Pub Date : 2011-06-26DOI: 10.1109/ICDL.2011.6015493
W. Schmidt, G. Bakale, A. Khrapak, K. Yoshino
Ionic and electronic charge carriers are usually injected into dielectric liquids either by ionization by high energy radiation or by photoelectric effect at an electrode. Here, we summarize and discuss data on the drift velocity as a function of applied electric field obtained with these methods. While the drift of ions can be described by Stokes' law of laminar motion up to the highest field strengths measured, the drift of electrons at higher electric field strengths is characterized by an increase of their energy above the thermal energy of the liquid, which enables them to initiate electronic reactions. The importance for the description of electric breakdown processes will be discussed.
{"title":"Drift velocity of ions and electrons in non-polar dielectric liquids at high electric field strengths","authors":"W. Schmidt, G. Bakale, A. Khrapak, K. Yoshino","doi":"10.1109/ICDL.2011.6015493","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015493","url":null,"abstract":"Ionic and electronic charge carriers are usually injected into dielectric liquids either by ionization by high energy radiation or by photoelectric effect at an electrode. Here, we summarize and discuss data on the drift velocity as a function of applied electric field obtained with these methods. While the drift of ions can be described by Stokes' law of laminar motion up to the highest field strengths measured, the drift of electrons at higher electric field strengths is characterized by an increase of their energy above the thermal energy of the liquid, which enables them to initiate electronic reactions. The importance for the description of electric breakdown processes will be discussed.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129777043","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 : 2011-06-26DOI: 10.1109/ICDL.2011.6015480
M. Wilson, I. Timoshkin, M. Given, S. Macgregor, M. Sinclair, K. Thomas, J. Lehr
Experimental data on the propagation of streamers in mineral oil is important for the design of high-voltage systems in the power and pulsed-power industries. In the present study, pre-breakdown delay times were measured for plane-parallel electrodes, and for two types of non-uniform electrode arrangement. For each geometry, the breakdown characteristics were determined for impulses of rise-time 100 ns, and also rise-time 1 µs. The maximum applied voltage magnitude was 400 kV, giving a maximum dV/dt of 4 kV/ns. For the non-uniform geometries with inter-electrode gap length of 8.5 mm, the time to breakdown was 2.5–3 times longer for impulses of rise-time 1 µs than for 100 ns rise-time. The time-to-breakdown data suggest that streamer propagation velocity increases with higher values of dV/dt. For example, the estimated propagation velocity for pin-plane geometry with a 1 µs rise-time is 10–12 km/s. At 100 ns rise-time for the same electrode geometry, the average propagation velocity exceeds 40 km/s. The results presented are intended to provide reference data for designers of oil-immersed high-voltage systems in both the power and pulsed-power industries.
{"title":"Effect of electrode geometry and rate of voltage rise on streamer propagation in mineral oil","authors":"M. Wilson, I. Timoshkin, M. Given, S. Macgregor, M. Sinclair, K. Thomas, J. Lehr","doi":"10.1109/ICDL.2011.6015480","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015480","url":null,"abstract":"Experimental data on the propagation of streamers in mineral oil is important for the design of high-voltage systems in the power and pulsed-power industries. In the present study, pre-breakdown delay times were measured for plane-parallel electrodes, and for two types of non-uniform electrode arrangement. For each geometry, the breakdown characteristics were determined for impulses of rise-time 100 ns, and also rise-time 1 µs. The maximum applied voltage magnitude was 400 kV, giving a maximum dV/dt of 4 kV/ns. For the non-uniform geometries with inter-electrode gap length of 8.5 mm, the time to breakdown was 2.5–3 times longer for impulses of rise-time 1 µs than for 100 ns rise-time. The time-to-breakdown data suggest that streamer propagation velocity increases with higher values of dV/dt. For example, the estimated propagation velocity for pin-plane geometry with a 1 µs rise-time is 10–12 km/s. At 100 ns rise-time for the same electrode geometry, the average propagation velocity exceeds 40 km/s. The results presented are intended to provide reference data for designers of oil-immersed high-voltage systems in both the power and pulsed-power industries.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129593343","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 : 2011-06-26DOI: 10.1109/ICDL.2011.6015479
M. Hogg, I. Timoshkin, M. Given, M. Wilson, S. Macgregor, R. Fouracre, J. Lehr
The complexity of the impulse breakdown of liquid water is reflected by the dependency of pre-breakdown processes on the polarity, rise-time and wave-shape of the applied impulses as well as on physical properties, such as electrical conductivity of water itself. Further understanding of the mechanisms of formation and propagation of impulse discharges in water and water solutions is therefore required to enable the development of pulsed power and plasma technologies. The paper presents a study of the dielectric behaviour of water stressed with high voltage impulses in a point-plane electrode topology. Water with different conductivities including distilled water, tap water and a water based ionic solution was investigated. The volt-time breakdown characteristic of water is discussed and the pre-breakdown time and nominal breakdown velocity have been obtained for both positive and negative polarity impulses. Potential breakdown mechanisms which can explain the observed polarity effects in the transient pre-breakdown processes in liquid water stressed with high voltage impulses are discussed.
{"title":"Liquid water stressed with HV impulses: Effect of polarity on transient pre-breakdown processes","authors":"M. Hogg, I. Timoshkin, M. Given, M. Wilson, S. Macgregor, R. Fouracre, J. Lehr","doi":"10.1109/ICDL.2011.6015479","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015479","url":null,"abstract":"The complexity of the impulse breakdown of liquid water is reflected by the dependency of pre-breakdown processes on the polarity, rise-time and wave-shape of the applied impulses as well as on physical properties, such as electrical conductivity of water itself. Further understanding of the mechanisms of formation and propagation of impulse discharges in water and water solutions is therefore required to enable the development of pulsed power and plasma technologies. The paper presents a study of the dielectric behaviour of water stressed with high voltage impulses in a point-plane electrode topology. Water with different conductivities including distilled water, tap water and a water based ionic solution was investigated. The volt-time breakdown characteristic of water is discussed and the pre-breakdown time and nominal breakdown velocity have been obtained for both positive and negative polarity impulses. Potential breakdown mechanisms which can explain the observed polarity effects in the transient pre-breakdown processes in liquid water stressed with high voltage impulses are discussed.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128228896","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 : 2011-06-26DOI: 10.1109/ICDL.2011.6015444
Du Yue-fan, Lv Yu-zhen, Zhou Jian-quan, Chen Mu-tian, Lian Xiao-xin, Li Cheng-rong
A class of mineral oil-based nanofluid has been developed by modifying mineral oil with TiO2 nanoparticle to enhance their dielectric performance. In this paper, we present the investigation results of aged nanofluids, which have been subjected to accelerated aging condition of 130°C for 6 days. Both AC breakdown voltage and PDIV tests were carried out according to ASTM standards respectively. It was found that AC breakdown voltage of nanofluids has been largely improved before and after aging 6 days. The mean value of PDIV in aged nanofluid achieves an increase of 1.16 times than that of mineral oil. In addition, the results of statistical data indicate that 1% probability breakdown voltage of nanofluid is 78.34kV, which is 8kV higher than that of mineral oil. The experimental results demonstrated that both breakdown voltage and PDIV of mineral oil can be significantly improved by modifying with TiO2 nanoparticles.
{"title":"Effect of Ageing on Insulating Property of Mineral Oil-based TiO2 Nanofluids","authors":"Du Yue-fan, Lv Yu-zhen, Zhou Jian-quan, Chen Mu-tian, Lian Xiao-xin, Li Cheng-rong","doi":"10.1109/ICDL.2011.6015444","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015444","url":null,"abstract":"A class of mineral oil-based nanofluid has been developed by modifying mineral oil with TiO2 nanoparticle to enhance their dielectric performance. In this paper, we present the investigation results of aged nanofluids, which have been subjected to accelerated aging condition of 130°C for 6 days. Both AC breakdown voltage and PDIV tests were carried out according to ASTM standards respectively. It was found that AC breakdown voltage of nanofluids has been largely improved before and after aging 6 days. The mean value of PDIV in aged nanofluid achieves an increase of 1.16 times than that of mineral oil. In addition, the results of statistical data indicate that 1% probability breakdown voltage of nanofluid is 78.34kV, which is 8kV higher than that of mineral oil. The experimental results demonstrated that both breakdown voltage and PDIV of mineral oil can be significantly improved by modifying with TiO2 nanoparticles.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"1213 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127822850","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 : 2011-06-26DOI: 10.1109/ICDL.2011.6015467
P. A. Vázquez, A. Castellanos
The 3D Electrohydrodynamic convection between parallel plates immersed in a dielectric liquid is studied numerically in a cylindrical cell. The distribution of charge is computed with Particl-In-Cell, the electric field with finite elements and the velocity field with an imposed roll. Critical values of the stability parameter are obtained for different mobilities and are compared with the value from the linear stability analysis.
{"title":"Stability analysis of the 3D electroconvective charged flow between parallel plates using the Particle-In-Cell method","authors":"P. A. Vázquez, A. Castellanos","doi":"10.1109/ICDL.2011.6015467","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015467","url":null,"abstract":"The 3D Electrohydrodynamic convection between parallel plates immersed in a dielectric liquid is studied numerically in a cylindrical cell. The distribution of charge is computed with Particl-In-Cell, the electric field with finite elements and the velocity field with an imposed roll. Critical values of the stability parameter are obtained for different mobilities and are compared with the value from the linear stability analysis.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133544968","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 : 2011-06-26DOI: 10.1109/ICDL.2011.6015454
D. Linhjell, S. Ingebrigtsen, L. Lundgaard, M. Unge
This is a study of the effect of the additives dimethylaniline (DMA) and trichloroethylene (TCE) on the pre-breakdown phenomena known as streamers, in a simple base liquid, cyclohexane. This has been done under a step-like impulse voltage in a long point-plane gap. The objective was mainly to find out which aspects of the chemistry of mineral transformer oils cause their good streamer-related dielectric properties, in particular the high voltage for the transition to a very fast mode of positive streamers, as pure cyclohexane does not have these good properties. It is found that DMA added indeed causes positive streamers to become very similar to positive streamers in mineral oil and has no effect on negative streamers. TCE causes the negative streamers to become more mineral-oil-like, and has only a little effect on positive streamers.
{"title":"Streamers in long point-plane gaps in cyclohexane with and without additives under step voltage","authors":"D. Linhjell, S. Ingebrigtsen, L. Lundgaard, M. Unge","doi":"10.1109/ICDL.2011.6015454","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015454","url":null,"abstract":"This is a study of the effect of the additives dimethylaniline (DMA) and trichloroethylene (TCE) on the pre-breakdown phenomena known as streamers, in a simple base liquid, cyclohexane. This has been done under a step-like impulse voltage in a long point-plane gap. The objective was mainly to find out which aspects of the chemistry of mineral transformer oils cause their good streamer-related dielectric properties, in particular the high voltage for the transition to a very fast mode of positive streamers, as pure cyclohexane does not have these good properties. It is found that DMA added indeed causes positive streamers to become very similar to positive streamers in mineral oil and has no effect on negative streamers. TCE causes the negative streamers to become more mineral-oil-like, and has only a little effect on positive streamers.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130567491","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 : 2011-06-26DOI: 10.1109/ICDL.2011.6015426
N. Rudranna, J. S. Rajan
Failure of transformers and reactors due to sulphur in transformer oil is reported in literature. The sulphur in oil by chemical reaction with copper produces copper sulphide which alters the electric field. One of the mitigation techniques followed by manufacturers is replacement of bare copper conductors with enameled copper conductors. In this study, an attempt is made to understand field distribution in transformer insulation due to enamel on the conductor. Finite Element Method (FEM) has been used to understand the electric field distribution in paper and oil with enamel on copper conductor.
{"title":"Effect of enamel covering of copper conductors in paper oil insulation of transformers","authors":"N. Rudranna, J. S. Rajan","doi":"10.1109/ICDL.2011.6015426","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015426","url":null,"abstract":"Failure of transformers and reactors due to sulphur in transformer oil is reported in literature. The sulphur in oil by chemical reaction with copper produces copper sulphide which alters the electric field. One of the mitigation techniques followed by manufacturers is replacement of bare copper conductors with enameled copper conductors. In this study, an attempt is made to understand field distribution in transformer insulation due to enamel on the conductor. Finite Element Method (FEM) has been used to understand the electric field distribution in paper and oil with enamel on copper conductor.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129966842","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 : 2011-06-26DOI: 10.1109/ICDL.2011.6015471
J. Raisin, P. Atten, J. Reboud
The basic process of coalescence of droplets in a flowing water-in-oil emulsion under the action of an electric field is considered. The coalescence probability depends on the ratio of time of close proximity of droplets and time of decrease of spacing down to drops contact. For two free drops aligned with the field, the dynamical problem consists in the deformation of the drops, their motion and the thinning of the oil film between the drops. For very small droplets, assuming a negligible interface deformation, a very small initial spacing and a high value of viscosity ratio leads to an order of magnitude estimate of the time required for the drops to achieve contact. Numerical simulations confirm that this time is roughly inversely proportional to the maximum initial electrostatic pressure pe0 at the facing interfaces and point up an influence of the electric Bond number defined as the ratio of electric and capillary forces.
{"title":"Field induced coalescence of two free water drops in a viscous dielectric fluid","authors":"J. Raisin, P. Atten, J. Reboud","doi":"10.1109/ICDL.2011.6015471","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015471","url":null,"abstract":"The basic process of coalescence of droplets in a flowing water-in-oil emulsion under the action of an electric field is considered. The coalescence probability depends on the ratio of time of close proximity of droplets and time of decrease of spacing down to drops contact. For two free drops aligned with the field, the dynamical problem consists in the deformation of the drops, their motion and the thinning of the oil film between the drops. For very small droplets, assuming a negligible interface deformation, a very small initial spacing and a high value of viscosity ratio leads to an order of magnitude estimate of the time required for the drops to achieve contact. Numerical simulations confirm that this time is roughly inversely proportional to the maximum initial electrostatic pressure pe0 at the facing interfaces and point up an influence of the electric Bond number defined as the ratio of electric and capillary forces.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132662697","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 : 2011-06-26DOI: 10.1109/ICDL.2011.6015421
Anders B Eriksson, Rongsheng Liu, C. Tornkvist
The properties of ester fluids and mineral oils differ in many cases in a qualitative way. This means that these liquids may look like very similar in some experiments while in others they behave very differently. These differences must be understood and taken into account in the design of ester filled transformers to avoid unexpected failures. Classic models such as the two-parameter Weibull statistics of breakdown voltage are in some respects too simple to properly catch the underlying physics. We discuss the importance of segregating initiation and propagation processes to properly interpret results of experiments with esters and mineral oil. In transformer design it is in some parts more important to avoid initiation while in others it is more important to stop propagating streamers. Furthermore, to obtain low probability statistics from high probability breakdown experiments, both average and spread of breakdown voltages are required. The difference in spread of initiation and propagation voltages is discussed. Esters and mineral oils behave in a qualitatively similar way regarding initiation while they differ substantially in the propagation process. In this paper we compare some different experiments in terms of initiation and propagation.
{"title":"Differences in streamer initiation and propagation in ester fluids and mineral oil","authors":"Anders B Eriksson, Rongsheng Liu, C. Tornkvist","doi":"10.1109/ICDL.2011.6015421","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015421","url":null,"abstract":"The properties of ester fluids and mineral oils differ in many cases in a qualitative way. This means that these liquids may look like very similar in some experiments while in others they behave very differently. These differences must be understood and taken into account in the design of ester filled transformers to avoid unexpected failures. Classic models such as the two-parameter Weibull statistics of breakdown voltage are in some respects too simple to properly catch the underlying physics. We discuss the importance of segregating initiation and propagation processes to properly interpret results of experiments with esters and mineral oil. In transformer design it is in some parts more important to avoid initiation while in others it is more important to stop propagating streamers. Furthermore, to obtain low probability statistics from high probability breakdown experiments, both average and spread of breakdown voltages are required. The difference in spread of initiation and propagation voltages is discussed. Esters and mineral oils behave in a qualitatively similar way regarding initiation while they differ substantially in the propagation process. In this paper we compare some different experiments in terms of initiation and propagation.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126875905","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 : 2011-06-26DOI: 10.1109/ICDL.2011.6015490
V. Tho, J. Augé, O. Lesaint
Aluminium nitrite (AlN) or alumina (Al2O3) substrates are widely used in power electronics modules, due to their ability to provide both electrical insulation, and heat conduction properties. A silicon gel usually covers the substrate, semiconductor chips, and bondings to prevent partial discharges (PD) from occurring within the module. However, at high voltage PDs can be observed in high electric field regions, mainly at the sharp edges of copper tracks on the substrate. In this study, we try to determine the origin of these PDs. Phase resolved PD recordings (PRPD) and optical visualization at very high sensitivity are carried out on substrates embedded in gel or insulating liquids. PD features are very different from those obtained in needle-plane geometry in gel or liquid, and do not depend on the nature of the liquid or gel. The main conclusion is that PDs recorded with substrates originate from the ceramic material itself, due to the presence of numerous μm-sized pores in sintered materials.
{"title":"Partial discharges and light emission from ceramic substrates embedded in liquids and gels","authors":"V. Tho, J. Augé, O. Lesaint","doi":"10.1109/ICDL.2011.6015490","DOIUrl":"https://doi.org/10.1109/ICDL.2011.6015490","url":null,"abstract":"Aluminium nitrite (AlN) or alumina (Al2O3) substrates are widely used in power electronics modules, due to their ability to provide both electrical insulation, and heat conduction properties. A silicon gel usually covers the substrate, semiconductor chips, and bondings to prevent partial discharges (PD) from occurring within the module. However, at high voltage PDs can be observed in high electric field regions, mainly at the sharp edges of copper tracks on the substrate. In this study, we try to determine the origin of these PDs. Phase resolved PD recordings (PRPD) and optical visualization at very high sensitivity are carried out on substrates embedded in gel or insulating liquids. PD features are very different from those obtained in needle-plane geometry in gel or liquid, and do not depend on the nature of the liquid or gel. The main conclusion is that PDs recorded with substrates originate from the ceramic material itself, due to the presence of numerous μm-sized pores in sintered materials.","PeriodicalId":364451,"journal":{"name":"2011 IEEE International Conference on Dielectric Liquids","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114751045","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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