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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.
Powiązania:
https://bibliotekanauki.pl/articles/412021.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Nonlinear load
surge generator
surge protection
loading effect
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.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 17, 3; 334-347
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
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.
Powiązania:
https://bibliotekanauki.pl/articles/351611.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
surge arrester
surge arrester counter
MO varistor
microstructure of ceramics
ceramic material degradation
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.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 1; 367-374
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
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.
Powiązania:
https://bibliotekanauki.pl/articles/175279.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
radial compressors
surge
Greitzer model
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.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2016, 133; 91-108
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antisurge Systems-State of the Art
Autorzy:
Grapow, Filip
Powiązania:
https://bibliotekanauki.pl/articles/1178312.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Surge
antisurge system
compressors
flow instabilities
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.
Źródło:
World Scientific News; 2017, 81, 2; 53-68
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Post−surge geometry and thermal structure of Hørbyebreen, central Spitsbergen
Autorzy:
Małecki, Jakub
Faucherre, Samuel
Strzelecki, Mateusz C.
Powiązania:
https://bibliotekanauki.pl/articles/2051391.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Arctic
Svalbard
glacier surge
glacier geometry changes
Źródło:
Polish Polar Research; 2013, 3; 305-321
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compressor modeling using Greitzer model validated by pressure oscillations
Autorzy:
Grapow, F.
Liśkiewicz, G.
Powiązania:
https://bibliotekanauki.pl/articles/175456.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
centrifugal compressor
surge
greitzer model
compressor modeling
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.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2016, 133; 69-89
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermographic and Electrical Test of Medium Voltage Surge Arresters
Autorzy:
Lisowska-Lis, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/114064.pdf
Data publikacji:
2019
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
surge arresters
medium voltage
thermography
discharge current
cooling
Opis:
The paper presents the results of a thermal test (conducted with thermographic camera, coupled with an electrical test) of medium voltage metal–oxide surge arresters. Surge arresters (for Uc=18 kV) were tested for the leakage current and surface temperature: for 5 minutes under state 50 Hz alternating voltage 18 kV. The surface temperature of the MOAs correlates with an increase in leakage current. The result shows that the 0.6 mA AC leakage current in the medium voltage metal–oxide surge arrester (18 kV) is above the stable operating point, and the loss of electrical power is higher than the effective heat dissipation in the arrester. After 5 minutes of high voltage impact U = 18 kV, the surface temperature of the surge arrester was (4.32±0.55) K higher than the initial temperature. The IR camera can be used to detect the faults of ZnO metal–oxide surge arresters that lead to an increase in surface temperature.
Źródło:
Measurement Automation Monitoring; 2019, 65, 2; 60-63
2450-2855
Pojawia się w:
Measurement Automation Monitoring
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One phase active filter with energy storage for active power surge compensation in feed line
Autorzy:
Sowa, K.
Baszyński, M.
Piróg, S.
Powiązania:
https://bibliotekanauki.pl/articles/141248.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
power quality
active power filter
power surge compensation
Opis:
The paper presents a concept of an active filter with energy storage. This solution can be used for the compensation of momentary one phase high power loads with discontinued power consumption (e.g. spot welding machines). Apart from the typical filtering capabilities, the system’s task is also the continuity of the input power from the feeder line and limiting its fluctuation. The proposed by the author’s solution can produce measurable economic benefits by reducing the rated power necessary to energize periodically operating loads and improving the indicators of electrical energy quality. The developed method of active power surges compensation enables a flexible approach to requirements concerning the rated power of the point to which the periodically operating loads with high peak current value are connected. The tests were conducted on a simulation model specially developed in Matlab & Simulink environment, proving high effectiveness of the presented solution.
Źródło:
Archives of Electrical Engineering; 2016, 65, 2; 221-234
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computer modelling of lighting power controller operation disturbed by 1.2/50 μs voltage lightning stroke
Autorzy:
Typańska, D.
Machczyński, W.
Powiązania:
https://bibliotekanauki.pl/articles/376687.pdf
Data publikacji:
2018
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
surge impulse
computer simulations
lighting installation
power regulator
Opis:
The article presents a computer simulation of a lighting installation disturbed by lightning surge. Modelled impulse voltage generator 1.2/50 μs, system with coupling/ decoupling system and a power semiconductor regulator used in light engineering have been described. The aim of the work was to investigate the influence of the surge impulse on the current flowing through the installation.
Źródło:
Poznan University of Technology Academic Journals. Electrical Engineering; 2018, 93; 159-168
1897-0737
Pojawia się w:
Poznan University of Technology Academic Journals. Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of metal oxide surge arresters as elements of overvoltage protection systems
Modelowanie ograniczników przepięć z tlenków metali jako elementów systemów ochrony przepięciowej
Autorzy:
Furgał, J.
Dau, S. K.
Powiązania:
https://bibliotekanauki.pl/articles/320307.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
ograniczniki przepięć
symulacje komputerowe
surge arresters
mathematical modelling
Opis:
Metal oxide surge arresters are used for protection of high and low voltage electric devices against overvoltages. Mathematical models of surge arresters should properly represent current-voltage dependencies of varistors during influence overvoltages. From among numerous models created so for two versions of a selected model were used for computer simulations of current-voltage dependences of surge arresters. Parameters of elements of the selected model can be calculated by use of data published in the catalogues. Current-voltage dependencies of the surge arrester designed for electric power systems of 110 kV for different current stroke were modelled. The results of computer simulations were compared with the experimental data.
Ograniczniki przepięć są powszechnie stosowane do ochrony przepięciowej urządzeń elektrycznych wysokiego i niskiego napięcia. Modele matematyczne ograniczników powinny właściwie odzwierciedlać charakterystyki napięciowo-prądowe warystorów podczas oddziaływania przepięć. Spośród wielu modeli opracowanych dotychczas do symulacji komputerowych zależności napięciowo-prądowych wybrano jeden model ograniczników. Parametry elementów modelu wyznaczono przy wykorzystaniu danych katalogowych. Modelowano zależności napięciowo-prądowe dla różnych udarów prądowych ogranicznika przepięć stosowanego w układach elektroenergetycznych 110 kV. Obliczenia porównano z wynikami badań.
Źródło:
Elektrotechnika i Elektronika; 2008, 27, 1; 14-19
1640-7202
Pojawia się w:
Elektrotechnika i Elektronika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Degradation Processes in Shield-Centring Elements of Surge Arresters
Autorzy:
Papliński, P.
Śmietanka, H.
Ranachowski, P.
Ranachowski, Zbigniew
Wieczorek, K.
Kudela, S. jr.
Powiązania:
https://bibliotekanauki.pl/articles/2203744.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
surge arrester
TSE glass textolite
discharge current
EDS method
Opis:
This paper presents the results of testing samples of shield-centering elements from medium-voltage surge arresters. The elements were made of TSE glass textolite. The elements have been dismantled from different operated surge arresters, which were subjected to discharge currents (short-circuit currents) of different intensity and duration. The discharge currents led to degradation of the tested elements with various degrees of advancement. The degradation was investigated using microscopic methods and energy-dispersive X-ray spectroscopy (EDS). Changes in the content of elements of the surface of textolite materials - as the degradation progresses - were documented. It was found that high discharge current flows resulted in melting of the organic binder, epoxy resin, especially its surface layer. Partial charring and even burning of the resin was noticeable. Furthermore, it was found that with increasing degradation on the surface of the TSE laminate, the carbon and oxygen content, which are part of the organic resin, decreases. Simultaneously the amount of silicon, calcium and aluminium, which are present in the glass fibres, increases. The charring effect of the resin and the formation of conductive paths result in a decrease in the performance of surge arresters and their subsequent failure.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 1; 237--242
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Operation of two-shaft gas turbine in the range of open anti-surge valve
Autorzy:
Dzida, M.
Frost, J.
Powiązania:
https://bibliotekanauki.pl/articles/260558.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
gas turbine
anti-surge valve
laboratory stand
experimental studies
Opis:
This paper presents experimental tests of full-scale two-shaft gas turbine in the range of open anti-surge valve (ASV). The tests were carried out in a laboratory gas- turbine test stand belonging to Department of Automation and Power Engineering , Faculty of Ocean Engineering and Ship Technology , Gdańsk University of Technology. The tests covered the start-up and low load operation of the turbine set in the range of open anti-surge valve.
Źródło:
Polish Maritime Research; 2017, 4; 85-92
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remote sensing of eskers from Vormsi and Väinameri vicinity, northwestern Estonia
Autorzy:
Aber, J. S.
Kalm, V.
Powiązania:
https://bibliotekanauki.pl/articles/2059322.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Estonia
Palivere
landsat
esker
subglacial meltwater
ice lobe surge
Opis:
We have utilised techniques of remote sensing in combination with ground observations in order to investigate eskers of the Vormsi and Väinameri region of northwestern Estonia. Landsat Thematic Mapper (TM) images were the basis for recognition and regional interpretation of esker systems, and kite aerial photography was employed for detailed, low-height views of selected eskers. A special Landsat TM composite was developed to enhance the display of shallow sea floor features. On this basis, we have extended known, land-based eskers across the sea floor, and we have identified additional probable eskers marked by shallow shoals and tiny islands. The known and suspected eskers of Vormsi and surroundings demonstrate a regular pattern in their distribution, which we suggest represents a subglacial drainage network that was anastomosing in character. The esker network is located along the central pathway of the Väinameri ice lobe, and the overall direction of drainage was toward the Palivere glacial limit. We interpret eskers of the Vormsi-Väinameri vicinity as evidence for substantial meltwater discharge beneath the Väinameri ice lobe, which terminated in a proglacial lake.
Źródło:
Geological Quarterly; 2001, 45, 4; 365-372
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of inlet distortion effects on axial compressor performance based on streamline curvature method
Autorzy:
Abbasi, S.
Pirnia, A.
Taghavi-Zenouz, R.
Powiązania:
https://bibliotekanauki.pl/articles/281973.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
axial compressor
performance map
inlet distortion
surge margin
streamline curvature
Opis:
In this paper, the effects of inlet flow distortion on performance maps and details of the flow field are investigated using the Streamline Curvature Method. The results are presented for both design and off-design conditions and compared with experimental data, which shows good agreement. The effects of inlet flow distortion are investigated by inlet total pressure variation in three different cases in the way that the average total pressure remains constant and equal to the design value. The results show that a relative increase in the total pressure at tip causes an increase in the pressure ratio and efficiency as well as a better performance in the choking region. Alternatively, a relative increase in the total pressure in hub causes opposite behavior and a better performance at the surging region.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 4; 1005-1015
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stable or not stable? Recognizing surge based on the pressure signal
Autorzy:
Garcia, D.
Liśkiewicz, G.
Powiązania:
https://bibliotekanauki.pl/articles/175253.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
singular spectrum analysis
nonlinear dynamics
statistical pattern recognition
compressor
surge
Opis:
The surge protection may be worth millions of dollars. This is typical price of a centrifugal compressor repair combined with additional cost of nonfunctionality of an industry employing it. This threat is normally secured by application of an antisurge systems. Typically they are activated at predefined working conditions when compressor mass flow rate approaches region affected by the surge. As a result those systems are vastly limiting its operational range usually by a desirable region where compressor attains large pressure ratio. Therefore, a modern antisurge systems are aiming at diminishing this tradeoff by reacting to the real pressure signal gathered at high frequency. This paper presents one of those methods employing singular spectrum analysis. This algorithm has not been widely used for this application, while it was shown herein that it may bring clear distinction between stable and nonstable working condition, even at presurge conditions. Hence in further perspective it may bring anti-surge protection quality, that was not met with another methods.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2016, 133; 55-68
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł

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