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Wyszukujesz frazę "surge" wg kryterium: Temat


Tytuł:
Nonlinear Load and RLC Pulse Shaping Surge Generator Models in Simulation Environment
Autorzy:
Edirisinghe, M.
Tematy:
Nonlinear load
surge generator
surge protection
loading effect
Pokaż więcej
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:
https://bibliotekanauki.pl/articles/412021.pdf  Link otwiera się w nowym oknie
Opis:
The present study was performed in order to understand how a nonlinear load affects the characteristics of the RLC pulse shaping surge generator waveforms under simulation studies. The obtained results were compared when analytical equations were used as source models for both 1.2/50 s voltage & 8/20 s current impulses. Three circuit models; Capacitor Bank generator, Combination waveform generator and Schaffner generator were evaluated under nonlinear loads varied from 10Ω to 106 Ω for voltage impulses and for current impulses it was from 10-4 Ω to 1 Ω. As it can perceive from the analysis, delay time, rise time and FWHM remain unchanged throughout the tested impedance range when used model equations as generator sources. It was found that for voltage impulses, these values were 4.95 μs, 1.20 μs and 81.8 μs respectively. For current impulses, these values were 16.2 μs, 8.02 μs and 20.7 μs respectively. However results obtained for generator circuit models shows that delay time, rise time and FWHM deviated from above values up to maximum of 35.15 %, 106.67 % & 115.16 % respectively for voltage impulses. For current impulses these deviations were up to maximum of 79.63 %, 48.75 % & 39.61 % respectively. The deviations were due to influence caused by the nonlinear load to the generator circuit parameters and effective internal impedance.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Studies on Degradation of Varistors Subjected to Operation in Surge Arresters and Surge Arrester Counters
Autorzy:
Papliński, P.
Wańkowicz, J.
Śmietanka, H.
Ranachowski, P.
Ranachowski, Z.
Kudela, S. jr.
Aleksiejuk, M.
Tematy:
surge arrester
surge arrester counter
MO varistor
microstructure of ceramics
ceramic material degradation
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Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/351611.pdf  Link otwiera się w nowym oknie
Opis:
The paper presents results of investigation of microstructure and micro-hardness for material of ZnO varistors applied to 110 kV surge arrester and surge arrester counter. The research combined two pairs of varistors, each consisted of one varistor subjected before to operation, while the other one was brand new unit and constituted a reference. All varistors were made of the same material by the reputable manufacture. The tests revealed a different degree of the material degradation for varistors subjected before to operation. This also refers to different degradation mechanism observed for the material of these varistors, if typical effects of degradation of aged ZnO varistors were considered as a reference. Physical state of spinel in the microstructure had a significant impact on the material degradation, however a considerable loosening of the microstructure associated with bismuth oxide was observed too. It was surprising, since the precipitates of the bismuth oxide phase most often showed very good binding to the ZnO matrix and high resistance to associated electrical, thermal and mechanical effects. The degradation effects in the ZnO matrix proved to be limited only.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Causes and effects of coastal dunes erosion during storm surge Axel in January 2017 on the southern Baltic Polish coast
Autorzy:
Łabuz, Tomasz Arkadiusz
Tematy:
storm surge
sea level
run-up
dune erosion
Baltic Sea
the Axel surge
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Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Powiązania:
https://bibliotekanauki.pl/articles/52566896.pdf  Link otwiera się w nowym oknie
Opis:
The study is dedicated to researching the storm surge Axel, the largest on the South Baltic coast in the 20th and 21st centuries. This unique event resulted in a very large erosion along the whole Polish Baltic Sea coast in January 2017 (max. HSL = 1.65 m, the average for the coast 1.36 m). Storm surge effects on the coast were followed based on field observations of dune retreat and analysis of hydrodynamic and meteorological parameters of the surge and its passage through the Baltic Sea. The material of dune erosion was collected based on cross-shore profiling of almost every 1 km, along the whole Polish sand barrier coast, before and after this storm. The work also studies the parameters of smaller storm surges from the end of 2016, which caused the lowering of beaches and dune erosion. A relationship was observed between erosion, and beach height and sea level (SL). The higher the beach, the lower the erosion that occurred. The average dune toe retreat was 5.1 m, and the largest exceeded 9–19 m (max. 42 m). The most important for dune erosion was the height of run-up, beach height and shore exposition for a surge. The largest dune erosion was observed during the heaviest SL with wave run-up higher than 3.8 m above mean sea level (AMSL). Each coast section was eroded, which also caused losses in infrastructure.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wewnętrzna ochrona odgromowa obiektów zabytkowych
Internal lightning protection in the monumental buildings
Autorzy:
Dłużniewski, A.
John, Ł.
Tematy:
ochrona przeciwprzepięciowa
strefowa ochrona przeciwprzepięciowa
udar elektryczny
electric surge
lightning protection zone
surge protectors
Pokaż więcej
Wydawca:
Centrum Naukowo-Badawcze Ochrony Przeciwpożarowej im. Józefa Tuliszkowskiego
Powiązania:
https://bibliotekanauki.pl/articles/373125.pdf  Link otwiera się w nowym oknie
Opis:
W artykule omówiono zasady ochrony urządzeń elektrycznych i elektronicznych znajdujących się w obiektach zabytkowych przed przepięciami. Ochrona przeciwprzepięciowa polega na zastosowaniu strefowej koncepcji ochrony urządzeń i systemów. Opisano podstawowe zasady ekranowania i prowadzenia instalacji elektrycznej i transmisji sygnałów w celu uniknięcia sprzężeń pomiędzy instalacjami znajdującymi się w zabytkowym obiekcie. Podano przykłady ochrony urządzeń elektronicznych znajdujących się w starych dworkach ze względu na ich znaczenie kulturalne. Pokazano również przykłady zabezpieczenia przed przepięciami systemów i urządzeń znajdujących się w zabytkowym obiekcie kolejowym na przykładzie nastawni dyspozytorskiej, które przystosowano do instalowania nowoczesnych urządzeń elektronicznych.
The article discusses the principle of protection of electrical and electronic equipment located in monumental buildings before the surge. Surge Protection is the partition using the concept of security devices and systems. Describes the basic principles of screening and conduct electrical signals and to avoid linkage between installations located in the monumental building. Protection are examples of electronic devices located in the old manor monumental because of their cultural significance. Showing examples of surge protection systems and equipment located in a historic building on the example of railway control room dispatcher, which is adapted to the installation of modern electronic devices.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical surge modeling based on the pressure oscillations in the stable operation range of the compressor
Autorzy:
Jaeschke, A.
Liśkiewicz, G.
Tematy:
radial compressors
surge
Greitzer model
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/175279.pdf  Link otwiera się w nowym oknie
Opis:
Prevention of surge phenomenon is a very active field of research in last decades. The Greitzer model is the most widely applied mathematical model describing the surge phenomenon. Two parameters that characterize the given compressing system: the Helmholtz oscillator frequency and the so-called B parameter have to be given as the input to Greitzer model. Although those parameters are easy to determine for simplified compressor models, they are extremely hard to predict in case of real industrial compressors. Moreover, in most cases it is impossible to analyse compressor unstable work, which makes this prediction even more speculative. Therefore the method that determines the parameters basing on the compressor stable operation is indispensable. In paper the regularly perturbed Greitzer model based method of predicting the behaviour of a compressor in the unstable operation basing on signals from its stable operation is proposed and discussed.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania z zakresu ochrony odgromowej wykonane na Politechnice Wrocławskiej
Lightning protection research carried out at Wroclaw university of technology
Autorzy:
Chrzan, K.L.
Tematy:
zwody aktywne
ogranicznik przepięć
gapped surge arresters
metal oxide surge arresters
early streamer emission terminals
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Wydawca:
Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
Powiązania:
https://bibliotekanauki.pl/articles/267395.pdf  Link otwiera się w nowym oknie
Opis:
Wymieniono pierwsze instalacje piorunochronów w Rzeczypospolitej i na Dolnym Śląsku. Opisano badania skuteczności zwodów pionowych na makiecie obserwatorium meteorologicznego oraz skuteczności zwodów aktywnych ESE. Przedstawiono najważniejsze osiągnięcia w zakresie badania odporności zabrudzeniowej odgromników zaworowych i ograniczników beziskiernikowych. Streszczono pomiary wytrzymałości udarowej zabrudzonych izolatorów.
The first installation of Franklin rods in Kingdom of Poland and in Silesia Province were listed. The investigation of Franklin rods efficacy and inefficacy of early streamer emission terminals were shown. The most important achievements in the research of pollution resistance of gapped and gapless surge arresters was reported. The measurements of lightning flashover voltage of polluted insulators were described.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antisurge Systems-State of the Art
Autorzy:
Grapow, Filip
Tematy:
Surge
antisurge system
compressors
flow instabilities
Pokaż więcej
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:
https://bibliotekanauki.pl/articles/1178312.pdf  Link otwiera się w nowym oknie
Opis:
Industry today can’t exist without compressors. Very often they are most important part of installation and profits of enterprise depends on them. Every failure of this machine results in stoppage of production and therefore enormous loses. One of the biggest threat to stable operation of compressors is flow instability called surge. It occurs in conditions of low mass flow rate and appears as an oscillations of pressure and mass flow and it’s capable of destroying machine in just few seconds. To prevent from this dangerous phenomenon antisurge systems are used. In this paper division of antisurge systems and literature study of current knowledge and technologies are presented. Examples of different types of antisurge systems and future trends are discussed. This paper summarize today’s state of knowledge about methods of prevention from surge.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compressor modeling using Greitzer model validated by pressure oscillations
Autorzy:
Grapow, F.
Liśkiewicz, G.
Tematy:
centrifugal compressor
surge
greitzer model
compressor modeling
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/175456.pdf  Link otwiera się w nowym oknie
Opis:
Nowadays compressors are used in almost every industry. Compressor failure can suspend production of the whole system so the importance of preventing from failures is obvious and essential. One of the most dangerous flow instabilities which is capable of destroying machine in few seconds is surge, which occurs in conditions of low mass flow rate. Greitzer model, apart from its long history, is still most common mathematical model describing surge. It is widely used to predict the surge onset and pressure oscillations during it. However, it is based on parameters that are not directly related to real machine and their choice is not always obvious. Therefore, the calculations may be inaccurate which results in wrong surge prediction. The other approach to Greitzer model is presented in this paper, which in some cases can assure that the process of compressor modeling is more accurate. The applicability of Greitzer surge model for real machines has been analyzed. Method of implementation is based on experimental pressure signal gathered during unstable work of compressor. Presented method is based on experimental compressor characteristic and outlet pressure signal from unstable work of compressor. From that data it is possible to determinate the value of Greitzer model’s parameters for selected operational point. Thanks to this method this model could be applied for reliable antisurge protection.
Dostawca treści:
Biblioteka Nauki
Artykuł

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