With the development of fast, and low-cost analog-digital converters (ADCs) and new mathematical procedures for waveform description, e.g., time encoded signal processing and recognition (TESPAR), novel approaches to detect and locate internal defects in the insulation of power transformers become feasible if the following requirements are fulfilled: the equivalent circuit of the insulating system, suitable for the fast partial discharge (PD) signals with risetimes of approximately 10 ns, is known; the response of the insulating system to PD signals injected at least at three different sites of each winding (top, center, bottom) is calculated, or measured at the signal tap-off points (i.e., bushings); and the pattern matrix of all calculated or measured signals exists: e.g., encoded and signal processes with TESPAR as a reference. The above mentioned requirements are examined for quasi-simultaneous detection and location of internal defects in power transformers. The method is applied to PD measurements on power transformers. >
{"title":"Detection and location of internal defects in the insulation of power transformers","authors":"J. Fuhr, M. Haessig, P. Boss, D. Tschudi, R. King","doi":"10.1109/14.249379","DOIUrl":"https://doi.org/10.1109/14.249379","url":null,"abstract":"With the development of fast, and low-cost analog-digital converters (ADCs) and new mathematical procedures for waveform description, e.g., time encoded signal processing and recognition (TESPAR), novel approaches to detect and locate internal defects in the insulation of power transformers become feasible if the following requirements are fulfilled: the equivalent circuit of the insulating system, suitable for the fast partial discharge (PD) signals with risetimes of approximately 10 ns, is known; the response of the insulating system to PD signals injected at least at three different sites of each winding (top, center, bottom) is calculated, or measured at the signal tap-off points (i.e., bushings); and the pattern matrix of all calculated or measured signals exists: e.g., encoded and signal processes with TESPAR as a reference. The above mentioned requirements are examined for quasi-simultaneous detection and location of internal defects in power transformers. The method is applied to PD measurements on power transformers. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73020129","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}
At present, several definitions of partial discharge inception voltage (PDIV) have been advanced. To establish the value of each of these definitions, four practical electrical insulating fluids are selected, and their PDIV is determined according to three of these different specifications. The results suggest that the use of PDIV as a quality criterion generally is not warranted. The significance of these findings is discussed. >
{"title":"The effect of the definition used in measuring partial discharge inception voltages","authors":"M. Pompili, C. Mazzetti, M. Libotte, E. Forster","doi":"10.1109/14.249373","DOIUrl":"https://doi.org/10.1109/14.249373","url":null,"abstract":"At present, several definitions of partial discharge inception voltage (PDIV) have been advanced. To establish the value of each of these definitions, four practical electrical insulating fluids are selected, and their PDIV is determined according to three of these different specifications. The results suggest that the use of PDIV as a quality criterion generally is not warranted. The significance of these findings is discussed. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72983848","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}
The partial discharge (PD) pattern recognition capability of a neural network, employing the multilayer perceptron technique with data input based on five discharge pulse form parameters, is examined. Simple discharge sources, consisting of artificially created cylindrical cavities with metallic and dielectric electrodes, are employed. The PD pattern discrimination capability is tested using cavities of equal depth but with different electrodes, and cavities of varying depths but with similar electrodes. Preliminary test results are positive. >
{"title":"PD pattern recognition with neural networks using the multilayer perceptron technique","authors":"A. Mazroua, M. Salama, R. Bartnikas","doi":"10.1109/14.249382","DOIUrl":"https://doi.org/10.1109/14.249382","url":null,"abstract":"The partial discharge (PD) pattern recognition capability of a neural network, employing the multilayer perceptron technique with data input based on five discharge pulse form parameters, is examined. Simple discharge sources, consisting of artificially created cylindrical cavities with metallic and dielectric electrodes, are employed. The PD pattern discrimination capability is tested using cavities of equal depth but with different electrodes, and cavities of varying depths but with similar electrodes. Preliminary test results are positive. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83302501","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}
A new test assembly for measuring the endurance of polymeric and ceramic films under the action of partial discharges (PDs) is presented. If experiments are performed under controlled ambient conditions (i.e., relative humidity), the test procedure gives times to breakdown which show low scatter. The effects of different test conditions on the times to breakdown and relevant data scatter are presented. The adoption of a phase reference PD analyzer (PRPDA) system, together with a video recording system, also gives information relevant to discharge mechanisms and film degradation processes. The test assembly is described and some results, relevant to polymeric films of different thickness, are presented. >
{"title":"Measuring the endurance of films in partial discharges","authors":"R. Bozzo, L. Centurioni, F. Guastavino","doi":"10.1109/14.249378","DOIUrl":"https://doi.org/10.1109/14.249378","url":null,"abstract":"A new test assembly for measuring the endurance of polymeric and ceramic films under the action of partial discharges (PDs) is presented. If experiments are performed under controlled ambient conditions (i.e., relative humidity), the test procedure gives times to breakdown which show low scatter. The effects of different test conditions on the times to breakdown and relevant data scatter are presented. The adoption of a phase reference PD analyzer (PRPDA) system, together with a video recording system, also gives information relevant to discharge mechanisms and film degradation processes. The test assembly is described and some results, relevant to polymeric films of different thickness, are presented. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81936945","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}
The partial discharge (PD) behavior of epoxy resin transformer coils in a temperature range between -30 and 180 degrees C is discussed. In particular, the PD inception voltage, which is a very important parameter for the judgement of the PD characteristic of a transformer over the temperature range, is considered. The PD inception voltage is determined at different static temperatures in step tests. The tempering of the coils occurs from the outside by submerging the oil in tempered fluid,as well as from the inside, with the help of current losses. Models of HV coils of distribution transformers are used as specimens. The dependencies between the PD inception voltage of the coils and parameters such as wire insulation and inner or outer tempering are determined and discussed. The results of long-term tests in which five coils are stressed with a voltage of 1.75 kV at a temperature of 175 degrees C for a duration of one year are presented. During this time PD measurements with a sensitivity of 2 pC were carried out. >
{"title":"The relation between thermal and electrical stress and the PD behavior of epoxy-resin transformers","authors":"H. Borsi","doi":"10.1109/14.249374","DOIUrl":"https://doi.org/10.1109/14.249374","url":null,"abstract":"The partial discharge (PD) behavior of epoxy resin transformer coils in a temperature range between -30 and 180 degrees C is discussed. In particular, the PD inception voltage, which is a very important parameter for the judgement of the PD characteristic of a transformer over the temperature range, is considered. The PD inception voltage is determined at different static temperatures in step tests. The tempering of the coils occurs from the outside by submerging the oil in tempered fluid,as well as from the inside, with the help of current losses. Models of HV coils of distribution transformers are used as specimens. The dependencies between the PD inception voltage of the coils and parameters such as wire insulation and inner or outer tempering are determined and discussed. The results of long-term tests in which five coils are stressed with a voltage of 1.75 kV at a temperature of 175 degrees C for a duration of one year are presented. During this time PD measurements with a sensitivity of 2 pC were carried out. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74849975","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}
Recent studies have determined the partial discharge inception voltage (PDIV) of several practical insulating oils using conventional PD measurements. They show that the PDIV is a reasonably reproducible quantity. Independently, using electrooptical techniques, the streamer inception voltages (SIVs) in these liquids have been measured. These SIV values are found to be reproducible, within experimental error. Both techniques yield similar inception values. These results suggest that the PD and streamer phenomena are closely related. It is shown that the PDIV is independent of the gap and hence the average electric field. The SIV is found to be independent of the applied voltage. These observations suggest that the inception of both phenomena is controlled by the local rather than the average applied field. The experimental observations are interpreted and a theory is advanced to explain them. >
{"title":"Partial discharges and streamers in liquid dielectrics-the significance of the inception voltage","authors":"E. Forster","doi":"10.1109/14.249367","DOIUrl":"https://doi.org/10.1109/14.249367","url":null,"abstract":"Recent studies have determined the partial discharge inception voltage (PDIV) of several practical insulating oils using conventional PD measurements. They show that the PDIV is a reasonably reproducible quantity. Independently, using electrooptical techniques, the streamer inception voltages (SIVs) in these liquids have been measured. These SIV values are found to be reproducible, within experimental error. Both techniques yield similar inception values. These results suggest that the PD and streamer phenomena are closely related. It is shown that the PDIV is independent of the gap and hence the average electric field. The SIV is found to be independent of the applied voltage. These observations suggest that the inception of both phenomena is controlled by the local rather than the average applied field. The experimental observations are interpreted and a theory is advanced to explain them. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77333144","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}
Experimentally obtained partial discharge pulse forms are compared with those derived theoretically, using a mathematical model of a short gap. The calculations indicate that, with overvolted short gaps, the apparent absence of the protracted ion current tail in the overall pulse form is due to the large excess of the electron current component generated by strongly enhanced cathode emission by the photoeffect and other phenomena. Under conditions of high overvoltage the ion-impact-induced emission, the ion fluxes and, consequently, the ion current component are greatly reduced as compared to the electron current. The long ion current tail, representing not more than a few percent of the total current, passes undetected. Pulseless and pseudo-glow discharges are considered. Preferred terms to designate the different forms of partial discharges are suggested. >
{"title":"On the character of different forms of partial discharge and their related terminologies","authors":"R. Bartnikas, J. Novak","doi":"10.1109/14.249369","DOIUrl":"https://doi.org/10.1109/14.249369","url":null,"abstract":"Experimentally obtained partial discharge pulse forms are compared with those derived theoretically, using a mathematical model of a short gap. The calculations indicate that, with overvolted short gaps, the apparent absence of the protracted ion current tail in the overall pulse form is due to the large excess of the electron current component generated by strongly enhanced cathode emission by the photoeffect and other phenomena. Under conditions of high overvoltage the ion-impact-induced emission, the ion fluxes and, consequently, the ion current component are greatly reduced as compared to the electron current. The long ion current tail, representing not more than a few percent of the total current, passes undetected. Pulseless and pseudo-glow discharges are considered. Preferred terms to designate the different forms of partial discharges are suggested. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81027081","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}
Current pulses caused by partial discharges (PDs) are measured using light-emitting diodes (LEDs) and fiber optics under impulse voltage conditions. This system has the advantage of having good isolation from the HV power supply and no effect from electromagnetic noise as compared with ordinary systems. It can detect a PD pulse having a half width of 3 ns, and has the capability of measuring PD pulse charges in the range of 1 to 2000 pC, when the optimum DC bias is applied. PD pulses and light emission or streamer formation in dielectric liquids are measured simultaneously by using an image converter camera. >
{"title":"Partial discharge measurements in dielectric liquids under impulse voltage","authors":"H. Yamashita","doi":"10.1109/14.249368","DOIUrl":"https://doi.org/10.1109/14.249368","url":null,"abstract":"Current pulses caused by partial discharges (PDs) are measured using light-emitting diodes (LEDs) and fiber optics under impulse voltage conditions. This system has the advantage of having good isolation from the HV power supply and no effect from electromagnetic noise as compared with ordinary systems. It can detect a PD pulse having a half width of 3 ns, and has the capability of measuring PD pulse charges in the range of 1 to 2000 pC, when the optimum DC bias is applied. PD pulses and light emission or streamer formation in dielectric liquids are measured simultaneously by using an image converter camera. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77981953","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}
The problem of the interpretation of partial discharge (PD) measurements is approached by means of the shape analysis of PD amplitude distributions. Experimental cumulative PD distributions, detected insulation systems of HV rotating machine stator windings, are plotted on a Weibull graph in order to identify multiple PD sources. Examples of the application of PD distribution shape analysis as a diagnostic tool for AC HV stator insulation systems are presented and discussed. The calibration procedure and the significance of average parameters for degradation inference are reviewed. >
{"title":"PD analysis of rotating AC machines","authors":"A. Contin, G. Rabach","doi":"10.1109/14.249371","DOIUrl":"https://doi.org/10.1109/14.249371","url":null,"abstract":"The problem of the interpretation of partial discharge (PD) measurements is approached by means of the shape analysis of PD amplitude distributions. Experimental cumulative PD distributions, detected insulation systems of HV rotating machine stator windings, are plotted on a Weibull graph in order to identify multiple PD sources. Examples of the application of PD distribution shape analysis as a diagnostic tool for AC HV stator insulation systems are presented and discussed. The calibration procedure and the significance of average parameters for degradation inference are reviewed. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77893773","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}
The contents of the past and present IEC Standards on partial discharge (PD) measurements are examined, in view of the preparation of a new edition. New standards should take into account the more sophisticated measuring systems produced in the last decades and their lower sensitivity to external disturbances. Little knowledge has however been added on the PD aging effects on HV apparatus. >
{"title":"Present state and prospects of standardization on PD measurements","authors":"G. Zingales","doi":"10.1109/14.249363","DOIUrl":"https://doi.org/10.1109/14.249363","url":null,"abstract":"The contents of the past and present IEC Standards on partial discharge (PD) measurements are examined, in view of the preparation of a new edition. New standards should take into account the more sophisticated measuring systems produced in the last decades and their lower sensitivity to external disturbances. Little knowledge has however been added on the PD aging effects on HV apparatus. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81833888","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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