Pub Date : 1982-06-07DOI: 10.1109/EIC.1982.7464453
R. Bozzo, G. Calci, P. Girdinio, P. Molfino, G. Molinari, A. Viviani
A model of impurity particle motion in a dielectric fluid under the action of an electric field, previously developed by some of the authors, is presented with the improvements suggested by both a larger amount of experimental data and the need of application to practical field configurations. A system for both computer-aided analysis of data obtained from high speed movie and electrical measurements about impurity particle motion and theoretical simulation of the phenomenon is presented, and some obtained results are displayed and discussed.
{"title":"A system for computer-aided theoretical and experimental analysis of impurity particle motion in dielectric liquids","authors":"R. Bozzo, G. Calci, P. Girdinio, P. Molfino, G. Molinari, A. Viviani","doi":"10.1109/EIC.1982.7464453","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464453","url":null,"abstract":"A model of impurity particle motion in a dielectric fluid under the action of an electric field, previously developed by some of the authors, is presented with the improvements suggested by both a larger amount of experimental data and the need of application to practical field configurations. A system for both computer-aided analysis of data obtained from high speed movie and electrical measurements about impurity particle motion and theoretical simulation of the phenomenon is presented, and some obtained results are displayed and discussed.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"7 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126847485","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464490
A. Bulinski, S. Bamji, J. Densley
The main points of the study reported in this paper are as follows: (i) The amount of moisture in XLPE does not affect the short term ac breakdown strength, provided the insulation is not subjected to electrical stress prior to the breakdown test. (ii) Preimmersing XLPE insulation in tap water prior to electrical aging at room temperature results in a reduction of more than 50% in the breakdown voltage. The preimmersion increases the moisture content, particularly liquid water at room temperature, resulting in increased degradation. (iii) Preimmersion does not have any effect on the breakdown voltage of cables electrically aged at 70°C or 90°C. (iv) For some aging conditions, the short term breakdown voltages of aged cables give no indication of the number of and times to breakdown of the cables during the electrical aging. (v) Direct voltage is quite sensitive to degradation of XLPE by the combined action of moisture and electric stress. Care must be exercised when dc testing aged cables in service. (vi) Complete drying of cables aged in water restores the breakdown voltage to its original value. The improvement is, however, only temporary and the breakdown voltage decreases at a faster rate when aging is continued. (vii) Temperature cycling of the insulation causes small changes in the short term ac breakdown voltage. However, the number of breakdowns occurring during the initial aging (1000 h) is much larger for the temperature cycled cable, indicating that temperature cycling could be an important variable in an accelerated aging test. Whether there is an optimum temperature change to produce maximum degradation still remains to be determined.
{"title":"The effects of moisture content, frequency and temperature on the life of miniature XLPE cables","authors":"A. Bulinski, S. Bamji, J. Densley","doi":"10.1109/EIC.1982.7464490","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464490","url":null,"abstract":"The main points of the study reported in this paper are as follows: (i) The amount of moisture in XLPE does not affect the short term ac breakdown strength, provided the insulation is not subjected to electrical stress prior to the breakdown test. (ii) Preimmersing XLPE insulation in tap water prior to electrical aging at room temperature results in a reduction of more than 50% in the breakdown voltage. The preimmersion increases the moisture content, particularly liquid water at room temperature, resulting in increased degradation. (iii) Preimmersion does not have any effect on the breakdown voltage of cables electrically aged at 70°C or 90°C. (iv) For some aging conditions, the short term breakdown voltages of aged cables give no indication of the number of and times to breakdown of the cables during the electrical aging. (v) Direct voltage is quite sensitive to degradation of XLPE by the combined action of moisture and electric stress. Care must be exercised when dc testing aged cables in service. (vi) Complete drying of cables aged in water restores the breakdown voltage to its original value. The improvement is, however, only temporary and the breakdown voltage decreases at a faster rate when aging is continued. (vii) Temperature cycling of the insulation causes small changes in the short term ac breakdown voltage. However, the number of breakdowns occurring during the initial aging (1000 h) is much larger for the temperature cycled cable, indicating that temperature cycling could be an important variable in an accelerated aging test. Whether there is an optimum temperature change to produce maximum degradation still remains to be determined.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121166881","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464439
W. K. Hogg, R. Miller, G. Rabach, D. Ryder
The methods of analysing the various individual partial discharge patterns using discriminating pulse amplitude techniques, in particular a multi-channel analyser (MCA) with several hundred pre-selected amplitude gates/channels, is in many instances a powerful method for assessing the relative quality of electrical insulating materials and systems to discharge attack.
{"title":"The relationship of partial discharge amplitude distributions with dielectric damage at different levels of voltage and frequency","authors":"W. K. Hogg, R. Miller, G. Rabach, D. Ryder","doi":"10.1109/EIC.1982.7464439","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464439","url":null,"abstract":"The methods of analysing the various individual partial discharge patterns using discriminating pulse amplitude techniques, in particular a multi-channel analyser (MCA) with several hundred pre-selected amplitude gates/channels, is in many instances a powerful method for assessing the relative quality of electrical insulating materials and systems to discharge attack.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"241 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133934943","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464450
C. Venkataseshaiah, C. N. Reddy, T. Eish
The results of experimental investigations on anomalous breakdown in polymethylmethacrylate (PMMA) immersed in transformer oil and subjected to switching surge voltages superimposed on direct voltage are reported in this paper. The anomalous breakdown voltage under such combined stresses was found to be much lower than that under direct voltage stresses alone. It is also affected by the relative polarities of the two voltages: When they are same, it increases considerably with increase in direct prestressing voltage; when they are opposite, it decreases a little. The polarity of the resultant applied voltage was also found to have effect on the distance of the anomalous breakdown location from the h.v. electrode. The duration of the superimposed switching surge (1.2/50 µs to 1000/10000 µs) also was found to affect the anomalous breakdown volt age. An attempt is made to explain such anomalous behaviour in modern solid synthetic insulating materials.
{"title":"Anomalous breakdown in PMMA under switching surges superimposed on direct voltage","authors":"C. Venkataseshaiah, C. N. Reddy, T. Eish","doi":"10.1109/EIC.1982.7464450","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464450","url":null,"abstract":"The results of experimental investigations on anomalous breakdown in polymethylmethacrylate (PMMA) immersed in transformer oil and subjected to switching surge voltages superimposed on direct voltage are reported in this paper. The anomalous breakdown voltage under such combined stresses was found to be much lower than that under direct voltage stresses alone. It is also affected by the relative polarities of the two voltages: When they are same, it increases considerably with increase in direct prestressing voltage; when they are opposite, it decreases a little. The polarity of the resultant applied voltage was also found to have effect on the distance of the anomalous breakdown location from the h.v. electrode. The duration of the superimposed switching surge (1.2/50 µs to 1000/10000 µs) also was found to affect the anomalous breakdown volt age. An attempt is made to explain such anomalous behaviour in modern solid synthetic insulating materials.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131670754","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464465
A. Hossam-eldin, A. M. Khalil
This paper reports recent investigations into the breakdown strength of oil-impregnated paper-lapped transformer conductors using three types of paper, namely, paper containing manila, crepe-paper and paper with controlled extension. The effect of paper characteristics, such as thickness, air impermeability and density on the insulating surge and alternating electric strength is investigated.
{"title":"Insulation strength and breakdown of impregnate D paper-lapped conductors for transformers","authors":"A. Hossam-eldin, A. M. Khalil","doi":"10.1109/EIC.1982.7464465","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464465","url":null,"abstract":"This paper reports recent investigations into the breakdown strength of oil-impregnated paper-lapped transformer conductors using three types of paper, namely, paper containing manila, crepe-paper and paper with controlled extension. The effect of paper characteristics, such as thickness, air impermeability and density on the insulating surge and alternating electric strength is investigated.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116997622","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464469
E. Gockenbach, J. Meppelink
The breakdown behaviour of model arrangements (rod to plane, sphere to plane) and natural size arrangements (ring to rod, coaxial cylinders) was studied using oscillating lightning impulse voltage and lightning impulse voltage in air and SF6. Using a simplified equivalent circuit, the voltage curve and the values of the circuit elements can be calculated. At the model arrangement as well as at a natural size arrangement breakdowns in air occured below the impulse withstand voltage Ud0 at both polarities in SF6 only by negative polarity at the natural size arrangement.
{"title":"Breakdown behaviour of nonuniform arrangements in air and SF6 using oscillating lightning impulse voltage","authors":"E. Gockenbach, J. Meppelink","doi":"10.1109/EIC.1982.7464469","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464469","url":null,"abstract":"The breakdown behaviour of model arrangements (rod to plane, sphere to plane) and natural size arrangements (ring to rod, coaxial cylinders) was studied using oscillating lightning impulse voltage and lightning impulse voltage in air and SF6. Using a simplified equivalent circuit, the voltage curve and the values of the circuit elements can be calculated. At the model arrangement as well as at a natural size arrangement breakdowns in air occured below the impulse withstand voltage Ud0 at both polarities in SF6 only by negative polarity at the natural size arrangement.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117191189","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464462
Y. Abed
The present work reports an experimental investigation of the effect of temperature rise on the leakage current and thermal breakdown in power cables under both A. C. and D. C. high voltages. An empirical equation was found to give the relation between the leakage current and the temperature of the insulation. It was observed that the thermal breakdown occurs when the heat generation in the insulation is larger than the heat dissipation in the surrounding soil. The variation of the leakage current with the temperature was well investigated and it was found that the leakage current increases with the increasing of insulation temperature. Leakage current in power cable predicts the critical breakdown voltage of the cable. It was anticipated that a significant of deterioration could be detected by measuring the leakage current at the operating temperature especially if the deterioration had progressed to a point where the cable failure is imminent.
{"title":"Effect of temperature rise on leakage current and breakdown of power cables","authors":"Y. Abed","doi":"10.1109/EIC.1982.7464462","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464462","url":null,"abstract":"The present work reports an experimental investigation of the effect of temperature rise on the leakage current and thermal breakdown in power cables under both A. C. and D. C. high voltages. An empirical equation was found to give the relation between the leakage current and the temperature of the insulation. It was observed that the thermal breakdown occurs when the heat generation in the insulation is larger than the heat dissipation in the surrounding soil. The variation of the leakage current with the temperature was well investigated and it was found that the leakage current increases with the increasing of insulation temperature. Leakage current in power cable predicts the critical breakdown voltage of the cable. It was anticipated that a significant of deterioration could be detected by measuring the leakage current at the operating temperature especially if the deterioration had progressed to a point where the cable failure is imminent.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122722441","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464496
N. Shimizu, J. Mori, M. Kosaki, K. Horii
This paper describes the effect of the oxygen absorbed in the free volume of polyethylene on electrical treeing phenomena. The ac tree initiation and growth were investigated at room temperature using virgin samples and also samples degassed by a vacuum pump. The tree starting voltage of the degassed samples is much higher than that of virgin samples. The experimental results show this improvement can be attributed to the removal of oxygen from PE. We also observed in detail the processes of tree initiation and growth in the degassed samples. The observations with other results led us to conclude that the charge carriers injected from the point electrode play a dominant role in the tree initiation.
{"title":"The effect of absorbed oxygen on electrical treeing in polymers","authors":"N. Shimizu, J. Mori, M. Kosaki, K. Horii","doi":"10.1109/EIC.1982.7464496","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464496","url":null,"abstract":"This paper describes the effect of the oxygen absorbed in the free volume of polyethylene on electrical treeing phenomena. The ac tree initiation and growth were investigated at room temperature using virgin samples and also samples degassed by a vacuum pump. The tree starting voltage of the degassed samples is much higher than that of virgin samples. The experimental results show this improvement can be attributed to the removal of oxygen from PE. We also observed in detail the processes of tree initiation and growth in the degassed samples. The observations with other results led us to conclude that the charge carriers injected from the point electrode play a dominant role in the tree initiation.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"232 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134041502","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464481
M. Gunasekaran
Polymer concrete is a composite material that is gaining interest internationally for a wide variety of applications. By virtue of its relatively low cost, its castability at room temperature, its good mechanical and dielectric properties, this material is being considered for use in outdoor and indoor high voltage insulation applications. This paper traces the historical development of polymer concrete for dielectric applications, and critically discusses the research and development data presently available (including those published for Polysil, a trade-marked version of one type of polymer concrete developed under the auspices of the Electric Power Research Institute of Palo Alto, California). Deficiencies in technical information, which need to to be rectified before the electric utility industry can and will routinely accept polymer concrete as a low-cost alternative to porcelain and epoxy insulation, are discussed. New data on dielectric grade polymer concrete subjected to multiple stress conditions is to be made available during the oral presentation of this paper. Recommendations are put forth for further characterizing polymer concrete to facilitate its ready acceptance in the electric utility industry.
{"title":"Polymer concrete as a dielectric material a critical assessment of the state-of-the-art","authors":"M. Gunasekaran","doi":"10.1109/EIC.1982.7464481","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464481","url":null,"abstract":"Polymer concrete is a composite material that is gaining interest internationally for a wide variety of applications. By virtue of its relatively low cost, its castability at room temperature, its good mechanical and dielectric properties, this material is being considered for use in outdoor and indoor high voltage insulation applications. This paper traces the historical development of polymer concrete for dielectric applications, and critically discusses the research and development data presently available (including those published for Polysil, a trade-marked version of one type of polymer concrete developed under the auspices of the Electric Power Research Institute of Palo Alto, California). Deficiencies in technical information, which need to to be rectified before the electric utility industry can and will routinely accept polymer concrete as a low-cost alternative to porcelain and epoxy insulation, are discussed. New data on dielectric grade polymer concrete subjected to multiple stress conditions is to be made available during the oral presentation of this paper. Recommendations are put forth for further characterizing polymer concrete to facilitate its ready acceptance in the electric utility industry.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115238198","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 : 1982-06-07DOI: 10.1109/EIC.1982.7464467
Y. Safar, A. Qureshi, N. Malik
Breakdown and corona inception voltages were measured for SF6, N2 mixtures using rod-plane gaps and positive impulse applied voltage. The results are in general agreement with previously publisbed reports. Corona discharges in these gases were also investigated The results indicate that in N2, streamer type corona exists. In SF6 - N2 mixtures with ≥ 1% of SF6 content, streamer type corona exists from 0.5 to 1 bar, whereas leader /streamer corona appears at pressure of 1. At high pressures, this type of corona results into a direct breakdown. In general, this type of corona extends into the gap in a stepped manner. The range of streamers, the size of the leader step and the time between leader steps decrease when SF6 content and/or gas pressure is increased. At law pressures (0.5 bars) in some mixtures (80% SF6) a pseudo glow/streamer type corona is observed.
{"title":"Impulse corona in positive rod-plane gaps filled with SF6 gas mixtures","authors":"Y. Safar, A. Qureshi, N. Malik","doi":"10.1109/EIC.1982.7464467","DOIUrl":"https://doi.org/10.1109/EIC.1982.7464467","url":null,"abstract":"Breakdown and corona inception voltages were measured for SF6, N2 mixtures using rod-plane gaps and positive impulse applied voltage. The results are in general agreement with previously publisbed reports. Corona discharges in these gases were also investigated The results indicate that in N2, streamer type corona exists. In SF6 - N2 mixtures with ≥ 1% of SF6 content, streamer type corona exists from 0.5 to 1 bar, whereas leader /streamer corona appears at pressure of 1. At high pressures, this type of corona results into a direct breakdown. In general, this type of corona extends into the gap in a stepped manner. The range of streamers, the size of the leader step and the time between leader steps decrease when SF6 content and/or gas pressure is increased. At law pressures (0.5 bars) in some mixtures (80% SF6) a pseudo glow/streamer type corona is observed.","PeriodicalId":422317,"journal":{"name":"1982 IEEE International Conference on Electrical Insulation","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114442905","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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