Pub Date : 2014-06-01DOI: 10.1109/ICDL.2014.6893098
D. A. K. Pham, T. M. T. Pham, E. Gockenbach, H. Borsi
The Frequency Response Analysis (FRA) based method is expected as an efficient one in diagnosis of mechanical failures in windings of power transformers, especially in cases other testing methods cannot provide any indication for the diagnostic. However, the current FRA assessment which is based on the relevant Chinese standard and other draft international standards is not sensitive enough in detecting such failures in all cases.
{"title":"Application of a new method in detecting a mechanical failure associated with series capacitance change in a power transformer winding","authors":"D. A. K. Pham, T. M. T. Pham, E. Gockenbach, H. Borsi","doi":"10.1109/ICDL.2014.6893098","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893098","url":null,"abstract":"The Frequency Response Analysis (FRA) based method is expected as an efficient one in diagnosis of mechanical failures in windings of power transformers, especially in cases other testing methods cannot provide any indication for the diagnostic. However, the current FRA assessment which is based on the relevant Chinese standard and other draft international standards is not sensitive enough in detecting such failures in all cases.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"3 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82749777","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 : 2014-06-01DOI: 10.1109/ICDL.2014.6893150
B. Dikarev, G. Karasev
This paper shows the dependence of the electrophysical characteristics for some hydraulic liquids on the level of purification. Commercial Hydraulic Liquids such as JI3-MΓ2, PMII and MΓE-10A (Russian designation) both in original state and after purification through the glass filters were studied by the conductometric measurements. Such important parameters as value of the volume resistivity ρ and mobility of charge carriers μ were calculated or measured.
{"title":"Charging and reversal currents in hydraulic liquids","authors":"B. Dikarev, G. Karasev","doi":"10.1109/ICDL.2014.6893150","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893150","url":null,"abstract":"This paper shows the dependence of the electrophysical characteristics for some hydraulic liquids on the level of purification. Commercial Hydraulic Liquids such as JI3-MΓ2, PMII and MΓE-10A (Russian designation) both in original state and after purification through the glass filters were studied by the conductometric measurements. Such important parameters as value of the volume resistivity ρ and mobility of charge carriers μ were calculated or measured.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"28 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82179941","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 : 2014-06-01DOI: 10.1109/ICDL.2014.6893133
F. Vahidi, S. Tenbohlen, M. Rosner, C. Perrier, H. Fink
The optimization of design and operation of converter transformers during test and operation needs understanding of insulation system behavior under AC, DC and mixed stress. In order to calculate the electrical field under all kinds of stresses, the material properties have to be known. The common metals exposed to noteworthy electric stress inside power transformers are copper (conductors) and aluminum (shields). Stainless steel is a material which is often used in dielectric material test arrangements. In typical arrangements bare metals as well as metals covered with insulators are found. In this contribution the influence of different bare electrode materials onto the conductivity values of mineral oil and onto their function of time is investigated. The behavior of each electrode material is also investigated at different measuring temperatures which shall be representative for the conditions of insulation during transformer operation.
{"title":"Influence of electrode material on conductivity measurements under DC stresses","authors":"F. Vahidi, S. Tenbohlen, M. Rosner, C. Perrier, H. Fink","doi":"10.1109/ICDL.2014.6893133","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893133","url":null,"abstract":"The optimization of design and operation of converter transformers during test and operation needs understanding of insulation system behavior under AC, DC and mixed stress. In order to calculate the electrical field under all kinds of stresses, the material properties have to be known. The common metals exposed to noteworthy electric stress inside power transformers are copper (conductors) and aluminum (shields). Stainless steel is a material which is often used in dielectric material test arrangements. In typical arrangements bare metals as well as metals covered with insulators are found. In this contribution the influence of different bare electrode materials onto the conductivity values of mineral oil and onto their function of time is investigated. The behavior of each electrode material is also investigated at different measuring temperatures which shall be representative for the conditions of insulation during transformer operation.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"19 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82049978","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 : 2014-06-01DOI: 10.1109/ICDL.2014.6893138
M. Frk, J. Máca, J. Libich
Oligobutadienes are viscous liquid polymers of butadiene with low relative molecular mass representing the raw material for polyurethanes production, which are widely used not only in the electrical engineering. The article describes the properties and accelerated degradation processes of variously modified oligobutadienes (LB 3000, LB 5000, LBH 3000 and LBM 32) due to effects of UV radiation. The behavior of materials in the course of UV degradation is observed in the AC electric field using the method of dielectric relaxation spectroscopy in the frequency range 20 Hz - 2 MHz and in the temperature interval 20 °C to -30 °C. Dielectric properties are measured using precision LRC meter Agilent E4980 including dielectric liquid test fixture Agilent 16452A immersed in to the water bath thermostat Medingen KT40. Frequency dependencies of the parts of complex permittivity are approximated by a mathematical function describing the position and shape of the relaxation maximum and information about the activation energy of relaxation process are added. The dielectric spectra changes of individual samples during the acceleration ageing by UV radiation are evaluated with respect to different molecular chain length and terminating functional group.
{"title":"Effect of UV radiation on the electrical properties of modified oligobutadienes","authors":"M. Frk, J. Máca, J. Libich","doi":"10.1109/ICDL.2014.6893138","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893138","url":null,"abstract":"Oligobutadienes are viscous liquid polymers of butadiene with low relative molecular mass representing the raw material for polyurethanes production, which are widely used not only in the electrical engineering. The article describes the properties and accelerated degradation processes of variously modified oligobutadienes (LB 3000, LB 5000, LBH 3000 and LBM 32) due to effects of UV radiation. The behavior of materials in the course of UV degradation is observed in the AC electric field using the method of dielectric relaxation spectroscopy in the frequency range 20 Hz - 2 MHz and in the temperature interval 20 °C to -30 °C. Dielectric properties are measured using precision LRC meter Agilent E4980 including dielectric liquid test fixture Agilent 16452A immersed in to the water bath thermostat Medingen KT40. Frequency dependencies of the parts of complex permittivity are approximated by a mathematical function describing the position and shape of the relaxation maximum and information about the activation energy of relaxation process are added. The dielectric spectra changes of individual samples during the acceleration ageing by UV radiation are evaluated with respect to different molecular chain length and terminating functional group.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"52 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79815430","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 : 2014-06-01DOI: 10.1109/ICDL.2014.6893129
M. Unge, S. Singha, S. Ingebrigtsen, D. Linhjell, L. Lundgaard
Molecular additives i.e. additives with specific molelcular propertie, has been shown to influence breakdown properties of dielectric liquids, in particular lightning impulse characteristics. In this study we investigate the propagation of streamers in a natural ester liquid with and without molecular additives in a needle plane electrode configuration with a 5 mm gap. In order to study streamer propagation, including fast events, in such a small gap, impulse voltages with 20-40 ns rise times are used. One molecular additive, dimethylaniline, has a low ionization potential and another, azobenzene, a low 1st excitation energy in comparison with the natural ester. Both additives increase the acceleration voltage with approximately 40% at a concentration of 5 w%. Different processes may be involved in the breakdown event for the different additives, which is indicated by differences in the breakdown voltage data.
{"title":"Influence of molecular additives on positive streamer propagation in ester liquids","authors":"M. Unge, S. Singha, S. Ingebrigtsen, D. Linhjell, L. Lundgaard","doi":"10.1109/ICDL.2014.6893129","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893129","url":null,"abstract":"Molecular additives i.e. additives with specific molelcular propertie, has been shown to influence breakdown properties of dielectric liquids, in particular lightning impulse characteristics. In this study we investigate the propagation of streamers in a natural ester liquid with and without molecular additives in a needle plane electrode configuration with a 5 mm gap. In order to study streamer propagation, including fast events, in such a small gap, impulse voltages with 20-40 ns rise times are used. One molecular additive, dimethylaniline, has a low ionization potential and another, azobenzene, a low 1st excitation energy in comparison with the natural ester. Both additives increase the acceleration voltage with approximately 40% at a concentration of 5 w%. Different processes may be involved in the breakdown event for the different additives, which is indicated by differences in the breakdown voltage data.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"35 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82035228","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 : 2014-06-01DOI: 10.1109/ICDL.2014.6893108
J. Viertel, K. Ohlsson, S. Singha
This work reports on an experimental study of the improvement of the viscosity and cold flow behavior of natural ester liquids without compromising on the excellent fire safety (> 300°C). Material variations in the form of a change in the molecular structure of the natural ester oil and as blends of a natural ester liquid with two different compounds are investigated. The impact of the molecular structure and blend concentration on the kinematic viscosity at different temperatures, the crystallization behavior (measured by differential scanning calorimetry (DSC)) and on the flash point is investigated. Results show that improvement of all physical properties at a time is a difficult task. The paper highlights the fact that by adding just one compound to a natural ester liquid it is impossible to improve thermal cooling properties (viscosities) and cold flow behavior (crystallization properties) without compromising the fire safety at the same time.
{"title":"Studies of the improvement of the viscosity of natural ester liquids","authors":"J. Viertel, K. Ohlsson, S. Singha","doi":"10.1109/ICDL.2014.6893108","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893108","url":null,"abstract":"This work reports on an experimental study of the improvement of the viscosity and cold flow behavior of natural ester liquids without compromising on the excellent fire safety (> 300°C). Material variations in the form of a change in the molecular structure of the natural ester oil and as blends of a natural ester liquid with two different compounds are investigated. The impact of the molecular structure and blend concentration on the kinematic viscosity at different temperatures, the crystallization behavior (measured by differential scanning calorimetry (DSC)) and on the flash point is investigated. Results show that improvement of all physical properties at a time is a difficult task. The paper highlights the fact that by adding just one compound to a natural ester liquid it is impossible to improve thermal cooling properties (viscosities) and cold flow behavior (crystallization properties) without compromising the fire safety at the same time.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"19 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84526407","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 : 2014-06-01DOI: 10.1109/ICDL.2014.6893125
J. Podesser, B. Wieser, M. Muhr, R. Schwarz, G. Pukel, M. Lashbrook
Since the middle of the 1970s the static electrification phenomenon was made responsible for several outages of forced cooled, high voltage power transformers. The forced oil flow results in electrostatic charging between the liquid and the solid insulation. Most of the research done till now in this field concerned the electrostatic charging behavior of mineral oil - cellulose insulation systems, conventionally applied in power transformers. The aim of the research activity at the Institute of High Voltage Engineering and System Management is the investigation of not so well studied solid - liquid couples. In this paper first investigations by the institute concerning static electrification of aramid in combination with different insulating liquids are shown.
{"title":"Static electrification of different solid-liquid couples used in transformers for insulation","authors":"J. Podesser, B. Wieser, M. Muhr, R. Schwarz, G. Pukel, M. Lashbrook","doi":"10.1109/ICDL.2014.6893125","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893125","url":null,"abstract":"Since the middle of the 1970s the static electrification phenomenon was made responsible for several outages of forced cooled, high voltage power transformers. The forced oil flow results in electrostatic charging between the liquid and the solid insulation. Most of the research done till now in this field concerned the electrostatic charging behavior of mineral oil - cellulose insulation systems, conventionally applied in power transformers. The aim of the research activity at the Institute of High Voltage Engineering and System Management is the investigation of not so well studied solid - liquid couples. In this paper first investigations by the institute concerning static electrification of aramid in combination with different insulating liquids are shown.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"71 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86401406","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 : 2014-06-01DOI: 10.1109/ICDL.2014.6893171
H. G. Tarchouna, F. Aitken, N. Bonifaci, K. von Haeften, J. Eloranta
The mobility of positively charged ions in supercritical helium at temperatures from 6 to 11 K and up to 20 bar was measured using corona discharges. Regions of increased and decreased hydrodynamic radius are interpreted in terms of growth, compression and solidification of ion clusters. Modelling of the mobility using a thermodynamic state equation for the ion-helium mixed system and a temperature dependent Cunningham correction provides best match with experimental data for a van der Waals helium-ion interaction term. Regions of large hydrodynamic radius and large compressibility are attributed to liquid-like behaviour.
{"title":"Mobility of positively charged ions in supercritical helium","authors":"H. G. Tarchouna, F. Aitken, N. Bonifaci, K. von Haeften, J. Eloranta","doi":"10.1109/ICDL.2014.6893171","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893171","url":null,"abstract":"The mobility of positively charged ions in supercritical helium at temperatures from 6 to 11 K and up to 20 bar was measured using corona discharges. Regions of increased and decreased hydrodynamic radius are interpreted in terms of growth, compression and solidification of ion clusters. Modelling of the mobility using a thermodynamic state equation for the ion-helium mixed system and a temperature dependent Cunningham correction provides best match with experimental data for a van der Waals helium-ion interaction term. Regions of large hydrodynamic radius and large compressibility are attributed to liquid-like behaviour.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"1 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75534220","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 : 2014-06-01DOI: 10.1109/ICDL.2014.6893114
V. Chirkov, Y. Stishkov, S. Vasilkov
The paper presents the results of the computer simulation of a single section of electrohydrodynamic (EHD) conduction pump with and without taking into account the enhancement of the dissociation rate under the effect of the strong electric field (the Wien effect). The numerical computations were carried out on the basis of the complete set of EHD equations using commercial software package COMSOL Multiphysics. The behavior of EHD flow inside the pump was investigated for different ratios between positive and negative ion mobilities and the effect of the latter on the pumping efficiency was estimated. The features of the pump operation in the case of the Wien effect occurrence were investigated. It was shown that the enhancement of the dissociation rate can lead to the reversion of EHD flow direction with increasing voltage. Besides, the results obtained in the presented computer model was compared to those obtained in the simplified one (based on the hydrostatic approach) and considerable discrepancy between the calculated pressure drops was revealed.
{"title":"Characteristics of electrohydrodynamic pump of the dissociation type: Low- and high-voltage ranges","authors":"V. Chirkov, Y. Stishkov, S. Vasilkov","doi":"10.1109/ICDL.2014.6893114","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893114","url":null,"abstract":"The paper presents the results of the computer simulation of a single section of electrohydrodynamic (EHD) conduction pump with and without taking into account the enhancement of the dissociation rate under the effect of the strong electric field (the Wien effect). The numerical computations were carried out on the basis of the complete set of EHD equations using commercial software package COMSOL Multiphysics. The behavior of EHD flow inside the pump was investigated for different ratios between positive and negative ion mobilities and the effect of the latter on the pumping efficiency was estimated. The features of the pump operation in the case of the Wien effect occurrence were investigated. It was shown that the enhancement of the dissociation rate can lead to the reversion of EHD flow direction with increasing voltage. Besides, the results obtained in the presented computer model was compared to those obtained in the simplified one (based on the hydrostatic approach) and considerable discrepancy between the calculated pressure drops was revealed.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"123 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85646450","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 : 2014-06-01DOI: 10.1109/ICDL.2014.6893130
M. Baur, M. Pompili
One of the most commonly used tests for measuring insulating liquids is the determination of dielectric breakdown voltage at 50 or 60 Hz. It is accepted worldwide that the determination of the breakdown voltage at power frequency give very useful information mainly related with moisture and particle content. However, the actual set-up recommended by IEC and ASTM have some limitations in terms of statistical scatter of mean value of the breakdown voltage. The present paper shows the influence on the scatter of the breakdown voltages (IEC 60156 Standard) if a relative low electrical field is applied before carrying out the test (pre-energizing). The application of this charging field might be capable to release free electrons into the insulating liquid and might have the effect to trigger the breakdown in a more deterministic manner. An improvement on the scatter of the mean values of the breakdown voltage may also occur by increasing the number of shots.
{"title":"Pre-energizing effect on breakdown voltage test for insulating liquids","authors":"M. Baur, M. Pompili","doi":"10.1109/ICDL.2014.6893130","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893130","url":null,"abstract":"One of the most commonly used tests for measuring insulating liquids is the determination of dielectric breakdown voltage at 50 or 60 Hz. It is accepted worldwide that the determination of the breakdown voltage at power frequency give very useful information mainly related with moisture and particle content. However, the actual set-up recommended by IEC and ASTM have some limitations in terms of statistical scatter of mean value of the breakdown voltage. The present paper shows the influence on the scatter of the breakdown voltages (IEC 60156 Standard) if a relative low electrical field is applied before carrying out the test (pre-energizing). The application of this charging field might be capable to release free electrons into the insulating liquid and might have the effect to trigger the breakdown in a more deterministic manner. An improvement on the scatter of the mean values of the breakdown voltage may also occur by increasing the number of shots.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"43 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84888092","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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