Wyniki 1-8 spośród 8 dla zapytania: authorDesc:"Joanna KOZIEŁ"

The influence of magnetic coupling factor k on value of impedance limiting fault current

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The society require reliable power network, that provides electric energy. In this article the rule of operation and construction of the superconducting fault current limiter of transformer type, which can be used in the future to increase security power network was described. The influence of magnetic coupling factor on value of impedance limiting fault current was theoretically analysed. Streszczenie Społeczeństwo wymaga niezawodnej sieci energetycznej dostarczającej energię. W tym artykule opisano zasadę działania i budowę nadprzewodnikowych ograniczników prądu typu transformatorowego, które mogą być w przyszłości stosowane dla zwiększenia bezpieczeństwa sieci energetycznej. Przeanalizowano teoretycznie wpływ współczynnika sprzężenia magnetycznego na wartość impedancji ograniczając[...]

Analysis of the impact of secondary winding impedance on the parameters of transformer type superconducting current limiters DOI:10.15199/48.2016.12.20

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W artykule zawarto klasyfikację nadprzewodnikowych ograniczników prądu zwarcia. W szczególności przedstawiono zasadę budowy i działania nadprzewodnikowego ogranicznika prądu typu transformatorowego. Omówiono funkcjonalny model fizyczny takiego ogranicznika zaprojektowany wykonany w Pracowni Technologii Nadprzewodnikowych Instytutu Elektrotechniki. Przedstawiono wyniki badań eksperymentalnych, analizę wpływu uzwojenia wtórnego ogranicznika na parametry nadprzewodnikowych ograniczników prądu typu transformatorowego i przedstawiono wynikające z analizy wnioski. (Analiza wpływu impedancji uzwojenia wtórnego na parametry nadprzewodnikowych ograniczników prądu typu transformatorowego). Abstract. The paper presents the classification of superconducting fault current limiters. In particular the principle of construction and operations of superconducting current limiter of transformer type is presented. Functional physical model of such a limiter, designed, manufactured in the Laboratory of Superconducting Technologies of Institute of Electrical Engineering. The paper presents the results of experimental research and the analysis of the impact of the secondary winding limiter on the performance of superconducting current limiters of a transformer type and the conclusions from the analysis are introduced. Słowa kluczowe: nadprzewodnictwo, ograniczenie prądu zwarcia, nadprzewodnikowy ogranicznik prądu typu transformatorowego, impedancja uzwojenia wtórnego. Keywords: superconductivity, limiting of short circuit current, transformer type superconducting fault current limiter, the impact of secondary winding impedance. Introduction Superconducting fault current limiters - SFCL are composed of superconducting elements of alternating impedance, being connected in series in an electrical circuit [1], [2]. They show a low impedance while operating in rated conditions of a protected electrical circuit, and high impedance in short circuit conditions in a [...]

Using the FTA method to analyze the quality of an uninterruptible power supply unitreparation UPS DOI:10.15199/48.2019.01.20

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Among the most important methods of hazard analysis and risk assessment, the authors applied the FTA method. The error tree method is a qualitative risk analysis method using logical tree structure, allowing to model the course of failure and then its analysis. In the FTA method, individual factors that can lead to an event and their potential effects are depicted in the socalled fault tree that shows the interdependencies between the potential main event and its causes. Identified factors (causes) plotted on the fault tree are interrelated and can be referred to as: specific failures (e.g. machines and devices), human errors (e.g. on the production line), first and second type errors, environmental conditions and other events that could lead to failure. In the 1990s, the use of FTA was started in the design of systems guaranteeing a high level of safety and reliability in the chemical, railway, IT and medical industries. It has also become a frequently used method in risk analysis and risk assessment alongside PHA and FMEA. Analysis of the FTA fault tree is therefore a graphical model of cause-and-effect relationships. The FTA scheme illustrates the causes whose effect is referred to as an uncertain event or risk. The result of the FTA analysis can be, for example, a logical tree showing the pressure tank crack scenario with highlighted errors of the first and second type. The first type of errors are production defects that appear while operating under design conditions. The second type of errors are errors of an element working in conditions for which the device was not intended. This is usually a mistake related to the wrong selection of an element for the process conditions. PHA (Preliminary Hazard Analysis) Preliminary Hazard Analysis (PHA) focuses on identifying any potential hazards and accidental events that can lead to a failure or accident. It is a non-standard method, based on knowledge available at the initi[...]

Iron - based superconductors - development prospects DOI:10.15199/48.2018.01.12

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The history of superconductivity reaches over 100 years back, when in 1911, Dutch physicist Heike Kamerlingh Onnes discovered loss of electrical resistance in mercury at near absolute zero temperature. Over time, superconductivity was discovered with the participation of further elements. In 1933 there was another breakthrough - the phenomenon of ideal diamagnetism in superconductors was discovered. It is directly responsible for commonly known magnetic levitation phenomenon. Fig. 1. Meissner-Ochsenfeld effect (magnetic levitation) [1] The progress of research led to the creation of the theory of superconductivity in both microscopic and macroscopic scale. Quantum phenomena, occurring in superconductors were discovered. In the eighties of the twentieth century, the so-called high temperature superconductors were discovered. Thanks to scientists hard work, critical temperature of superconductors was systematically raised. 2008 year brought the discovery of the iron-based superconductors in LaFeAsO1-xFx compound. The importance of iron-based superconductors discovery is that they have several unique properties, which are not present in other types of superconductors. It also turned out that there are many varieties of iron superconductors. Each of them has specific electromagnetic properties. [3] Iron-based superconductors retain it’s superconducting properties in strong magnetic fields, while the density of currents flowing through this type of superconductors is relatively small. Research is currently underway to improve this parameter, but this is achieved at the cost of lowering the critical temperature of the superconductor [4]. The properties of iron-based superconductors are making it an object of various applications - electric vehicles, wind turbines and medical equipment are just some of the potential applications of iron superconductors. Fig. 2 Crystalli[...]

Analysis of the current distribution in layers of a second generation superconducting tapes DOI:10.15199/48.2019.01.17

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Despite good failure statistics, transformers are one of the weak points of the transmission system. That is why a lot of attention is paid to ensuring protection of transformers, which minimises the risk of emergency situations. The basic operational problem of superconducting transformers (HTS) is the necessity of uninterrupted maintenance of superconducting windings at cryogenic temperature and not allowing losses of the superconducting state in them. The condition in which the HTS windings come out of superconductivity should be treated as an emergency condition of the HTS transformer's operation, which makes switching it on difficult and threatens interrupting the continuity of the windings as a result of their thermal damage. The substitute diagram of the HTS transformer does not deviate substantially from the conventional transformer scheme (Figure 1). Fig. 1. Substitute diagram of the HTS transformer Resistances R1HTS and R2HTS, representing power losses in the windings, are non-linear in the function of changes in current intensity, changes in the strength of external magnetic field and temperature changes. The non-linearity of R1HTS and R2HTS resistance is determined by the properties of superconducting winding wires. Second-generation high-temperature cables (2G HTS), currently used on windings of superconductor transformers, are made in the form of tapes with a layer structure (Fig. 2) [1][2]. They are relatively thin wires, compared to copper winding wires, and the superconductor alone constitutes only 5% of the entire cable's volume. The SCS4050 cable with a critical current of 87 A has a thickness of 0.1 mm and a width of 4 mm. The thickness of the superconductor layer is 1 m in it. The remaining volume consists of metallic layers. The SCS12050 cable with a critical current of 333 A differs only in its width, which in this case is 12 mm. Fig. 2. Structure of the 2G HTS cable from SuperPower Inc. [1[...]

Modelowanie powrotnej charakterystyki rozgałęzionej taśmy nadprzewodnikowej HTS 2G

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Praca przedstawia algorytm modelowania powrotnej charakterystyki rozgałęzionej nadprzewodników HTS dla potrzeb dynamicznego modelowania obwodów. Podstawą rozważań jest typowa makroskopowa charakterystyka prądowo- napięciowa taśmy nadprzewodnikowej HTS. Uwzględniając specyfikę i potrzebę analiz obwodowych autorzy proponują zastosowanie modelu Preisacha z charakterystyką statyczną w postaci funkcji wykładniczej. Jako podstawę dyskusji zaproponowano przebiegi charakterystyk prądowo-napięciowych taśmy HTS SF12050 firmy SuperPower. Abstract. The paper presents the algorithm for modeling the return branched characteristics of HTS superconductors for the dynamic modeling of circuits. The basis of the considerations is the typical macroscopic characteristic of the current - voltage HTS superconducting tape. Taking into account the specificity and the need for circuit analysis the authors propose the application of the Preisach model with the static characteristics as a exponential function. As a basis for discussion we propose the current-voltage characteristics of HTS tapes SF12050 produced by SuperPower Inc (The branched reverse characteristic modeling in HTS 2G tape) Słowa kluczowe: nadprzewodnictwo, taśmy nadprzewodnikowe HTS 2G, prąd krytyczny, nadprzewodnikowy ogranicznik prądu zwarcia. Keywords: superconductivity, superconducting tape HTS 2G, critical current, superconducting fault current limiter. Wstęp Precyzyjny, makroskopowy model matematyczny jest szczególnie ważnym komponentem w analizie właściwości dynamicznych urządzeń z elementami nadprzewodnikowymi. Nieliniowość znaczących parametrów jest właściwością wykorzystywaną w pracy wielu urządzeń, w tym nadprzewodnikowego ogranicznika prądu zwarcia (SFCL), który działa analogicznie jak transformator z przełącznikiem wartości rezystancji (element nadprzewodnikowy) w obwodzie wtórnym [1]. W związku z możliwościami analitycznymi, pomiarowymi oraz numerycznymi, zasadne jest poszukiwanie[...]

Badania eksperymentalne modelu transformatora z uzwojeniami wykonanymi z taśmy nadprzewodnikowej HTS drugiej generacji

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W artykule przedstawiono wyniki badań eksperymentalnych 1-fazowego modelu transformatora nadprzewodnikowego ze szczególnym uwzględnieniem możliwości ograniczania wartości prądu zwarcia przez uzwojenie nadprzewodnikowe, ze względu na parametry techniczne zastosowanej taśmy nadprzewodnikowej, w szczególności uwzględniając rezystywność taśm w stanie rezystywnym, w temperaturze 77 K. Abstract. This article presents the results of an experimental investigation of a 1-phase model of a superconducting transformer, with special regard to the possibility of limiting the short-circuit current by the superconducting winding, according to the parameters of the HTS tapes used, in particular their resistivity in normal state at a temperature of 77 K. (Experimental investigation of the model of superconducting transformer with the windings made of 2G HTS tape). Słowa kluczowe: transformator nadprzewodnikowy, ograniczanie prądów zwarcia, taśmy 2G HTS, rezystancja zwarcia. Keywords: superconducting transformer, fault current limitation, tape 2G HTS, resistance short-circuit. Wprowadzenie Nowe taśmy nadprzewodnikowe HTS drugiej generacji wytwarzane na bazie itru (YBCO), o wysokiej rezystywności w stanie rezystywnym w temperaturze 77K, umożliwiają budowę transformatorów odpornych na zwarcia i ograniczających prądy zwarcia. Przekroczenie wartość prądu krytycznego zastosowanej taśmy HTS, na skutek zwarcia, powoduje gwałtowne przejście uzwojeń nadprzewodnikowych do stanu rezystywnego, co skutkuje wzrostem impedancji zwarcia transformatora na skutek pojawienia się rezystancji uzwojeń. Wzrost impedancji zwarcia transformatora powoduje ograniczenie prądu zwarcia nawet do wartości niższych niż wartość prądu znamionowego transformatora nadprzewodnikowego[1]. Rys.1. Model jednofazowego transformatora nadprzewodnikowego Wzrost wartość impedancji uzwojeń transformatorów nadprzewodnikowych na skutek zwarcia, czemu towarzyszy zjawisko samoograniczenia prądu zwa[...]

The intensity of electromagnetic fields in the range of GSM 900, GSM 1800 DECT, UMTS, WLAN in built-up areas DOI:10.15199/48.2018.12.45

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The effect of civilisation development associated with radio communication and radio diffusion technologies is the widespread exposure to electromagnetic fields in the field of high frequencies in the environment. Radio and television broadcasting stations, GSM base stations, or broadcasting devices from the WiFi band are indispensable in the present world. It is important, however, that they work and are located in such a way that on the one hand they optimally fulfil their telecommunications functions, and on the other - minimally affect the environment, mainly in terms of the level of electromagnetic radiation in urban areas. From the point of view of environmental and human protection, as well as electromagnetic compatibility, it becomes important to monitor and measure the electromagnetic field (in particular the electrical component) produced by devices operating on communication frequencies. Socio-scientific needs of the study of the impact of radio communication installations and devices are governed by governmental institutions as well as research centers [1-11]. Conclusions from many studies are not unequivocal, although most often there is no statistically significant relationship between exposure and chronic or acute symptoms of health. A special case is the study of the influence of the electromagnetic field on the human reproductive system, reproductive processes - including the developing embryo and then the fetus. Knowledge on this subject is still developing and all conditions of human reproduction are still unknown. Many scientific publications, among others in terms of the impact of the electromagnetic field on semen are contradictory. Some have a beneficial effect on the sperm's movement parameters, while others have an inverse effect [1,2,3,7]. The actual levels of electromagnetic radiation values to which people are subjected depend on existing installations and radio communication devices in the imme[...]

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