Pub Date : 1995-09-17DOI: 10.1109/ISEIM.1995.496611
T. Tsurumizu, Y. Yamano
We have studied the elimination of surface leaders by using a hollow electrode. The leader is the last stage of a surface streamer before flashover. We present the effect of the hollow electrode on the reduction of AC partial discharges (PD) under low voltage near the onset voltage of the PD.
{"title":"Reduction of AC surface partial discharges by use of a hollow electrode","authors":"T. Tsurumizu, Y. Yamano","doi":"10.1109/ISEIM.1995.496611","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496611","url":null,"abstract":"We have studied the elimination of surface leaders by using a hollow electrode. The leader is the last stage of a surface streamer before flashover. We present the effect of the hollow electrode on the reduction of AC partial discharges (PD) under low voltage near the onset voltage of the PD.","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129993559","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 : 1995-09-17DOI: 10.1109/ISEIM.1995.496498
D. Das-Gupta, P. Scarpa
The electrical ageing behaviour of a dielectric material in an adverse environment may be investigated by a study of its polarization and dielectric behaviour. The present work reports such a study with polyethylene under AC stress in a humid environment. In addition, the polarization and dielectric relaxation behaviour have also been correlated with studies of thermally stimulated discharge currents (TSDC) and thermal transient currents (TTC).
{"title":"Polarization and dielectric behaviour of AC aged polyethylene","authors":"D. Das-Gupta, P. Scarpa","doi":"10.1109/ISEIM.1995.496498","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496498","url":null,"abstract":"The electrical ageing behaviour of a dielectric material in an adverse environment may be investigated by a study of its polarization and dielectric behaviour. The present work reports such a study with polyethylene under AC stress in a humid environment. In addition, the polarization and dielectric relaxation behaviour have also been correlated with studies of thermally stimulated discharge currents (TSDC) and thermal transient currents (TTC).","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132190752","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 : 1995-09-17DOI: 10.1109/ISEIM.1995.496521
P. Chavarría, W.F. Araujo
Impulse and DC breakdown tracks of 4 and 30 cm point-plane air gaps were investigated. For smaller gap in both voltage types, the positive-voltage breakdown tracks were found to wander further away from the axis than for negative voltage. For 30 cm point-plane gap the results are inverted, the trajectories of the electrical discharges for negative polarities, as a general rule, may travel more outward from the axis than for positive polarities. This shows that the electrical breakdown trajectories depends on the various discharge modes, so that simple models like that proposed by Watson are unsuited for explaining breakdown tracks.
{"title":"Impulse and DC breakdown tracks of air in point-plane gaps","authors":"P. Chavarría, W.F. Araujo","doi":"10.1109/ISEIM.1995.496521","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496521","url":null,"abstract":"Impulse and DC breakdown tracks of 4 and 30 cm point-plane air gaps were investigated. For smaller gap in both voltage types, the positive-voltage breakdown tracks were found to wander further away from the axis than for negative voltage. For 30 cm point-plane gap the results are inverted, the trajectories of the electrical discharges for negative polarities, as a general rule, may travel more outward from the axis than for positive polarities. This shows that the electrical breakdown trajectories depends on the various discharge modes, so that simple models like that proposed by Watson are unsuited for explaining breakdown tracks.","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114213321","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 : 1995-09-17DOI: 10.1109/ISEIM.1995.496541
K. Yamazawa, K. Sugiura, W. Machidori, H. Yamashita
The relation between light emission phenomena and partial discharge (PD) current pulses in liquid nitrogen under impulse voltages is reported. The results of simultaneous measurements using optical and electrical methods are shown and their significance is discussed.
{"title":"Observation of prebreakdown light emission phenomena in liquid nitrogen","authors":"K. Yamazawa, K. Sugiura, W. Machidori, H. Yamashita","doi":"10.1109/ISEIM.1995.496541","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496541","url":null,"abstract":"The relation between light emission phenomena and partial discharge (PD) current pulses in liquid nitrogen under impulse voltages is reported. The results of simultaneous measurements using optical and electrical methods are shown and their significance is discussed.","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121288348","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 : 1995-09-17DOI: 10.1109/ISEIM.1995.496619
A. Nakayama
Fuji Electric has recently introduced a vacuum pressure impregnation (VPI) system for air-cooled turbine generator stator windings in the 30/spl sim/260MVA class. To accompany this, we have also developed a new insulation system for this VPI system, called the F-resin/GII insulation system. This insulation system is equipped with characteristics for operation over a long period of time and excellent heat cycle resistance. In this article, an evaluation of the mechanical characteristics of the main insulation for the new VPI insulation system is described.
{"title":"Evaluation of mechanical characteristics for a new vacuum pressure impregnation insulation system","authors":"A. Nakayama","doi":"10.1109/ISEIM.1995.496619","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496619","url":null,"abstract":"Fuji Electric has recently introduced a vacuum pressure impregnation (VPI) system for air-cooled turbine generator stator windings in the 30/spl sim/260MVA class. To accompany this, we have also developed a new insulation system for this VPI system, called the F-resin/GII insulation system. This insulation system is equipped with characteristics for operation over a long period of time and excellent heat cycle resistance. In this article, an evaluation of the mechanical characteristics of the main insulation for the new VPI insulation system is described.","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"274 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121360354","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 : 1995-09-17DOI: 10.1109/ISEIM.1995.496499
K. Yoshino
It is demonstrated that various types of novel polymers exhibiting not only insulating but also conducting and even superconducting characteristics can be prepared by appropriate molecular design. It is also indicated that the development of new synthetic methods and preparation techniques and completely new aspects appear even in the known traditional polymers. In the future, the author is convinced that polymeric materials will become much more important in electrical machines and cables.
{"title":"Novel properties of new types of conducting and insulating polymers and their composites","authors":"K. Yoshino","doi":"10.1109/ISEIM.1995.496499","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496499","url":null,"abstract":"It is demonstrated that various types of novel polymers exhibiting not only insulating but also conducting and even superconducting characteristics can be prepared by appropriate molecular design. It is also indicated that the development of new synthetic methods and preparation techniques and completely new aspects appear even in the known traditional polymers. In the future, the author is convinced that polymeric materials will become much more important in electrical machines and cables.","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126853505","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 : 1995-09-17DOI: 10.1109/ISEIM.1995.496616
N. Yoshimura, W. xinsheng, S. Kumagai, A. Shikimura, S. Hasegawa
The tracking resistances of various polymer insulating materials under artificial acid rain are evaluated. It is shown that due to the erosion and degradation effect of acid rain, the surface of the materials becomes more rough, and the surface hydrophobicity decreases, which results in a decrease of the tracking resistance of the materials. Because of the differences of microchemical structure and physical morphology, the resistances to tracking of the various materials against acid rain are different.
{"title":"The influence of acid rain on the resistance to tracking of polymer insulating materials","authors":"N. Yoshimura, W. xinsheng, S. Kumagai, A. Shikimura, S. Hasegawa","doi":"10.1109/ISEIM.1995.496616","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496616","url":null,"abstract":"The tracking resistances of various polymer insulating materials under artificial acid rain are evaluated. It is shown that due to the erosion and degradation effect of acid rain, the surface of the materials becomes more rough, and the surface hydrophobicity decreases, which results in a decrease of the tracking resistance of the materials. Because of the differences of microchemical structure and physical morphology, the resistances to tracking of the various materials against acid rain are different.","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"151 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116630191","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 : 1995-09-17DOI: 10.1109/ISEIM.1995.496529
T. Czaszejko
A preliminary study of the influence of the short exposure to DC voltage on the growth of water trees in XLPE cable insulation was performed. The DC voltage of 4U/sub 0/ (where U/sub 0/ is the rms rated voltage) was applied for the duration of 15 minutes prior to AC aging, in one set of samples, and in the middle of AC aging, in another set of identical samples. The results have shown an increase of the average length of water trees grown in samples subjected to DC voltage compared with those not exposed to DC voltage. The result was similar for accelerated aging with the liquid needle electrode method and for plain samples aged under rated voltage.
{"title":"Some aspects of water tree growth in XLPE insulation exposed to DC voltage","authors":"T. Czaszejko","doi":"10.1109/ISEIM.1995.496529","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496529","url":null,"abstract":"A preliminary study of the influence of the short exposure to DC voltage on the growth of water trees in XLPE cable insulation was performed. The DC voltage of 4U/sub 0/ (where U/sub 0/ is the rms rated voltage) was applied for the duration of 15 minutes prior to AC aging, in one set of samples, and in the middle of AC aging, in another set of identical samples. The results have shown an increase of the average length of water trees grown in samples subjected to DC voltage compared with those not exposed to DC voltage. The result was similar for accelerated aging with the liquid needle electrode method and for plain samples aged under rated voltage.","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114445133","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 : 1995-09-17DOI: 10.1109/ISEIM.1995.496549
E. Neagu, R. Neagu
Summary form only given, as follows. It is known that the conduction current through a dielectric material is related to space charge accumulation in the material. It is important to know the amount of charge stored in dielectric. Valuable information concerning charge stored in a dielectric material is obtained by using thermally stimulated discharge current method. We propose to use a variant of this method for space charge study as follows. An electric field is applied to the sample for a given time at a sufficiently high temperature so that the space charge formation process has an important role. Immediately after field removal the sample is not cooled down for polarization and space charge freezing. In contrast the sample is heated up and the released current is measured. Because the temperature is higher than forming temperature the measured current is determined by space charge existing in the sample; this method is known as thermally stimulated space charge current. The sample is heated at a temperature at which it is still mechanically stable. The experiment is continued at this temperature by measuring the isothermal final discharging current. When the measured current is in the parasitic limit it is considered that all the existing space charge in the dielectric has vanished. The relation between the total charge that flows through circuit during charging and the total charge liberated from the dielectric is analyzed.
{"title":"A method for space charge study in dielectrics","authors":"E. Neagu, R. Neagu","doi":"10.1109/ISEIM.1995.496549","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496549","url":null,"abstract":"Summary form only given, as follows. It is known that the conduction current through a dielectric material is related to space charge accumulation in the material. It is important to know the amount of charge stored in dielectric. Valuable information concerning charge stored in a dielectric material is obtained by using thermally stimulated discharge current method. We propose to use a variant of this method for space charge study as follows. An electric field is applied to the sample for a given time at a sufficiently high temperature so that the space charge formation process has an important role. Immediately after field removal the sample is not cooled down for polarization and space charge freezing. In contrast the sample is heated up and the released current is measured. Because the temperature is higher than forming temperature the measured current is determined by space charge existing in the sample; this method is known as thermally stimulated space charge current. The sample is heated at a temperature at which it is still mechanically stable. The experiment is continued at this temperature by measuring the isothermal final discharging current. When the measured current is in the parasitic limit it is considered that all the existing space charge in the dielectric has vanished. The relation between the total charge that flows through circuit during charging and the total charge liberated from the dielectric is analyzed.","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114959291","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 : 1995-09-17DOI: 10.1109/ISEIM.1995.496593
C. Banmongkol, T. Mori, T. Mizutani, M. Ishioka, I. Ishino
The authors have investigated the high-field phenomena in low-density polyethylene (LDPE). The objective of this paper is to study the relationship between molecular structure and the high-field phenomena at high temperature near the melting point of LDPE. The results can be summarized as follows. (1) The high-field current and the breakdown strength strongly depend upon film density determined by the concentration of methyl group. (2) The breakdown strength can be qualitatively estimated from the measurement of the high-field current. This incident as well as the above result suggests that a thermal process takes part in the dielectric breakdown of LDPE film at 90/spl deg/C. (3) Both the type and the concentration of carbonyl groups affect the high-field current of LDPE.
{"title":"Influence of molecular structure on high-field phenomena in LDPE films","authors":"C. Banmongkol, T. Mori, T. Mizutani, M. Ishioka, I. Ishino","doi":"10.1109/ISEIM.1995.496593","DOIUrl":"https://doi.org/10.1109/ISEIM.1995.496593","url":null,"abstract":"The authors have investigated the high-field phenomena in low-density polyethylene (LDPE). The objective of this paper is to study the relationship between molecular structure and the high-field phenomena at high temperature near the melting point of LDPE. The results can be summarized as follows. (1) The high-field current and the breakdown strength strongly depend upon film density determined by the concentration of methyl group. (2) The breakdown strength can be qualitatively estimated from the measurement of the high-field current. This incident as well as the above result suggests that a thermal process takes part in the dielectric breakdown of LDPE film at 90/spl deg/C. (3) Both the type and the concentration of carbonyl groups affect the high-field current of LDPE.","PeriodicalId":130178,"journal":{"name":"Proceedings of 1995 International Symposium on Electrical Insulating Materials","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125313110","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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