Pub Date : 1982-06-07DOI: 10.1109/EIC.1982.7464470
A. Vlastós, A. Salem, Cunyi Yu
The influence of the electrode surface roughness on the impulse breakdown probabilities of pressurized SF6 was examined in a coaxial cylinder electrode geometry (cylinder diameters 70/30 mm) for both polarities at a pressure p of 6 bara. The results show that (a) for both positive and negative polarity, an increase of the maximum height of irregularities Rmax of the inner electrode leads to a reduction of the breakdown electric field E prevailing at the inner electrode; (b) for negative polarity, the 1% breakdown field on the inner electrode is lower than for positive polarity; (c) for negative polarity, the standard deviation is smaller resulting in a bigger difference between the 50% breakdown probabilities for the two voltage polarities; (d) the experimentally obtained plots of E/p versus pRmax under constant pressure (6 bara) and Rmax variable (between 10 and 50 µm) are appreciably deviating from these obtained from a one protrusion theoretical model, especially at low values of pRmax, and the E/p shows a weaker dependence on pRmax than does the theoretical model. However, plots of E/p versus pRmax obtained under variable pressure (2–6 bara) and Rmax constant (about 15 µm) are in better agreement with the theoretical model.
{"title":"Influence of electrode surface roughness on the impulse breakdown probabilities of SF6","authors":"A. Vlastós, A. Salem, Cunyi Yu","doi":"10.1109/EIC.1982.7464470","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464470","url":null,"abstract":"The influence of the electrode surface roughness on the impulse breakdown probabilities of pressurized SF6 was examined in a coaxial cylinder electrode geometry (cylinder diameters 70/30 mm) for both polarities at a pressure p of 6 bara. The results show that (a) for both positive and negative polarity, an increase of the maximum height of irregularities Rmax of the inner electrode leads to a reduction of the breakdown electric field E prevailing at the inner electrode; (b) for negative polarity, the 1% breakdown field on the inner electrode is lower than for positive polarity; (c) for negative polarity, the standard deviation is smaller resulting in a bigger difference between the 50% breakdown probabilities for the two voltage polarities; (d) the experimentally obtained plots of E/p versus pRmax under constant pressure (6 bara) and Rmax variable (between 10 and 50 µm) are appreciably deviating from these obtained from a one protrusion theoretical model, especially at low values of pRmax, and the E/p shows a weaker dependence on pRmax than does the theoretical model. However, plots of E/p versus pRmax obtained under variable pressure (2–6 bara) and Rmax constant (about 15 µm) are in better agreement with the theoretical model.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116669769","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464483
S. Rzad, J. Devins, R. Schwabe
Using shadowgraphic techniques in conjunction with an Imacon camera, measurements of streamer velocities and minimum voltage required for streamer propagation (MVP) have been made with and without dc superimposed on voltage steps (1.2 µs rise time). This has been done in point-plane geometries and semi-uniform fields in a transformer oil alone as well as with pressboard barriers. Velocities and MVP have also been measured for streamers propagating on the surface between cylindrical electrodes perpendicular to insulating sheets having a ground plane on the opposite side. Again the influence of superimposed dc was assessed. The solid materials used were polymethylmethacrylate and pressboard. Measurements with the latter material were made using an optical multichannel analyzer to follow the light emission from the propagating streamer.
{"title":"The influence of a dc bias on streamers produced by step voltages in transformer oil with and without insulating surfaces","authors":"S. Rzad, J. Devins, R. Schwabe","doi":"10.1109/EIC.1982.7464483","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464483","url":null,"abstract":"Using shadowgraphic techniques in conjunction with an Imacon camera, measurements of streamer velocities and minimum voltage required for streamer propagation (MVP) have been made with and without dc superimposed on voltage steps (1.2 µs rise time). This has been done in point-plane geometries and semi-uniform fields in a transformer oil alone as well as with pressboard barriers. Velocities and MVP have also been measured for streamers propagating on the surface between cylindrical electrodes perpendicular to insulating sheets having a ground plane on the opposite side. Again the influence of superimposed dc was assessed. The solid materials used were polymethylmethacrylate and pressboard. Measurements with the latter material were made using an optical multichannel analyzer to follow the light emission from the propagating streamer.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124581449","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464475
R. Brealey, P. Juneau, J. Zlupko
An investigation has been made of the feasibility of grading an electric field by means of electrically active particulate fillers in polymeric matrix materials. Concepts investigated included linear resistive, nonlinear resistive and capacitive grading. This paper describes the design, fabrication and electrical evaluation of bulk-graded filled polymer insulators. The design emphasized in the study was a capacitively graded 23 kV post insulator.
{"title":"Fabrication design and electrical evaluation of bulk-graded filled polymer post insulators","authors":"R. Brealey, P. Juneau, J. Zlupko","doi":"10.1109/EIC.1982.7464475","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464475","url":null,"abstract":"An investigation has been made of the feasibility of grading an electric field by means of electrically active particulate fillers in polymeric matrix materials. Concepts investigated included linear resistive, nonlinear resistive and capacitive grading. This paper describes the design, fabrication and electrical evaluation of bulk-graded filled polymer insulators. The design emphasized in the study was a capacitively graded 23 kV post insulator.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127976360","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464468
Y. Qiu, E. Kuffel, M. Raghuveer
Impulse ratios of nearly uniform field gaps were measured in compressed N2, SF6 and in ambient air surrounded by an insulating cylinder. For a 5-mm sphere gap irradiated by a mercury-are lamp an erroneous impulse ratio as high as 2.5 was recorded in both air and N2, while a considerably lower impulse ratio (≈ 1.5) was obtained in SF6, all measurements being made at 100 kPa. When 1 mCi caesium was used as an irradiation source the impulse ratio for the sphere gap in N2 and SF6 became unity at 100 kPa and slightly above unity at 400 kPa. For a 30mm point-sphere gap impulse ratios were measured in He, N2, CO, CO2 and SF6. Impulse ratio as high as approx. 2.9 was recorded in both He and N2 under negative polarity and as low as 0.62 was obtained in SF6 within the corona-stabilized pressure range. Also, in weakly attaching gases, CO and CO2, impulse ratios lower than unity were found in some pressure ranges under positive polarity.
{"title":"Impulse ratios of uniform and non-uniform field gaps in compressed gases","authors":"Y. Qiu, E. Kuffel, M. Raghuveer","doi":"10.1109/EIC.1982.7464468","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464468","url":null,"abstract":"Impulse ratios of nearly uniform field gaps were measured in compressed N2, SF6 and in ambient air surrounded by an insulating cylinder. For a 5-mm sphere gap irradiated by a mercury-are lamp an erroneous impulse ratio as high as 2.5 was recorded in both air and N2, while a considerably lower impulse ratio (≈ 1.5) was obtained in SF6, all measurements being made at 100 kPa. When 1 mCi caesium was used as an irradiation source the impulse ratio for the sphere gap in N2 and SF6 became unity at 100 kPa and slightly above unity at 400 kPa. For a 30mm point-sphere gap impulse ratios were measured in He, N2, CO, CO2 and SF6. Impulse ratio as high as approx. 2.9 was recorded in both He and N2 under negative polarity and as low as 0.62 was obtained in SF6 within the corona-stabilized pressure range. Also, in weakly attaching gases, CO and CO2, impulse ratios lower than unity were found in some pressure ranges under positive polarity.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132479689","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464442
C. Cooke, E. Williams, K. Wright
A series of controlled experiments using injected electron space charge layers has been used to study discharge propagation. This experimental technique is unique in its ability to investigate discharges where equipotential surfaces are not the major sources of the field but rather space-charge clouds provide the driving force.
{"title":"Electrical discharge propagation in space-charged PMMA","authors":"C. Cooke, E. Williams, K. Wright","doi":"10.1109/EIC.1982.7464442","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464442","url":null,"abstract":"A series of controlled experiments using injected electron space charge layers has been used to study discharge propagation. This experimental technique is unique in its ability to investigate discharges where equipotential surfaces are not the major sources of the field but rather space-charge clouds provide the driving force.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"47 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132624564","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464446
S. Grzybowski, E. Kuffel
The paper describes the influence of sequential flashover numbers on the flashover voltage as well as on the surface deterioration of the polymethylmethacrylate, tetrafluoroethylene and polyethylene insulators in vacuum. Observations of track formation have been made by an electron microscope to examine the shape of the treed-tracks during their growth. Attempts have been made to explain the mechanism of flashover across thermoplastic materials in vacuum.
{"title":"The effect of surface detorioration of thermoplastic materials in vacuum","authors":"S. Grzybowski, E. Kuffel","doi":"10.1109/EIC.1982.7464446","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464446","url":null,"abstract":"The paper describes the influence of sequential flashover numbers on the flashover voltage as well as on the surface deterioration of the polymethylmethacrylate, tetrafluoroethylene and polyethylene insulators in vacuum. Observations of track formation have been made by an electron microscope to examine the shape of the treed-tracks during their growth. Attempts have been made to explain the mechanism of flashover across thermoplastic materials in vacuum.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132082427","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464435
E. Fort, J. C. Botts
During the last fifteen years, the emphasis in stator insulation for central station generators has shifted from electrical to physical properties. To meet this requirement change, the Westinghouse Thermalastic Epoxy insulation system was developed, in which the previously used polyester resins were replaced with epoxy resins. The improved physical properties of this new resin system resulted in a mechanically stronger coil insulation. The insulation was also found to be able to better withstand thermal cycling forces, reflecting both its improved mechanical and thermal characteristics. In addition, its superior resistance to water diffusion ïndicated a great safety margin in the unlikely case of internal leaks in water-cooled windings.
{"title":"Development of thermalastic epoxy for large high voltage generators","authors":"E. Fort, J. C. Botts","doi":"10.1109/EIC.1982.7464435","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464435","url":null,"abstract":"During the last fifteen years, the emphasis in stator insulation for central station generators has shifted from electrical to physical properties. To meet this requirement change, the Westinghouse Thermalastic Epoxy insulation system was developed, in which the previously used polyester resins were replaced with epoxy resins. The improved physical properties of this new resin system resulted in a mechanically stronger coil insulation. The insulation was also found to be able to better withstand thermal cycling forces, reflecting both its improved mechanical and thermal characteristics. In addition, its superior resistance to water diffusion ïndicated a great safety margin in the unlikely case of internal leaks in water-cooled windings.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133823884","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464452
G. G. Stone, Steven A. Boggs
Continuous observation of partial discharge may enable warning of incipient failure of gas-insulated switchgear (GIS). This paper reports measurements of partial discharges from electric treeing in epoxy, as well as from artificial defects in a GIS test piece. The measurements were performed with an ultrawide detection bandwidth (up to 1 GHz). Some partial discharge pulses have durations of at most a few nanoseconds; a multichannel analyzer capable of responding to such fast pulses was developed for these experiments.
{"title":"Wide band measurements of partial discharge in epoxy","authors":"G. G. Stone, Steven A. Boggs","doi":"10.1109/EIC.1982.7464452","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464452","url":null,"abstract":"Continuous observation of partial discharge may enable warning of incipient failure of gas-insulated switchgear (GIS). This paper reports measurements of partial discharges from electric treeing in epoxy, as well as from artificial defects in a GIS test piece. The measurements were performed with an ultrawide detection bandwidth (up to 1 GHz). Some partial discharge pulses have durations of at most a few nanoseconds; a multichannel analyzer capable of responding to such fast pulses was developed for these experiments.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126830017","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464466
M. Alem, J. Laghari
The deposition of contaminants on a HVDC insulator is primarily governed by the inwardly-directed component of the electric field at the insulator surface. This component is calculated for a string-type insulator with and without grading rings. The results seem to explain satisfactorily the formation of a clean (“contaminant-free”) ring surrounding the insulator pin as well as around the insulator edge. An optimum ratio of the diameter of the grading ring to the insulator disc occurs for various insulator lengths. The contamination pattern on the surface of the insulator in the absence of wind forces can therefore be predicted to a certain degree of accuracy. The results are presented and discussed in the light of theoretical models.
{"title":"A prediction of deposition of contaminants on insulator surface with and without grading rings","authors":"M. Alem, J. Laghari","doi":"10.1109/EIC.1982.7464466","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464466","url":null,"abstract":"The deposition of contaminants on a HVDC insulator is primarily governed by the inwardly-directed component of the electric field at the insulator surface. This component is calculated for a string-type insulator with and without grading rings. The results seem to explain satisfactorily the formation of a clean (“contaminant-free”) ring surrounding the insulator pin as well as around the insulator edge. An optimum ratio of the diameter of the grading ring to the insulator disc occurs for various insulator lengths. The contamination pattern on the surface of the insulator in the absence of wind forces can therefore be predicted to a certain degree of accuracy. The results are presented and discussed in the light of theoretical models.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"327 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116599251","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464494
B. S. Hansen, Frede Levring
As a part of the investigation of partial discharges and their deterious interactions with solid insulation material, two partial discharge types, slowly and rapidly developing discharges, have been investigated. This paper summarizes the nature of the two discharge types, with emphasis on the rapidly developing discharges which have been investigated most recently.
{"title":"Optical investigations of the spatial and temporal development of partial discharges in polyethylene","authors":"B. S. Hansen, Frede Levring","doi":"10.1109/EIC.1982.7464494","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464494","url":null,"abstract":"As a part of the investigation of partial discharges and their deterious interactions with solid insulation material, two partial discharge types, slowly and rapidly developing discharges, have been investigated. This paper summarizes the nature of the two discharge types, with emphasis on the rapidly developing discharges which have been investigated most recently.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123413379","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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