Pub Date : 2006-10-01DOI: 10.1109/CEIDP.2006.312042
F. O'Sullivan, Sehee Lee, M. Zahn, L. Pettersson, Rongsheng Liu, O. Hjortstam, T. Auletta, U. Gafvert
Transformer oil is one of the most important and widely used of all dielectric liquids. Significant research into the insulating properties of transformer oil has been carried out. Much of this work has focused on the development of streamers, and how they can result in the electrical breakdown of the oil. Due to the complex nature of transformer oil no universally accepted model describing streamer initiation and propagation has emerged. In this paper, a model is developed which explores the role played by electric field dependent ionic dissociation in the initiation and propagation of streamers in transformer oil. This model couples the electrodynamics of charge transport to thermal enhancement in transformer oil. Using the COMSOL Multiphysics software application and the finite element method, the model is solved to show that ionic dissociation alone will not lead to a high enough temperature rise to initiate a streamer in transformer oil.
{"title":"Modeling the Effect of Ionic Dissociation on Charge Transport in Transformer Oil","authors":"F. O'Sullivan, Sehee Lee, M. Zahn, L. Pettersson, Rongsheng Liu, O. Hjortstam, T. Auletta, U. Gafvert","doi":"10.1109/CEIDP.2006.312042","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.312042","url":null,"abstract":"Transformer oil is one of the most important and widely used of all dielectric liquids. Significant research into the insulating properties of transformer oil has been carried out. Much of this work has focused on the development of streamers, and how they can result in the electrical breakdown of the oil. Due to the complex nature of transformer oil no universally accepted model describing streamer initiation and propagation has emerged. In this paper, a model is developed which explores the role played by electric field dependent ionic dissociation in the initiation and propagation of streamers in transformer oil. This model couples the electrodynamics of charge transport to thermal enhancement in transformer oil. Using the COMSOL Multiphysics software application and the finite element method, the model is solved to show that ionic dissociation alone will not lead to a high enough temperature rise to initiate a streamer in transformer oil.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127951593","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 : 2006-10-01DOI: 10.1109/CEIDP.2006.311991
L. Lamarre, É. David
In order to assess the state of the rotating machine insulation winding system, time-domain dielectric measurements are frequently conducted. Time-domain measurements are commonly used in the field in the form of polarization/depolarization test (PDC), high voltage ramped test or other type DC tests. Such measurements, which are related to the low-frequency dielectric response of the insulation system, depend on the insulating materials, the way the components of the insulation system are laid out, the aging of the materials and on external factors such as temperature, moisture absorption or contamination. In the paper, measurements conducted in the time domain are presented for modern epoxy mica winding insulation technology. The influence of the temperature is investigated for epoxy-mica insulation systems for stator bars and a correction procedure for insulation resistance (IR) for epoxy mica insulation is suggested.
{"title":"Dielectric response of rotating machine stator insulation system","authors":"L. Lamarre, É. David","doi":"10.1109/CEIDP.2006.311991","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.311991","url":null,"abstract":"In order to assess the state of the rotating machine insulation winding system, time-domain dielectric measurements are frequently conducted. Time-domain measurements are commonly used in the field in the form of polarization/depolarization test (PDC), high voltage ramped test or other type DC tests. Such measurements, which are related to the low-frequency dielectric response of the insulation system, depend on the insulating materials, the way the components of the insulation system are laid out, the aging of the materials and on external factors such as temperature, moisture absorption or contamination. In the paper, measurements conducted in the time domain are presented for modern epoxy mica winding insulation technology. The influence of the temperature is investigated for epoxy-mica insulation systems for stator bars and a correction procedure for insulation resistance (IR) for epoxy mica insulation is suggested.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121358917","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 : 2006-10-01DOI: 10.1109/CEIDP.2006.312084
U. Gafvert, O. Hjortstam, Y. Serdyuk, C. Tornkvist, L. Walfridsson
In this paper we report on basic studies of the electric fields under DC stress in a composite insulation consisting of transformer oil and oil-impregnated pressboard, typical for HVDC converter transformers. The time dependent electrical fields in our model geometry are measured using electro-optic Kerr method, and theoretically studied with an ion drift-diffusion conduction model. The measured and calculated electrical fields are compared and analyzed.
{"title":"Modeling and Measurements of Electric Fields in Composite Oil/Cellulose Insulation","authors":"U. Gafvert, O. Hjortstam, Y. Serdyuk, C. Tornkvist, L. Walfridsson","doi":"10.1109/CEIDP.2006.312084","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.312084","url":null,"abstract":"In this paper we report on basic studies of the electric fields under DC stress in a composite insulation consisting of transformer oil and oil-impregnated pressboard, typical for HVDC converter transformers. The time dependent electrical fields in our model geometry are measured using electro-optic Kerr method, and theoretically studied with an ion drift-diffusion conduction model. The measured and calculated electrical fields are compared and analyzed.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128794912","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 : 2006-10-01DOI: 10.1109/CEIDP.2006.311938
S. Pélissou, S. Besner, M. Frechette, K. Cole, D. Desgagnes
This paper presents a preliminary electrical and thermal characterization carried out on an epoxy nanocomposite material. It consisted of an epoxy matrix containing micrometric quartz and a small amount of nanoclay. AC electrical breakdown (ACBD) was performed on sheet samples with and without nanomaterial. The thermal characterization of this composite material and its reference includes thermogravimetry (TGA) and differential scanning calorimetry (DSC). The results show that the ACBD strength is slightly affected by the presence of such concentration of nanomaterial in the epoxy: greatest ACBD voltage and less disperse data. The thermal analyses of the polymer composite showed that decomposition temperature remain almost unchanged with addition of such a small amount of nanoclay.
{"title":"Preliminary Characterization of a Nanodielectric Material","authors":"S. Pélissou, S. Besner, M. Frechette, K. Cole, D. Desgagnes","doi":"10.1109/CEIDP.2006.311938","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.311938","url":null,"abstract":"This paper presents a preliminary electrical and thermal characterization carried out on an epoxy nanocomposite material. It consisted of an epoxy matrix containing micrometric quartz and a small amount of nanoclay. AC electrical breakdown (ACBD) was performed on sheet samples with and without nanomaterial. The thermal characterization of this composite material and its reference includes thermogravimetry (TGA) and differential scanning calorimetry (DSC). The results show that the ACBD strength is slightly affected by the presence of such concentration of nanomaterial in the epoxy: greatest ACBD voltage and less disperse data. The thermal analyses of the polymer composite showed that decomposition temperature remain almost unchanged with addition of such a small amount of nanoclay.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116396874","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 : 2006-10-01DOI: 10.1109/CEIDP.2006.312068
X. Liu, A. Ellis, W. Arnold
The strength and conductivity of carbon nanotubes make them attractive materials for incorporation into composite materials for use in electrically lossy structures. Applications could include light-weight structures that are absorptive of radio and microwave signals. We have derivatised multi-walled nanotubes by acid treatment, formed them into layers on resistor-like chips, and then subjected these to dielectric characterization between 200 Hz and 1.8 GHz. Especially in the case of thicker layers, a highly-frequency-dependent behavior was observed. This was reduced when the electrode contacts were improved.
{"title":"HF/Microwave Impedance of Carbon Nanotube Films","authors":"X. Liu, A. Ellis, W. Arnold","doi":"10.1109/CEIDP.2006.312068","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.312068","url":null,"abstract":"The strength and conductivity of carbon nanotubes make them attractive materials for incorporation into composite materials for use in electrically lossy structures. Applications could include light-weight structures that are absorptive of radio and microwave signals. We have derivatised multi-walled nanotubes by acid treatment, formed them into layers on resistor-like chips, and then subjected these to dielectric characterization between 200 Hz and 1.8 GHz. Especially in the case of thicker layers, a highly-frequency-dependent behavior was observed. This was reduced when the electrode contacts were improved.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125406678","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}
This paper summarizes the common hydrophobicity change characteristics of silicone rubber insulators in the North Temperature Zone, according to the results of a series of outdoor tests. The tests were conducted for over a year on an outdoor experimental flat roof in Beijing, China, which belongs to the North Temperature Zone. All samples were not energized and suffered from the various natural environmental stresses. The samples were investigated using the HC method. The test results show that the hydrophobicity of SIR insulators can decrease and even lose in winter. After winter, with the change of season, different samples have the different hydrophobic recovery capacity. The influences of several typical environmental stresses such as ambient temperature, precipitation and ultraviolet radiation, to the hydrophobicity of silicone rubber insulators are also analyzed. Finally, based on the test results, the dynamic hydrophobicity monitoring method of silicone rubber insulators in the North Temperature Zone is discussed.
{"title":"An outdoor investigation on hydrophobicity of silicone rubber insulators in the Temperature Zone","authors":"Linjie Zhao, Chengrong Li, Jisha Yao, Shuqi Zhang, JunXiong, Guoqiang Xu, Weidong Zhang","doi":"10.1109/CEIDP.2006.311949","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.311949","url":null,"abstract":"This paper summarizes the common hydrophobicity change characteristics of silicone rubber insulators in the North Temperature Zone, according to the results of a series of outdoor tests. The tests were conducted for over a year on an outdoor experimental flat roof in Beijing, China, which belongs to the North Temperature Zone. All samples were not energized and suffered from the various natural environmental stresses. The samples were investigated using the HC method. The test results show that the hydrophobicity of SIR insulators can decrease and even lose in winter. After winter, with the change of season, different samples have the different hydrophobic recovery capacity. The influences of several typical environmental stresses such as ambient temperature, precipitation and ultraviolet radiation, to the hydrophobicity of silicone rubber insulators are also analyzed. Finally, based on the test results, the dynamic hydrophobicity monitoring method of silicone rubber insulators in the North Temperature Zone is discussed.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125564512","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 : 2006-10-01DOI: 10.1109/CEIDP.2006.312012
X. Liu, D. Kasten, S. Sebo, D. Grosjean, D. Schweickart
Partial discharge (PD) experiments in argon and helium have been performed for 60 Hz AC energization, under pressures from 101.3 kPa (760 Torr) down to 0.27 kPa (2 Torr). The electrode arrangement was a twisted pair of insulated conductors taken from a standard aircraft wiring harness. The paper describes the physical PD test setup and electrical connections for AC energization. The results are presented in terms of PD current pulse waveforms and their analysis, reflecting the effects of pressure and voltage.
{"title":"Partial Discharge Measurements for a Twisted Pair of Insulated Conductors at Low Pressures -- Pulse Waveform Analysis for Argon and Helium","authors":"X. Liu, D. Kasten, S. Sebo, D. Grosjean, D. Schweickart","doi":"10.1109/CEIDP.2006.312012","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.312012","url":null,"abstract":"Partial discharge (PD) experiments in argon and helium have been performed for 60 Hz AC energization, under pressures from 101.3 kPa (760 Torr) down to 0.27 kPa (2 Torr). The electrode arrangement was a twisted pair of insulated conductors taken from a standard aircraft wiring harness. The paper describes the physical PD test setup and electrical connections for AC energization. The results are presented in terms of PD current pulse waveforms and their analysis, reflecting the effects of pressure and voltage.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128117507","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 : 2006-10-01DOI: 10.1109/CEIDP.2006.311986
T. Furuhashi, K. Tohyama, T. Imai, Y. Murata
Crosslinked polyethylene (XLPE) is widely used as the insulator for power cable. Water tree degradation phenomenon is the one of typical problem for the electrical insulation of power cable. In this paper, to confirm whether a signal of a fundamental component and the third harmonics peculiar to the water tree deteriorated sample appears by changing the applied frequency, the dissipation current waveform observations was carried out at 50 and 500 Hz. As the results of dissipation current waveform observation, it was found that the trend of the electric field dependence of both the fundamental component and third harmonics for the water tree deteriorated LDPE sheet sample considerably varied from that for LDPE without water tree at 50 Hz. However in the case of observation at 500 Hz, it was not admitted that a signal peculiar to water tree emerged in electric field dependence of both the fundamental component and the third harmonics in the water tree deteriorated LDPE sheet sample.
{"title":"Dissipation Current Waveform of Water Tree Deteriorated Low Density Polyethylene Sheet","authors":"T. Furuhashi, K. Tohyama, T. Imai, Y. Murata","doi":"10.1109/CEIDP.2006.311986","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.311986","url":null,"abstract":"Crosslinked polyethylene (XLPE) is widely used as the insulator for power cable. Water tree degradation phenomenon is the one of typical problem for the electrical insulation of power cable. In this paper, to confirm whether a signal of a fundamental component and the third harmonics peculiar to the water tree deteriorated sample appears by changing the applied frequency, the dissipation current waveform observations was carried out at 50 and 500 Hz. As the results of dissipation current waveform observation, it was found that the trend of the electric field dependence of both the fundamental component and third harmonics for the water tree deteriorated LDPE sheet sample considerably varied from that for LDPE without water tree at 50 Hz. However in the case of observation at 500 Hz, it was not admitted that a signal peculiar to water tree emerged in electric field dependence of both the fundamental component and the third harmonics in the water tree deteriorated LDPE sheet sample.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124348097","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 : 2006-10-01DOI: 10.1109/CEIDP.2006.312070
S. Diaham, M. Locatelli, T. Lebey
An unstable behavior of Al/polyimide/Al capacitor structures has been observed by isothermal dielectric spectroscopy at 275degC with a progressive decrease of the dielectric permittivity and the loss factor. In spite of a close similarity with the typical dielectric behaviors involved by crystallization phenomena for crystallizable polymers, DSC measurements have not exhibited an exothermic crystallization peak up to 500degC which can exclude this assumption. Moreover, residual polar impurities such as moisture, solvent and polyamic acid, seems to have been completely removed of the PI films after a high temperature process curing at 400degC, as shown by FTIR spectroscopy. These elements lead to prove that the dielectric stabilization should not be due to PI bulk chemical changes, but could involve an evolution of the metal/PI interface.
{"title":"High Temperature Dielectric Behavior of Al/Polyimide/Al Capacitor Structures","authors":"S. Diaham, M. Locatelli, T. Lebey","doi":"10.1109/CEIDP.2006.312070","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.312070","url":null,"abstract":"An unstable behavior of Al/polyimide/Al capacitor structures has been observed by isothermal dielectric spectroscopy at 275degC with a progressive decrease of the dielectric permittivity and the loss factor. In spite of a close similarity with the typical dielectric behaviors involved by crystallization phenomena for crystallizable polymers, DSC measurements have not exhibited an exothermic crystallization peak up to 500degC which can exclude this assumption. Moreover, residual polar impurities such as moisture, solvent and polyamic acid, seems to have been completely removed of the PI films after a high temperature process curing at 400degC, as shown by FTIR spectroscopy. These elements lead to prove that the dielectric stabilization should not be due to PI bulk chemical changes, but could involve an evolution of the metal/PI interface.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124472846","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 : 2006-10-01DOI: 10.1109/CEIDP.2006.311978
H. Ding, Z. Wang, P. Jarman
This paper presents the lightning impulse voltage test results of service-aged pressboards taken from a failed power transformer after 29 years' service. Impulse voltage tests have revealed that there is a significant reduction of breakdown voltages, most probably due to the degradation of mechanical strength. The minimum impulse electric strength may reduce approximately by 30% after 29 years' service. Test results on the service-aged pressboard also indicate that when the moisture content in pressboard is less than 4%, there is no significant correlation between the reductions of the impulse electric strength with increasing moisture content.
{"title":"Effect of ageing on the impulse breakdown strength of oil-impregnated pressboard used in power transformers","authors":"H. Ding, Z. Wang, P. Jarman","doi":"10.1109/CEIDP.2006.311978","DOIUrl":"https://doi.org/10.1109/CEIDP.2006.311978","url":null,"abstract":"This paper presents the lightning impulse voltage test results of service-aged pressboards taken from a failed power transformer after 29 years' service. Impulse voltage tests have revealed that there is a significant reduction of breakdown voltages, most probably due to the degradation of mechanical strength. The minimum impulse electric strength may reduce approximately by 30% after 29 years' service. Test results on the service-aged pressboard also indicate that when the moisture content in pressboard is less than 4%, there is no significant correlation between the reductions of the impulse electric strength with increasing moisture content.","PeriodicalId":219099,"journal":{"name":"2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123732531","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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