Pub Date : 1988-10-16DOI: 10.1109/CEIDP.1988.26322
W. Yin, H. Zhang
The steady photocurrents of polyimide (PI) film samples were measured. It is shown that the dark currents of PI films vary with drawing ratios, but their steady photocurrents are almost the same. In addition, the decay curves of the photocurrents change significantly with drawing ratios. It is suggested that the variation of structure during drawing or stretching may give rise to the variation of the trap structures which affect carrier transport in drawn PI films. The method of photostimulated current is used to study the variation of trap depth resulting from stretching of drawn PI films. The effect of line intensity on photoconductivity is also investigated.<>
{"title":"Photoelectrical properties of oriented polyimide films","authors":"W. Yin, H. Zhang","doi":"10.1109/CEIDP.1988.26322","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26322","url":null,"abstract":"The steady photocurrents of polyimide (PI) film samples were measured. It is shown that the dark currents of PI films vary with drawing ratios, but their steady photocurrents are almost the same. In addition, the decay curves of the photocurrents change significantly with drawing ratios. It is suggested that the variation of structure during drawing or stretching may give rise to the variation of the trap structures which affect carrier transport in drawn PI films. The method of photostimulated current is used to study the variation of trap depth resulting from stretching of drawn PI films. The effect of line intensity on photoconductivity is also investigated.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133692994","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 : 1988-10-16DOI: 10.1109/CEIDP.1988.26374
B. Crichton, R. Fouracre, M. Given
The authors consider a theoretical model describing the migration of ions in a solid dielectric under the influence of an applied AC stress. In this model, it is considered that ionic motion is a hopping process between adjacent ion-trapping sites and that an ion experiences changes in its potential energy as it moves through the solid. The general model shows that in a solid where there exists a flux of ions driven by a local gradient in the concentration the application of an AC field will enhance any component of this which is parallel to the field, irrespective of the polarity of the ionic charge. Furthermore, if the applied field is nonuniform then the model shows that there will be an additional component of the flux of ions in the direction of decreasing field strength. The authors consider the practical case where the concentration gradient, the applied field, and the field gradient are all parallel.<>
{"title":"Some considerations of the enhancement of ion migration in polymers under AC stress","authors":"B. Crichton, R. Fouracre, M. Given","doi":"10.1109/CEIDP.1988.26374","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26374","url":null,"abstract":"The authors consider a theoretical model describing the migration of ions in a solid dielectric under the influence of an applied AC stress. In this model, it is considered that ionic motion is a hopping process between adjacent ion-trapping sites and that an ion experiences changes in its potential energy as it moves through the solid. The general model shows that in a solid where there exists a flux of ions driven by a local gradient in the concentration the application of an AC field will enhance any component of this which is parallel to the field, irrespective of the polarity of the ionic charge. Furthermore, if the applied field is nonuniform then the model shows that there will be an additional component of the flux of ions in the direction of decreasing field strength. The authors consider the practical case where the concentration gradient, the applied field, and the field gradient are all parallel.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133685893","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 : 1988-10-16DOI: 10.1109/CEIDP.1988.26321
M. Ishii, M. Komatsubara
The contact angle and the time for a water film to be formed on a surface are measured to investigate the hydrophobicity of UV (ultraviolet) irradiated materials. Ethylene propylene rubber and silicone rubber, both commonly used for graphic organic insulators, were adopted as specimens. For comparison, polyethylene and polymethylmethacrylate were also tested. The correlation between UV irradiation time and the time to the formation of a water film under fog is shown. It is found that the contact angle is closely related to the formation of a conductive film on a surface. It is concluded that the measurement of the contact angle seems to be an effective method to evaluate the hydrophobicity of materials in spite of its simplicity.<>
{"title":"Hydrophobicity of organic insulating materials","authors":"M. Ishii, M. Komatsubara","doi":"10.1109/CEIDP.1988.26321","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26321","url":null,"abstract":"The contact angle and the time for a water film to be formed on a surface are measured to investigate the hydrophobicity of UV (ultraviolet) irradiated materials. Ethylene propylene rubber and silicone rubber, both commonly used for graphic organic insulators, were adopted as specimens. For comparison, polyethylene and polymethylmethacrylate were also tested. The correlation between UV irradiation time and the time to the formation of a water film under fog is shown. It is found that the contact angle is closely related to the formation of a conductive film on a surface. It is concluded that the measurement of the contact angle seems to be an effective method to evaluate the hydrophobicity of materials in spite of its simplicity.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"147 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122150369","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 : 1988-10-16DOI: 10.1109/CEIDP.1988.26353
B. S. Manjunath, K. Dwarakanath, K.S. Arunachala Sastry, K. Ravi
Experiments were conducted to determine the 50% flashover voltages (V/sub 50/) over the pressure range of 0.14 to 0.45 MPa absolute, using lightning (1.2/50 mu s) and switching (100/2500 mu s) impulse voltages, under uniform electric fields having two electrodes of Rogowski profile, with a gap spacing varying from 4 to 30 mm. Results indicate that the breakdown strength of SF/sub 6/ gas exhibits slight saturation at higher pressures (above 0.3 MPa). The effect is higher for switching surge voltages than for impulse voltages. The polarity effect is observed both under lightning and switching surge voltages and is more pronounced at higher gas pressures and larger gap spacings. The V/sub 50/ values with switching surge voltages are generally lower than the corresponding lightning impulse voltage values.<>
{"title":"Uniform field breakdown in SF/sub 6/ gas at high pressures under lightning and switching surge voltages","authors":"B. S. Manjunath, K. Dwarakanath, K.S. Arunachala Sastry, K. Ravi","doi":"10.1109/CEIDP.1988.26353","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26353","url":null,"abstract":"Experiments were conducted to determine the 50% flashover voltages (V/sub 50/) over the pressure range of 0.14 to 0.45 MPa absolute, using lightning (1.2/50 mu s) and switching (100/2500 mu s) impulse voltages, under uniform electric fields having two electrodes of Rogowski profile, with a gap spacing varying from 4 to 30 mm. Results indicate that the breakdown strength of SF/sub 6/ gas exhibits slight saturation at higher pressures (above 0.3 MPa). The effect is higher for switching surge voltages than for impulse voltages. The polarity effect is observed both under lightning and switching surge voltages and is more pronounced at higher gas pressures and larger gap spacings. The V/sub 50/ values with switching surge voltages are generally lower than the corresponding lightning impulse voltage values.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126003385","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 : 1988-10-16DOI: 10.1109/CEIDP.1988.26311
D.L. Adkins-Loree, M. Giesselmann, M. Kristiansen
Investigation of holdoff voltage behavior in axial magnetic fields was carried out on three types of ignitrons: a commercial metal-walled NL-2909 ignitron, a large glass-walled ignitron, and a custom-made, metal-walled, demountable ignitron. The NL-2909 and the demountable ignitron displayed profound reductions in their respective holdoff voltages dropping to less than 4% of their original value at relatively low axial magnetic fields. Furthermore, both of these tubes showed a very slow recovery toward full holdoff potential as the axial magnetic field was increased. However, the recovery of the NL-2909 was almost twice as fast as the recovery of the demountable ignitron. With an applied field, the holdoff voltage of the glass-walled tube dropped to around 30% of its original value. The magnetic field value at which the reduction took place was almost the required field of the demountable ignitron and over four times the field required by the NL-2909. The reduction of the breakdown voltage in the presence of an axial magnetic field is shown to be caused by the deflection of primary electrons of suitable energy into a cycloidal motion around the anode.<>
{"title":"Dielectric strength of high power ignitrons in axial magnetic fields","authors":"D.L. Adkins-Loree, M. Giesselmann, M. Kristiansen","doi":"10.1109/CEIDP.1988.26311","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26311","url":null,"abstract":"Investigation of holdoff voltage behavior in axial magnetic fields was carried out on three types of ignitrons: a commercial metal-walled NL-2909 ignitron, a large glass-walled ignitron, and a custom-made, metal-walled, demountable ignitron. The NL-2909 and the demountable ignitron displayed profound reductions in their respective holdoff voltages dropping to less than 4% of their original value at relatively low axial magnetic fields. Furthermore, both of these tubes showed a very slow recovery toward full holdoff potential as the axial magnetic field was increased. However, the recovery of the NL-2909 was almost twice as fast as the recovery of the demountable ignitron. With an applied field, the holdoff voltage of the glass-walled tube dropped to around 30% of its original value. The magnetic field value at which the reduction took place was almost the required field of the demountable ignitron and over four times the field required by the NL-2909. The reduction of the breakdown voltage in the presence of an axial magnetic field is shown to be caused by the deflection of primary electrons of suitable energy into a cycloidal motion around the anode.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"129 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129570010","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 : 1988-10-16DOI: 10.1109/CEIDP.1988.26325
F. Campbell, E.L. Brancato, A. Bruning
Summary form only given. Experimental and theoretical procedures used to study arc-induced tracking and pyrolysis of organic insulation are described. It is found that both energy and power level affect the results. The strong nonlinear arc resistance (voltage vs. current characteristic) leads to a theoretical and experimental result that contradicts conventional wisdom. It is found that power in the system with the insulation arc starts at minimum power with minimum practical circuit impedance, then increases to a local maximum as the impedance increases, and then decreases as the impedance is further increased. It is shown that the experimental damage severity correlates with this variation in power for the materials tested.<>
{"title":"Arc-induced tracking and pyrolysis of organic insulation","authors":"F. Campbell, E.L. Brancato, A. Bruning","doi":"10.1109/CEIDP.1988.26325","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26325","url":null,"abstract":"Summary form only given. Experimental and theoretical procedures used to study arc-induced tracking and pyrolysis of organic insulation are described. It is found that both energy and power level affect the results. The strong nonlinear arc resistance (voltage vs. current characteristic) leads to a theoretical and experimental result that contradicts conventional wisdom. It is found that power in the system with the insulation arc starts at minimum power with minimum practical circuit impedance, then increases to a local maximum as the impedance increases, and then decreases as the impedance is further increased. It is shown that the experimental damage severity correlates with this variation in power for the materials tested.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"349 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117070923","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 : 1988-10-16DOI: 10.1109/CEIDP.1988.26327
S. Aivaliotis, J. Chan, M. Hartley
The evaluation of commercially available standard and TR-XLPE (tree-retardant cross-linked polyethylene) to the 1987 standard was carried out. The results have been compared to accelerated aging data obtained from miniature cable tests and from extensive full-size cable tests based on the 1982 standard. It was demonstrated that the commercial TR-XLPE insulation exhibited a greater resistance to electrical voltage than the standard XLPE as evidenced by its higher retention of breakdown voltage with aging. Significantly fewer and smaller bow-tie trees were observed in the TR-XLPE. There appeared to be no significant difference in vented tree growth in the two materials.<>
{"title":"Accelerated aging of 15 kV cable insulated with standard and tree retardant XLPE","authors":"S. Aivaliotis, J. Chan, M. Hartley","doi":"10.1109/CEIDP.1988.26327","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26327","url":null,"abstract":"The evaluation of commercially available standard and TR-XLPE (tree-retardant cross-linked polyethylene) to the 1987 standard was carried out. The results have been compared to accelerated aging data obtained from miniature cable tests and from extensive full-size cable tests based on the 1982 standard. It was demonstrated that the commercial TR-XLPE insulation exhibited a greater resistance to electrical voltage than the standard XLPE as evidenced by its higher retention of breakdown voltage with aging. Significantly fewer and smaller bow-tie trees were observed in the TR-XLPE. There appeared to be no significant difference in vented tree growth in the two materials.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131394891","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 : 1988-10-16DOI: 10.1109/CEIDP.1988.26323
H. M. Banford, D. Tedford, M. Ayoubi
A measurement system was developed to carry out frequency domain dielectric spectroscopy and TSDC (thermally stimulated discharge currents) automatically on multiple samples which can be irradiated in helium over a wide temperature range from 5 to 300 K. The system was used to study the dielectric behavior of polyimide and low-density polyethylene (LDPE) as a function of temperature and gamma radiation. Measurements of loss in polyimide and LDPE gamma-irradiated at 5 K to doses of 10/sup 5/ Gy show no effects of radiation. A TSDC signal was observed for polyimide irradiated to 10/sup 5/ Gy. The small currents evident at low temperatures are probably due to geminate carriers, and there is a beta peak around 170 K.<>
{"title":"The dielectric behaviour of polymers irradiated at 5 K","authors":"H. M. Banford, D. Tedford, M. Ayoubi","doi":"10.1109/CEIDP.1988.26323","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26323","url":null,"abstract":"A measurement system was developed to carry out frequency domain dielectric spectroscopy and TSDC (thermally stimulated discharge currents) automatically on multiple samples which can be irradiated in helium over a wide temperature range from 5 to 300 K. The system was used to study the dielectric behavior of polyimide and low-density polyethylene (LDPE) as a function of temperature and gamma radiation. Measurements of loss in polyimide and LDPE gamma-irradiated at 5 K to doses of 10/sup 5/ Gy show no effects of radiation. A TSDC signal was observed for polyimide irradiated to 10/sup 5/ Gy. The small currents evident at low temperatures are probably due to geminate carriers, and there is a beta peak around 170 K.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121459053","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 : 1988-10-16DOI: 10.1109/CEIDP.1988.26359
M. Sadeghzadeh-Araghi, W. G. Chadband, P. Watson
A video camera and a video frame store were used to record negative discharge growth in liquid dielectrics. The initiation of the discharge and its transition through the instability region were investigated. Viscosity is shown to be an important parameter in liquid-dielectric breakdown. Highly viscous materials can be effectively immobile over the short times (several microseconds) involved in streamer initiation and growth, and it is found that discharges in such systems may show similarities to those observed in plastics.<>
{"title":"A study of initial negative discharge growth using video camera and frame store","authors":"M. Sadeghzadeh-Araghi, W. G. Chadband, P. Watson","doi":"10.1109/CEIDP.1988.26359","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26359","url":null,"abstract":"A video camera and a video frame store were used to record negative discharge growth in liquid dielectrics. The initiation of the discharge and its transition through the instability region were investigated. Viscosity is shown to be an important parameter in liquid-dielectric breakdown. Highly viscous materials can be effectively immobile over the short times (several microseconds) involved in streamer initiation and growth, and it is found that discharges in such systems may show similarities to those observed in plastics.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115368289","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 : 1988-10-16DOI: 10.1109/CEIDP.1988.26377
H. M. Banford, R. Fouracre, G. Chen, D. Tedford
Transient pulses or spikes of current under direct applied fields were observed in LDPE (low-density polyethylene) following gamma irradiation in ambient air to doses between 10/sup 4/ and 10/sup 6/ Gy. This pulse activity is a function of field strength, dose, and temperature. It is concluded that the origins of the pulses are probably either gas production or charge generation.<>
{"title":"Transient current pulses in gamma-irradiated polyethylene","authors":"H. M. Banford, R. Fouracre, G. Chen, D. Tedford","doi":"10.1109/CEIDP.1988.26377","DOIUrl":"https://doi.org/10.1109/CEIDP.1988.26377","url":null,"abstract":"Transient pulses or spikes of current under direct applied fields were observed in LDPE (low-density polyethylene) following gamma irradiation in ambient air to doses between 10/sup 4/ and 10/sup 6/ Gy. This pulse activity is a function of field strength, dose, and temperature. It is concluded that the origins of the pulses are probably either gas production or charge generation.<<ETX>>","PeriodicalId":149735,"journal":{"name":"1988. Annual Report., Conference on Electrical Insulation and Dielectric Phenomena","volume":"46 9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115577852","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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