Pub Date : 1989-10-29DOI: 10.1109/CEIDP.1989.69586
J. J. O'Dwyer
Exact solutions for electrothermal breakdown have been given by H.J. Wintle (1981) for the case of a DC voltage between plane parallel thermally conducting electrodes. Wintle's solutions require specific functional dependence on temperature for both electrical and thermal conductivities, and he gives three pairs of suitable functions. In the present work, one of Wintle's models is chosen to extend the exact solutions to coaxial cylinders and concentric spheres. The boundary conditions used are either a thermally insulating inner electrode and a thermally conducting outer electrode, or both electrodes thermally conducting. For a thermally insulating center electrode, and an electrode radius ratio of 5, the field distorts to an almost constant value for a voltage that is 90% of critical; for a voltage that is 99% of critical, the field at the outer electrode is 10 times the value of the field at the inner electrode.<>
{"title":"Some exact solutions for electrothermal breakdown","authors":"J. J. O'Dwyer","doi":"10.1109/CEIDP.1989.69586","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69586","url":null,"abstract":"Exact solutions for electrothermal breakdown have been given by H.J. Wintle (1981) for the case of a DC voltage between plane parallel thermally conducting electrodes. Wintle's solutions require specific functional dependence on temperature for both electrical and thermal conductivities, and he gives three pairs of suitable functions. In the present work, one of Wintle's models is chosen to extend the exact solutions to coaxial cylinders and concentric spheres. The boundary conditions used are either a thermally insulating inner electrode and a thermally conducting outer electrode, or both electrodes thermally conducting. For a thermally insulating center electrode, and an electrode radius ratio of 5, the field distorts to an almost constant value for a voltage that is 90% of critical; for a voltage that is 99% of critical, the field at the outer electrode is 10 times the value of the field at the inner electrode.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"45 1","pages":"442-446"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81061850","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 : 1989-10-29DOI: 10.1109/CEIDP.1989.69591
K. Fukushi, M. Nagai, Y. Kamata
The dielectric strength of GFRPs (glass-fiber-reinforced plastics) under combined application of electrical and mechanical stresses was investigated in liquid He, liquid N/sub 2/, and silicone oil at room temperature. With the combined application of tensile and electrical stresses in cryogenic liquids, the dielectric breakdown of GFRPs occurred prior to mechanical breakdown when the applied electrical stress was lower than the DBS (dielectric breakdown strength) of GFRPs without tensile stress. In the case of tensile stress application under constantly applied electrical stress, the DBS and GFRPs decreased markedly. The reason for the large DBS decrease of GFRPs was the occurrence of microcracks in matrix resins because of their brittleness at cryogenic temperatures. Combining GFRP with polyimide film in cryogenic liquids lessened the decrease in DBS. Compared with tensile stress application, the influence of compressive stress on the DBS of GFRPs was very small.<>
{"title":"Dielectric breakdown strength of GFRPs under mechanical stresses in cryogenic liquids","authors":"K. Fukushi, M. Nagai, Y. Kamata","doi":"10.1109/CEIDP.1989.69591","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69591","url":null,"abstract":"The dielectric strength of GFRPs (glass-fiber-reinforced plastics) under combined application of electrical and mechanical stresses was investigated in liquid He, liquid N/sub 2/, and silicone oil at room temperature. With the combined application of tensile and electrical stresses in cryogenic liquids, the dielectric breakdown of GFRPs occurred prior to mechanical breakdown when the applied electrical stress was lower than the DBS (dielectric breakdown strength) of GFRPs without tensile stress. In the case of tensile stress application under constantly applied electrical stress, the DBS and GFRPs decreased markedly. The reason for the large DBS decrease of GFRPs was the occurrence of microcracks in matrix resins because of their brittleness at cryogenic temperatures. Combining GFRP with polyimide film in cryogenic liquids lessened the decrease in DBS. Compared with tensile stress application, the influence of compressive stress on the DBS of GFRPs was very small.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"58 1","pages":"471-476"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86967381","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 : 1989-10-29DOI: 10.1109/CEIDP.1989.69582
L. Hatfield, E. R. Boerwinkle
Measurements of the SEEC (secondary electron emission coefficient) on samples of Lucite and Lexan cut from commercially available bar stock exhibit large variations from sample to sample. This scatter is too large to be explained by experimental uncertainties. It is proposed that the sample surfaces really are different due to the inhomogeneous bar stock. Techniques exist for measuring the density and composition of the polymers and it is suggested that these should be applied to the surface of these samples. The problem is not trivial, however, because the SEEC measurements probe only a thin surface layer. Therefore, the surface density, composition, and structure must be analyzed using techniques which also probe only a thin layer, such as X-ray photoelectron spectroscopy.<>
{"title":"Secondary electron emission from a thin coating on Lucite and Lexan substrates","authors":"L. Hatfield, E. R. Boerwinkle","doi":"10.1109/CEIDP.1989.69582","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69582","url":null,"abstract":"Measurements of the SEEC (secondary electron emission coefficient) on samples of Lucite and Lexan cut from commercially available bar stock exhibit large variations from sample to sample. This scatter is too large to be explained by experimental uncertainties. It is proposed that the sample surfaces really are different due to the inhomogeneous bar stock. Techniques exist for measuring the density and composition of the polymers and it is suggested that these should be applied to the surface of these samples. The problem is not trivial, however, because the SEEC measurements probe only a thin surface layer. Therefore, the surface density, composition, and structure must be analyzed using techniques which also probe only a thin layer, such as X-ray photoelectron spectroscopy.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"100 1","pages":"414-421"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90307941","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 : 1989-10-29DOI: 10.1109/CEIDP.1989.69537
L. Dascalescu, A. Iuga, R. Morar, A. Ifrim
Two sets of corona-discharge electrodes, wire and needle type, have been tested on laboratory electroseparators. As compared to needle-type electrodes, the wire-type ones are characterized by: (i) a larger possibility of adjusting the parameters which determine the field in the active zone of the separator; (ii) a less complicated manufacturing technology; and (iii) smaller quantities of ozone generated during corona discharge. Needle-type electrodes, on the other hand, have at least three favorable characteristics: (i) not being affected by vibrations; (ii) lower corona voltages; and (iii) higher slopes of V-A digrams (which means an increased corona effect). Based on these facts, the authors have used this kind of electrode with the ELSIM-2 insulation-metal electroseparator. Pilot-plant tests of electroseparation were effected on chopped PVC-insulated copper wire scrap and on a mica-feldspar-quartz mixture, using various field configurations, to validate the efficacy of the design. High-purity electroinsulating materials were obtained and then incorporated into different types of electrical insulation.<>
{"title":"Corona-discharge electrodes for improved electrostatic separation of electroinsulating materials","authors":"L. Dascalescu, A. Iuga, R. Morar, A. Ifrim","doi":"10.1109/CEIDP.1989.69537","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69537","url":null,"abstract":"Two sets of corona-discharge electrodes, wire and needle type, have been tested on laboratory electroseparators. As compared to needle-type electrodes, the wire-type ones are characterized by: (i) a larger possibility of adjusting the parameters which determine the field in the active zone of the separator; (ii) a less complicated manufacturing technology; and (iii) smaller quantities of ozone generated during corona discharge. Needle-type electrodes, on the other hand, have at least three favorable characteristics: (i) not being affected by vibrations; (ii) lower corona voltages; and (iii) higher slopes of V-A digrams (which means an increased corona effect). Based on these facts, the authors have used this kind of electrode with the ELSIM-2 insulation-metal electroseparator. Pilot-plant tests of electroseparation were effected on chopped PVC-insulated copper wire scrap and on a mica-feldspar-quartz mixture, using various field configurations, to validate the efficacy of the design. High-purity electroinsulating materials were obtained and then incorporated into different types of electrical insulation.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"1 1","pages":"143-148"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86688283","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 : 1989-10-29DOI: 10.1109/CEIDP.1989.69550
D. Das-Gupta, J. Densley
The authors report preliminary results of a polarization study using thermally stimulated discharge current (TSDC) measurements and the thermal current transient technique on XLPE (cross-linked polyethylene) samples in which water trees have been grown. A schematic representation of the observed current transients at the onset or removal of a step input of thermal radiation is shown. Values of the peak thermal transient current I/sub p/ of control samples and aged samples after poling at 6.14*10/sup 6/ Vm/sup -1/ and after the TSDC runs are given. It may be observed that the I/sub p/ value increases by two orders of magnitude after aging of 472.2 h followed by a DC poling at a field of 6.14*10/sup 6/ Vm/sup -1/. In addition, the TSDC spectra for (unaged) control samples and samples in which water trees have been grown are shown. It is observed that the dominant TSDC peak at 80 degrees C increases significantly for samples with increasing aging time.<>
{"title":"Polarization phenomena in cross-linked polyethylene (XLPE) containing water-trees","authors":"D. Das-Gupta, J. Densley","doi":"10.1109/CEIDP.1989.69550","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69550","url":null,"abstract":"The authors report preliminary results of a polarization study using thermally stimulated discharge current (TSDC) measurements and the thermal current transient technique on XLPE (cross-linked polyethylene) samples in which water trees have been grown. A schematic representation of the observed current transients at the onset or removal of a step input of thermal radiation is shown. Values of the peak thermal transient current I/sub p/ of control samples and aged samples after poling at 6.14*10/sup 6/ Vm/sup -1/ and after the TSDC runs are given. It may be observed that the I/sub p/ value increases by two orders of magnitude after aging of 472.2 h followed by a DC poling at a field of 6.14*10/sup 6/ Vm/sup -1/. In addition, the TSDC spectra for (unaged) control samples and samples in which water trees have been grown are shown. It is observed that the dominant TSDC peak at 80 degrees C increases significantly for samples with increasing aging time.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"4612 1 1","pages":"224-229"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86887326","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 : 1989-10-29DOI: 10.1109/CEIDP.1989.69564
T. Mizutani, Y. Suzuoki, T. Furuta, M. Ieda, T. Suzuki
The space charge behavior in PE (polyethylene) was investigated using the laser-induced pressure pulse (LIPP) technique and the piezoelectrically induced pressure step (PIPS) wave technique. Specimens used were 25- mu m-thick films and 0.6- and 1-mm-thick plates of low-density PE nominally free from additives. The LIPP measurement was carried out on a spectrum which was polarized at 333 K for 15 min and subsequently short-circuited at room temperature. The PIPS measurement was carried out on a 25- mu m-thick specimen under an applied field. Positive space charge was found to exist in the PE bulk, and negative space charge due to electron injection was dominant at high fields. Oxidation of PE was found to enhance electron and hole injection.<>
{"title":"Direct observation of space charge distribution in polyethylene","authors":"T. Mizutani, Y. Suzuoki, T. Furuta, M. Ieda, T. Suzuki","doi":"10.1109/CEIDP.1989.69564","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69564","url":null,"abstract":"The space charge behavior in PE (polyethylene) was investigated using the laser-induced pressure pulse (LIPP) technique and the piezoelectrically induced pressure step (PIPS) wave technique. Specimens used were 25- mu m-thick films and 0.6- and 1-mm-thick plates of low-density PE nominally free from additives. The LIPP measurement was carried out on a spectrum which was polarized at 333 K for 15 min and subsequently short-circuited at room temperature. The PIPS measurement was carried out on a 25- mu m-thick specimen under an applied field. Positive space charge was found to exist in the PE bulk, and negative space charge due to electron injection was dominant at high fields. Oxidation of PE was found to enhance electron and hole injection.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"45 1","pages":"309-314"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85866841","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 : 1989-10-29DOI: 10.1109/CEIDP.1989.69562
S. Mahdavi, C. Alquié, J. Lewiner
The authors present direct measurements of charge distributions in coaxial cables conducted during the application of a high voltage, using the pressure wave propagation (PWP) method. It is shown that, as could be expected, the main effects take place near the inner electrode, where the applied electric field is the largest. Near this electrode, charges are transferred which lead to the creation of homocharges and to a decrease of the interfacial electric field. Heterocharges build up with time and compensate the effect of the homocharges on this electric field. A stabilized state is reached at 50 degrees C after approximately 120 hours. Heterocharges of two types have been observed, some localized very close to the inner electrode, the others extending over a quarter of the insulator. The origin of the first type can be attributed to the diffusion in the insulator of impurities present in the inner semiconducting electrode impurities dissociated by the local electric field. These results demonstrate that the PWP method can be applied to the study of high-voltage cables.<>
{"title":"Measurement of charge distributions in coaxial structures-application to high voltage cables","authors":"S. Mahdavi, C. Alquié, J. Lewiner","doi":"10.1109/CEIDP.1989.69562","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69562","url":null,"abstract":"The authors present direct measurements of charge distributions in coaxial cables conducted during the application of a high voltage, using the pressure wave propagation (PWP) method. It is shown that, as could be expected, the main effects take place near the inner electrode, where the applied electric field is the largest. Near this electrode, charges are transferred which lead to the creation of homocharges and to a decrease of the interfacial electric field. Heterocharges build up with time and compensate the effect of the homocharges on this electric field. A stabilized state is reached at 50 degrees C after approximately 120 hours. Heterocharges of two types have been observed, some localized very close to the inner electrode, the others extending over a quarter of the insulator. The origin of the first type can be attributed to the diffusion in the insulator of impurities present in the inner semiconducting electrode impurities dissociated by the local electric field. These results demonstrate that the PWP method can be applied to the study of high-voltage cables.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"222 1","pages":"296-302"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86393915","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 : 1989-10-29DOI: 10.1109/CEIDP.1989.69554
H. Muto, S. Bamji, A. Bulinski, R. Densley
The authors report a study of a possible relationship between oxidation and water tree growth in laboratory-molded polyethylene under controlled conditions. To accelerate the oxidation which might occur during growth, a test series was performed at 75 degrees C in addition to room temperature. After aging for preset times, specimens were removed and microtomed into 0.5-mm slices, and the insulation was checked for water trees with a microscope. The specimens were then dried for 20 h at 40 degrees C under vacuum, and the oxidation level was measured by FTIR (Fourier transform infrared) spectroscopy coupled to an infrared microscope. Similar oxidation levels of treed and nontreed regions of insulation aged at room temperature indicate that oxidation is not required for the water tree growth. However, the tests at 75 degrees C show that treed regions oxidize more rapidly at higher temperatures. This may be due to the contaminants in the trees acting as catalysts for oxidation.<>
{"title":"A study of oxidation and water treeing in polyethylene","authors":"H. Muto, S. Bamji, A. Bulinski, R. Densley","doi":"10.1109/CEIDP.1989.69554","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69554","url":null,"abstract":"The authors report a study of a possible relationship between oxidation and water tree growth in laboratory-molded polyethylene under controlled conditions. To accelerate the oxidation which might occur during growth, a test series was performed at 75 degrees C in addition to room temperature. After aging for preset times, specimens were removed and microtomed into 0.5-mm slices, and the insulation was checked for water trees with a microscope. The specimens were then dried for 20 h at 40 degrees C under vacuum, and the oxidation level was measured by FTIR (Fourier transform infrared) spectroscopy coupled to an infrared microscope. Similar oxidation levels of treed and nontreed regions of insulation aged at room temperature indicate that oxidation is not required for the water tree growth. However, the tests at 75 degrees C show that treed regions oxidize more rapidly at higher temperatures. This may be due to the contaminants in the trees acting as catalysts for oxidation.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"1 1","pages":"247-252"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79859010","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 : 1989-10-29DOI: 10.1109/CEIDP.1989.69575
S. Yen, L. Lowry, C. Bankston, V. Capozzi
A reflective X-ray diffraction method developed to determine the absolute X/sub c/ (crystallinity) of UX and BX (uniaxially and biaxially oriented) PC (polycarbonate) film is described. Conditions for achieving optimum properties for producing BX high-X/sub c/ and isotropic PC film were found. For BX PC film of identical thickness to UX PC film the electric breakdown strength was found to be proportional to X/sub c/. The thermal and mechanical properties as well as the direct-current electric breakdown strengths of the newly developed isotropic high-X/sub c/ BX PC film are compared with those of the anisotropic commercial PC capacitor film. Capacitors made from the high-X/sub c/ isotropic BX PC film when subjected to a 1000-hour 100 degrees C, 42-V DC life test showed no change in dissipation factor and no change in capacitance, and they met 100 degrees C insulation resistance test requirements. In general, it is concluded that this novel BX PC film is much superior to the traditional UX commercial capacitor PC film.<>
{"title":"Morphology and dielectric properties of uniaxially and biaxially-oriented polycarbonate capacitor films","authors":"S. Yen, L. Lowry, C. Bankston, V. Capozzi","doi":"10.1109/CEIDP.1989.69575","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69575","url":null,"abstract":"A reflective X-ray diffraction method developed to determine the absolute X/sub c/ (crystallinity) of UX and BX (uniaxially and biaxially oriented) PC (polycarbonate) film is described. Conditions for achieving optimum properties for producing BX high-X/sub c/ and isotropic PC film were found. For BX PC film of identical thickness to UX PC film the electric breakdown strength was found to be proportional to X/sub c/. The thermal and mechanical properties as well as the direct-current electric breakdown strengths of the newly developed isotropic high-X/sub c/ BX PC film are compared with those of the anisotropic commercial PC capacitor film. Capacitors made from the high-X/sub c/ isotropic BX PC film when subjected to a 1000-hour 100 degrees C, 42-V DC life test showed no change in dissipation factor and no change in capacitance, and they met 100 degrees C insulation resistance test requirements. In general, it is concluded that this novel BX PC film is much superior to the traditional UX commercial capacitor PC film.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"14 1","pages":"375-383"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77744237","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 : 1989-10-29DOI: 10.1109/CEIDP.1989.69556
K. Kudo
The polarity effect of the impulse tree inception and complete breakdown (puncture) of low-density polyethylene is described as a function of the radius of the needle tip. Furthermore, the morphology of the impulse tree and breakdown channels is examined. It is shown that the puncture field strength E/sub b/ for both polarities is about 6 MV/cm at 500 mu m and is of the same order as the intrinsic breakdown strength of low-density polyethylene. The shapes of impulse tree and breakdown channels for both polarities are shown for varying tip radius and gap distance. Although the E/sub b/ obtained has almost the same value as the intrinsic breakdown strength at larger tip radii, it can be seen that the morphologies of the breakdown channels for the two polarities are different. Especially at larger tip radii, the difference of the morphology is remarkable. One explanation for this difference may be the high-density gaseous plasma and the joule heating in the tree channels.<>
{"title":"Impulse treeing breakdown in polyethylene under non-uniform and quasi-uniform fields","authors":"K. Kudo","doi":"10.1109/CEIDP.1989.69556","DOIUrl":"https://doi.org/10.1109/CEIDP.1989.69556","url":null,"abstract":"The polarity effect of the impulse tree inception and complete breakdown (puncture) of low-density polyethylene is described as a function of the radius of the needle tip. Furthermore, the morphology of the impulse tree and breakdown channels is examined. It is shown that the puncture field strength E/sub b/ for both polarities is about 6 MV/cm at 500 mu m and is of the same order as the intrinsic breakdown strength of low-density polyethylene. The shapes of impulse tree and breakdown channels for both polarities are shown for varying tip radius and gap distance. Although the E/sub b/ obtained has almost the same value as the intrinsic breakdown strength at larger tip radii, it can be seen that the morphologies of the breakdown channels for the two polarities are different. Especially at larger tip radii, the difference of the morphology is remarkable. One explanation for this difference may be the high-density gaseous plasma and the joule heating in the tree channels.<<ETX>>","PeriodicalId":10719,"journal":{"name":"Conference on Electrical Insulation and Dielectric Phenomena,","volume":"43 1","pages":"259-264"},"PeriodicalIF":0.0,"publicationDate":"1989-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78552471","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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