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Wyświetlanie 1-15 z 26
Tytuł:
Wyznaczanie pradu rozruchowego i momentu rozruchowego dla silników asynchronicznych
Determination of starting current and starting torque for asynchronous motors
Autorzy:
Zieliński, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/1374073.pdf
Data publikacji:
2008
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
silnik indukcyjny
silniki elektryczne
prąd rozruchowy silnika
moment rozruchowy
Opis:
Calculation of the starting parameters for three-phase asynchronous motors is a very important issue as these parameters determine whether a motor can be satisfactorily used in a driving system and characterize it from the point of view of supply mains. The article discusses methods of determining initial starting current and initial starting torque with the omission of issues connected with electromagnetic transient processes, the influence of thermal states, and the effect of parasitic torques. Direct determination of these parameters is relatively complex, which is why they are often determined in an indirect way. Two methods are described, which allow to establish the aforementioned parameters: the tangent method and the short-circuit reactance distribution method. The methods consist in an extrapolation of short circuit characteristics obtained at reduced voltage. The results of research and the comparison of parameter calculations refer to two induction motors: squirrel cage and slip ring.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2008, 80; 147-150
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Host-parasite relations between Oligochaeta and helminths
Układ żywiciel-pasożyt w przypadku skąposzczetów i helmintów
Sistema khozjain-parazit v sluchae oligokhetov i gelmintov
Autorzy:
Supriga, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/2162121.pdf
Data publikacji:
1976
Wydawca:
Polskie Towarzystwo Parazytologiczne
Źródło:
Wiadomości Parazytologiczne; 1976, 22, 4-5; 413-415
0043-5163
Pojawia się w:
Wiadomości Parazytologiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Racjonalna praca silników asynchronicznych klatkowych przy zmianie skojarzenia uzwojeń z trójkąta w gwiazdę
Efficient operation of asynchronous squirrel-cage motors at the change from delta to star winding connection
Autorzy:
Zieliński, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/2076381.pdf
Data publikacji:
2007
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
silnik asynchroniczny klatkowy
silnik klatkowy
uzwojenie
Opis:
Three-phase asynchronous motor with a squirrel-cage rotor that is the most often applied in the industry has its disadvantages, which get revealed at a low-load motor operation or at its idling. High current input and low power factor at idling are among the disadvantages. Electrical energy saving is possible owing to the increased energy indices such as efficiency or power factor. The power factor value to a considerable degree depends on the load. Hence, in cases when the load varies within a wide range an adequate voltage reduction causes its increase. When voltage is reduced such quantities as: torque overload capacity, slip, rotor current and total power losses increase. The motor supply voltage can be varied in a continuous or a step mode. In some cases in order to considerably enhance energy indices and obtain significant energy savings it is enough to apply a two-step voltage regulation. It is mostly when the time-load run of the motor approaches intermittent running with idling breaks. The paper presents a solution that makes possible to enhance energy indices that is to make the motor operation more efficient with the application of a delta-to-star change of the winding connection. The method consists in that at the startup and full-load phase the motor operates at the delta connection of the windings, while at lower load values a switch to the star connection is performed. Additionally, runs of quantities that are characteristic for an efficient motor operation (power factor, efficiency, slip, current input) and have been obtained based on laboratory measurements performed at the delta-to-star switch of the stator winding connection have been determined.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2007, 77; 125-128
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Porównanie wskaźników energetycznych przy energooszczędnej pracy silnika klatkowego, realizowanej przez skokową regulację napięcia
A comparison of the energy indices in low-energy operation of a squirrel-cage motor, achieved in steps through regulation of the supply voltage
Autorzy:
Zieliński, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/1372557.pdf
Data publikacji:
2011
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
silnik elektryczny
silnik klatkowy
regulacja napięcia
energooszczędność
Opis:
Economic effectiveness of the operation of a propulsion system depends on energy indices of motors. Along with the type of operation, the load can vary greatly. Most induction motors operate at load which is considerably lower than their nominal load. Operation at small load or idle run has an adverse effect, when energy indices of the motor, such as power factor and energy efficiency, are very low. There is a need to improve these indices and establish conditions for optimum motor operation. If the motor's load is lower than its nominal load, supply voltage should be lowered to make the energy indices as high as possible. Thus, supplying the motor with voltage which varies depending on the degree of load brings positive results. At nominal load, the motor must by supplied with nominal voltage, however, as the load decreases, the voltage should be accordingly lowered. Lowering the supply voltage will result in decreased energy losses, which are connected with it, as well as increased energy efficiency and power factor. This leads to lower power consumption and thus to saving electric energy. The paper presents transients of current supplied from the mains, the power factor, and motor energy efficiency for various degrees of voltage changes ensuring the motor,s low-energy operation.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2011, 3, 91; 187-190
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of coagulants used for lake restoration on Daphnia magna Straus (Crustacea, Cladocera)
Wpływ koagulantów używanych do rekultywacji jezior na Daphnia magna Straus
Autorzy:
Piasecki, W.G.
Zacharzewski, D.
Powiązania:
https://bibliotekanauki.pl/articles/85071.pdf
Data publikacji:
2010
Wydawca:
Akademia Pomorska w Słupsku
Tematy:
coagulant
lake restoration
Daphnia magna
Crustacea
Cladocera
iron coagulant
aluminium coagulant
toxicity
eutrophication
technical restoration
lake condition
Opis:
This study examined the influence of ferric and aluminium coagulants (PIX 113 and PAX 18) and ferrous sulphate, used for lake restoration, on growth and mortality of cladocerans Daphnia magna Straus. We observed that addition of these coagulants in concentrations comparable to those used in various restored lakes reduced significantly the increase of Daphnia biomass comparing to the results obtained in the samples without coagulants. This phenomenon was directly proportional to the coagulant concentration. Ferrous sulphate turns out to have been the most toxic compound, while PAX 18 was the less harmful. Ferric coagulants also caused crustacean mortality ranging from 4 to 36%.
Badano wpływ koagulantów żelazowych i glinowych (PIX 113 i PAX 18) oraz siarczanu żelaza II, używanych do rekultywacji jezior, na wzrost i śmiertelność wioślarki Daphnia magna Straus. Stwierdzono, że dodanie do wody koagulantów w stężeniach porównywalnych ze stosowanymi na jeziorach rekultywowanych powoduje istotny spadek przyrostu biomasy Daphnia w stosunku do wyników otrzymywanych w próbach bez koagulantów. Zjawisko to jest wprost proporcjonalne do stężenia koagulantu. Najbardziej toksyczny okazał się siarczan żelaza II, najmniej – PAX 18. Obecność koagulantów żelazowych powoduje również śmiertelność skorupiaków na poziomie od 4% do 36%.
Źródło:
Baltic Coastal Zone. Journal of Ecology and Protection of the Coastline; 2010, 14
1643-0115
Pojawia się w:
Baltic Coastal Zone. Journal of Ecology and Protection of the Coastline
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ rodzaju wymuszenia na wybór struktury sterowania wektorowego
Selection of a vector control structure depending on the kind of an input signal
Autorzy:
Zieliński, W.G.
Michałowska, J.
Powiązania:
https://bibliotekanauki.pl/articles/2076338.pdf
Data publikacji:
2006
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
sterowanie wektorowe
sterowanie polowo zorientowane
silnik indukcyjny
Opis:
Vector control of induction motor torque and speed yields very good static and dynamic properties. Systems that apply such control become a standard solution that is widely used even for drives of high requirements. When vector control is applied aside with amplitudes and frequencies phases of rotational vectors of motor currents and flux linkages are determined. Correct orientation of the vectors can be maintained due to the control system both in steady and transient states. In the paper field-oriented vector control is discussed and kinds of input signals for that type of control are determined. Kind of an input signal is important for the motor operation as its dynamic properties get essentially changed then. Particular attention has been paid to voltage and current signals and control possibilities have been determined for each of them. Additionally, attention has been paid to the selection of control orientation with respect to the vector of magnetic field in the motor.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2006, 75; 41-45
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The cranial anatomy of the Early Jurassic turtle Kayentachelys aprix
Autorzy:
Sterli, J.
Joyce, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/22757.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
cranial anatomy
Cryptodira
Testudines
Jurassic
Early Jurassic
turtle
Kayentachelys aprix
evolution
fossil record
Kayenta Formation
Arizona
paleontology
systematics
Opis:
The fossil turtle Kayentachelys aprix is known from Early Jurassic sediments of the Kayenta Formation, Arizona, USA. The detailed description of this taxon’s cranium offered in this paper demonstrates that this turtle presents a mixture of primitive and derived character states. Among others, the presence of an interpterygoid vacuity, a basipterygoid process, a prootic that is exposed in ventral view, and a foramen posterius canalis carotici interni that is formed entirely by the basisphenoid are generally considered primitive for turtles. On the other hand, the presence of an undivided apertura narium, a well developed cavum tympani, an incipient cavum postoticum, and an unpaired vomer are considered to be derived. Kayentachelys aprix has previously been hypothesized to be the oldest stem cryptodiran turtle because of the presence of a flat, vertical plate on the processus pterygoideus externus, and the presence of a processus trochlearis oticum. However, the presence of these characters cannot be confirmed in the available specimens. Other putative stemcryptodiran characters, such as the prefrontal−vomer contact and the presence of an epipterygoid, are herein corroborated as being symplesiomorphies, because they generally appear to be present in basal turtles.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ nasycenia obwodu magnetycznego i wypierania prądu na przebiegi momentu elektromagnetycznego i prądu podczas rozruchu wysokoobrotowych silników klatkowych
Influence of the saturation of the magnetic circuit and skin effect on the transients of electromagnetic torque and current during the start up of high-speed motors
Autorzy:
Zielińska, M.J.
Zieliński, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/1372567.pdf
Data publikacji:
2011
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
silnik elektryczny
silnik klatkowy
silnik wysokoobrotowy
rozruch silnika
obwód magnetyczny
moment elektromagnetyczny
Opis:
High speed squirrel-cage motors are a relatively unknown group of machines, mainly due to their particular application. High rotational speed is achieved by supplying the motors with 400-1500Hz frequency voltage. Their operation in special conditions results in the fact that their structure and some properties differ from those of squirrel-cage induction machines supplied with 50Hz frequency voltage. The use of closed rotor slots causes strong saturation of the magnetic circuit for the slot leakage flux. Changes in the current in the slot causes a varying state of saturation and thus rotor leakage inductance is not a constant parameter. When determining the rotor winding leakage inductance for classic induction motors supplied with 50Hz frequency voltage, the influence of the saturation of the magnetic circuit for the leakage flux is usually omitted. This is a standard approach and an equivalent scheme, mentioned in literature, is used in such a case. Identification of the inductance in motors supplied with high frequency voltage, in which the phenomenon of core saturation occurs, is a relatively complex issue due to the complicated distribution of magnetic flux, and especially the leakage flux. The value of leakage inductance was determined experimentally. The paper presents differential equations describing a mathematical model and transients of the current and electromagnetic torque, obtained by simulating the start-up of a squirrel-cage high-speed motor.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2011, 3, 91; 183-186
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Opracowanie algorytmów regulacji napięcia zasilania wysokoobrotowych silników klatkowych celem zapewnienia zadanego momentu krytycznego lub rozruchowego
Developing algorithms for regulating the supply voltage of squirrel-cage high-speed motors in order to obtain the given breakdown or starting torque
Autorzy:
Zielińska, M.J.
Zieliński, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/1373228.pdf
Data publikacji:
2010
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
maszyna elektryczna
silnik indukcyjny klatkowy
silnik wysokoobrotowy
moment krytyczny silnika
moment rozruchowy
napięcie zasilania
Opis:
Obtaining a high value of the breakdown or starting torque in an asynchronous motor is a very important issue from the point of view of improving its operational properties. These values can be determined based on data of a typical equivalent scheme. This refers to motors without the skin effect in the cage bar or those in which the phenomenon has been omitted. In a high-speed motor, the phenomena of core saturation and skin effect influence the parameters of the equivalent scheme, which are not constant values and depend on the frequency of supply voltage and the value of the current in the bar of the rotor's cage. In consequence, an equivalent scheme valid for classic motors should not be used for analysis of the performance of a high-speed motor. Based on an equivalent scheme which takes into account the influence of frequency on its parameters, the article describes how supply voltage was selected in order to guarantee the preservation of the given breakdown or starting torque. The calculations were made for three motors representing low, medium and high power machines.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2010, 86; 247-250
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Poślizgowa charakterystyka admitancji stojana silnika indukcyjnego uzyskana przy zastosowaniu symulacji komputerowej
Slip characteristic of induction motor admittance stator obtained with the application of computer simulation
Autorzy:
Zielińska, M.J.
Zieliński, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/2076364.pdf
Data publikacji:
2006
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
silnik indukcyjny
stojan
symulacja komputerowa
Opis:
Slip characteristic of induction motor admittance is the admittance locus at varied slip and constant frequency of feeding voltage. Circle diagram can graphically represent the characteristic only in the case when electromagnetic parameters of a machine are constant. Circle diagram makes an important tool at the evaluation of an asynchronous motor operation. Based on the diagram it is possible to find for an arbitrary slip not only values of electrical parameters but also mechanical parameters such as torque, mechanical power and rotational speed. The paper presents a comparative analysis of classical methods for circle diagram elaboration and of their accuracy. Computer simulation of an admittance slip characteristic has been performed with the Matlab-Simulink software, based on dependences that determine admittance of a motor. The analysis concerns conditions when equivalent network parameters of an asynchronous motor are constant and the characteristic is represented by a circle. When electromagnetic parameters of a motor are not constant then the characteristic essentially differs from a typical circle diagram. It mainly concerns a squirrel-cage motor with closed slots in the rotor, fed with high-frequency voltage. In the mentioned case saturation of the closure occurs under the influence of a leakage flux. It has been shown that a shape of the characteristic depends on many parameters of a motor as well as on the way the leakage reactance changes.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2006, 75; 47-51
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena oszczędności energii elektrycznej przy skokowej regulacji napięcia w silniku asynchronicznym klatkowym
Evaluation of electrical energy savings at step regulation of voltage in an asynchronous squirrel-cage motor
Autorzy:
Zielińska, M.J.
Zieliński, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/2077253.pdf
Data publikacji:
2007
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
silnik asynchroniczny klatkowy
silnik klatkowy
regulacja napięcia
energooszczędność
Opis:
In order to enhance energy indices and obtain electrical energy savings for an asynchronous squirrel-cage motor operating on a long-time basis at a load lower than the rated load it needs to reduce its supply voltage. Efficient operation obtained that way can apply to a single motor or a set of motors driving the same machines. Motor load can vary within a wide range depending on the operation kind. Particularly disadvantageous is operation at little load or at idling, when energy indices of the motor are very low. In such a case it is necessary to apply voltage that can be varied depending on the load factor. When voltage is changed simultaneously with a load change the motor runs at higher values of the indices that decide over electrical energy consumption. At the rated load a motor should be supplied with rated voltage and when the load gets reduced the supply voltage should also be adequately decreased. The lowest voltage is required at the idle run. Relative value of the voltage is then of ca 0.3. Voltage reduction brings about a decrease of voltage-dependent energy losses and an increase of efficiency and the power factor, which leads to the power input reduction and consequently to electrical energy savings. The paper presents motor operation conditions that should be met at a sudden voltage change and rules for enhancing energy indices on the basis of algorithms that maintain such parameters as: minimal current, maximal power factor and maximum efficiency at a preset level. Additionally, runs of the basic motor quantities such as: current input, power factor, efficiency, and slip at step-regulated supply voltage have been determined
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2007, 77; 121-124
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metoda wyznaczania poślizgowych charakterystyk admitancji wysokoobrotowego silnika klatkowego
A method of determining the slipping characteristics of admittance of a squirrel-cage high-speed motor
Autorzy:
Zielińska, M.J.
Zieliński, W.G.
Powiązania:
https://bibliotekanauki.pl/articles/1373219.pdf
Data publikacji:
2010
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
maszyna elektryczna
silnik indukcyjny klatkowy
silnik wysokoobrotowy
admitancja
Opis:
High speed squirrel-cage induction motors are supplied with a high frequency voltage ranging from 400 to 1500Hz. The highest frequencies, i.e., the highest rotation speeds, arise from technological needs and are limited by manufacturing possibilities. These motors have a structure and electromagnetic properties that differentiate them from classic machines. In particular, they are distinguished by the high frequency of supply voltage, intensive cooling introduced to reduce the size of the motor, and closed rotor slots used to minimize vibrations and noise. The paper presents how slip characteristics of admittance of a squirrel-cage motor were determined on the basis of laboratory measurements conducted with current of variable frequency. This characteristic is the geometric locus of motor admittance with the slip ranging from + ∞ to - ∞ and an assumed constant frequency of supply voltage. The image of these characteristics differs considerably from a typical pie chart and it evidences the differences in electromagnetic properties in comparison with typical induction motors. Changes in the current in the slot causes a varying state of saturation and thus rotor leakage inductance is not a constant parameter.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2010, 86; 251-254
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 26

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