tests for Determination of Arrhenius Curve Parameters","authors":"J. Luksich, A. Sbravati, A. Yerges, K. Rapp, C. Mcshane","doi":"10.1109/EIC.2018.8481088","DOIUrl":"https://doi.org/10.1109/EIC.2018.8481088","url":null,"abstract":"This paper reviews the natural ester aging data found in Annex B of IEEE C57.154 and adds new aging data that extends the original aging times. It presents the results from almost 3.5 years of accelerated aging tests, consisting of thermally upgraded Kraft paper in soybean oil and high oleic sunflower oil using both glass and steel aging vessels. Aging temperatures were 150°C, 160 °C, 170°C and 180 °C. Additional aging systems consisting of thermally upgraded Kraft paper in mineral oil were run as reference systems. The paper in mineral oil aged at rates consistent with the IEEE mineral oil unit life equation, sufficing the test validation criteria defined in IEEE C57.100. The natural ester data was consistent between the soybean oil and high oleic sunflower oils as well as between the glass and steel aging systems. The unit life coefficient is recalculated incorporating the new data, confirming the previously adopted values of thermal classes.","PeriodicalId":184139,"journal":{"name":"2018 IEEE Electrical Insulation Conference (EIC)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117249145","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}
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