Pub Date : 1998-06-22DOI: 10.1109/ICSD.1998.709297
Seiichi Takei, Y. Tanabe, Y. Ohki
Conduction process of thermoplastic polyimide has been examined. The as-received sample shows a current with a peak at /spl sim/230/spl deg/C even when any poling bias has been applied. However, this spontaneous current disappears if the measurement is repeated. Conduction current decreases if the sample was heat-treated. It is considered that impurities such as K and Na remaining in the sample are responsible for the current peak or the spontaneous current.
{"title":"Electrical properties of thermoplastic polyimide","authors":"Seiichi Takei, Y. Tanabe, Y. Ohki","doi":"10.1109/ICSD.1998.709297","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709297","url":null,"abstract":"Conduction process of thermoplastic polyimide has been examined. The as-received sample shows a current with a peak at /spl sim/230/spl deg/C even when any poling bias has been applied. However, this spontaneous current disappears if the measurement is repeated. Conduction current decreases if the sample was heat-treated. It is considered that impurities such as K and Na remaining in the sample are responsible for the current peak or the spontaneous current.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"2 1","pages":"349-352"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89214498","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709272
G. Raju, M. A. Sussi
Conduction currents in Teflon (PolyTetraFluoroEthylene, PTFE) films having thickness of 50 /spl mu/m and 130 /spl mu/m are measured over a temperature range of 40-200/spl deg/C and electric field strengths up to 246 kV cm/sup -1/. The importance of space charge effects in both ionic and electronic conduction at different temperature ranges are discussed.
{"title":"Factors influencing conduction currents in Teflon","authors":"G. Raju, M. A. Sussi","doi":"10.1109/ICSD.1998.709272","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709272","url":null,"abstract":"Conduction currents in Teflon (PolyTetraFluoroEthylene, PTFE) films having thickness of 50 /spl mu/m and 130 /spl mu/m are measured over a temperature range of 40-200/spl deg/C and electric field strengths up to 246 kV cm/sup -1/. The importance of space charge effects in both ionic and electronic conduction at different temperature ranges are discussed.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"4 1","pages":"249-252"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76736666","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709298
T. Oommen, G. Frimpong, J. M. Walden
Polymeric materials, both natural and synthetic, produce static electrification by friction. However, these materials have not been studied well in a flow system with insulating fluids. Since power transformers use certain polymeric materials for conductor insulation, it is a matter of interest whether these materials would produce a charge effect. Polyvinyl formal insulation films are used over the primary conductor strands of transformers. A study was undertaken to understand the flow electrification behavior of this family of polymers. Both polyvinyl formal and polyzinyl butyral formulations were tested, both in the dissolved state, and as a deposited film. Although the polyvinyl formals tested showed negligible charge effects in the dissolved state, many of the polyvinyl butyrals (Butvars) exhibited high charge tendency in transformer oil. The deposited film of Butvars also showed high charging, but the degree of charging of the films showed a reverse order when compared to the charging in the dissolved state.
{"title":"Certain high charging polymeric materials in transformer oil","authors":"T. Oommen, G. Frimpong, J. M. Walden","doi":"10.1109/ICSD.1998.709298","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709298","url":null,"abstract":"Polymeric materials, both natural and synthetic, produce static electrification by friction. However, these materials have not been studied well in a flow system with insulating fluids. Since power transformers use certain polymeric materials for conductor insulation, it is a matter of interest whether these materials would produce a charge effect. Polyvinyl formal insulation films are used over the primary conductor strands of transformers. A study was undertaken to understand the flow electrification behavior of this family of polymers. Both polyvinyl formal and polyzinyl butyral formulations were tested, both in the dissolved state, and as a deposited film. Although the polyvinyl formals tested showed negligible charge effects in the dissolved state, many of the polyvinyl butyrals (Butvars) exhibited high charge tendency in transformer oil. The deposited film of Butvars also showed high charging, but the degree of charging of the films showed a reverse order when compared to the charging in the dissolved state.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"22 1","pages":"353-356"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78005800","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709344
E. Mårtensson, B. Nettelbled, U. Gafvert, L. Palmqvist
In this contribution, we present results from a study of a field grading material, consisting of a matrix made of ethylene-propylene rubber (EPDM) filled with both silicon carbide (SiC) and carbon black (CB). The material properties have been electrically characterized and analyzed both at low voltage in frequency domain and at high voltage in time domain. Space charge measurements have also been performed.
{"title":"Electrical properties of field grading materials with silicon carbide and carbon black","authors":"E. Mårtensson, B. Nettelbled, U. Gafvert, L. Palmqvist","doi":"10.1109/ICSD.1998.709344","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709344","url":null,"abstract":"In this contribution, we present results from a study of a field grading material, consisting of a matrix made of ethylene-propylene rubber (EPDM) filled with both silicon carbide (SiC) and carbon black (CB). The material properties have been electrically characterized and analyzed both at low voltage in frequency domain and at high voltage in time domain. Space charge measurements have also been performed.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"72 1","pages":"548-552"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80430292","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709340
C. Pinto
Measurements performed on stator winding insulation indicate variations in capacitance and tan /spl delta/ values with voltage even in the absence of partial discharge activity. One of the most obvious reasons for this variation is the presence of the non-linear field stress grading system employed at the slot ends. Other reasons include interfacial and space charge polarization phenomena, due to a variety of reasons including contamination of the windings, as well as, the effects of electrostatic forces on delaminated stator insulation. As partial discharge activity results in change in the instantaneous capacitance with voltage, it could also be considered as a case of non linear behaviour of the insulation. The paper discusses a generalized approach to study the influence of non-linear behaviour on the variations of capacitance and losses. Case studies are employed to illustrate the usefulness of measurements on the stator windings in service.
{"title":"A generalized approach for the study of the non linear behaviour of stator winding insulation","authors":"C. Pinto","doi":"10.1109/ICSD.1998.709340","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709340","url":null,"abstract":"Measurements performed on stator winding insulation indicate variations in capacitance and tan /spl delta/ values with voltage even in the absence of partial discharge activity. One of the most obvious reasons for this variation is the presence of the non-linear field stress grading system employed at the slot ends. Other reasons include interfacial and space charge polarization phenomena, due to a variety of reasons including contamination of the windings, as well as, the effects of electrostatic forces on delaminated stator insulation. As partial discharge activity results in change in the instantaneous capacitance with voltage, it could also be considered as a case of non linear behaviour of the insulation. The paper discusses a generalized approach to study the influence of non-linear behaviour on the variations of capacitance and losses. Case studies are employed to illustrate the usefulness of measurements on the stator windings in service.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"24 1","pages":"528-532"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75723752","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709301
U. Nilsson, R. Dammert, A. Campus, A. Sneck, H. Jakosuo-Jansson
It is well known that the physical, mechanical, optical and electrical properties are affected by the sample morphology. The aim of the work was to gain knowledge and basic understanding of the morphology of polyethylene materials used for power cable insulation. A permanganic etching procedure with subsequent TEM microscopy was used to reveal the crystalline structure of the specimens. The effects of antioxidant (Santox R type) and peroxide crosslinking of low density polyethylene (LDPE) and acrylate polymer were investigated in this study.
{"title":"Morphology of polyethylene for power cable insulation: effects of antioxidant and crosslinking","authors":"U. Nilsson, R. Dammert, A. Campus, A. Sneck, H. Jakosuo-Jansson","doi":"10.1109/ICSD.1998.709301","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709301","url":null,"abstract":"It is well known that the physical, mechanical, optical and electrical properties are affected by the sample morphology. The aim of the work was to gain knowledge and basic understanding of the morphology of polyethylene materials used for power cable insulation. A permanganic etching procedure with subsequent TEM microscopy was used to reveal the crystalline structure of the specimens. The effects of antioxidant (Santox R type) and peroxide crosslinking of low density polyethylene (LDPE) and acrylate polymer were investigated in this study.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"71 1","pages":"365-367"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76522129","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709284
K. Bromley, L. Dissado, J. Fothergill
The movement of residual positive charges along the walls of tree tubules and into the surrounding polymer is a critical determining factor in the shape (bush or branch) of electrical trees. Positive charge that has a higher mobility along tubule walls promotes single discharges propagating to the tree tip. Lower mobility positive wall charge tends to more, but perhaps smaller, discharges. The former may favour branch tree growth, the latter bush trees. Spread out positive wall charge may occur when there are a number of discharges per half cycle. The resulting damage may favour bifurcation (transverse extension).
{"title":"Discharges, space charge, and the shape of electrical trees","authors":"K. Bromley, L. Dissado, J. Fothergill","doi":"10.1109/ICSD.1998.709284","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709284","url":null,"abstract":"The movement of residual positive charges along the walls of tree tubules and into the surrounding polymer is a critical determining factor in the shape (bush or branch) of electrical trees. Positive charge that has a higher mobility along tubule walls promotes single discharges propagating to the tree tip. Lower mobility positive wall charge tends to more, but perhaps smaller, discharges. The former may favour branch tree growth, the latter bush trees. Spread out positive wall charge may occur when there are a number of discharges per half cycle. The resulting damage may favour bifurcation (transverse extension).","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"33 1","pages":"295-300"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81610998","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709328
M. Lakner, Jakob Rhyner, D. Sologuren
The electric performance (breakdown strength, ageing) of industrially manufactured insulation materials is usually far worse than that of laboratory made samples. The main reason of this discrepancy is commonly attributed to various kinds of impurities as, e.g., small metal particles, introduced by the large scale manufacturing process. We have intentionally introduced small elongated metal particles with well defined shape (length varying from 0.1 to 1 mm, diameter from 10 to 100 /spl mu/m) into alumina-filled epoxy insulation, oriented in the electric field direction. We have performed accelerated ageing tests at elevated ac electric fields between 10 and 28 kV/mm. The dependence of the time-to-breakdown as a function of the applied electric field and the particle size can be understood in terms of a field enhancement at the particle ends, leading to charge injection. We find a simple scaling relation between the lifetime and the injected space charge.
{"title":"Effect of small metal particles on ageing of epoxy insulation","authors":"M. Lakner, Jakob Rhyner, D. Sologuren","doi":"10.1109/ICSD.1998.709328","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709328","url":null,"abstract":"The electric performance (breakdown strength, ageing) of industrially manufactured insulation materials is usually far worse than that of laboratory made samples. The main reason of this discrepancy is commonly attributed to various kinds of impurities as, e.g., small metal particles, introduced by the large scale manufacturing process. We have intentionally introduced small elongated metal particles with well defined shape (length varying from 0.1 to 1 mm, diameter from 10 to 100 /spl mu/m) into alumina-filled epoxy insulation, oriented in the electric field direction. We have performed accelerated ageing tests at elevated ac electric fields between 10 and 28 kV/mm. The dependence of the time-to-breakdown as a function of the applied electric field and the particle size can be understood in terms of a field enhancement at the particle ends, leading to charge injection. We find a simple scaling relation between the lifetime and the injected space charge.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"104 1","pages":"477-480"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80830171","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709276
C. Bertin, J. Guastavino, M. Briot, A. Campus, P. Druot
An approach was made to understand the role played by the microstructure of a LPDE in the ageing process of this material under electric stress. An optical observation and an image treatment of the structure evolution reveal a physical behaviour comparable to a "fatigue process". Although the applied field was about 35 times the working field of a cable we have not observed any tree in the samples.
{"title":"Direct optical observation of polyethylene microstructures under field and temperature conditions, before any degradation","authors":"C. Bertin, J. Guastavino, M. Briot, A. Campus, P. Druot","doi":"10.1109/ICSD.1998.709276","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709276","url":null,"abstract":"An approach was made to understand the role played by the microstructure of a LPDE in the ageing process of this material under electric stress. An optical observation and an image treatment of the structure evolution reveal a physical behaviour comparable to a \"fatigue process\". Although the applied field was about 35 times the working field of a cable we have not observed any tree in the samples.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"34 1","pages":"265-268"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78516993","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709342
S. Watanabe, N. Hayashi, H. Takeuchi, Y. Uchida, D. Dykes, G. Touchard, M. Ieda
It is well known that titanium materials can be used as photocatalysers for the adsorption of nitrogen oxides (NOx). In Osaka, such materials are already being tested on the surfaces of pavements and building walls. They are also used in anti-bacteria tiles in operating theatres. In the field of electrical engineering, too, the high relative permittivity of titanium allows these materials to play an important role in two areas: firstly as field relaxation agents, and secondly as high-voltage insulators to enhance the performance capacity of machinery. To meet the strenuous demands that these electrical uses place on the materials, two recourses are available to material designers: either the development of new materials, or the control of electrical fields within existing ones. The authors of this paper have attempted to manufacture a material permitting the control of field forces by taking advantage of properties of functionally graded materials (FGMs). The basic idea behind this is to guard against damage to machinery by bringing about relaxation in those parts where field forces are too high and increasing forces in parts where they are too low. The FGMs described in this paper are combined from titanium oxide and Korean kaolin. They allow a graded change in relative permittivity between the two surfaces. The paper compares the relative permittivities of these FGMs with those of 15 kinds of uniform material. There is a concluding discussion on the field relaxation effect.
{"title":"Electrical applications of titanium-based FGMs manufactured by progressive lamination","authors":"S. Watanabe, N. Hayashi, H. Takeuchi, Y. Uchida, D. Dykes, G. Touchard, M. Ieda","doi":"10.1109/ICSD.1998.709342","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709342","url":null,"abstract":"It is well known that titanium materials can be used as photocatalysers for the adsorption of nitrogen oxides (NOx). In Osaka, such materials are already being tested on the surfaces of pavements and building walls. They are also used in anti-bacteria tiles in operating theatres. In the field of electrical engineering, too, the high relative permittivity of titanium allows these materials to play an important role in two areas: firstly as field relaxation agents, and secondly as high-voltage insulators to enhance the performance capacity of machinery. To meet the strenuous demands that these electrical uses place on the materials, two recourses are available to material designers: either the development of new materials, or the control of electrical fields within existing ones. The authors of this paper have attempted to manufacture a material permitting the control of field forces by taking advantage of properties of functionally graded materials (FGMs). The basic idea behind this is to guard against damage to machinery by bringing about relaxation in those parts where field forces are too high and increasing forces in parts where they are too low. The FGMs described in this paper are combined from titanium oxide and Korean kaolin. They allow a graded change in relative permittivity between the two surfaces. The paper compares the relative permittivities of these FGMs with those of 15 kinds of uniform material. There is a concluding discussion on the field relaxation effect.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"744 1","pages":"539-542"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84490579","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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