Pub Date : 1991-07-08DOI: 10.1109/ICPADM.1991.172304
G. Liang-yu, Liu Yaonan, Xi Baofeng
The relationship between the morphology and the properties of aromatic polyamide 1313 (Nomex) fiber is studied systematically. Methods for increasing the crystallinity and orientation of Nomex fiber are discussed on the basis of a crystal structure model. The triclinic lattice form and the desired properties can be obtained by keeping the temperature of the heat treatment higher than that used for maximum crystallization rate and by using a higher drawing ratio. Experiments have confirmed these conclusions. The batch products have obtained the desired properties.<>
{"title":"The influence of the morphology on properties of aromatic polyamide fibre","authors":"G. Liang-yu, Liu Yaonan, Xi Baofeng","doi":"10.1109/ICPADM.1991.172304","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172304","url":null,"abstract":"The relationship between the morphology and the properties of aromatic polyamide 1313 (Nomex) fiber is studied systematically. Methods for increasing the crystallinity and orientation of Nomex fiber are discussed on the basis of a crystal structure model. The triclinic lattice form and the desired properties can be obtained by keeping the temperature of the heat treatment higher than that used for maximum crystallization rate and by using a higher drawing ratio. Experiments have confirmed these conclusions. The batch products have obtained the desired properties.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"153 1","pages":"1238-1241 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88434466","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 : 1991-07-08DOI: 10.1109/ICPADM.1991.172272
D. Allan, C. Jones, B. Sharp
The authors describe practical insulation life assessment techniques developed within the Queensland Electricity Commission for the estimation of remaining useful life of its large power transformers. Novel aspects of the technique are: (i) the use of a database of oil test results for statistical analysis of several aging indicators, to derive an 'insulation age' for the transformer; (ii) the extraction of paper samples from in-situ transformers for analysis of their degree of polymerization (DP); and (iii) the application of appropriate life models to typical power transformers to determine remaining life on a probabilistic basis. These analyses are supported by studies on dismantled large power transformers at the Commission's workshop, to determine the DP profile through typical transformers. From this, relationships are estimated between the DP at hot spots in the transformer and that obtained at convenient sampling locations.<>
{"title":"Studies of the condition of insulation in aged power transformers. 1. Insulation condition and remnant life assessments for in-service units","authors":"D. Allan, C. Jones, B. Sharp","doi":"10.1109/ICPADM.1991.172272","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172272","url":null,"abstract":"The authors describe practical insulation life assessment techniques developed within the Queensland Electricity Commission for the estimation of remaining useful life of its large power transformers. Novel aspects of the technique are: (i) the use of a database of oil test results for statistical analysis of several aging indicators, to derive an 'insulation age' for the transformer; (ii) the extraction of paper samples from in-situ transformers for analysis of their degree of polymerization (DP); and (iii) the application of appropriate life models to typical power transformers to determine remaining life on a probabilistic basis. These analyses are supported by studies on dismantled large power transformers at the Commission's workshop, to determine the DP profile through typical transformers. From this, relationships are estimated between the DP at hot spots in the transformer and that obtained at convenient sampling locations.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"38 1","pages":"1116-1119 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77343851","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 : 1991-07-08DOI: 10.1109/ICPADM.1991.172155
T. Ishida, Y. Mizuno, M. Nagao, M. Kosaki
The authors developed a personal-computer-aided partial discharge analyzing system for SPMD (swarming pulsed microdischarge) measurement. The system has two detection methods for partial discharge measurement: a conventional pulse charge method and a balanced Lissajous figure method. The former failed to detect SPMD due to the sensitivity limit of the detector, while the latter integrated all charges including SPMD per half cycle. Therefore, the difference between the charge integrals of partial discharges per half cycle measured by these two methods must be a good measure of SPMD. Based on this idea, a new parameter, the SPMD ratio, was introduced. Using the developed system, partial discharge characteristics were studied for the CIGRE method II specimen with internal void in order to examine the factor in the presence of SPMD. The results show that the magnitude of applied voltage, its frequency, and roughness of the void surface affect the appearance of SPMD.<>
{"title":"Development and application of partial discharge analyzing system for swarming pulsive microdischarges","authors":"T. Ishida, Y. Mizuno, M. Nagao, M. Kosaki","doi":"10.1109/ICPADM.1991.172155","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172155","url":null,"abstract":"The authors developed a personal-computer-aided partial discharge analyzing system for SPMD (swarming pulsed microdischarge) measurement. The system has two detection methods for partial discharge measurement: a conventional pulse charge method and a balanced Lissajous figure method. The former failed to detect SPMD due to the sensitivity limit of the detector, while the latter integrated all charges including SPMD per half cycle. Therefore, the difference between the charge integrals of partial discharges per half cycle measured by these two methods must be a good measure of SPMD. Based on this idea, a new parameter, the SPMD ratio, was introduced. Using the developed system, partial discharge characteristics were studied for the CIGRE method II specimen with internal void in order to examine the factor in the presence of SPMD. The results show that the magnitude of applied voltage, its frequency, and roughness of the void surface affect the appearance of SPMD.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"1 1","pages":"676-679 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86978033","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 : 1991-07-08DOI: 10.1109/ICPADM.1991.172062
Y. Mizuno, T. Ohe, K. Nomizu, Hideo Muneyasu, M. Nagao, M. Kosaki, N. Shimizu, K. Horii
The mechanical and electrical properties of ethylene propylene rubber (EPR) pieces were made in comparison with polyethylene (PE) in the cryogenic temperature region to examine the possibility for use in solid electrical insulation material of superconducting cables. The mechanical properties of EPR are preferable to those of PE because of its low shrinkage. The electric strength and dielectric loss tangent of EPR are comparable to those of PE at liquid helium temperature. Based on these encouraging results, an extruded EPR-insulated cable was fabricated and its 15 m length was cooled down to liquid helium temperature successfully. A partial discharge experiment at the temperature showed good electrical characteristics.<>
{"title":"Evaluation of ethylene propylene rubber as an electrical insulation material of superconducting cable","authors":"Y. Mizuno, T. Ohe, K. Nomizu, Hideo Muneyasu, M. Nagao, M. Kosaki, N. Shimizu, K. Horii","doi":"10.1109/ICPADM.1991.172062","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172062","url":null,"abstract":"The mechanical and electrical properties of ethylene propylene rubber (EPR) pieces were made in comparison with polyethylene (PE) in the cryogenic temperature region to examine the possibility for use in solid electrical insulation material of superconducting cables. The mechanical properties of EPR are preferable to those of PE because of its low shrinkage. The electric strength and dielectric loss tangent of EPR are comparable to those of PE at liquid helium temperature. Based on these encouraging results, an extruded EPR-insulated cable was fabricated and its 15 m length was cooled down to liquid helium temperature successfully. A partial discharge experiment at the temperature showed good electrical characteristics.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"18 1","pages":"317-321 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85665631","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 : 1991-07-08DOI: 10.1109/ICPADM.1991.172300
Z. Yingsuo, Bai Yi
It has been found that the accuracy of the constant slope (CS) method was +or-16.6 degrees C as compared with conventional aging (CA) (its standard deviation of error Delta t, S=8.3 degrees C). A scientific approach to the study of the CS method is presented here. It is noted that this method possesses a certain investigation value, and may be able to help one understand the change law of activation energy in CA, as well as present the complex relation between various rapid methods in order to explore the possibility of developing a higher-accuracy and really practical rapid method.<>
{"title":"A study on constant slope method for rapid thermal endurance tests of dielectrics","authors":"Z. Yingsuo, Bai Yi","doi":"10.1109/ICPADM.1991.172300","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172300","url":null,"abstract":"It has been found that the accuracy of the constant slope (CS) method was +or-16.6 degrees C as compared with conventional aging (CA) (its standard deviation of error Delta t, S=8.3 degrees C). A scientific approach to the study of the CS method is presented here. It is noted that this method possesses a certain investigation value, and may be able to help one understand the change law of activation energy in CA, as well as present the complex relation between various rapid methods in order to explore the possibility of developing a higher-accuracy and really practical rapid method.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"65 1","pages":"1225-1228 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91216433","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 : 1991-07-08DOI: 10.1109/ICPADM.1991.172203
E. W. Jansen, M. Zahn
A drift/diffusion flow electrification model is developed for bipolar conduction in a turbulent liquid dielectric between rotating concentric cylindrical electrodes with open-circuited, short-circuited, or DC voltage energized electrodes. Experimental data are used to estimate model parameters such as the density of each charge carrier at the electrode walls and the mobility ratio of the charge carriers. Typical experimental measurements indicate wall charge densities much larger than the equilibrium charge densities of each carrier, invalidating a quasiequilibrium ohmic conductivity model as the local conductivity near the wall is enhanced over the equilibrium conductivity. Specific electrode wall charge densities are found which yield near self-consistent solutions with measurements of open-circuit voltage, short-circuit current, and turbulent core charge densities. Experimental DC voltage excitation across the cylinders is treated in anticipation of future measurements.<>
{"title":"A drift/diffusion conduction model for flow electrification of turbulent liquid dielectrics","authors":"E. W. Jansen, M. Zahn","doi":"10.1109/ICPADM.1991.172203","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172203","url":null,"abstract":"A drift/diffusion flow electrification model is developed for bipolar conduction in a turbulent liquid dielectric between rotating concentric cylindrical electrodes with open-circuited, short-circuited, or DC voltage energized electrodes. Experimental data are used to estimate model parameters such as the density of each charge carrier at the electrode walls and the mobility ratio of the charge carriers. Typical experimental measurements indicate wall charge densities much larger than the equilibrium charge densities of each carrier, invalidating a quasiequilibrium ohmic conductivity model as the local conductivity near the wall is enhanced over the equilibrium conductivity. Specific electrode wall charge densities are found which yield near self-consistent solutions with measurements of open-circuit voltage, short-circuit current, and turbulent core charge densities. Experimental DC voltage excitation across the cylinders is treated in anticipation of future measurements.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"46 1","pages":"858-862 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74451457","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 : 1991-07-08DOI: 10.1109/ICPADM.1991.172258
M. Takeuchi
An effective dielectric constant of heterogeneous layers, in which BaTiO/sub 3/ particles are dispersed in a polymer mix, has been studied experimentally. When the experimental values of an effective dielectric constant for the BaTiO/sub 3/-polymer layers were plotted against the volume fraction of BaTiO/sub 3/, it was found that the experimental values were inside the Hashin-Shtrikman bounds and fit the van Beek theory. Changes in the effective dielectric constant for the Cu-particle-glycerinum system associated with the sedimentation of the Cu particles were also examined. The results obtained confirmed that the effective dielectric constant of a heterogeneous system changes, depending on the phase configuration, even at a constant volume fraction of each phase.<>
{"title":"An experimental study on the effective dielectric constant of heterogeneous media","authors":"M. Takeuchi","doi":"10.1109/ICPADM.1991.172258","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172258","url":null,"abstract":"An effective dielectric constant of heterogeneous layers, in which BaTiO/sub 3/ particles are dispersed in a polymer mix, has been studied experimentally. When the experimental values of an effective dielectric constant for the BaTiO/sub 3/-polymer layers were plotted against the volume fraction of BaTiO/sub 3/, it was found that the experimental values were inside the Hashin-Shtrikman bounds and fit the van Beek theory. Changes in the effective dielectric constant for the Cu-particle-glycerinum system associated with the sedimentation of the Cu particles were also examined. The results obtained confirmed that the effective dielectric constant of a heterogeneous system changes, depending on the phase configuration, even at a constant volume fraction of each phase.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"32 1","pages":"1064-1067 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74782740","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 : 1991-07-08DOI: 10.1109/ICPADM.1991.172254
Yang Baitun, Liufu De, T. Demin, Liu Yaonan
The phenomenon of PET (polyethylene terephthalate) breakdown during short circuit discharge is studied. A theoretical model for detrapping by collisional ionization is proposed for interpretation of the breakdown mechanism. The coefficient for detrapping by collisional ionization and the relation between it and the velocity of the discharging are obtained. A critical electric field of the short circuit breakdown by space charges due to collisional ionization by detrapping is also suggested for solid dielectrics, and confirmed experimentally. The critical field is directly proportional to the thickness of the dielectric and inversely proportional to the detrapping coefficient of the collisional ionization, the time constant of the discharging circuit, and the dielectric constant.<>
{"title":"Breakdown mechanism of the charged solid dielectric during short circuit discharge","authors":"Yang Baitun, Liufu De, T. Demin, Liu Yaonan","doi":"10.1109/ICPADM.1991.172254","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172254","url":null,"abstract":"The phenomenon of PET (polyethylene terephthalate) breakdown during short circuit discharge is studied. A theoretical model for detrapping by collisional ionization is proposed for interpretation of the breakdown mechanism. The coefficient for detrapping by collisional ionization and the relation between it and the velocity of the discharging are obtained. A critical electric field of the short circuit breakdown by space charges due to collisional ionization by detrapping is also suggested for solid dielectrics, and confirmed experimentally. The critical field is directly proportional to the thickness of the dielectric and inversely proportional to the detrapping coefficient of the collisional ionization, the time constant of the discharging circuit, and the dielectric constant.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"62 1","pages":"1048-1051 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76952452","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 : 1991-07-08DOI: 10.1109/ICPADM.1991.172019
M. Fukuzawa, M. Iwamoto
The authors investigated both the tree-initiation voltage and the length of the path generated in an LDPE (low-density polyethylene) specimen due to the electrical treeing under a needle-plane electrode system. They then measured both thermally stimulated current (TSC) and thermally stimulated surface potential (TSSP) generated in an LDPE specimen, which is biased by the application of either DC or AC voltage. The authors also investigated the mechanism of electrical breakdown initiated by the treeing by studying the relationship between the tree-initiation voltage determined by the experiment and the space charge field determined by the thermally stimulated electrical measurements. It was concluded that the distance between the centroid of the space charge formed in an LDPE film and the tip of the needle electrode was approximately the same as the length of the path generated by the electrical treeing.<>
{"title":"On the mechanism of electrical breakdown initiated by the treeing: measurement of the space charge field formed in an LDPE film","authors":"M. Fukuzawa, M. Iwamoto","doi":"10.1109/ICPADM.1991.172019","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172019","url":null,"abstract":"The authors investigated both the tree-initiation voltage and the length of the path generated in an LDPE (low-density polyethylene) specimen due to the electrical treeing under a needle-plane electrode system. They then measured both thermally stimulated current (TSC) and thermally stimulated surface potential (TSSP) generated in an LDPE specimen, which is biased by the application of either DC or AC voltage. The authors also investigated the mechanism of electrical breakdown initiated by the treeing by studying the relationship between the tree-initiation voltage determined by the experiment and the space charge field determined by the thermally stimulated electrical measurements. It was concluded that the distance between the centroid of the space charge formed in an LDPE film and the tip of the needle electrode was approximately the same as the length of the path generated by the electrical treeing.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"18 1","pages":"244-246 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77323924","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 : 1991-07-08DOI: 10.1109/ICPADM.1991.172234
M. Abedi, B. Vahidi, M.R. Chatri
A highly interactive and user-friendly program called Lightning Analysis (LA) is introduced. The numerical execution is based on the two points method of J.G. Anderson (1982). LA is capable of predicting the shielding failure, back flashover, and total lightning tripout rates for different tower design and climatic conditions. LA is applied to assess the flashover (shielding failure) and back flashover across 400-kV insulators in Iran. The total tripout rates of Iranian 400-kV lines are presented.<>
{"title":"A PC based interactive software for lightning performance evaluation of transmission lines and its application to insulators of 400 kV lines in Iran","authors":"M. Abedi, B. Vahidi, M.R. Chatri","doi":"10.1109/ICPADM.1991.172234","DOIUrl":"https://doi.org/10.1109/ICPADM.1991.172234","url":null,"abstract":"A highly interactive and user-friendly program called Lightning Analysis (LA) is introduced. The numerical execution is based on the two points method of J.G. Anderson (1982). LA is capable of predicting the shielding failure, back flashover, and total lightning tripout rates for different tower design and climatic conditions. LA is applied to assess the flashover (shielding failure) and back flashover across 400-kV insulators in Iran. The total tripout rates of Iranian 400-kV lines are presented.<<ETX>>","PeriodicalId":6450,"journal":{"name":"[1991] Proceedings of the 3rd International Conference on Properties and Applications of Dielectric Materials","volume":"85 1","pages":"969-971 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1991-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78140618","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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