Pub Date : 1975-11-01DOI: 10.1109/CEIDP.1975.7736663
E. Franke, E. Czekaj
High voltage dc is applied to the center conductor of submarine telecommunication coaxial cables to power evenly spaced amplifiers.1 Typical systems installed thus far have powering voltages between 3 and 6 kV, with the outer conductor in contact with sea water. Although no problems with tree growth in the polyethylene insulation have been encountered, new systems presently planned will require higher terminal voltages. In order to ensure the continued high reliability of submarine cable systems, an investigation of possible water tree growth in the polyethylene cabe core was initiated. It had been assumed that water trees do not grow with direct current.2,3 Based on our initial experiments, it appears that water trees do indeed initiate and grow with dc electrical stress, but at a much slower rate than with ac.
{"title":"Water tree growth in polyethylene with direct current","authors":"E. Franke, E. Czekaj","doi":"10.1109/CEIDP.1975.7736663","DOIUrl":"https://doi.org/10.1109/CEIDP.1975.7736663","url":null,"abstract":"High voltage dc is applied to the center conductor of submarine telecommunication coaxial cables to power evenly spaced amplifiers.1 Typical systems installed thus far have powering voltages between 3 and 6 kV, with the outer conductor in contact with sea water. Although no problems with tree growth in the polyethylene insulation have been encountered, new systems presently planned will require higher terminal voltages. In order to ensure the continued high reliability of submarine cable systems, an investigation of possible water tree growth in the polyethylene cabe core was initiated. It had been assumed that water trees do not grow with direct current.2,3 Based on our initial experiments, it appears that water trees do indeed initiate and grow with dc electrical stress, but at a much slower rate than with ac.","PeriodicalId":121906,"journal":{"name":"Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1975","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116897333","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 : 1975-11-01DOI: 10.1109/CEIDP.1975.7736667
R. Patsch
Encouraged by economic considerations, great efforts have been undertaken in the last decade to improve solid-state hv cable insulations. A multitude of additives was examined with the aim of upgrading the electric strength of polyethylene commonly used for hv cables. Hundreds of laboratory tests, mainly based on a method proposed by Kitchin and Pratt,1 were carried out; but most additives which increased tree inception voltage were not successful in experiments with full size or prototype cables. This is often due to the fact that in a remote ground electrode arrangement or flat brick-shaped specimen (often preferred to ascertain tree inception by optical observation) the correlation between test voltage and field strength at the needle tip may be influenced by the surface conductivity of the polymer. Additives increasing the surface conductivity of the examined polymer over a critical value depending on the geometry of the specimen and the properties of the embedding fluid may make the electric field between needle tip and the opposite electrode more uniform. Hence the field enhancement at the needle tip is decreased and the critical field strength leading to tree initiation can only be attained at higher test voltages.2
{"title":"Breakdown of polymer: Tree initiation and growth","authors":"R. Patsch","doi":"10.1109/CEIDP.1975.7736667","DOIUrl":"https://doi.org/10.1109/CEIDP.1975.7736667","url":null,"abstract":"Encouraged by economic considerations, great efforts have been undertaken in the last decade to improve solid-state hv cable insulations. A multitude of additives was examined with the aim of upgrading the electric strength of polyethylene commonly used for hv cables. Hundreds of laboratory tests, mainly based on a method proposed by Kitchin and Pratt,1 were carried out; but most additives which increased tree inception voltage were not successful in experiments with full size or prototype cables. This is often due to the fact that in a remote ground electrode arrangement or flat brick-shaped specimen (often preferred to ascertain tree inception by optical observation) the correlation between test voltage and field strength at the needle tip may be influenced by the surface conductivity of the polymer. Additives increasing the surface conductivity of the examined polymer over a critical value depending on the geometry of the specimen and the properties of the embedding fluid may make the electric field between needle tip and the opposite electrode more uniform. Hence the field enhancement at the needle tip is decreased and the critical field strength leading to tree initiation can only be attained at higher test voltages.2","PeriodicalId":121906,"journal":{"name":"Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1975","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125958280","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 : 1975-11-01DOI: 10.1109/CEIDP.1975.7736632
S. Carr
Persistent electrical polarizations can be established in most polymer films by poling at elevated temperatures. A variety of contributions are now known to make major contributions to this polarization; these include preferred orientation of dipolar groups, asymmetrically displaced ionized species, asymmetrically distributed charged groups created in the polymer molecules themselves, and ions injected from external sources into the polymer solid. As long as characteristic times associated with relaxation of these electrical anisotropies are long compared with the observation period, then the material will effectively retain whatever is the net polarization. It follows, then, that heating these materials will quicken these relaxation processes, and one can stimulate the discharge of these polarizations thermally. Analysis of the temperature-dependence of the overall depolarization of such a polymer specimen will usually reveal that the various contributions to total polarization discharge more or less individually. Some discharge steps will display Arrhenius-type kinetics, corresponding to simple solid state diffusional transport or to the onset of mobility of small groups of atoms in polymer chains; other discharge steps may display WLF-type kinetics, implying that the depolarization event requires mobility of whole segments of polymer backbones.
{"title":"Non-uniformities of electrical polarization in polyacrylonitrile films","authors":"S. Carr","doi":"10.1109/CEIDP.1975.7736632","DOIUrl":"https://doi.org/10.1109/CEIDP.1975.7736632","url":null,"abstract":"Persistent electrical polarizations can be established in most polymer films by poling at elevated temperatures. A variety of contributions are now known to make major contributions to this polarization; these include preferred orientation of dipolar groups, asymmetrically displaced ionized species, asymmetrically distributed charged groups created in the polymer molecules themselves, and ions injected from external sources into the polymer solid. As long as characteristic times associated with relaxation of these electrical anisotropies are long compared with the observation period, then the material will effectively retain whatever is the net polarization. It follows, then, that heating these materials will quicken these relaxation processes, and one can stimulate the discharge of these polarizations thermally. Analysis of the temperature-dependence of the overall depolarization of such a polymer specimen will usually reveal that the various contributions to total polarization discharge more or less individually. Some discharge steps will display Arrhenius-type kinetics, corresponding to simple solid state diffusional transport or to the onset of mobility of small groups of atoms in polymer chains; other discharge steps may display WLF-type kinetics, implying that the depolarization event requires mobility of whole segments of polymer backbones.","PeriodicalId":121906,"journal":{"name":"Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1975","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116823019","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 : 1975-11-01DOI: 10.1109/CEIDP.1975.7736648
C. King, R. A. Thomas
Most dielectric loss measurements are made by using a capacitance bridge. Bridge methods however require standard capacitors. These capacitors have dielectric loss tangents of about 10−5 and loss tangents smaller than this cannot easily be measured with bridge techniques. Furthermore, the measurement is a relative rather than an absolute one, and thus its precision is dependent on how precisely the loss of the standard capacitor is known.1
{"title":"The calorimetric measurement of low temperature dielectric loss","authors":"C. King, R. A. Thomas","doi":"10.1109/CEIDP.1975.7736648","DOIUrl":"https://doi.org/10.1109/CEIDP.1975.7736648","url":null,"abstract":"Most dielectric loss measurements are made by using a capacitance bridge. Bridge methods however require standard capacitors. These capacitors have dielectric loss tangents of about 10−5 and loss tangents smaller than this cannot easily be measured with bridge techniques. Furthermore, the measurement is a relative rather than an absolute one, and thus its precision is dependent on how precisely the loss of the standard capacitor is known.1","PeriodicalId":121906,"journal":{"name":"Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1975","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114553754","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 : 1975-11-01DOI: 10.1109/CEIDP.1975.7736666
Y. Yamada, S. Yamanouchi, S. Miyamoto
Electrical defects in cross-linked polyethylene insulated cables (XLPE cable) such as voids and contaminants in XLPE or characteristics of XLPE such as crystallinity and microporosity have been investigated in relation to the electrical characteristics of XLPE cable. Very small defects which can be observed with a microscope are being investigated. The authors studied the relation between the ac breakdown strength of XLPE cables and the void size in XLPE insulation considering the discharge inception in the voids.
{"title":"The relation between voids in XLPE insulation and electrical breakdown strength of XLPE insulated cables","authors":"Y. Yamada, S. Yamanouchi, S. Miyamoto","doi":"10.1109/CEIDP.1975.7736666","DOIUrl":"https://doi.org/10.1109/CEIDP.1975.7736666","url":null,"abstract":"Electrical defects in cross-linked polyethylene insulated cables (XLPE cable) such as voids and contaminants in XLPE or characteristics of XLPE such as crystallinity and microporosity have been investigated in relation to the electrical characteristics of XLPE cable. Very small defects which can be observed with a microscope are being investigated. The authors studied the relation between the ac breakdown strength of XLPE cables and the void size in XLPE insulation considering the discharge inception in the voids.","PeriodicalId":121906,"journal":{"name":"Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1975","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130095376","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 : 1975-11-01DOI: 10.1109/CEIDP.1975.7736677
R. Coelho
If a semi-insulating layer is placed in a transverse conductivity gradient, the continuity of the steady-state current density implies the existence of a distortion of the otherwise uniform electric field, and consequently the presence of a space-charge distribution in the sample. This is a classical problem, and its solution is elementary, provided that the material conductivity is a true conductivity, namely is independent of the electric field.
{"title":"Theory of the space-charge buildup and current transient in a semi-insulating layer with a conductivity gradient","authors":"R. Coelho","doi":"10.1109/CEIDP.1975.7736677","DOIUrl":"https://doi.org/10.1109/CEIDP.1975.7736677","url":null,"abstract":"If a semi-insulating layer is placed in a transverse conductivity gradient, the continuity of the steady-state current density implies the existence of a distortion of the otherwise uniform electric field, and consequently the presence of a space-charge distribution in the sample. This is a classical problem, and its solution is elementary, provided that the material conductivity is a true conductivity, namely is independent of the electric field.","PeriodicalId":121906,"journal":{"name":"Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1975","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115477308","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 : 1975-11-01DOI: 10.1109/CEIDP.1975.7736629
T. J. Sonnonstine, M. Perlman
In the search for new materials useful in electrophotography, it has been recognized that there are photoconducting insulators whose charge transport properties are governed by a drift mobility that is not constant, but varies with electric field. The most prominent of these materials is the organic polymer poly-N-vinyl-carbazole (PVK)1 and its complexes with organic electron acceptors such as 2, 4, 7-trinitro-9-fluorenone (TNF).2 Further, there is increasing evidence that the drift mobility in materials as varied as polyethylene3 and Ge(Li)4 depends on electric field.
{"title":"Xerographic discharge in insulators with Poole-Frenkel drift mobility","authors":"T. J. Sonnonstine, M. Perlman","doi":"10.1109/CEIDP.1975.7736629","DOIUrl":"https://doi.org/10.1109/CEIDP.1975.7736629","url":null,"abstract":"In the search for new materials useful in electrophotography, it has been recognized that there are photoconducting insulators whose charge transport properties are governed by a drift mobility that is not constant, but varies with electric field. The most prominent of these materials is the organic polymer poly-N-vinyl-carbazole (PVK)1 and its complexes with organic electron acceptors such as 2, 4, 7-trinitro-9-fluorenone (TNF).2 Further, there is increasing evidence that the drift mobility in materials as varied as polyethylene3 and Ge(Li)4 depends on electric field.","PeriodicalId":121906,"journal":{"name":"Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1975","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124503530","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 : 1975-11-01DOI: 10.1109/CEIDP.1975.7736643
K. Mathes, T. O. Rouse
For some time a needle-to-sphere impulse breakdown test (ASTM D-3300) has been used for characterization of insulating oils used in high voltage equipment. Several observations can be made based upon a long background of use with this test.
{"title":"Influence of aromatic compounds in oil on pirelli gassing and impulse surge breakdown","authors":"K. Mathes, T. O. Rouse","doi":"10.1109/CEIDP.1975.7736643","DOIUrl":"https://doi.org/10.1109/CEIDP.1975.7736643","url":null,"abstract":"For some time a needle-to-sphere impulse breakdown test (ASTM D-3300) has been used for characterization of insulating oils used in high voltage equipment. Several observations can be made based upon a long background of use with this test.","PeriodicalId":121906,"journal":{"name":"Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1975","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128541051","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 : 1975-11-01DOI: 10.1109/CEIDP.1975.7736679
J. Burnham, J. Mosher
The Hughes Phoenix radar transmitter uses a liquid dielectric as a coolant. In order to withstand the high temperatures in the transmitter, a silicate ester (the ester of silica acid and 2-ethyl butanol) has been chosen. One of the disadvantages of this liquid is the degradation products caused by contaminants such as water, organic acids, and inorganic salts. Since the radar systems may be repaired aboard an aircraft carrier, contamination of the liquid dielectric coolant is likely and it is important to monitor the concentrations of these contaminants. This is particularly true for the high voltage radar transmitter. The amount of ionizable contaminant is measured by monitoring the volume resistivity of the coolant. The water content of the coolant is measured by an electronic water sensor.
{"title":"The measurement of water content of silicate ester dielectric fluids by electronic means","authors":"J. Burnham, J. Mosher","doi":"10.1109/CEIDP.1975.7736679","DOIUrl":"https://doi.org/10.1109/CEIDP.1975.7736679","url":null,"abstract":"The Hughes Phoenix radar transmitter uses a liquid dielectric as a coolant. In order to withstand the high temperatures in the transmitter, a silicate ester (the ester of silica acid and 2-ethyl butanol) has been chosen. One of the disadvantages of this liquid is the degradation products caused by contaminants such as water, organic acids, and inorganic salts. Since the radar systems may be repaired aboard an aircraft carrier, contamination of the liquid dielectric coolant is likely and it is important to monitor the concentrations of these contaminants. This is particularly true for the high voltage radar transmitter. The amount of ionizable contaminant is measured by monitoring the volume resistivity of the coolant. The water content of the coolant is measured by an electronic water sensor.","PeriodicalId":121906,"journal":{"name":"Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1975","volume":"1997 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116685092","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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