A COMPARISON BETWEEN OPERATING CONDITIONS OF INVERTERFED ASYNCHRONOUS MOTORS

1978 ◽  
pp. 399-404
Author(s):  
E. Pagano ◽  
A. Perfetto
Keyword(s):  
Operating Conditions ◽  
Asynchronous Motors

scholarly journals Calculation of the Capacity for the Operation of a Mini-Energy Complex Based on an Inde-pendently Operating Asynchronous Generator

2021 ◽  
Vol 64 (1) ◽  
pp. 40-50
Author(s):  
S. V. Konstantinova ◽  
A. Yu. Kapustinskii ◽  
T. M. Yaroshevich
Keyword(s):  
Alternative Energy ◽  
High Speed ◽  
Frequency Converter ◽  
Operating Conditions ◽  
Electric System ◽  
Energy Complex ◽  
Alternative Energy Sources ◽  
Asynchronous Motors ◽  
Asynchronous Generator ◽  
Equivalent Circuit Parameters

The article present the analysis of the operation of the mini-energy complex (MEC) based on alternative energy sources. An asynchronous generator (AG) was taken as energy source. The IEC operates independently with standard power parameters without the use of a frequency converter. To operate independently, AG needs a source of reactive excitation current. Based on the calculations carried out and the results obtained with the use of the experimental facility,the operating conditions of the MEC with standard parameters of electricity under varying load have been analyzed. A characteristic feature of the autonomous MEC is the commensurate capacity of the generating device and consumers. Therefore, any power consumer on/off leads both to significant changes of local electric system parameters and affects the operation of the generator itself. In this article, the main attention is paid to the influence of three-phase motor load on stable AG operation. When the MEC operates independently, reliable self-excitation of the asynchronous generator and the start-up of consumers whose power is commensurate with the generating unit must be ensured. It is also necessary to ensure the maintenance of voltage stability, the possibility of automatic operation of the generating unit, and the preservation of its integrity in emergency modes. Thus, for stable MEC-based AG operation the nature of the load should be taken take into account, the parameters of the of the local grid should be known as well as the exact availability of consumers and their characteristics, and also equivalent circuit parameters of asynchronous motors. In addition, it is necessary to accurately calculate the capacity when changing the parameters of the electrical system, so as not to lose the self-excitation of the asynchronous generator, which is equivalent to disconnecting the entire load of the generator and causes a sharp increase in speed. To solve these problems, it is necessary to create a high-speed MEC control system.

scholarly journals Vector control system of electric traction drive with power losses minimization

2021 ◽  
Vol 2131 (4) ◽  
pp. 042090
Author(s):  
T S Titova ◽  
A M Evstaf’ev ◽  
A A Pugachev
Keyword(s):  
Control System ◽  
Vector Control ◽  
Operating Conditions ◽  
Limiting Factors ◽  
Power Losses ◽  
Diesel Generator ◽  
Traction Drive ◽  
Asynchronous Motors ◽  
Electric Traction ◽  
Vector Control System

Abstract Based on the operating conditions analysis of electric traction drives of locomotives, it has been established that the vector control systems for an asynchronous motor fully satisfy all the requirements. On the basis of a T-shaped equivalent circuit, a mathematical model of an induction motor is presented, taking into account losses in the stator steel, the effect of the rotor current and saturation displacement. An algorithm for the formation of the optimal, from the point of view of power losses, task for the rotor flux linkage when using a vector control system with the orientation of the axes of the coordinate system along the rotor magnetic field, is developed. The limiting factors are the limitations on the current and voltage of the motor stator, the diesel generator set power. A shared control system for an electric traction drive with asynchronous motors has been developed, which provides direct control of wheel slip with a subordinate vector control system that minimizes power losses. The results of modeling in a steady-state operation and a start-up mode for an electric traction drive of a two-axle bogie with axial support and 630 kW asynchronous motors with the use of various options for organizing circuit reentrances are presented.

scholarly journals Analysis of influencing factors affecting the operational reliability of low-voltage asynchronous electric motors

2021 ◽  
Vol 23 (3) ◽  
pp. 95-104
Author(s):  
V. V. Romanova ◽  
S. V. Khromov ◽  
K. V. Suslov
Keyword(s):  
Influencing Factors ◽  
Electric Motor ◽  
Low Voltage ◽  
Operational Reliability ◽  
Operating Conditions ◽  
Electric Motors ◽  
Asynchronous Motors ◽  
Reverse Sequence ◽  
Stress Asymmetry ◽  
Asynchronous Electric Motors

THE PURPOSE. The main purpose of the work is a comprehensive study of external influences that affect the operational reliability of low-voltage asynchronous motors. Attention is focused on the evaluation of the operational reliability of electric motors, the systematization of their operating conditions, with the simultaneous impact of a group of operational factors. Among these factors that are subject to detailed analysis, we will highlight the following: the asymmetry of the stress and its duration, loading of the motor, the temperature of the environment. In this regard, it becomes obvious that the task of improving the operational reliability of low-voltage asynchronous electric motors depends on a qualitative study of the quantitative values of external influencing factors in various operating modes of electric motors. METHODS. The tool for implementing this task is a visual and effective simulation tool Simulink interactive programming environment Matlab. RESULTS. The research was performed on an asynchronous electric motor with a short-circuited rotor AIR160S8 with PH = 7,5 kW, rated speed n = 1500 rpm. The physical processes of the electric motor under study were modeled by changing the following parameters: the coefficient of stress asymmetry in the reverse sequence (K2U), the load on the motor shaft (Kz), the ambient temperature (tocr), and the duration of stress asymmetry in the reverse sequence (T). Based on the obtained simulation results, groups of planes of the studied quantities are constructed. CONCLUSION. A set of studies performed using the Matlab software package allowed us to estimate the limits of acceptable values of external factors and identify the area of acceptable operation of asynchronous motors. The analysis and discussion of the research results were carried out, and measures were proposed to improve the operational reliability of asynchronous electric motors.

scholarly journals Analysis of influencing factors affecting the operational reliability of low-voltage asynchronous electric motors

2021 ◽  
Vol 23 (3) ◽  
pp. 80-89
Author(s):  
V. V. Romanova ◽  
S. V. Khromov ◽  
K. V. Suslov
Keyword(s):  
Influencing Factors ◽  
Electric Motor ◽  
Low Voltage ◽  
Operational Reliability ◽  
Operating Conditions ◽  
Electric Motors ◽  
Asynchronous Motors ◽  
Reverse Sequence ◽  
Stress Asymmetry ◽  
Asynchronous Electric Motors

THE PURPOSE. The main purpose of the work is a comprehensive study of external influences that affect the operational reliability of low-voltage asynchronous motors. Attention is focused on the evaluation of the operational reliability of electric motors, the systematization of their operating conditions, with the simultaneous impact of a group of operational factors. Among these factors that are subject to detailed analysis, we will highlight the following: the asymmetry of the stress and its duration, loading of the motor, the temperature of the environment. In this regard, it becomes obvious that the task of improving the operational reliability of low-voltage asynchronous electric motors depends on a qualitative study of the quantitative values of external influencing factors in various operating modes of electric motors. METHODS. The tool for implementing this task is a visual and effective simulation tool Simulink interactive programming environment Matlab. RESULTS. The research was performed on an asynchronous electric motor with a short-circuited rotor AIR160S8 with PH = 7,5 kW, rated speed n = 1500 rpm. The physical processes of the electric motor under study were modeled by changing the following parameters: the coefficient of stress asymmetry in the reverse sequence (K2U), the load on the motor shaft (Kz), the ambient temperature (tocr), and the duration of stress asymmetry in the reverse sequence (T). Based on the obtained simulation results, groups of planes of the studied quantities are constructed. CONCLUSION. A set of studies performed using the Matlab software package allowed us to estimate the limits of acceptable values of external factors and identify the area of acceptable operation of asynchronous motors. The analysis and discussion of the research results were carried out, and measures were proposed to improve the operational reliability of asynchronous electric motors.

Cathodoluminescence of Catalyst Crystallites

1982 ◽  
Vol 40 ◽  
pp. 664-665
Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
D.B. Darby ◽  
C. Warwick
Keyword(s):  
Defect Density ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Semiconductor Materials ◽  
Environmental Cell ◽  
High Resolution Structure ◽  
Commercially Important ◽  
Crystallographic Defects ◽  
Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

1994 ◽  
Vol 52 ◽  
pp. 412-413
Author(s):  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Damage ◽  
Low Dose ◽  
Dynamic Range ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Digital Data ◽  
Ccd Cameras ◽  
Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

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