Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893115
M. Becerra, H. Frid
A self-consistent numerical model is presented in order to study the electrohydrodynamic (EHD) motion generated by a stationary, space-charge limited injection of charge in the point-plane geometry. In this multiphysics model, the continuity equations for charge carriers and Poisson's equation are coupled with Navier-Stokes equations and the heat equation. This model is used to study the EHD motion of cyclohexane in the negative point-plane geometry for sharp points with tip radius of 0.2 μm. It is shown that the injection of charges from a very sharp point electrode results in the formation of a thin plume with high liquid velocity. The results show large differences in the liquid velocity close to the point electrode compared to the average velocity estimated by the well-known electrohydrodynamic mobility. The difference between the width of the charged core and the hydrodynamic plume is analyzed and presented. It is shown that the local heating of the liquid is strongly reduced by the convective losses generated by EHD motion. Finally, it is found that the liquid temperature in cyclohexane in the vicinitiy of sharp points under space charge limited injection can reach temperatures slightly above boiling temperature, without generating bubbles.
{"title":"Electrohydrodynamic motion due to space-charge limited injection of charges in cyclohexane","authors":"M. Becerra, H. Frid","doi":"10.1109/ICDL.2014.6893115","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893115","url":null,"abstract":"A self-consistent numerical model is presented in order to study the electrohydrodynamic (EHD) motion generated by a stationary, space-charge limited injection of charge in the point-plane geometry. In this multiphysics model, the continuity equations for charge carriers and Poisson's equation are coupled with Navier-Stokes equations and the heat equation. This model is used to study the EHD motion of cyclohexane in the negative point-plane geometry for sharp points with tip radius of 0.2 μm. It is shown that the injection of charges from a very sharp point electrode results in the formation of a thin plume with high liquid velocity. The results show large differences in the liquid velocity close to the point electrode compared to the average velocity estimated by the well-known electrohydrodynamic mobility. The difference between the width of the charged core and the hydrodynamic plume is analyzed and presented. It is shown that the local heating of the liquid is strongly reduced by the convective losses generated by EHD motion. Finally, it is found that the liquid temperature in cyclohexane in the vicinitiy of sharp points under space charge limited injection can reach temperatures slightly above boiling temperature, without generating bubbles.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"8 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74381389","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893075
Takashi Suzuki, T. Kano, A. Kanetani, S. Hatada, F. Kurihara
For this study, we conducted accelerating experiments to investigate the aging of paper in PFAE and mineral oil. After the aging test, we evaluated paper tensile strength, water content of oils, and acid value of oils. As a result of the paper aging test, Kraft paper was found to degrade slower in PFAE than in mineral oil in a nitrogen atmosphere. Besides, we examined the relationships between the water contents of PFAE and paper. This examination revealed that water migrated readily from paper to PFAE. In addition, we measured the infrared spectroscopy of PFAE having various water contents. Consequently, it is suggested that water molecules are trapped by the ester group. These results indicate that water migrates readily from paper to PFAE.
{"title":"Comparative study of the insulation paper aging in palm fatty acid ester (PFAE) and mineral oil","authors":"Takashi Suzuki, T. Kano, A. Kanetani, S. Hatada, F. Kurihara","doi":"10.1109/ICDL.2014.6893075","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893075","url":null,"abstract":"For this study, we conducted accelerating experiments to investigate the aging of paper in PFAE and mineral oil. After the aging test, we evaluated paper tensile strength, water content of oils, and acid value of oils. As a result of the paper aging test, Kraft paper was found to degrade slower in PFAE than in mineral oil in a nitrogen atmosphere. Besides, we examined the relationships between the water contents of PFAE and paper. This examination revealed that water migrated readily from paper to PFAE. In addition, we measured the infrared spectroscopy of PFAE having various water contents. Consequently, it is suggested that water molecules are trapped by the ester group. These results indicate that water migrates readily from paper to PFAE.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"22 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91531261","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893096
J. Weesmaa, M. Sterner, B. Pahlavanpour, L. Bergeld, J. Nunes
Dissolved Gas Analysis (DGA) is a common tool used to understand the condition and processes ongoing inside the transformer. Increased levels of certain gasses in the transformer oil can be measured and interpreted according to guidelines. By the analysis of amounts of hydrogen, volatile hydrocarbons and carbon oxides dissolved in the insulating oil dielectric and thermal faults can be detected at an early stage.
{"title":"Study about stray gas generation in transformer oil at different temperatures","authors":"J. Weesmaa, M. Sterner, B. Pahlavanpour, L. Bergeld, J. Nunes","doi":"10.1109/ICDL.2014.6893096","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893096","url":null,"abstract":"Dissolved Gas Analysis (DGA) is a common tool used to understand the condition and processes ongoing inside the transformer. Increased levels of certain gasses in the transformer oil can be measured and interpreted according to guidelines. By the analysis of amounts of hydrogen, volatile hydrocarbons and carbon oxides dissolved in the insulating oil dielectric and thermal faults can be detected at an early stage.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"40 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86218564","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893161
K. S. Kassi, I. Fofana, F. Megnefhi, A. Betie, Z. Yeo
The useful functional life of a power transformer is determined by the life of the paper insulation. Therefore polyaramid based synthetic insulation paper, with better thermal stability emerged for application in transformers. In this research work, the quality of mineral oil aged with hybrid solid insulation is investigated. Comparison was made with traditional mineral oil impregnated cellulose paper to provide base line for comparison. The samples underwent thermal accelerated aging procedure according to ASTM-D1934 standard. The aged samples were furthermore submitted to local overheating. The condition of oil samples collected from each aging vessel was assessed using several diagnostic techniques, namely the dissolved decay products (DDP), the insoluble decay products (Turbidity), the interfacial tension (IFT) and the moisture content. The results indicate that oil aged with hybrid solid insulation depicts less dissolved and insoluble decay products and less polar contaminants at some aging stages especially after the application of a local overheating.
{"title":"Decay products in mineral oil: A comparative study between hybrid and conventional insulation systems","authors":"K. S. Kassi, I. Fofana, F. Megnefhi, A. Betie, Z. Yeo","doi":"10.1109/ICDL.2014.6893161","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893161","url":null,"abstract":"The useful functional life of a power transformer is determined by the life of the paper insulation. Therefore polyaramid based synthetic insulation paper, with better thermal stability emerged for application in transformers. In this research work, the quality of mineral oil aged with hybrid solid insulation is investigated. Comparison was made with traditional mineral oil impregnated cellulose paper to provide base line for comparison. The samples underwent thermal accelerated aging procedure according to ASTM-D1934 standard. The aged samples were furthermore submitted to local overheating. The condition of oil samples collected from each aging vessel was assessed using several diagnostic techniques, namely the dissolved decay products (DDP), the insoluble decay products (Turbidity), the interfacial tension (IFT) and the moisture content. The results indicate that oil aged with hybrid solid insulation depicts less dissolved and insoluble decay products and less polar contaminants at some aging stages especially after the application of a local overheating.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"11 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87596539","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893100
Edward Casserly, Jimmy M. Rasco
Refinery processing determines the chemistry of the base oils used in transformer oils. Increasing the severity of the processing leads to a more stable base oil. Performance additives can modify the chemistry of the system and potentially lead to unintended consequences. This study examines how processing differences and additives affect the generation of stray gasses at low temperatures.
{"title":"Stray gassing of refinery streams and transformer oil produced from them","authors":"Edward Casserly, Jimmy M. Rasco","doi":"10.1109/ICDL.2014.6893100","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893100","url":null,"abstract":"Refinery processing determines the chemistry of the base oils used in transformer oils. Increasing the severity of the processing leads to a more stable base oil. Performance additives can modify the chemistry of the system and potentially lead to unintended consequences. This study examines how processing differences and additives affect the generation of stray gasses at low temperatures.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"47 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78829501","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893173
N. Bernard, B. Čuček
This paper deals with four most established physical and chemical methods for monitoring age-related changes in transformer oils. It presents the findings of acidity, interfacial tension, dielectric dissipation factor, and IR spectrophotometry tests, carried out on six samples of new mineral transformer oils from various suppliers, after artificial oil aging according to the IEC 61125 C standard method. Also test results from twelve differently aged operating transformers oil samples are presented. A comparative sensitivity analysis was carried out for each test method. The findings were considered from the aspect of the degree of sensitivity for measuring oil aging processes degree in the individual methods, which is significant for the appropriate assessment of operating transformer oil suitability and issuing timely recommendations for implementing maintenance measures on a transformer. The four test methods discussed were also considered in terms of complexity, oil sample size and test measurement uncertainty. The paper shows the valid criteria for transformer oils quality according to IEC 60296 and IEC 60422 standards and critically assesses methods for establishing the aging degree of oils. A proposal for improvement and revision of the IEC 61125 C standard has been presented that takes into account the use of various methods for assessing the oxidation stability of new mineral oils.
{"title":"Methods for monitoring age-related changes in transformer oils","authors":"N. Bernard, B. Čuček","doi":"10.1109/ICDL.2014.6893173","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893173","url":null,"abstract":"This paper deals with four most established physical and chemical methods for monitoring age-related changes in transformer oils. It presents the findings of acidity, interfacial tension, dielectric dissipation factor, and IR spectrophotometry tests, carried out on six samples of new mineral transformer oils from various suppliers, after artificial oil aging according to the IEC 61125 C standard method. Also test results from twelve differently aged operating transformers oil samples are presented. A comparative sensitivity analysis was carried out for each test method. The findings were considered from the aspect of the degree of sensitivity for measuring oil aging processes degree in the individual methods, which is significant for the appropriate assessment of operating transformer oil suitability and issuing timely recommendations for implementing maintenance measures on a transformer. The four test methods discussed were also considered in terms of complexity, oil sample size and test measurement uncertainty. The paper shows the valid criteria for transformer oils quality according to IEC 60296 and IEC 60422 standards and critically assesses methods for establishing the aging degree of oils. A proposal for improvement and revision of the IEC 61125 C standard has been presented that takes into account the use of various methods for assessing the oxidation stability of new mineral oils.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"22 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74197467","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893087
N. Hayakawa, S. Nishimachi, Tastuya Mastuoka, H. Kojima, M. Hanai, H. Okubo
We systematically investigated and discussed the ac breakdown (BD) characteristics and mechanisms of liquid nitrogen (LN2) for different pressures (0.1-0.3 MPa) and temperatures (65-77 K) under quasi-uniform electric field (field utilization factor ζ = 0.986-0.674). The BD strength (EB) in sub-cooled LN2 (SLN2) was analyzed and discussed in terms of size effect, taking account of the stressed liquid volume (SLV) with the electric field distribution in SLN2. We also included the other reseachers' data on BD characteristics of LN2, and extended the evaluation by applying the concept of α % SLV (SLV with the electric field strength higher than the decisive electric field factor (α) of the highest electric field strength). As the result, we found that EB with the 50 % probability decreased linearly with the increase in α % SLV on a universal line, i.e. EB = 78.4 × (α % SLV) -1/8.15, irrespective of the pressure and temperature of LN2.
{"title":"Breakdown characteristics and size effect in sub-cooled liquid nitrogen","authors":"N. Hayakawa, S. Nishimachi, Tastuya Mastuoka, H. Kojima, M. Hanai, H. Okubo","doi":"10.1109/ICDL.2014.6893087","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893087","url":null,"abstract":"We systematically investigated and discussed the ac breakdown (BD) characteristics and mechanisms of liquid nitrogen (LN<sub>2</sub>) for different pressures (0.1-0.3 MPa) and temperatures (65-77 K) under quasi-uniform electric field (field utilization factor ζ = 0.986-0.674). The BD strength (E<sub>B</sub>) in sub-cooled LN<sub>2</sub> (SLN<sub>2</sub>) was analyzed and discussed in terms of size effect, taking account of the stressed liquid volume (SLV) with the electric field distribution in SLN<sub>2</sub>. We also included the other reseachers' data on BD characteristics of LN<sub>2</sub>, and extended the evaluation by applying the concept of α % SLV (SLV with the electric field strength higher than the decisive electric field factor (α) of the highest electric field strength). As the result, we found that E<sub>B</sub> with the 50 % probability decreased linearly with the increase in α % SLV on a universal line, i.e. E<sub>B</sub> = 78.4 × (α % SLV) <sup>-1/8.15</sup>, irrespective of the pressure and temperature of LN<sub>2</sub>.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"604 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77436569","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893127
B. Du, X. Li
Liquid insulation plays a significant role in the design and operation of power system. There is good evidence in the literature that the addition of nanoparticles to conventional transformer oils can lead to significant increases both in electrical and thermal characteristics. In this paper, spherical BN nanoparticles with high thermal conductivity were added into transformer oil to form nanofluids, with the aim of enhancing electrical and thermal properties. Electrical properties and thermal characteristics of oil samples before and after modification were measured. It was found that the nanofluids have higher AC breakdown voltage and relative permittivity, lower dissipation factor which indicates better electrical properties compared with pure oil. In order to investigate the effect of BN nanoparticles on thermal properties, temperature changes and heat distribution of the nanofluids with different concentrations of BN particles in thermal conductivity process were measured by an infrared thermal imager and a temperature sensor. Obtained results showed that, under the same experimental condition, the heat dissipation of nanofluids with higher concentration of BN particles was faster. It is concluded that the added BN fillers have a very significant effect on electrical and thermal properties in transformer oil-based fluids.
{"title":"High thermal conductivity transformer oil filled with BN nanoparticles","authors":"B. Du, X. Li","doi":"10.1109/ICDL.2014.6893127","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893127","url":null,"abstract":"Liquid insulation plays a significant role in the design and operation of power system. There is good evidence in the literature that the addition of nanoparticles to conventional transformer oils can lead to significant increases both in electrical and thermal characteristics. In this paper, spherical BN nanoparticles with high thermal conductivity were added into transformer oil to form nanofluids, with the aim of enhancing electrical and thermal properties. Electrical properties and thermal characteristics of oil samples before and after modification were measured. It was found that the nanofluids have higher AC breakdown voltage and relative permittivity, lower dissipation factor which indicates better electrical properties compared with pure oil. In order to investigate the effect of BN nanoparticles on thermal properties, temperature changes and heat distribution of the nanofluids with different concentrations of BN particles in thermal conductivity process were measured by an infrared thermal imager and a temperature sensor. Obtained results showed that, under the same experimental condition, the heat dissipation of nanofluids with higher concentration of BN particles was faster. It is concluded that the added BN fillers have a very significant effect on electrical and thermal properties in transformer oil-based fluids.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"55 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78814462","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893146
B. Lehouidj, S. Sahra, A. Nacer, H. Moulai, A. Beroual
The present work is aimed at the survey of currents, emitted lights and energies associated to positive and negative streamers propagation in three dielectric liquids: mineral oil, tetra-ester and toluene in a point-plane electrode arrangement under High Voltage Direct Current (HVDC) stresses. The applied fields range between those corresponding to low energy level discharges till those relative to high energy arcing. The influence of the applied voltage level and the gap distance on the shape and magnitude of these characteristics are also investigated. The approach is also oriented towards the analysis of the frequency behavior and inter-correlation function between currents and corresponding emitted lights.
{"title":"Streamer currents, emitted lights and energies into dielectric liquids submitted to DC stress","authors":"B. Lehouidj, S. Sahra, A. Nacer, H. Moulai, A. Beroual","doi":"10.1109/ICDL.2014.6893146","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893146","url":null,"abstract":"The present work is aimed at the survey of currents, emitted lights and energies associated to positive and negative streamers propagation in three dielectric liquids: mineral oil, tetra-ester and toluene in a point-plane electrode arrangement under High Voltage Direct Current (HVDC) stresses. The applied fields range between those corresponding to low energy level discharges till those relative to high energy arcing. The influence of the applied voltage level and the gap distance on the shape and magnitude of these characteristics are also investigated. The approach is also oriented towards the analysis of the frequency behavior and inter-correlation function between currents and corresponding emitted lights.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"25 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77310125","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893093
O. Hjortstam, Håkan Faleke, C. Tornkvist, Anders B Eriksson
This paper aims at presenting results related to electrical breakdown of oil paper insulation systems by puncturing of paper insulation. In the investigations the used experimental setup is a needle-plane geometry with sheets of paper inserted in the oil gap. The voltage applied to the needle is a Lightning Impulse (LI) of positive polarity. The propagation of streamers was studied by an ultra-high-speed frame camera. The streamers were always initiated at the needle tip and were classified as 2nd mode streamers. In some cases the streamer spread out along the top of the paper without puncturing it. In other cases the streamer punctures the paper and continues to propagate below the paper. Differences between the two cases are discussed and analyzed. It is found that the paper puncture voltage coincide with the voltage at which the Laplace field below the paper sheet reach the critical field for streamer initiation.
{"title":"Ultra high speed camera studies of paper puncture in oil-cellulose insulation systems under LI testing","authors":"O. Hjortstam, Håkan Faleke, C. Tornkvist, Anders B Eriksson","doi":"10.1109/ICDL.2014.6893093","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893093","url":null,"abstract":"This paper aims at presenting results related to electrical breakdown of oil paper insulation systems by puncturing of paper insulation. In the investigations the used experimental setup is a needle-plane geometry with sheets of paper inserted in the oil gap. The voltage applied to the needle is a Lightning Impulse (LI) of positive polarity. The propagation of streamers was studied by an ultra-high-speed frame camera. The streamers were always initiated at the needle tip and were classified as 2nd mode streamers. In some cases the streamer spread out along the top of the paper without puncturing it. In other cases the streamer punctures the paper and continues to propagate below the paper. Differences between the two cases are discussed and analyzed. It is found that the paper puncture voltage coincide with the voltage at which the Laplace field below the paper sheet reach the critical field for streamer initiation.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"75 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79498517","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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