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Wyświetlanie 1-15 z 34
Tytuł:
Thermal problems during start-up of cage induction motors
Autorzy:
Mróz, Jan
Bogusz, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2173615.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cage induction motor
direct start-up
softstart
winding temperature
silnik indukcyjny klatkowy
rozruch bezpośredni
soft-start
start miękki
temperatura uzwojenia
Opis:
This article considers the problem of the rise in temperature of the windings of an induction motor during start-up. Excessive growth of thermal stresses in the structure of a cage winding increases the probability of damage to the winding of the rotor. For the purpose of analysis of the problem, simplified mathematical relationships are given, enabling the comparison of quantities of energy released in a rotor winding during start-up by different methods. Also, laboratory tests were carried out on a specially adapted cage induction motor enabling measurement of the temperature of a rotor winding during its operation. Because there was no possibility of investigating motors in medium- and high-power drive systems, the authors decided to carry out tests on a low-power motor. The study concerned the start-up of a drive system with a 4 kW cage induction motor. Changes in the winding temperature were recorded for three cases: direct online start-up, soft starting, and the use of a variable-frequency drive (VFD). Conclusions were drawn based on the results obtained. In high-power motors, the observed phenomena occur with greater intensity, because of the use of deep bar and double cage rotors. For this reason, indication is made of the particular need for research into the energy aspects of different start-up methods for medium- and high-power cage induction motors in conditions of prolonged start-up.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 3; art. no. e137058
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal problems during start-up of cage induction motors
Autorzy:
Mróz, Jan
Bogusz, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2128166.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cage induction motor
direct start-up
softstart
winding temperature
silnik indukcyjny klatkowy
rozruch bezpośredni
soft-start
start miękki
temperatura uzwojenia
Opis:
This article considers the problem of the rise in temperature of the windings of an induction motor during start-up. Excessive growth of thermal stresses in the structure of a cage winding increases the probability of damage to the winding of the rotor. For the purpose of analysis of the problem, simplified mathematical relationships are given, enabling the comparison of quantities of energy released in a rotor winding during start-up by different methods. Also, laboratory tests were carried out on a specially adapted cage induction motor enabling measurement of the temperature of a rotor winding during its operation. Because there was no possibility of investigating motors in medium- and high-power drive systems, the authors decided to carry out tests on a low-power motor. The study concerned the start-up of a drive system with a 4 kW cage induction motor. Changes in the winding temperature were recorded for three cases: direct online start-up, soft starting, and the use of a variable-frequency drive (VFD). Conclusions were drawn based on the results obtained. In high-power motors, the observed phenomena occur with greater intensity, because of the use of deep bar and double cage rotors. For this reason, indication is made of the particular need for research into the energy aspects of different start-up methods for medium- and high-power cage induction motors in conditions of prolonged start-up.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 3; e137058, 1--7
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On-road exhaust emissions from passenger cars fitted with a start-stop system
Badania emisji spalin samochodów osobowych z systemem start-stop w rzeczywistych warunkach ruchu
Autorzy:
Merkisz, J.
Pielecha, I.
Pielecha, J.
Brudnicki, K.
Powiązania:
https://bibliotekanauki.pl/articles/224329.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
system start-stop
spaliny
badania emisji spalin
start-stop system
exhaust emission
real traffic conditions
Opis:
The paper presents the results of on-road (city traffic) exhaust emission and fuel consumption tests related to a vehicle fitted with a start-stop system. The tests of different types of vehicle cruise cycles were performed on road portions of several kilometers under different traffic conditions. For the tests a portable exhaust analyzer SEMTECH DS was used. It measured the concentrations of the exhaust components and the exhaust gas mass flow. As a result the authors determined the usefulness of the engine disengaging systems in vehicles under the conditions of city traffic.
W artykule przedstawiono rezultaty z badań emisji związków szkodliwych z silnika oraz zużycia paliwa pojazdu wyposażonego w układ start-stop w rzeczywistych warunkach ruchu miejskiego. Testy dla różnych typów przejazdów wykonywano na odcinkach kilkudziesięciu kilometrów w różnych warunkach drogowych. Do pomiarów stężenia związków toksycznych wykorzystano mobilny analizator do badań toksyczności SEMTECH DS firmy SENSORS. Analizator umożliwiał pomiar stężenia związków szkodliwych, mierząc jednocześnie masowe natężenie spalin. W efekcie otrzymanych wyników, określony został sens stosowania układów wyłączających silnik w warunkach ruchu miejskiego.
Źródło:
Archives of Transport; 2011, 23, 1; 37-46
0866-9546
2300-8830
Pojawia się w:
Archives of Transport
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prediction of Martensite Start Temperatures of Highly Alloyed Steels
Autorzy:
Lee, Seok-Jae
Jung, Minsu
Powiązania:
https://bibliotekanauki.pl/articles/2049415.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
martensite start temperature
empirical equation
highly alloyed steel
Opis:
We propose an empirical equation to predict the martensite start temperatures of highly alloyed steels containing more than 3 wt.% of Ni or Cr or 2 wt.% of Mo, W, or Co. The martensite start temperature calculated by the proposed equation was in good agreement with experimental data owing to not only the derivation from experimental data of alloy steels with a wide range of chemical compositions but also the interaction term between carbon and carbide-forming alloying elements.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 1; 107-111
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dziecko sześcioletnie w szkole. Przygotowanie i dobry start — analiza teoretyczno-praktyczna (Six-year-old child in the school. Preparation and good start — theoretical-practical analysis)
Autorzy:
Myszkowska-Litwa, Marta
Powiązania:
https://bibliotekanauki.pl/articles/707211.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Źródło:
Rocznik Komisji Nauk Pedagogicznych; 2015, LXVIII
0079-3418
Pojawia się w:
Rocznik Komisji Nauk Pedagogicznych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of transient states in the start-up path during voltage and start-up power application
Autorzy:
Grządzielski, Ireneusz
Olejnik, Bartosz
Zakrzewski, Mikołaj
Powiązania:
https://bibliotekanauki.pl/articles/949916.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
blackout
electric power system
restoration power
Opis:
During a blackout, after the post-disaster collapse of an electric power system (EPS), units of thermal power plants should switch-over to the house load operation mode (PPW). However, regarding the dynamics of a post-disaster blackout process, many units can be in forced outage Therefore, restart of these units from the start-up sources with a self-start capability is necessary. The Transmission Network Code in force imposes periodic tests and system tests for such sources. Any system test must be preceded and followed by simulation investigations in which the possibilities: (1) to bring voltage to the started-up power plant by a starting path and (2) to activate the highest-power auxiliaries (PW) of the unit being started-up are evaluated. In the paper, chosen results of simulative investigations of the transient phenomena in the starting path from the hydroelectric power plant of Włocławek (HPP Włocławek) to the thermal power plant of Pątnów (w (TPP Pątnów), related to the system test conducted in September 2017 have been presented.
Źródło:
Archives of Electrical Engineering; 2019, 68, 4; 749-769
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Steam turbines start-ups
Autorzy:
Banaszkiewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/175428.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
turbine
numerical computations
liquid flow parameters
Opis:
The article presents a procedure and the chosen results of numerical computations of liquid flow parameters, which use the data from their measurements realized on the test stand, for the model of formed suction intake with a rib, supplied by the screened open wet well. Comparative analysis of numerical computations and these determined by measurements, did concern the standard flow acceptance criteria.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2014, 126; 169-198
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes in aerodynamic parameters for 5-stage steam turbine during warming and gradual start-up to nominal operating parameters
Autorzy:
Hoznedl, M.
Bednář, L.
Tajč, L.
Powiązania:
https://bibliotekanauki.pl/articles/175267.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
steam turbine
experimental measurement
warming
start-up
efficiency
Opis:
The results of experiments on the 5-stage steam turbine are presented. The parameters of individual stages as well as the whole turbine are observed during the gradual start-up to nominal operating parameters. The pressures and temperatures are shown at stages in idling, heating up the experimental turbine and during the transition to operating speed. A greater attention is devoted to three selected operational conditions with different processed enthalpy drops. Problems with efficiency and enthalpy drops measurement during warming are described. The attempts to measure flow parameters quickly and without time for heating of turbine casings and other parts are often in the experimental research caused byprice of the survey. This contributionÞs task is to inform about these situations and to avoid confused and untrue results obtained by somewhat hasty measurements due to reduction and optimisation of costs.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2016, 134; 45-62
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic and steady state performance comparison of line-start permanent magnet synchronous motors with interior and surface rotor magnets
Autorzy:
Ogbuka, C.
Nwosu, C.
Agu, M.
Powiązania:
https://bibliotekanauki.pl/articles/141537.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
PMSM
line-start
damper winding
airgap torque
reluctance torque
saliency
Opis:
A comprehensive comparison of the dynamic and steady state performance characteristics of permanent magnet synchronous motors (PMSM) with interior and surface rotor magnets for line-start operation is presented. The dynamic model equations of the PMSM, with damper windings, are utilized for dynamic studies. Two typical loading scenarios are examined: step and ramp loading. The interior permanent magnet synchronous motor (IPMSM) showed superior asynchronous performance under no load, attaining faster synchronism compared to the surface permanent magnet synchronous motor (SPMSM). With step load of 10 Nm at 2 s the combined effect of the excitation and the reluctance torque forced the IPMSM to pull into synchronism faster than the SPMSM which lacks saliency. The ability of the motors to withstand gradual load increase, in the synchronous mode, was examined using ramp loading starting from zero at 2 s. SPMSM lost synchronism at 12 s under 11 Nm load while the IPMSM sustained synchronism until 41 seconds under 40 Nm load. This clearly suggests that the IPMSM has superior load-withstand capability. The superiority is further buttressed with the steady state torque analysis where airgap torque in IPMSM is enhanced by the reluctance torque within 90E to 180E torque angle.
Źródło:
Archives of Electrical Engineering; 2016, 65, 1; 105-116
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Start Acceleration of the Space GPS Receiver
Autorzy:
Kovář, Pavel
Powiązania:
https://bibliotekanauki.pl/articles/1844470.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
FPGA
navigation
low earth orbit
acquisition accelerator
Opis:
The cold start of the space GPS receiver, i.e. the start without any information about the receiver position, satellite constellation, and time, is complicated by a large Doppler shift of a navigation signal caused by the satellite movement on the Earth orbit. That increases about five times the search space of the navigation signals compared to the standard GPS receiver. The paper investigates a method of the acceleration of the GPS receiver cold start time designed for the pico- and femto-satellites. The proposed method is based on a combination of the paralel search in Doppler frequency and PRN codes and the serial search in code phase delay. It can shorten the cold start time of the GPS receiver operating on LEO orbit from about 300 to 60 seconds while keeping the simplicity of FPGA signal processor and low power consumption. The developed algorithm was successfully implemented and tested in the piNAV GPS receiver. The Energy required for the obtaining of the position fix was reduced five times from 36 on to 7.7 Joules. This improvement enables applications of such receiver for the position determination in smaller satellites like Pocket Cube or femto-satellites with a lower energy budget than the Cube Satellite.
Źródło:
International Journal of Electronics and Telecommunications; 2020, 66, 4; 745-752
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zaburzenia rozwoju ruchowego dziecka przed startem szkolnym (Motor development disorders in children before the start of school)
Autorzy:
Kowalewski, Ireneusz
Powiązania:
https://bibliotekanauki.pl/articles/707231.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Źródło:
Rocznik Komisji Nauk Pedagogicznych; 2014, LXVII
0079-3418
Pojawia się w:
Rocznik Komisji Nauk Pedagogicznych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of a start-up process in LSPMSMs with aluminum and copper rotor bars considering the coupling of electromagnetic and thermal phenomena
Autorzy:
Baranski, Mariusz
Szelag, Wojciech
Lyskawinski, Wiesław
Powiązania:
https://bibliotekanauki.pl/articles/141163.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aluminum and copper cage
coupled electromagnetic-thermal phenomena
FE model of LSPMSM
measurement verification
start-up process
Opis:
The paper presents an FE model of coupled electromagnetic and thermal phenomena in Line Start Permanent Magnet Synchronous Motors (LSPMSMs). An algorithm for solving equations of a discrete model using the FEM has been presented. On the basis of this algorithm the author’s personally developed software for the analysis of coupled electromagnetic-thermal phenomena in the LSPMS motors was elaborated. This software was used to analyze the start-up process of motors with identical stator and rotor magnetic circuits and different materials of the starting cage. The start-up process of motors with the squirrel-cage made of aluminum and copper was considered. The influence of temperature on the start-up process has been taken into account. The results of simulation tests were compared with the results of measurements.
Źródło:
Archives of Electrical Engineering; 2019, 68, 4; 933-946
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asynchronous slip-ring motor synchronized with permanent magnets
Autorzy:
Glinka, T.
Bernatt, J.
Powiązania:
https://bibliotekanauki.pl/articles/140518.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
motor with permanent magnets
slip-ring rotor winding
asynchronous start
Opis:
The electric LSPMSM motor presented in the paper differs from standard induction motor by rotor design. The insulated start-up winding is located in slots along the rotor circumference. The winding ends are connected to the slip-rings. The rotor core contains permanent magnets. The electromechanical characteristics for synchronous operation were calculated, as were the start-up characteristics for operation with a shortcircuited rotor winding. Two model motors were used for the calculations, the V-shaped Permanent Magnet (VPM) – Fig. 3, and the Linear Permanent Magnet (IPM) – Fig. 4, both rated at 14.5 kW. The advantages of the investigated motor are demonstrated in the conclusions.
Źródło:
Archives of Electrical Engineering; 2017, 66, 1; 199-206
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Validating performance based critical actions in a high tech start-up
Autorzy:
Vuoti, V. P.
Takala, J.
Mäntylä, A.
Liu, Y.
Yang, W.
binti Abdul Malek, N. A.
Kronman, P.
Kreuzer, A.
Zafar, A.
Powiązania:
https://bibliotekanauki.pl/articles/406824.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sustainable competitive advantage
sense and respond
manufacturing strategy index
operations strategy
balanced critical factor index
operations start up
case study
Opis:
The objective of this study is to analyze a Finnish manufacturing case company’s operational competitiveness. A proposed analytical model based on analyses the corresponding angles of the strategic triangles (Prospector, Analyzer, and Defender). The model compares the angle differences between the strategy and resource triangles with opinions from different management groups of informants. It was found out that Normalized Scaled Critical Factor Index (NSCFI) model is more scientific comparing to formal ones through validation. Calculations based on the MSI questionnaire resulted in medium high values for the Prospector strategy both for past- and future orientation. S&R calculations regarding the past orientation resulted in low values for all strategy types, except P-NSCFI for Analyzer. Moreover this study covers a case, in where Balanced Critical Factor Index (BCFI) was used defining company annual strategy plan.
Źródło:
Management and Production Engineering Review; 2014, 5, 1; 74-86
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of start energy of Stirling engine type alpha
Autorzy:
Kropiwnicki, Jacek
Powiązania:
https://bibliotekanauki.pl/articles/240606.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Stirling engines
system efficiency
low temperature supply
silniki Sterlinga
wydajność systemu
zasilanie
niska temperatura
Opis:
The Stirling engine type alpha is composed of two cylinders (expansion space E and compression space C), regenerator that forms the space between the cylinders and the buffer space (under the pistons). Before the start-up and as a result of long-term operation, the average pressure in the working space (above the pistons) and in the buffer space is the same. However, in the initial phase of operation, the average pressure in the working space is different then the average pressure in the buffer space depending on the crankshaft starting position (starting angle). This, in turn, causes a large variation in the starting torque. An additional unfavorable factor caused by a large variation in the course of the indicated torque is the rotational speed variation and the formation of torsional vibrations in the drive system. After some time, depending on the quality of the engine piston sealing, the average pressure in the working and buffer space will equalize. The occurrence of the above-described phenomenon affects the selection of the starting electric motor, which can be significantly reduced, when the crankshaft starting position is optimized (the starting torque is several times greater than the average torque occurring in the generator operation mode). This paper presents the analysis of the impact of the crankshaft starting position on the course of the indicated torque and the resulting start-up energy. Starting the engine at an unfavorable position of the crankshaft may, in extreme cases, increase the starting torque even three times.
Źródło:
Archives of Thermodynamics; 2019, 40, 3; 243-259
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 34

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