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Wyświetlanie 1-15 z 1003
Tytuł:
Magnetizing current effect minimization in current transformers
Autorzy:
Dusza, D.
Rzepecki, B.
Powiązania:
https://bibliotekanauki.pl/articles/1813967.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
current transformer
value converter
ratio
error minimization
magnetizing current effect
current transformer's error
current measurement
Opis:
Magnetizing current effect minimization in current transformers is considered in this paper. Double-core current transformer operation is described in the following text. The influence of the magnetizing current, which is a significant element of current transformer's error, has been minimized in a new type of double-core current transformer connection. The accuracy evaluation of built double-core current transformer has been carried out according to obtained transformation precision.
Źródło:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały; 2013, 69, 33; 469--476
1733-0718
Pojawia się w:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inductive current transducers in the frequency range up to 150 kHz
Autorzy:
Kosobudzki, G.
Dusza, D.
Powiązania:
https://bibliotekanauki.pl/articles/1193468.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
current
Rogowski coil
inductive current transducer
Opis:
The article presents the results of the research on inductive current transducers in the form of a uniform winding non-magnetic ring with a rigid and flexible construction encompassing the flow of processed current in the frequency range of up to 150 kHz. The results for the developed transducer were related to the results obtained in simulations conducted on the transducer simplified model. The frequency tests of this type of transducers are of key significance in the assessment of the applicability of a given transducer in the measurements of network signals with high-order harmonics, and particularly in the assessment of the construction capacity of inductive current transducers in the form of the Rogowski coil.
Źródło:
Power Electronics and Drives; 2017, 2, 37/2; 167-176
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Current density in the unscreened three-phase high-current busduct
Autorzy:
Szczegielniak, T.
Piątek, Z.
Kusiak, D.
Powiązania:
https://bibliotekanauki.pl/articles/97582.pdf
Data publikacji:
2014
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
analytical method
high-current busduct
current density
Opis:
Design of the high-current busducts on high currents and voltages causes necessity precise describing of electromagnetic, dynamic and thermal effects. Knowledge of the relations between electrodynamics and constructional parameters is necessary in the optimization construction process of the high-current busducts. Information about distribution electromagnetic field is a base into analysis of electrodynamics and thermal effects in the high-current busducts. The paper presents analytical calculations of the current density in the three-phase high-current busduct which phase conductors are placed in vertex of a square. Into account were taken skin and proximity effect. The electromagnetic field produced by high-current busducts are usually calculated numerically with the use of a computer. However, the analytical calculation of the electromagnetic field is preferable, because it results in a mathematical expression for showing its dependences on various parameters of the line arrangement.
Źródło:
Computer Applications in Electrical Engineering; 2014, 12; 57-64
1508-4248
Pojawia się w:
Computer Applications in Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multiple output CMOS current amplifier
Autorzy:
Pankiewicz, B.
Powiązania:
https://bibliotekanauki.pl/articles/201141.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
current amplifier
current follower
current mirror
CMOS technology
wzmacniacz prądowy
prąd
technologia CMOS
Opis:
In this paper the multiple output current amplifier basic cell is proposed. The triple output current mirror and current follower circuit are described in detail. The cell consists of a split nMOS differential pair and accompanying biasing current sources. It is suitable for low voltage operation and exhibits highly linear DC response. Through cell devices scaling, not only unity, but also any current gains are achievable. As examples, a current amplifier and bandpass biquad section designed in CMOS TSMC 90nm technology are presented. The current amplifier is powered from a 1.2V supply. MOS transistors scaling was chosen to obtain output gains equal to -2, 1 and 2. Simulated real gains are -1.941, 0.966 and 1.932 respectively. The 3dB passband obtained is above 20MHz, while current consumption is independent of input and output currents and is only 7.77μA. The bandpass biquad section utilises the previously presented amplifier, two capacitors and one resistor, and has a Q factor equal to 4 and pole frequency equal to 100 kHz.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2016, 64, 2; 301-306
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Indukcyjny przetwornik prądu sieciowego ze zworami ferromagnetycznymi
Power line current sensor with ferromagnetic cramps
Autorzy:
Dusza, D.
Nowak, J.
Powiązania:
https://bibliotekanauki.pl/articles/152173.pdf
Data publikacji:
2012
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
prąd
przetwarzanie
przetwornik indukcyjny
current
processing
current sensor
Opis:
W artykule przedstawiono wyniki badań właściwości modeli przetworników prądu sieciowego składających się z cewek cylindrycznych zwartych magnetowodami ferromagnetycznymi. Otrzymane wyniki dowodzą, że można osiągnąć dużą czułość przetwarzania, dobrą liniowość oraz dużą odporność na zakłócenia elektromagnetyczne przetworników charakteryzujących się prostą technologią realizacji. Przetworniki ze zworami ferromagnetycznymi mogą być montowane na przewodach prądowych bez przerywania obwodu prądowego.
The paper deals with an inductive current transducer in the form of cylindrical coils (Fig. 2) with ferromagnetic cramps (Figs. 3 and 4). The investigation results of properties and influence of external magnetic fields on the processing accuracy are presented. They show that it is possible to achieve high sensitivity, good linearity of the transient characteristic (Fig. 6) and high resistance to electromagnetic disturbances (Fig. 5 shows the results for a transducer with four coils, while Fig. 7. for a transducer with two coils). Use of cramps made of permalloy enables obtaining better results (Fig. 8). The proposed solution for current transducer construction is characterized by implementation of simple technology. Transducers with ferromagnetic cramps (ferrite, permalloy, electrical sheet, nanocrystalline materials) can be installed on current wires without breaking a current circuit. Research of the influence of disturbances from external magnetic fields plays a key role in the quality assessment of current transducers.
Źródło:
Pomiary Automatyka Kontrola; 2012, R. 58, nr 11, 11; 981-983
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Differential protection with better stabilization for external faults
Zabezpieczenie różnicowe z lepszą stabilizacją dla zwarć zewnętrznych
Autorzy:
Solak, K.
Rebizant, W.
Powiązania:
https://bibliotekanauki.pl/articles/410581.pdf
Data publikacji:
2011
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
current differential criterion
current transformer
fuzzy logic
saturation
Opis:
This paper presents a new differential protection scheme for transmission lines with application of fuzzy signal processing and support of phase comparison criterion. Traditional differential relays may have problems with proper classification of external faults with CT saturation. Better protection stabilization for such cases is obtained with support of fuzzy signal processing. In proposed solution the input signals as well as the standard percentage characteristic are fuzzified. The performance of presented fuzzy protection scheme has been tested with the signals generated with use of EMTP-ATP program and compared to the traditional solution.
W artykule zaprezentowano nowe zabezpieczenie różnicowe, w którym zastosowano rozmyte przetwarzanie sygnałów oraz dodatkowe kryterium porównawczo-fazowe. Proponowane zabezpieczenie jest bardziej odporne na zwarcia zewnętrzne z nasyceniem przekładników prądowych, co potwierdziły przeprowadzone testy. Proponowany algorytm testowany był na sygnałach pochodzących z symulacji w EMTP-ATP, a wyniki porównano ze standardowym przekaźnikiem różnicowym.
Źródło:
Present Problems of Power System Control; 2011, 1; 39-48
2084-2201
Pojawia się w:
Present Problems of Power System Control
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parametric-active compensation of earth fault current in an IT-type network
Autorzy:
German-Galkin, S.
Hrynkiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1193299.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
IT-type networks
earth current
fault current compensation
Opis:
The parametric-active compensation of earth leakage currents which minimalized virtual capacitance current in ships of IT-type network has been discussed. The protection is based on automatic compensation of leakage earth currents. The protection system is governed by a controller. The results of simulation tests have been presented. The parametric-active compensation of earth leakage currents which minimalized virtual capacitance current in ships with IT-type network has been discussed.
Źródło:
Power Electronics and Drives; 2017, 2, 37/1; 81-87
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-Cartesian Frame Transformation-Based Control of a Three-Phase Power Converter During Unbalanced Voltage Dip – Part II: Simulation And Experiment
Autorzy:
Iwański, Grzegorz
Maciejewski, Paweł
Łuszczyk, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/1193687.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
AC/DC
power conversion
current control
current limitation
Opis:
The paper presents a control method for the three-phase power converter operating under unbalanced grid voltage conditions. The method uses a new transformation to the non-Cartesian frame, which makes the controlled current vector components balanced in this frame even if originally the three-phase current is referenced as unbalanced. Furthermore, Park’s transformation makes the controlled variables constant, which allows to apply proportional–integral terms as current controllers independent of the required control target. Several control targets known from literature have been analyzed with regard to the required new transformation parameters, and the transformation parameters for all targets have been found. Simulation results are shown to prove the theoretical analysis, and the experimental test results are presented as practical validation of the proposed use of the non-Cartesian frame in control.
Źródło:
Power Electronics and Drives; 2019, 4, 39; 63-77
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The power electronics controlled current source utilized in the reference current generator
Autorzy:
Gwóźdź, M.
Powiązania:
https://bibliotekanauki.pl/articles/377579.pdf
Data publikacji:
2013
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
power electronics
current controlled voltage source
current generator
Opis:
The paper considers wide-band voltage controlled power electronics current source. The current source has been designed as a part of 1-channel reference current generator designed for current meters testing. The control module of the generator utilizes specialized Analog Devices Inc. DSPs based microcomputer module for power electronics applications. Used solutions have allowed obtain high quality referencing of the output current within reference signal. The paper presents the structure and selected aspects of the control algorithm of the current source. Also selected investigations results of laboratory prototype of generator with utilization of controlled current source are presented.
Źródło:
Poznan University of Technology Academic Journals. Electrical Engineering; 2013, 76; 9-14
1897-0737
Pojawia się w:
Poznan University of Technology Academic Journals. Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Klimatyczny wskaźnik aktywności Prądu Labradorskiego
Climatic index of Labrador Current activity
Autorzy:
Marsz, A. A.
Powiązania:
https://bibliotekanauki.pl/articles/260933.pdf
Data publikacji:
2003
Wydawca:
Stowarzyszenie Klimatologów Polskich
Tematy:
prądy morskie
Prąd Labradorski
sea current
Labrador Current
Opis:
Some of the sea currents show strong activity in climate formation and this fact is well known. Their activity represented as a time function is not stable but proves to be changeable. For this reason it seems quite reasonable to introduce appropriate indexes which could be used to characte-rise activity of a given current and, in an indirect way, to describe heat masses carried with this current. The aim of this article is to present an index which characterises the climatic activity of the Labrador Current. The basis to create such an index is the number of icebergs carried with this current. In consecutive ice seasons (October - September) this number passed south of 48°N of E from New Foundland (data from ?International Ice Patrol?). Changeable from year to year number of icebergs carried to the North Atlantic (see fig. 2) primarily represents the increase or decrease in the intensity of the Labrador Current. As the number of icebergs moved to the Atlantic comprises random component, which is very high, in order to create the index a logarythm was used to reduce the changeability of the amplitude. Formula [ 1 ] has been proposed to be used to calculate the index of intensity of the Labrador Current (WPL): WPL= (ln(G + 1))/2 where: ln - natural logarythm (base = e), G - the number of icebergs noted in a given ice season. Values of WPL index calculated in this way dated in January in ice season over a period 1900?2002 have been presented in Table 2 and their course in Fig. 3. The value of WPL indicates quite strong correlation with both winter (DJFM) and annual NAO indexes (r ~ 0.5), however the analysis showed that NAO is not the only element having influence on the Labrador Current activity. The analysis, carried out at random, of relations between the values of WPL and different climatic and hydroclimatic elements indicated to the fact that most of the relations are shifted/delayed in time - changeability of WPL takes place earlier than changes in these elements. For instance, the air temperature in August the following year in most area of Poland proves to have not too strong but clear correlation with the changes in WPL. Numerous correlations between WPL and occurring later monthly values of air temperature and monthly sums of precipitation at stations in the Atlantic sector of Arctica have been observed. The size of sea ice cover in the Barents Sea in the following year has shown especially high correlation with the changeability of WPL (the changeability of WPL explains ~50% of changeability in the area of the sea ice cover of the Barents Sea in January the following year). In this way WPL seems to be potentially useful in long term predictors of weather forecasts. The delayed activity of WPL can be explained by means of the following cause- and-effect chain of actions: winter (DJFM) atmpspheric circulation over the Davis Strait and the Labrador Sea has influence on the activity of the Labrador Current - the activity of the Labrador Current has influence on the extent and size of the anomalies in SST in the Labrador Sea and in NW part of the Atlantic (MJJA) - the presence of such anomalies in SST has a modifying effect on the atmospheric circulation occurring in the following autumn (SON) and winter (DJFM).
Źródło:
Problemy Klimatologii Polarnej; 2003, 13; 43-58
1234-0715
Pojawia się w:
Problemy Klimatologii Polarnej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparison of the metrological properties of two-core current transformers
Porównanie właściwości metrologicznych dwurdzeniowych przekładników prądowych
Autorzy:
Dusza, D.
Powiązania:
https://bibliotekanauki.pl/articles/156954.pdf
Data publikacji:
2014
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
current
processing
current transducer
prąd
przetwarzanie
przekładnik prądowy
Opis:
The paper presents a comparative analysis of the two-core Brooks and Brooks &Holtz transformers used in precision measuring systems. The derived relations indicate that the two-core Brooks & Holtz transformer has much better metrological properties. The metrological analysis was verified by the results of tests carried out on standard transformers. The analysis and the results can be used in the design of two-core transformers.
W artykule przedstawiono porównanie właściwości metrologicznych przekładników prądowych Brooksa oraz Brooksa i Holtza [3]. W rozdziale 2.1 przedstawiono przekładnik jednordzeniowy, którego błąd opisano za pomocą impedancji jego obwodu zastępczego (rys. 1b). W rozdziale 2.2 pokazano schemat zastępczy przekładnika Brooksa i na tej podstawie wyprowadzono wzór (2) określający błąd przekładnika. Przy założeniu (3) uproszczono wzór (2) do postaci (5), z którego wynika, że błąd przekładnika zależy głównie od impedancji obciążenia. Pokazano również wpływ błędu przekładnika pomocniczego ACIT (6) na błąd przetwarzania przekładnika Brooksa. Ze wzoru (10) wynika, że magnetowód przekładnika pomocniczego powinien być wykonany z materiału ferromagnetycznego o dużej wartości przenikalności początkowej, tj. permaloj, taśma amorficzna. W rozdziale 2.3 pokazano strukturę i analizę przekładnika Brooksa i Holtza. Z analizy wynika, że przekładnik ten powinien charakteryzować się lepszymi parametrami metrologicznymi, niż przekładnik Brooksa i Holtza, ponieważ w równaniu występuje iloczyn błędów przekładnika głównego i pomocniczego. W rozdziale 3 pokazano zastosowane układy pomiarowe do wyznaczania błędów przekładnika Brooksa (rys. 4) oraz Brooksa i Holtza (rys.5), które realizują metodę kompensacyjno-różnicową. W rozdziale 4 przedstawiono wyniki badań dla błędów prądowych i kątowych. Z otrzymanych wyników badań określono klasę przekładnika Brooksa jako 0,5 oraz dla połączenia Brooksa i Holtza 0,05.
Źródło:
Pomiary Automatyka Kontrola; 2014, R. 60, nr 8, 8; 568-572
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Measurements on Loudspeaker Distortion: Current vs. Voltage Control
Autorzy:
Meriläinen, E.
Powiązania:
https://bibliotekanauki.pl/articles/176516.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
current driving
current control
loudspeaker distortion
current distortion
inductance non-linearity
voice coil former
Opis:
Modulation and harmonic distortion produced by ordinary moving-coil direct-radiator drive units are measured under current control and voltage control. A realistic two-tone test signal is used to investigate the detrimental effect of the voice coil electromotive forces on the voltage-to-current conversion that is critical with voltage control. Dramatic improvements in distortion performance are obtained with current control. Current nonlinearities in voltage-controlled speakers are shown to be the dominant source of modulation and odd harmonic distortions at signal frequencies above the fundamental resonance region. Currents in conductive voice coil formers also seem to be significant sources of distortion; with current control and non-conductive formers, odd harmonics and related modulation products virtually vanished in the upper midrange.
Źródło:
Archives of Acoustics; 2017, 42, 1; 71-81
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Verification of the value of leakage current amperage of a rod insulator surface determined using an electric model of its surface percolation
Autorzy:
Frączak, P.
Powiązania:
https://bibliotekanauki.pl/articles/97353.pdf
Data publikacji:
2016
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
insulator percolation current amperage
insulator percolation current amperage verification
Opis:
This work presents simulation of calculations related to the value of leakage current amperage on a porcelain surface of a rod insulator performed using the percolation theory. Surface of a rod insulator has been presented in the percolation model for grid nodes. This model is an electric circuit which includes a resistance grid and a power (voltage) source. This model includes a randomised method of “filled” node creation within the grid. The procedure of simulation calculations of the leakage current amperage using the percolation model included creation of its equivalent circuit and declaration of appropriate current analysis in the PSpice program. Thus obtained values of leakage current on amperage the surface of a rod insulator were compared with values measured on insulators studied at the testing station. Similar values of leakage current amperage on surfaces of insulators were obtained in simulation calculations (for the percolation theory), and in actual measurements at the testing station.
Źródło:
Computer Applications in Electrical Engineering; 2016, 14; 201-209
1508-4248
Pojawia się w:
Computer Applications in Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and test of a new high-current electronic current transformer with a Rogowski coil
Autorzy:
Zhang, M.
Li, K.
He, S.
Wang, J.
Powiązania:
https://bibliotekanauki.pl/articles/221051.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Rogowski coil
high-current
electronic current transformers
electrical measurements
Opis:
This paper describes the design and test of a new high-current electronic current transformer based on a Rogowski coil. For better performances, electronic current transformers are used to replace conventional electro-magnetic inductive current transformers based on ferromagnetic cores and windings to measure high-current on the high voltage distribution grids. The design of a new high-current electronic current transformer is described in this paper. The principal schemes of the prototype and partial evaluation results are presented. Through relative tests it is known that the prototype has a wide dynamic range and frequency band, and it can allow high accuracy measurements.
Źródło:
Metrology and Measurement Systems; 2014, 21, 1; 121-132
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on optimal configuration of fault current limiter based on reliability in large power network
Autorzy:
Zeng, Jianjun
Zhang, Yonggao
Powiązania:
https://bibliotekanauki.pl/articles/949918.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
configuration optimization
fault current limiter
reliability
short circuit current
Opis:
With the availability of UHV engineering technology, the scale of the power network is expanding, and the level of the short-circuit current is getting higher, which brings hidden trouble to the safe and stable operation of the power network. Further this article issued a method that optimized the configuration of a current limiter based on the reliability of the power network. According to the reliability analysis under the influence of a short circuit, the quantitative evaluation of reliability of the power network is realized by the calculation of the short-circuit current. A quantitative model is established among reliability evaluation and the short-circuit current as well as load loss, the candidate installation site of a current limiter can be determined according to reliability quantification results. This method uses the particle swarm optimization algorithm to optimize the distribution of the limiter, aiming at the reliability level and the minimum number of current limiters in the short circuit of a power grid. Finally, taking the actual power grid of a province as an example, the result shows that this method can reduce the search space of the optimal solution, optimize the configuration of the current limiter, and effectively limit the short-circuit current and improve the reliability of the power network.
Źródło:
Archives of Electrical Engineering; 2020, 69, 3; 661-677
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 1003

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