Pub Date : 1993-10-17DOI: 10.1109/CEIDP.1993.378950
S. Elkhodary, R. Hackam
The build up with time of the accumulated charge density on an acrylic glass rod insulator having a fixed length and fixed diameter of 30 mm was measured in SF/sub 6/. The charge density is found to increase linearly with increasing voltage at a fixed pressure, to increase linearly with increasing gas pressure in the range 0.1-0.13 MPa, to be almost constant in the range 0.13-0.5 MPa at a fixed applied voltage, and to increase with increasing voltage at a fixed E/p. The rate of charge build-up depends on time; it initially increases rapidly, and then increase slowly until saturation is reached. The charge polarity corresponds to that of the adjacent electrode. These results suggest that the role of the ionized species within the volume of the gas in charging the insulator is less significant than the charging of the insulator by injection of current from the electrodes, which is governed by the total surface and volume resistances of the insulator.<>
{"title":"Generation of surface charges on an insulator in SF/sub 6/ gas","authors":"S. Elkhodary, R. Hackam","doi":"10.1109/CEIDP.1993.378950","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378950","url":null,"abstract":"The build up with time of the accumulated charge density on an acrylic glass rod insulator having a fixed length and fixed diameter of 30 mm was measured in SF/sub 6/. The charge density is found to increase linearly with increasing voltage at a fixed pressure, to increase linearly with increasing gas pressure in the range 0.1-0.13 MPa, to be almost constant in the range 0.13-0.5 MPa at a fixed applied voltage, and to increase with increasing voltage at a fixed E/p. The rate of charge build-up depends on time; it initially increases rapidly, and then increase slowly until saturation is reached. The charge polarity corresponds to that of the adjacent electrode. These results suggest that the role of the ionized species within the volume of the gas in charging the insulator is less significant than the charging of the insulator by injection of current from the electrodes, which is governed by the total surface and volume resistances of the insulator.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"159 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127550832","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378929
A. Gustafsson, U. Gedde
Styrene polymers were used to study the influence of chemical structure on resistance to PD (partial discharges). It was found that the monomer structure has a great influence on the PD stability. The behavior can be explained by the ease with which radicals are formed. The driving force for the formation of radicals during the degradation is enhanced by electron-donating substituents by the stabilization of benzylic type radicals. Copolymerization of styrene with p-phenylstyrene and 2-vinylnaphthalene (1-20 wt%) produced polymers with higher PD-stability than PS. This demonstrates that the size of the aromatic system is a positive factor regarding PD resistance and that typical voltage stabilizers may also be effective when they are chemically bonded to the main chain.<>
{"title":"The effect of monomer structure in styrene polymers on the resistance towards PD in air","authors":"A. Gustafsson, U. Gedde","doi":"10.1109/CEIDP.1993.378929","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378929","url":null,"abstract":"Styrene polymers were used to study the influence of chemical structure on resistance to PD (partial discharges). It was found that the monomer structure has a great influence on the PD stability. The behavior can be explained by the ease with which radicals are formed. The driving force for the formation of radicals during the degradation is enhanced by electron-donating substituents by the stabilization of benzylic type radicals. Copolymerization of styrene with p-phenylstyrene and 2-vinylnaphthalene (1-20 wt%) produced polymers with higher PD-stability than PS. This demonstrates that the size of the aromatic system is a positive factor regarding PD resistance and that typical voltage stabilizers may also be effective when they are chemically bonded to the main chain.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121736119","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378911
C. Le Gressus, G. Blaise
It is shown that a critical space charge variation is the cause of insulator sample damage ranging from atom size to macroscopic size. This finding has implications for space charge characterization. Correlation of the space charge characteristics to breakdown strength requires the critical conditions for initiating breakdown. These conditions are related to such material intrinsic parameters as the trap energy distribution, the trap spatial distribution, the schubweg, and the modification of the free energy of the charged sample. The crucial point is therefore not how to measure the charge distribution but how to characterize trapping/detrapping critical parameters.<>
{"title":"Insulator damages related to charge detrapping","authors":"C. Le Gressus, G. Blaise","doi":"10.1109/CEIDP.1993.378911","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378911","url":null,"abstract":"It is shown that a critical space charge variation is the cause of insulator sample damage ranging from atom size to macroscopic size. This finding has implications for space charge characterization. Correlation of the space charge characteristics to breakdown strength requires the critical conditions for initiating breakdown. These conditions are related to such material intrinsic parameters as the trap energy distribution, the trap spatial distribution, the schubweg, and the modification of the free energy of the charged sample. The crucial point is therefore not how to measure the charge distribution but how to characterize trapping/detrapping critical parameters.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115043745","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378958
E. Forster
Results of a study of streamer initiation in organic liquids under uniform field conditions are presented. It is shown that, under pulse conditions, streamers can initiate from both the cathode and the anode, with the probability for the occurrence of the latter event being somewhat lower than that for the former. The significance of these findings is discussed in terms of initiation models developed for streamer initiation under nonuniform field conditions.<>
{"title":"Streamer initiation in organic liquids under uniform field conditions","authors":"E. Forster","doi":"10.1109/CEIDP.1993.378958","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378958","url":null,"abstract":"Results of a study of streamer initiation in organic liquids under uniform field conditions are presented. It is shown that, under pulse conditions, streamers can initiate from both the cathode and the anode, with the probability for the occurrence of the latter event being somewhat lower than that for the former. The significance of these findings is discussed in terms of initiation models developed for streamer initiation under nonuniform field conditions.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130301336","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378877
B. Hanson, A. B. Reynolds
The effect of flaws and thermal and radiation aging of flaws on the electrical breakdown of low-voltage cable was studied. AC breakdown voltages of XLPE (cross-linked polyethylene) and EPR (ethylene-propylene rubber) cables were measured for both damaged and undamaged cable. Three types of flaws were studied: scrapes, transverse cuts, and longitudinal cuts. Some cables were radiated-aged up to 1 MGy and others were thermally aged at 130/spl deg/C for up to 50 days. Results to date indicate little effect of aging on breakdown voltage and a linear decrease in breakdown voltage with decreasing thickness beneath scrapes and transverse cuts below some threshold thickness. Calculated electric field distributions at breakdown indicate that breakdown occurs by partial discharge in pores.<>
{"title":"Effect of aging of breakdown voltage of artificially damaged cable","authors":"B. Hanson, A. B. Reynolds","doi":"10.1109/CEIDP.1993.378877","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378877","url":null,"abstract":"The effect of flaws and thermal and radiation aging of flaws on the electrical breakdown of low-voltage cable was studied. AC breakdown voltages of XLPE (cross-linked polyethylene) and EPR (ethylene-propylene rubber) cables were measured for both damaged and undamaged cable. Three types of flaws were studied: scrapes, transverse cuts, and longitudinal cuts. Some cables were radiated-aged up to 1 MGy and others were thermally aged at 130/spl deg/C for up to 50 days. Results to date indicate little effect of aging on breakdown voltage and a linear decrease in breakdown voltage with decreasing thickness beneath scrapes and transverse cuts below some threshold thickness. Calculated electric field distributions at breakdown indicate that breakdown occurs by partial discharge in pores.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"1206 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131326652","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378891
M. Kosaki, A. Minoda, Y. Mitsuyama, Y. Mizuno, M. Nagao
The authors report results on the treeing resistivity of EPR (ethylene-propylene rubber) at both liquid nitrogen temperature and room temperature, and the effect of fillers on treeing. A treeing test method was established for opaque sample based on the detection of partial discharges. At room temperature, fillers lower the tree initiation voltage slightly but the growth of tree channels is inhibited by fillers. The tree initiation voltage at liquid nitrogen temperature is about three times higher than that at room temperature. Fillers improve treeing resistivity slightly. EPR has sufficient resistance to treeing at liquid nitrogen temperature. High reliability is expected during the long term operation of extruded EPR-insulated superconducting power cables considered by the authors.<>
{"title":"Treeing of ethylene-propylene rubber in cryogenic temperature region","authors":"M. Kosaki, A. Minoda, Y. Mitsuyama, Y. Mizuno, M. Nagao","doi":"10.1109/CEIDP.1993.378891","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378891","url":null,"abstract":"The authors report results on the treeing resistivity of EPR (ethylene-propylene rubber) at both liquid nitrogen temperature and room temperature, and the effect of fillers on treeing. A treeing test method was established for opaque sample based on the detection of partial discharges. At room temperature, fillers lower the tree initiation voltage slightly but the growth of tree channels is inhibited by fillers. The tree initiation voltage at liquid nitrogen temperature is about three times higher than that at room temperature. Fillers improve treeing resistivity slightly. EPR has sufficient resistance to treeing at liquid nitrogen temperature. High reliability is expected during the long term operation of extruded EPR-insulated superconducting power cables considered by the authors.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134379913","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378946
M. Pépin, A. Younsi, H. Wintle
Charge build-up on the surface of a dielectric is investigated on the injection of charge from electrodes lying flush with the insulator surface. The materials tested were 19 /spl mu/m PET (polyethylene terephthalate) and 25 /spl mu/m PI. Some tests were also done on LDPE (low-density polyethylene) and Nylon 6-6. UV (ultraviolet) irradiation was carried out with a 4 W short wavelength tube (254 nm), giving an intensity of about 200 /spl mu/W/cm/sup 2/ at the sample plane. The results suggest that there is little effect without UV light. In gaseous ambients, there is homocharge injection at the electrode edges, presumably due to photoionization of the plastic near the anode, and of the electrode metal near the cathode. Once launched, negative charges propagate along the surface with a mobility comparable to a bulk mobility typical of ionic motion. In vacuum, a general photoionization of the surface also occurs, and this builds up until the original field at the surface is annulled.<>
{"title":"Surface charging: Field and photo effects","authors":"M. Pépin, A. Younsi, H. Wintle","doi":"10.1109/CEIDP.1993.378946","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378946","url":null,"abstract":"Charge build-up on the surface of a dielectric is investigated on the injection of charge from electrodes lying flush with the insulator surface. The materials tested were 19 /spl mu/m PET (polyethylene terephthalate) and 25 /spl mu/m PI. Some tests were also done on LDPE (low-density polyethylene) and Nylon 6-6. UV (ultraviolet) irradiation was carried out with a 4 W short wavelength tube (254 nm), giving an intensity of about 200 /spl mu/W/cm/sup 2/ at the sample plane. The results suggest that there is little effect without UV light. In gaseous ambients, there is homocharge injection at the electrode edges, presumably due to photoionization of the plastic near the anode, and of the electrode metal near the cathode. Once launched, negative charges propagate along the surface with a mobility comparable to a bulk mobility typical of ionic motion. In vacuum, a general photoionization of the surface also occurs, and this builds up until the original field at the surface is annulled.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133002551","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378968
R. E. Barker
The author addresses the transfer of charge during collisions between small particles, idealized as spheres, in terms of classical electrostatics. The topics considered include the distribution of charge between spheres of different radii left in contact for a long time and the rate of transfer through finite resistances during transient contact. The model has implications for a variety of phenomena from the charging of hail stones to triboelectric effects in dry powders such as sugar, flour, and xerographic toner particles. An attempt is made to develop a simple two-body model for charge transfer between colliding spheres which will provide a framework to answer questions about equilibrium charging and rate of exchange if only classical electrostatics were applicable. This sets the stage for inferences about many-body processes and the modifications that quantum mechanics might impose.<>
{"title":"Considerations in charge transfer by transient contact of small particles","authors":"R. E. Barker","doi":"10.1109/CEIDP.1993.378968","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378968","url":null,"abstract":"The author addresses the transfer of charge during collisions between small particles, idealized as spheres, in terms of classical electrostatics. The topics considered include the distribution of charge between spheres of different radii left in contact for a long time and the rate of transfer through finite resistances during transient contact. The model has implications for a variety of phenomena from the charging of hail stones to triboelectric effects in dry powders such as sugar, flour, and xerographic toner particles. An attempt is made to develop a simple two-body model for charge transfer between colliding spheres which will provide a framework to answer questions about equilibrium charging and rate of exchange if only classical electrostatics were applicable. This sets the stage for inferences about many-body processes and the modifications that quantum mechanics might impose.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124783515","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378940
S. Jayaram
The dielectric strength of transformer oil under the influence of temperature and flow conditions was studied experimentally. As a function of flow rates (0 to 65 mL/s), the dielectric strength increased flow by /spl sim/10%. As a function of temperature (20 to 100/spl deg/C), the dielectric strength fell rapidly near the boiling temperature of water (> 80 /spl deg/C), and increased with temperature between 20 and 80/spl deg/C. It is concluded that the variations in the observed breakdown strength of the oil studied (Voltesso 35) can be related to variations in the solubility of water vapor and gases in the oil, and effect stress-induced liquid motion on particles and gas bubbles.<>
{"title":"Effects of thermal and viscous drag forces on AC breakdown characteristics of transformer oil","authors":"S. Jayaram","doi":"10.1109/CEIDP.1993.378940","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378940","url":null,"abstract":"The dielectric strength of transformer oil under the influence of temperature and flow conditions was studied experimentally. As a function of flow rates (0 to 65 mL/s), the dielectric strength increased flow by /spl sim/10%. As a function of temperature (20 to 100/spl deg/C), the dielectric strength fell rapidly near the boiling temperature of water (> 80 /spl deg/C), and increased with temperature between 20 and 80/spl deg/C. It is concluded that the variations in the observed breakdown strength of the oil studied (Voltesso 35) can be related to variations in the solubility of water vapor and gases in the oil, and effect stress-induced liquid motion on particles and gas bubbles.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129448720","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 : 1993-10-17DOI: 10.1109/CEIDP.1993.378896
K. Kaminaga, T. Suzuki, T. Uozumi, T. Haga, N. Yasuda, T. Fukui
A chemical analysis of LDPE (low-density polyethylene) applied above and below the luminescence inception voltage was performed. The authors also examined the time dependence of the luminescence intensity and the spectrum of the luminescence, considering the mechanism of degradation of LDPE in a high electric field. The luminescence inception stress is about 60kV/mm if the stress mitigating effect due to the space charge is disregarded. It was lower by about 200kV/mm than the electrical tree inception stress. When voltage above the luminescence inception voltage was applied to LDPE, a free radical and an oxide were detected by ESR (electron spin resonance) and XPS (X-ray photoelectron spectroscopy), respectively. The time dependence of the luminescence intensity under constant AC voltage was examined. The luminescence intensity is shown to be stable in the initial stage. However, an intense light was observed after a certain period of voltage application.<>
{"title":"The mechanism of degradation of polyethylene in a high electrical field","authors":"K. Kaminaga, T. Suzuki, T. Uozumi, T. Haga, N. Yasuda, T. Fukui","doi":"10.1109/CEIDP.1993.378896","DOIUrl":"https://doi.org/10.1109/CEIDP.1993.378896","url":null,"abstract":"A chemical analysis of LDPE (low-density polyethylene) applied above and below the luminescence inception voltage was performed. The authors also examined the time dependence of the luminescence intensity and the spectrum of the luminescence, considering the mechanism of degradation of LDPE in a high electric field. The luminescence inception stress is about 60kV/mm if the stress mitigating effect due to the space charge is disregarded. It was lower by about 200kV/mm than the electrical tree inception stress. When voltage above the luminescence inception voltage was applied to LDPE, a free radical and an oxide were detected by ESR (electron spin resonance) and XPS (X-ray photoelectron spectroscopy), respectively. The time dependence of the luminescence intensity under constant AC voltage was examined. The luminescence intensity is shown to be stable in the initial stage. However, an intense light was observed after a certain period of voltage application.<<ETX>>","PeriodicalId":149803,"journal":{"name":"Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP '93)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117224722","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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