Pub Date : 1999-06-27DOI: 10.1109/ICSD.1998.709343
M. Driga, A. Wu
A novel transient Finite Element-Boundary Element (FE-BE) numerical code is presented. This FE-BE method code calculates electric field distributions in high voltage insulation systems with complex boundaries and with nonhomogeneous characteristics. The very accurate representation of the 3-D space distribution of electric fields is achieved by using, concomitantly, the finite and the boundary element methods-in time-thus eliminating the drawbacks characteristic to each of the methods when applied separately. The boundary element method (BEM) is applied to the lossless regions and the finite element method (FEM) is applied to the lossy and nonhomogeneous domains of the field. Undesirable phenomena, due to high voltage gradient, are usually localized at the onset. To accurately model them, separate temporal and spatial scales, different from the scale for regular discharges, are adopted. On the temporal side, a particularly small time step to accommodate the frequency is chosen. For the space, a rezoning capability is adopted to gain fine grid solution. The coarse grid solution is used to interpolate the boundary conditions for the newly created points in a recursive refinement process based on an adaptive procedure. Several practical examples of the transient modeling of high field effects are presented.
{"title":"Transient, finite element-boundary element methods for modeling high field effects in nonhomogeneous solid dielectrics","authors":"M. Driga, A. Wu","doi":"10.1109/ICSD.1998.709343","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709343","url":null,"abstract":"A novel transient Finite Element-Boundary Element (FE-BE) numerical code is presented. This FE-BE method code calculates electric field distributions in high voltage insulation systems with complex boundaries and with nonhomogeneous characteristics. The very accurate representation of the 3-D space distribution of electric fields is achieved by using, concomitantly, the finite and the boundary element methods-in time-thus eliminating the drawbacks characteristic to each of the methods when applied separately. The boundary element method (BEM) is applied to the lossless regions and the finite element method (FEM) is applied to the lossy and nonhomogeneous domains of the field. Undesirable phenomena, due to high voltage gradient, are usually localized at the onset. To accurately model them, separate temporal and spatial scales, different from the scale for regular discharges, are adopted. On the temporal side, a particularly small time step to accommodate the frequency is chosen. For the space, a rezoning capability is adopted to gain fine grid solution. The coarse grid solution is used to interpolate the boundary conditions for the newly created points in a recursive refinement process based on an adaptive procedure. Several practical examples of the transient modeling of high field effects are presented.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"26 1","pages":"543-547"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78279502","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709244
A. Contin, G. Montanari, A. Cavallini
Results of investigations performed in order to verify whether the Power Spectral Density Function (PSDF), estimated from a sample of Partial Discharge (PD) pulse signals, can summarize the spectral characteristics of the whole population of discharge pulses generated by a PD phenomenon, are reported. The PSDF of sequences of PD pulses produced by either corona or surface discharges, taken as a reference, are compared with those obtained from samples of each population, selected using the Poisson technique. It is shown that an accurate PSDF is obtained already with a relatively-small amount of pulses, particularly for corona discharges, and that the PSDF of the two PD phenomena differ at high frequencies.
{"title":"Power spectral density estimation of randomly sampled partial discharge signals","authors":"A. Contin, G. Montanari, A. Cavallini","doi":"10.1109/ICSD.1998.709244","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709244","url":null,"abstract":"Results of investigations performed in order to verify whether the Power Spectral Density Function (PSDF), estimated from a sample of Partial Discharge (PD) pulse signals, can summarize the spectral characteristics of the whole population of discharge pulses generated by a PD phenomenon, are reported. The PSDF of sequences of PD pulses produced by either corona or surface discharges, taken as a reference, are compared with those obtained from samples of each population, selected using the Poisson technique. It is shown that an accurate PSDF is obtained already with a relatively-small amount of pulses, particularly for corona discharges, and that the PSDF of the two PD phenomena differ at high frequencies.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"44 1","pages":"135-138"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73473591","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709315
R. Ross, F. Schmuck, M. Megens
GFR (Glass Fibre Reinforced) epoxy insulators are very useful where both mechanical and electrical stress are to be endured. Outdoor applications are e.g. suspension insulators in overhead lines and hollow insulators for cable terminations and bushings. Indoor applications can be found in switch gear in the form of support insulators or pull rods. The present paper focuses on indoor applications in particular. Discussed are: the equipment and possible environmental impact, the kind of degradation to be expected, principles of fog tests, the application of fog tests to rank materials and finally a discussion of the results.
{"title":"Evaluation of contamination resistance of GFR epoxy rods for indoor application by means of a salt fog test","authors":"R. Ross, F. Schmuck, M. Megens","doi":"10.1109/ICSD.1998.709315","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709315","url":null,"abstract":"GFR (Glass Fibre Reinforced) epoxy insulators are very useful where both mechanical and electrical stress are to be endured. Outdoor applications are e.g. suspension insulators in overhead lines and hollow insulators for cable terminations and bushings. Indoor applications can be found in switch gear in the form of support insulators or pull rods. The present paper focuses on indoor applications in particular. Discussed are: the equipment and possible environmental impact, the kind of degradation to be expected, principles of fog tests, the application of fog tests to rank materials and finally a discussion of the results.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"74 1","pages":"422-425"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74302223","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709217
R. Liu, A. Jaksts, C. Tornkvist, M. Bergkvist
Transformer oil and oil-impregnated pressboard are major insulating materials in a HVDC (high voltage direct current) converter transformer which provides electrical power transformation between an AC and a DC system. However, the dc component on the valve side of a HVDC converter transformer gives rise to special conditions, regarding space charge for example, for the insulating materials. In this paper, the relationship between moisture and space charge in oil-impregnated pressboard was investigated under dc electrical fields at room temperature. Formation, accumulation and distribution of space charge were studied using a PWP (pressure wave propagation) technique with the moisture concentration varying between 0.3% and 1.7% by weight. Experiments have shown that moisture influences seriously space charge distribution and thus electric field distribution in oil-impregnated pressboard. The higher the moisture concentration, the faster the establishment of space charge and the deeper the charge penetration into the insulation. The influence of moisture on the distribution of space charge should be taken into consideration in the design of an insulating system under HVDC.
{"title":"Moisture and space charge in oil-impregnated pressboard under HVDC","authors":"R. Liu, A. Jaksts, C. Tornkvist, M. Bergkvist","doi":"10.1109/ICSD.1998.709217","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709217","url":null,"abstract":"Transformer oil and oil-impregnated pressboard are major insulating materials in a HVDC (high voltage direct current) converter transformer which provides electrical power transformation between an AC and a DC system. However, the dc component on the valve side of a HVDC converter transformer gives rise to special conditions, regarding space charge for example, for the insulating materials. In this paper, the relationship between moisture and space charge in oil-impregnated pressboard was investigated under dc electrical fields at room temperature. Formation, accumulation and distribution of space charge were studied using a PWP (pressure wave propagation) technique with the moisture concentration varying between 0.3% and 1.7% by weight. Experiments have shown that moisture influences seriously space charge distribution and thus electric field distribution in oil-impregnated pressboard. The higher the moisture concentration, the faster the establishment of space charge and the deeper the charge penetration into the insulation. The influence of moisture on the distribution of space charge should be taken into consideration in the design of an insulating system under HVDC.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"1 1","pages":"17-22"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74552087","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709324
U. Fromm, L. Ming, T. Schutte, L. Walfridsson, A. Kron, R. Liu, D. Windmar
For an improved design of high voltage apparatus a material with a low dielectric constant and a relatively high breakdown strength is advantageous. Therefore the insulating properties of polymer foam with closed pores are investigated. It was found, that for a foam with closed gas filled spheres the breakdown voltage is close to the partial discharge inception voltage and it depends on the void size and the degree of foaming. For practical applications a void diameter lower than 50 /spl mu/m in combination with a high gas content is desirable. The tested foam had a breakdown strength of 6 kV/mm and a relative dielectric constant of 1.1. Using this material a decrease of 30% of the size of high voltage electrodes can be achieved.
对于高压装置的改进设计，具有低介电常数和相对高击穿强度的材料是有利的。为此，研究了闭孔泡沫聚合物的绝缘性能。研究发现，对于封闭充气球泡沫，击穿电压与局部放电起始电压接近，击穿电压与气泡大小和发泡程度有关。在实际应用中，需要小于50 /spl μ m /m的空隙直径和高气体含量。测试泡沫的击穿强度为6 kV/mm，相对介电常数为1.1。使用这种材料可以使高压电极的尺寸减小30%。
{"title":"Electric field control by polymer foam","authors":"U. Fromm, L. Ming, T. Schutte, L. Walfridsson, A. Kron, R. Liu, D. Windmar","doi":"10.1109/ICSD.1998.709324","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709324","url":null,"abstract":"For an improved design of high voltage apparatus a material with a low dielectric constant and a relatively high breakdown strength is advantageous. Therefore the insulating properties of polymer foam with closed pores are investigated. It was found, that for a foam with closed gas filled spheres the breakdown voltage is close to the partial discharge inception voltage and it depends on the void size and the degree of foaming. For practical applications a void diameter lower than 50 /spl mu/m in combination with a high gas content is desirable. The tested foam had a breakdown strength of 6 kV/mm and a relative dielectric constant of 1.1. Using this material a decrease of 30% of the size of high voltage electrodes can be achieved.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"8 1","pages":"460-463"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74578618","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709347
V. Matko, D. Donlagic
An humidity sensor using a sensitive capacitive-dependent crystal is described. The authors describe the probe sensitivity (i.e. the dependence of df on dCx). In addition, a new idea of excitation of the entire humidity sensor with stochastic test signals is described, and the humidity surface-measuring method is given. This includes the influence of test signals on the weighting function uncertainty and on the A/D to D/A conversion. The results of air-humidity measurement and water absorption measurement in glass-fiber resins are shown experimentally. The uncertainty of the surface humidity measurement is less than 0.2% (T=15-25 /spl deg/C and air-humidity=50 to 98%).
{"title":"Highly sensitive humidity sensor for dielectric measurement (water absorption) in glass-fiber resins","authors":"V. Matko, D. Donlagic","doi":"10.1109/ICSD.1998.709347","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709347","url":null,"abstract":"An humidity sensor using a sensitive capacitive-dependent crystal is described. The authors describe the probe sensitivity (i.e. the dependence of df on dCx). In addition, a new idea of excitation of the entire humidity sensor with stochastic test signals is described, and the humidity surface-measuring method is given. This includes the influence of test signals on the weighting function uncertainty and on the A/D to D/A conversion. The results of air-humidity measurement and water absorption measurement in glass-fiber resins are shown experimentally. The uncertainty of the surface humidity measurement is less than 0.2% (T=15-25 /spl deg/C and air-humidity=50 to 98%).","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"1 1","pages":"561-564"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72689133","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709263
D. Gavrilă, L. Lamarre, M. R. Mitroi
In the present paper, an experimental study of the conduction phenomena in the composite insulator material mica-epoxy-novolac is presented, with an effort to suggest the possible conduction mechanisms. The study comprises the analyses of the influence of the temperature and frequencies of the electric field on the conductivity. The statistical analysis is performed of the results obtained the algorithm used for fitting the experimental data was Rosenbrock quasi-Newton.
{"title":"Electric conductivity of the composite insulator mica-epoxy-novalac","authors":"D. Gavrilă, L. Lamarre, M. R. Mitroi","doi":"10.1109/ICSD.1998.709263","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709263","url":null,"abstract":"In the present paper, an experimental study of the conduction phenomena in the composite insulator material mica-epoxy-novolac is presented, with an effort to suggest the possible conduction mechanisms. The study comprises the analyses of the influence of the temperature and frequencies of the electric field on the conductivity. The statistical analysis is performed of the results obtained the algorithm used for fitting the experimental data was Rosenbrock quasi-Newton.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"55 1","pages":"214-217"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80174323","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709221
U. Nilsson, A. Campus, A. Gustafsson, P. Carstensen, C. Tornkvist, F. Ruter
The space charge accumulation in highly polar polyolefins compared with polyethylene homopolymer have been evaluated with the pressure wave propagation technique. It was found that homocharges dominate in the copolymers while mainly heterocharges are present in LDPE homopolymer. The difference between degassed peroxide crosslinked compounds based either on EBA or LDPE or a blend of the two was less. Heterocharges were typically the main feature in all these samples.
{"title":"Space charge behaviour of highly polar polyolefins","authors":"U. Nilsson, A. Campus, A. Gustafsson, P. Carstensen, C. Tornkvist, F. Ruter","doi":"10.1109/ICSD.1998.709221","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709221","url":null,"abstract":"The space charge accumulation in highly polar polyolefins compared with polyethylene homopolymer have been evaluated with the pressure wave propagation technique. It was found that homocharges dominate in the copolymers while mainly heterocharges are present in LDPE homopolymer. The difference between degassed peroxide crosslinked compounds based either on EBA or LDPE or a blend of the two was less. Heterocharges were typically the main feature in all these samples.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"16 1","pages":"36-39"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81835461","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709230
S. Hvidsten, E. Ildstad, H. Faremo
The nonlinear dielectric response of water tree degraded XLPE power cable insulation has been found to be an important additional diagnostic criterion. It has been experimentally shown that in case of long water trees the dielectric response increase more than proportional with increasing test voltage above a certain voltage level. In this paper we present possible explanations for the formation of nonlinear dielectric response based upon the mechanical damage theory of water treeing. In order to verify the proposed hypothesis, we have performed electric field computations, water content and microscopy treeing analysis.
{"title":"Mechanisms causing nonlinear dielectric response of water treed XLPE cables","authors":"S. Hvidsten, E. Ildstad, H. Faremo","doi":"10.1109/ICSD.1998.709230","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709230","url":null,"abstract":"The nonlinear dielectric response of water tree degraded XLPE power cable insulation has been found to be an important additional diagnostic criterion. It has been experimentally shown that in case of long water trees the dielectric response increase more than proportional with increasing test voltage above a certain voltage level. In this paper we present possible explanations for the formation of nonlinear dielectric response based upon the mechanical damage theory of water treeing. In order to verify the proposed hypothesis, we have performed electric field computations, water content and microscopy treeing analysis.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"45 1","pages":"73-78"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85941928","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 : 1998-06-22DOI: 10.1109/ICSD.1998.709234
G. Urbani, R. Brooks
The recovery voltage method (RVM) provides detailed information about the aging process of oil-paper insulation. Regular testing (e.g. every 1-3 years) with RVM supports: tracking the measured transformer's aging; comparison between transformers; planning of maintenance or further use. The measured values from an RVM test provide a characteristic of the current state of the insulation regardless of whether standard or non-standard curves are produced. The correct interpretation of the result depends, however, on the form of the curve and requires more knowledge and experience in the case of non-standard curves.
{"title":"Using the recovery voltage method to evaluate aging in oil-paper insulation","authors":"G. Urbani, R. Brooks","doi":"10.1109/ICSD.1998.709234","DOIUrl":"https://doi.org/10.1109/ICSD.1998.709234","url":null,"abstract":"The recovery voltage method (RVM) provides detailed information about the aging process of oil-paper insulation. Regular testing (e.g. every 1-3 years) with RVM supports: tracking the measured transformer's aging; comparison between transformers; planning of maintenance or further use. The measured values from an RVM test provide a characteristic of the current state of the insulation regardless of whether standard or non-standard curves are produced. The correct interpretation of the result depends, however, on the form of the curve and requires more knowledge and experience in the case of non-standard curves.","PeriodicalId":13148,"journal":{"name":"ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132)","volume":"97 1","pages":"93-97"},"PeriodicalIF":0.0,"publicationDate":"1998-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81210923","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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