The physical processes occurring during recovery of a vacuum interrupter after high-current interruption are surveyed. New results have been obtained by the application of modern diagnostic techniques like laser shadow imaging, laser-induced fluorescence of atoms and of metal vapor ions, Mie scattering of droplets, and high-resolution recording of voltage and current on digital oscilloscopes. The density of metal vapor produced by the arc determines the kind of breakdown processes occurring after current zero. Liquid droplets and residual plasma play a minor role. The commonly used contact material, i.e., copper-chromium, is compared with pure copper, and its advantage is explained by the surface structure of the melt. >
{"title":"Investigation of high-current interruption of vacuum circuit breakers","authors":"E. Dullni, E. Schade","doi":"10.1109/14.231543","DOIUrl":"https://doi.org/10.1109/14.231543","url":null,"abstract":"The physical processes occurring during recovery of a vacuum interrupter after high-current interruption are surveyed. New results have been obtained by the application of modern diagnostic techniques like laser shadow imaging, laser-induced fluorescence of atoms and of metal vapor ions, Mie scattering of droplets, and high-resolution recording of voltage and current on digital oscilloscopes. The density of metal vapor produced by the arc determines the kind of breakdown processes occurring after current zero. Liquid droplets and residual plasma play a minor role. The commonly used contact material, i.e., copper-chromium, is compared with pure copper, and its advantage is explained by the surface structure of the melt. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75373369","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}
The inherent high reliability of vacuum interrupters is determined by the maintenance of a high degree of vacuum in the vacuum tube for a long time. Rise of internal pressure exceeding a certain threshold value causes loss of the current switching capability and, at a pressure that is about one or two orders higher, the loss of the electric insulating properties. Pressure measurements after manufacturing and reexamining the internal pressure of vacuum interrupters after several years of service require different procedures, measuring methods, and diagnostic techniques. The fundamentals of a new method based on the measuring of emission currents immediately after arc polishing of the contacts are presented. This method is appropriate for estimating the internal pressure of the vacuum interrupters after long-time service and for giving information about the remaining safety margin. >
{"title":"Measurement of emission currents immediately after arc polishing of contacts-Method for internal-pressure diagnostics of vacuum interrupters","authors":"F. Frontzek, D. Konig","doi":"10.1109/14.231553","DOIUrl":"https://doi.org/10.1109/14.231553","url":null,"abstract":"The inherent high reliability of vacuum interrupters is determined by the maintenance of a high degree of vacuum in the vacuum tube for a long time. Rise of internal pressure exceeding a certain threshold value causes loss of the current switching capability and, at a pressure that is about one or two orders higher, the loss of the electric insulating properties. Pressure measurements after manufacturing and reexamining the internal pressure of vacuum interrupters after several years of service require different procedures, measuring methods, and diagnostic techniques. The fundamentals of a new method based on the measuring of emission currents immediately after arc polishing of the contacts are presented. This method is appropriate for estimating the internal pressure of the vacuum interrupters after long-time service and for giving information about the remaining safety margin. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81156815","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}
The time dependence of late discharges in high-voltage vacuum circuit breakers after current interruption has been measured as a function of the mechanical and electrical stress exerted on the vacuum circuit breaker bottle. A correlation between the occurrence of strong, shocklike acceleration peaks of >10/sup 4/ m/s/sup 2/ and the increase of the probability of late discharges has been found. A reduction of the shock wave amplitudes by simple mechanical damping results in a reduction of the probability of late strikes by as much as 50%. It is concluded that most of the late discharges observed in these experiments are caused by particles which adhere loosely to the contact and vapor shield surfaces, and which are released by the strong mechanical shocks. >
{"title":"Mechanical shocks as cause of late discharges in vacuum circuit breakers","authors":"R. Gebel, W. Hartmann","doi":"10.1109/14.231527","DOIUrl":"https://doi.org/10.1109/14.231527","url":null,"abstract":"The time dependence of late discharges in high-voltage vacuum circuit breakers after current interruption has been measured as a function of the mechanical and electrical stress exerted on the vacuum circuit breaker bottle. A correlation between the occurrence of strong, shocklike acceleration peaks of >10/sup 4/ m/s/sup 2/ and the increase of the probability of late discharges has been found. A reduction of the shock wave amplitudes by simple mechanical damping results in a reduction of the probability of late strikes by as much as 50%. It is concluded that most of the late discharges observed in these experiments are caused by particles which adhere loosely to the contact and vapor shield surfaces, and which are released by the strong mechanical shocks. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86589989","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}
As part of a study on HV design concepts for microwave tubes, a number of different insulator designs have been studied. Analysis of the measured DC current, partial discharge activity and breakdown voltage shows that surface charging of insulators is a key mechanism in the breakdown process and in the conditioning process. Insulator parameters are not only the breakdown voltage, but also the conditioning speed and the sensitivity to gas exposure or charge leakage. In all these respects insulators with a field enhancement at the anode are superior. Field enhancements at the cathode are less harmful if stepped insulator shapes are chosen. Effective conditioning requires at least a limited number of breakdowns. With sufficient conditioning breakdowns, all insulator geometries tested reached a breakdown field exceeding 12 kV/mm. >
{"title":"The effect of insulator charging on breakdown and conditioning","authors":"J. Wetzer, P. Wouters","doi":"10.1109/14.231551","DOIUrl":"https://doi.org/10.1109/14.231551","url":null,"abstract":"As part of a study on HV design concepts for microwave tubes, a number of different insulator designs have been studied. Analysis of the measured DC current, partial discharge activity and breakdown voltage shows that surface charging of insulators is a key mechanism in the breakdown process and in the conditioning process. Insulator parameters are not only the breakdown voltage, but also the conditioning speed and the sensitivity to gas exposure or charge leakage. In all these respects insulators with a field enhancement at the anode are superior. Field enhancements at the cathode are less harmful if stepped insulator shapes are chosen. Effective conditioning requires at least a limited number of breakdowns. With sufficient conditioning breakdowns, all insulator geometries tested reached a breakdown field exceeding 12 kV/mm. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78070422","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}
Thin films of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ deposited on copper and stainless steel electrodes by a flame spray method were tested in vacuum at electric fields ranging from 10 to 100 kV/cm. Field electron emission current was measured from the surfaces before and after the application of the film. Metallic surfaces, of 20 cm/sup 2/ in surface, cooled to LN/sub 2/ ( approximately 90 K) temperatures showed a 1.75 to 2*increase in current. The coated surfaces showed a 5 to 6* increment in current when compared to room temperature metallic surfaces. Stainless steel electrodes with a surface area of 20 cm/sup 2/, which were coated by a flame spray process and tested under vacuum, showed a similar behavior. Coating procedures and experimental results are shown. >
{"title":"Field electron emission from large-area Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ superconducting films in vacuum","authors":"J. Elizondo, J. Taylor","doi":"10.1109/14.231531","DOIUrl":"https://doi.org/10.1109/14.231531","url":null,"abstract":"Thin films of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ deposited on copper and stainless steel electrodes by a flame spray method were tested in vacuum at electric fields ranging from 10 to 100 kV/cm. Field electron emission current was measured from the surfaces before and after the application of the film. Metallic surfaces, of 20 cm/sup 2/ in surface, cooled to LN/sub 2/ ( approximately 90 K) temperatures showed a 1.75 to 2*increase in current. The coated surfaces showed a 5 to 6* increment in current when compared to room temperature metallic surfaces. Stainless steel electrodes with a surface area of 20 cm/sup 2/, which were coated by a flame spray process and tested under vacuum, showed a similar behavior. Coating procedures and experimental results are shown. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82079261","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}
Aspects of HV breakdown associated with vacuum interrupters are discussed, based on the author's personal experience. In particular, cold cathode arc stability, electrical contact phenomena, and particle effects are considered. >
{"title":"Electrical breakdown in vacuum interrupters","authors":"G. Farrall","doi":"10.1109/14.231541","DOIUrl":"https://doi.org/10.1109/14.231541","url":null,"abstract":"Aspects of HV breakdown associated with vacuum interrupters are discussed, based on the author's personal experience. In particular, cold cathode arc stability, electrical contact phenomena, and particle effects are considered. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80594173","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}
Both experimental investigations and computer simulations of multiple prestrikes and associated prestriking overvoltages during energizing a capacitive load (capacitor bank or unloaded cable) by a vacuum circuit breaker are presented. It has been found that the prestriking overvoltage is associated with multiple prestrikes, and the circuit parameters or arrangements play important roles on the severity of the prestriking overvoltages. A simple computer simulation program is established and verified with the experimental results. Further simulations of several probable practical cases are also provided. Normally, overvoltages will not exceed 3 PU, but higher values are possible in special cases due to resonances in cable-line-cable networks. >
{"title":"Switching transients during energizing capacitive load by a vacuum circuit breaker","authors":"Y. Fu, G. Damstra","doi":"10.1109/14.231549","DOIUrl":"https://doi.org/10.1109/14.231549","url":null,"abstract":"Both experimental investigations and computer simulations of multiple prestrikes and associated prestriking overvoltages during energizing a capacitive load (capacitor bank or unloaded cable) by a vacuum circuit breaker are presented. It has been found that the prestriking overvoltage is associated with multiple prestrikes, and the circuit parameters or arrangements play important roles on the severity of the prestriking overvoltages. A simple computer simulation program is established and verified with the experimental results. Further simulations of several probable practical cases are also provided. Normally, overvoltages will not exceed 3 PU, but higher values are possible in special cases due to resonances in cable-line-cable networks. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82750419","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}
Breakdown phenomena on alumina RF windows for S-band high-power use were investigated using a resonant ring. Occasional flashovers were observed on TiN-coated surfaces, though the multipactor effect is suppressed by the coating. The flashovers show luminescence with a treelike pattern, resulting in a limitation of the transmittable power through the window. This flashover threshold depends on the dielectric materials; a sapphire with F-center defects shows a lower threshold. For further investigations of the flashover mechanism under a RF field, in situ measurements of the charges built up on the surface both before and after flashover and high-speed photography observations of the flashover avalanches were made. The results indicate an electron communication; its relaxation leaves positive charges on the surface. The relaxation time is found to be 10/sup 6/ m/s. >
{"title":"Surface flashover on alumina RF windows for high-power use","authors":"Y. Saito, S. Michizono, S. Anami, S. Kobayashi","doi":"10.1109/14.231539","DOIUrl":"https://doi.org/10.1109/14.231539","url":null,"abstract":"Breakdown phenomena on alumina RF windows for S-band high-power use were investigated using a resonant ring. Occasional flashovers were observed on TiN-coated surfaces, though the multipactor effect is suppressed by the coating. The flashovers show luminescence with a treelike pattern, resulting in a limitation of the transmittable power through the window. This flashover threshold depends on the dielectric materials; a sapphire with F-center defects shows a lower threshold. For further investigations of the flashover mechanism under a RF field, in situ measurements of the charges built up on the surface both before and after flashover and high-speed photography observations of the flashover avalanches were made. The results indicate an electron communication; its relaxation leaves positive charges on the surface. The relaxation time is found to be 10/sup 6/ m/s. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88679483","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}
CuCr is generally accepted and applied as contact material in vacuum switches. Although CuCr has many well-known advantages it has, compared to CuBi, the disadvantage of welding more easily at high current-closing operations of circuit breakers. Thus, a currentless separation of the welds occurring after closing operations affects the dielectric properties of the open contact gap. In this study welding forces as well as field enhancement factors beta and breakdown voltages of the contacts after currentless opening are investigated and used as diagnostic tools in order to study the influence of different CuCr compositions and manufacturing processes on the performance of butt-type contacts installed in a model vacuum breaker chamber. >
{"title":"Insulation characteristics and welding behavior of vacuum switch contacts made from various CuCr alloys","authors":"J. Ballat, D. Konig","doi":"10.1109/14.231545","DOIUrl":"https://doi.org/10.1109/14.231545","url":null,"abstract":"CuCr is generally accepted and applied as contact material in vacuum switches. Although CuCr has many well-known advantages it has, compared to CuBi, the disadvantage of welding more easily at high current-closing operations of circuit breakers. Thus, a currentless separation of the welds occurring after closing operations affects the dielectric properties of the open contact gap. In this study welding forces as well as field enhancement factors beta and breakdown voltages of the contacts after currentless opening are investigated and used as diagnostic tools in order to study the influence of different CuCr compositions and manufacturing processes on the performance of butt-type contacts installed in a model vacuum breaker chamber. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87740991","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}
A two-dimensional computer analysis of the surface charging on angled insulators has been performed by using the Monte Carlo simulation method. Results are compared to the charge in equilibrium model, originally proposed by C.H. de Tourreil and K.D. Srivastava (1973). >
采用蒙特卡罗模拟方法对倾斜绝缘子表面电荷进行了二维计算机分析。结果与最初由C.H. de Tourreil和K.D. Srivastava(1973)提出的平衡模型中的电荷进行了比较。>
{"title":"Monte Carlo simulation of surface charge on angled insulators in vacuum","authors":"O. Yamamoto, T. Hara, I. Nakanishi, M. Hayashi","doi":"10.1109/14.231554","DOIUrl":"https://doi.org/10.1109/14.231554","url":null,"abstract":"A two-dimensional computer analysis of the surface charging on angled insulators has been performed by using the Monte Carlo simulation method. Results are compared to the charge in equilibrium model, originally proposed by C.H. de Tourreil and K.D. Srivastava (1973). >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77017984","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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