The variation in soil resistivity have a considerable influence on the performance of most grounding systems, affecting both the value of ground resistance, the ground potential rise, the step and touch surface potentials. This paper presents a suggested mathematical model to examine the behavior of earthing system in non-uniform three-layer soil conditions. The study of the apparent soil resistivity of a driven ground rod as well as the value obtained by the four-point Wenner method has been done and its dependence on the characteristic of each layer is discussed. A comparison between the two methods is emphasized. Finally, the results demonstrate that there is a predicable relationship between the calculated results obtained by these two methods.
{"title":"Evaluation of earth resistivity for grounding systems in non‐uniform soil structure","authors":"M. E. Ghourab","doi":"10.1002/ETEP.4450060309","DOIUrl":"https://doi.org/10.1002/ETEP.4450060309","url":null,"abstract":"The variation in soil resistivity have a considerable influence on the performance of most grounding systems, affecting both the value of ground resistance, the ground potential rise, the step and touch surface potentials. This paper presents a suggested mathematical model to examine the behavior of earthing system in non-uniform three-layer soil conditions. The study of the apparent soil resistivity of a driven ground rod as well as the value obtained by the four-point Wenner method has been done and its dependence on the characteristic of each layer is discussed. A comparison between the two methods is emphasized. Finally, the results demonstrate that there is a predicable relationship between the calculated results obtained by these two methods.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"6 1","pages":"195-200"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450060309","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51090002","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}
Manufacturers, customers and the International Standards are paying more and more attention to the concept of quality of an industrial product. In particular the definition and measurement of the electric power quality is destined to become a big problem. Under sinusoidal, symmetric and balanced conditions, the power-quality problem is basically a loading quality problem; otherwise, it may be also a supplying quality problem. The paper discusses the measurement of some electric power-quality indices. It also considers the problem of separating the utility contribution to the power quality deterioration from the customer one.
{"title":"Measurement of the electric power quality and related problems","authors":"A. Ferrero, A. Menchetti, R. Sasdelli","doi":"10.1002/ETEP.4450060607","DOIUrl":"https://doi.org/10.1002/ETEP.4450060607","url":null,"abstract":"Manufacturers, customers and the International Standards are paying more and more attention to the concept of quality of an industrial product. In particular the definition and measurement of the electric power quality is destined to become a big problem. Under sinusoidal, symmetric and balanced conditions, the power-quality problem is basically a loading quality problem; otherwise, it may be also a supplying quality problem. The paper discusses the measurement of some electric power-quality indices. It also considers the problem of separating the utility contribution to the power quality deterioration from the customer one.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"6 1","pages":"401-406"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450060607","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51090840","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}
M. Poljak, Boris Bojanić, Tomislav Hafner, Josip Tomašević
The basic characteristics of a new concept of combined transformers consisting of an inverse current transformer and a voltage transformer with open core, are described. The results of the research and testing of impulse and AC voltage distribution, accuracy class, influence of the current transformer on the voltage transformer and vice versa are given. Thanks to its technology and simplicity, the new concept allows the commercial manufacture of combined transformers for the highest equipment voltages up to 420 kV inclusive.
{"title":"A New Concept of Combined Transformers","authors":"M. Poljak, Boris Bojanić, Tomislav Hafner, Josip Tomašević","doi":"10.1002/ETEP.4450060404","DOIUrl":"https://doi.org/10.1002/ETEP.4450060404","url":null,"abstract":"The basic characteristics of a new concept of combined transformers consisting of an inverse current transformer and a voltage transformer with open core, are described. The results of the research and testing of impulse and AC voltage distribution, accuracy class, influence of the current transformer on the voltage transformer and vice versa are given. Thanks to its technology and simplicity, the new concept allows the commercial manufacture of combined transformers for the highest equipment voltages up to 420 kV inclusive.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"6 1","pages":"253-258"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450060404","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51089665","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 and power equations of three-phase circuits with unbalanced non-linear loads supplied from asymmetrical and non-sinusoidal voltage source are developed in the paper. It is suggested that the form of the power equations should be adjusted to the goal for which they are developed. Their form, which may be convenient for interpretation of power phenomena, may therefore differ from the one developed for studies on the supply and loading quality. Also it is shown that power properties of a circuit cannot be wholly determined in its static state. They can be determined, however, if the circuit response to the supply changes is observed. Such an observation and analysis of the circuit response are considered as a dynamic approach. It may provide a control algorithm for adaptive compensators.
{"title":"Dynamic, power‐quality‐oriented approach to power theory and compensation of asymmetrical systems under non‐sinusoidal conditions","authors":"L. Czarnecki","doi":"10.1002/ETEP.4450040505","DOIUrl":"https://doi.org/10.1002/ETEP.4450040505","url":null,"abstract":"Current and power equations of three-phase circuits with unbalanced non-linear loads supplied from asymmetrical and non-sinusoidal voltage source are developed in the paper. It is suggested that the form of the power equations should be adjusted to the goal for which they are developed. Their form, which may be convenient for interpretation of power phenomena, may therefore differ from the one developed for studies on the supply and loading quality. Also it is shown that power properties of a circuit cannot be wholly determined in its static state. They can be determined, however, if the circuit response to the supply changes is observed. Such an observation and analysis of the circuit response are considered as a dynamic approach. It may provide a control algorithm for adaptive compensators.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"1 1","pages":"347-356"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450040505","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51084908","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}
In order to economize on electrical energy and materials a higher load of electrical motors is necessary. In this way it is possible that the motors operate above their rated power. Consequently, the rated temperature of the winding is exceeded and, therefore, its lifetime is shortened. For the description of the winding aging process the consumed life is an appropriate quantity. The meaning of this quantity is explained and its application is demonstrated.
{"title":"About the concept of consumed life of electrical machine windings and its application","authors":"R. Busch","doi":"10.1002/ETEP.4450080205","DOIUrl":"https://doi.org/10.1002/ETEP.4450080205","url":null,"abstract":"In order to economize on electrical energy and materials a higher load of electrical motors is necessary. In this way it is possible that the motors operate above their rated power. Consequently, the rated temperature of the winding is exceeded and, therefore, its lifetime is shortened. For the description of the winding aging process the consumed life is an appropriate quantity. The meaning of this quantity is explained and its application is demonstrated.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"8 1","pages":"105-110"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450080205","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51095016","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}
Measurements were made of the sum of cathode-fall and anode-fall voltages, i .e. electrode-fall voltage U fall for SF 6 and air arcs at a pressure of 0.1 MPa in a wide current range from 10 A to 20 kA. The arcs were burned between electrodes of iron, tungsten, copper-tungsten, copper and titanium. For each electrode, U fall at a given current was estimated as the arc voltage at the zero gap length between the electrodes, which was extrapolated from arc voltages measured in short gaps with lengths below 3 mm. The electrode-fall voltage U fall of the SF 6 arc proved to be 17.5 V, 13.8 V, 17.5 V, 17.5 V and 17.3 V for the Fe, W, Cu-W Cu and Ti electrodes, respectively. The electrode-fall voltage U fall was affected by the electrode material, while U fall of the air arc is almost the same as that of the SF 6 arc. It was also found that U fall of each arc at a given electrode was independent of current in the above range.
{"title":"Electrode-fall voltages of SF6 and air arcs between electrodes of Fe, W, Cu-W, Cu and Ti in the current range from 10 A to 20 kA","authors":"Y. Yokomizu, T. Matsumura, R. Henmi, Y. Kito","doi":"10.1002/ETEP.4450080206","DOIUrl":"https://doi.org/10.1002/ETEP.4450080206","url":null,"abstract":"Measurements were made of the sum of cathode-fall and anode-fall voltages, i .e. electrode-fall voltage U fall for SF 6 and air arcs at a pressure of 0.1 MPa in a wide current range from 10 A to 20 kA. The arcs were burned between electrodes of iron, tungsten, copper-tungsten, copper and titanium. For each electrode, U fall at a given current was estimated as the arc voltage at the zero gap length between the electrodes, which was extrapolated from arc voltages measured in short gaps with lengths below 3 mm. The electrode-fall voltage U fall of the SF 6 arc proved to be 17.5 V, 13.8 V, 17.5 V, 17.5 V and 17.3 V for the Fe, W, Cu-W Cu and Ti electrodes, respectively. The electrode-fall voltage U fall was affected by the electrode material, while U fall of the air arc is almost the same as that of the SF 6 arc. It was also found that U fall of each arc at a given electrode was independent of current in the above range.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"19 1","pages":"111-115"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450080206","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51095181","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}
In industrial and commercial sectors, loads are becoming increasingly sensitive to brief supply voltage disturbances. As a consequence, today voltage dips have more impact than just a few years ago. Fast voltage conditioners, improving the load immunity characteristics and accordingly reducing the expected number of load interruptions or malfunctions due to supply voltage dips, can allow large cost savings. Different categories of voltage conditioners are existing today, ranging from energy-stored devices (like uninterruptible power supply) to no energy-stored devices (like static voltage booster). To reduce the effects of supply voltage dips on a given plant, usually several different possible arrangements must be investigated, depending on the conditioners type, size and bus location. To determine the optimal arrangement is not always immediate. A methodology based on the minimum revenue requirement (MRR) is proposed in the paper, and a numerical example is given as well.
{"title":"Cost-benefit evaluation of voltage conditioners installation in industrial and commercial power systems","authors":"S. Quaia, F. Tosato","doi":"10.1002/ETEP.4450080603","DOIUrl":"https://doi.org/10.1002/ETEP.4450080603","url":null,"abstract":"In industrial and commercial sectors, loads are becoming increasingly sensitive to brief supply voltage disturbances. As a consequence, today voltage dips have more impact than just a few years ago. Fast voltage conditioners, improving the load immunity characteristics and accordingly reducing the expected number of load interruptions or malfunctions due to supply voltage dips, can allow large cost savings. Different categories of voltage conditioners are existing today, ranging from energy-stored devices (like uninterruptible power supply) to no energy-stored devices (like static voltage booster). To reduce the effects of supply voltage dips on a given plant, usually several different possible arrangements must be investigated, depending on the conditioners type, size and bus location. To determine the optimal arrangement is not always immediate. A methodology based on the minimum revenue requirement (MRR) is proposed in the paper, and a numerical example is given as well.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"8 1","pages":"423-428"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450080603","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51098510","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}
M. Abdel-Salam, M. El-Sadek, A. A. Ibrahim, A. Ahmed
This paper extends a linear-programming optimization-based method proposed before for reactive-power scheduling using generator terminal voltages and reactive powers, transformer tap-settings and switchable reactive power sources as control variables. The system configuration following contingencies is considered - for the first time - as an additional control variable in the optimization-method. It is proposed to use all of tile possible modifications of system configuration by opening one or two lines simultaneously. For this to be accurately achieved, a technique was proposed for ranking the line outages, which is based on system losses obtained by AC and/or DC load-flow studies. The ranking agreed satisfactorily with the voltage-reactive power index used for contingency analysis in system security studies. Voltage stability is checked before and after optimum adjustment of the control variables and proved to be better after optimum adjustment.
{"title":"Voltage profile optimization as influenced by power‐system configuration","authors":"M. Abdel-Salam, M. El-Sadek, A. A. Ibrahim, A. Ahmed","doi":"10.1002/ETEP.4450080610","DOIUrl":"https://doi.org/10.1002/ETEP.4450080610","url":null,"abstract":"This paper extends a linear-programming optimization-based method proposed before for reactive-power scheduling using generator terminal voltages and reactive powers, transformer tap-settings and switchable reactive power sources as control variables. The system configuration following contingencies is considered - for the first time - as an additional control variable in the optimization-method. It is proposed to use all of tile possible modifications of system configuration by opening one or two lines simultaneously. For this to be accurately achieved, a technique was proposed for ranking the line outages, which is based on system losses obtained by AC and/or DC load-flow studies. The ranking agreed satisfactorily with the voltage-reactive power index used for contingency analysis in system security studies. Voltage stability is checked before and after optimum adjustment of the control variables and proved to be better after optimum adjustment.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"8 1","pages":"469-475"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450080610","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51098980","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 approach presented in this paper relays on the identification of load parameters in terms ofpassive impedances. It is aimed to the evaluation of unbalanced and reactive currents of an n-phase system so as to allow load compensation by means of passive components. The paper discusses also an identification method of the line parameters, from which the maximum voltage distortion caused by an individual load can be estimated. This also results in an evaluation method of the power factor, which can be used for tariffation.
{"title":"Load- and line identification in multi-phase systems: A compensation-oriented approach","authors":"P. Mattavelli, P. Tenti","doi":"10.1002/ETEP.4450060602","DOIUrl":"https://doi.org/10.1002/ETEP.4450060602","url":null,"abstract":"The approach presented in this paper relays on the identification of load parameters in terms ofpassive impedances. It is aimed to the evaluation of unbalanced and reactive currents of an n-phase system so as to allow load compensation by means of passive components. The paper discusses also an identification method of the line parameters, from which the maximum voltage distortion caused by an individual load can be estimated. This also results in an evaluation method of the power factor, which can be used for tariffation.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"6 1","pages":"373-380"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450060602","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51090851","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}
This paper proposes the application of the unbalanced fundamental power as a merit figure to establish a prediction method of the voltage unbalance emission levels produced by the connection of unbalanced loads. The total apparent power, as criterion for optimal compensation, is discussed when it is applied to loads which are sensitive to voltage unbalances such as generators and motors. The analysis of these aspects is made according to recommendations for voltage unbalances.
{"title":"Assessment of unbalance emission level produced by loads using the apparent power components","authors":"J. G. Mayordomo, L. F. Beites, J. L. Gutierrez","doi":"10.1002/ETEP.4450060603","DOIUrl":"https://doi.org/10.1002/ETEP.4450060603","url":null,"abstract":"This paper proposes the application of the unbalanced fundamental power as a merit figure to establish a prediction method of the voltage unbalance emission levels produced by the connection of unbalanced loads. The total apparent power, as criterion for optimal compensation, is discussed when it is applied to loads which are sensitive to voltage unbalances such as generators and motors. The analysis of these aspects is made according to recommendations for voltage unbalances.","PeriodicalId":50474,"journal":{"name":"European Transactions on Electrical Power","volume":"6 1","pages":"381-386"},"PeriodicalIF":0.0,"publicationDate":"2007-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ETEP.4450060603","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51090933","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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