scholarly journals Method for Monitoring the Stator Core of a Powerful Turbo Generator

2021 ◽  
Vol 64 (4) ◽  
pp. 303-313
Author(s):  
A. S. Levitskyi ◽  
Ie. O Zaitsev ◽  
M. V. Panchik
Keyword(s):  
Automatic Measurement ◽  
Capacitive Sensor ◽  
Relative Displacement ◽  
Specific Pressure ◽  
Stator Core ◽  
Steel Sheets ◽  
The Core ◽  
Turbo Generator ◽  
Local Closure ◽  
Control Samples

The article is devoted to the development of an automatic method and device for monitoring the pressing of the stator core of a powerful turbo generator during its assembling at the manufacturer. The core is assembled and pressed in an upright position in separate parts; at each stage, it is necessary to monitor places with weakened solidity. The unevenness of the compaction density causes a relative displacement of the active steel sheets and losses of iron, as well as the appearance and development of certain defects (loosening of the teeth of the extreme packages, coloring of fragments of the active steel sheets, local closure of the sheets and heating of the packages), which can eventually cause severe accidents and failure of the turbo generator. Existing methods, including automatic ones, do not allow performing reliable monitoring. The method proposed by the authors for detecting places with weakened solidity is based on automatic measurement of the specific pressure of pressing during deformation of special control samples. A device for its implementation has been developed, which is a ring installed on the end surface of the core. Cells with control samples are evenly placed in the ring. The largest decrease in the sample thickness caused by the highest specific pressure corresponds to the smallest defect, and vice versa. As a pressure converter, it is proposed to use a flat metal membrane and a capacitive sensor with a digital output. The characteristics of the converter were calculated and experimentally verified. The specific pressure measurement results were processed using a special electronic unit. The device that has been developed makes it possible to improve labor productivity when monitoring the core, diagnose defects with greater reliability and eliminate them, and, ultimately, increase the reliability of the turbo generator as well as its durability.

scholarly journals MEASURING THE STROKE OF CONE DISK SPRINGS IN POWER ACCUMULATORS OF THE TURBOGENERATOR STATOR CORE USING A CAPACITIVE SENSOR

2018 ◽  
Vol 9 (2) ◽  
pp. 121-129 ◽  
Author(s):  
A. S. Levytskyi ◽  
I. O. Zaitsev ◽  
K. O. Kobzar
Keyword(s):  
Analytical Calculation ◽  
Capacitive Sensor ◽  
Response Characteristic ◽  
Calculation Model ◽  
High Potential ◽  
Stator Core ◽  
Response Characteristics ◽  
The Core ◽  
Electric Capacity ◽  
Coplanar Electrodes

The troubleproof and efficient work of powerful turbogenerators depends on the stability of their main mechanical parameters, which include the stator core pressing. The aim of the work was to describe the possibility of using a multielement capacitive sensor with coplanar electrodes to measure the movement of disk springs of the stabilizer systems power batteries in the turbogenerator stator core.The state of the core pressurizer can be indirectly assessed by measuring the displacement of the disk springs in power accumulators, which are installed on the tightening prism of the core instead of the compression nuts. To measure the movement of springs, a coplanar capacitive sensor with sectoral electrodes built into the power accumulators design is proposed. Each sector contains its own elementary sensor formed by coplanar electrodes. Each elementary sensor in each sector is placed on an annular dielectric plate and is formed by coplanar electrodes that are part of coaxial concentric rings. The sensor consists of a high-potential, low-potential and grounded electrodes. A grounded electrode is located between the high-potential and low-potential electrodes, as well as around them.A simplified analytical calculation model for obtaining the analytical response characteristic of the change in the informative component of the sensor electric capacity on the course of the disk springs in the CA is presented. The reliability of the model and the response characteristics are confirmed experimentally by testing a laboratory prototype of a capacitive sensor.

scholarly journals A Comprehensive Analysis on Transient Electromagnetic Force Behavior of Stator Windings in Turbo-Generator

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Hong-Chun Jiang ◽  
Yu-Ling He ◽  
Gui-Ji Tang ◽  
Ming-Xing Xu
Keyword(s):  
Electromagnetic Force ◽  
Mechanical Response ◽  
Comprehensive Analysis ◽  
Simplified Model ◽  
Force Density ◽  
Stator Core ◽  
Stator Windings ◽  
Fea Model ◽  
Transient Electromagnetic ◽  
Turbo Generator

This paper presents a comprehensive analysis on the transient electromagnetic force behavior of the stator windings in a QFSN-600-2YHG type turbo-generator. Different from other studies, this paper investigates not only the distribution regularities of the resultant force and the force density, but also the force harmonic characteristics, and the mechanical responses which will cause sensitive impact on the insulation wearing. The whole work is generally based on a proposed simplified model and the 3D finite element coupling calculation. The simplified model contains two parts. The first part is the theoretical model that employs the approximate solution of the image current to obtain the analytic formula of the electromagnetic force on the end windings conveniently. The second part is the FEA model that employs only the end windings and one-tenth of the stator core to save the calculating memory and, meanwhile, obtain the qualified electromagnetic force as well as the mechanical response. It is shown that the nose-top, the connection point between the line part and the end part, and the middle of the involute are the three most dangerous positions of the end winding to sustain serious insulation wearing. Moreover, the winding, which endures the maximum mechanical response, is neither always consistent with the one that has the largest resultant electromagnetic force nor directly in accordance with the winding that affords the most intensive electromagnetic force density. The findings in this paper will be beneficial for the insulation monitoring and the manufacturing improvement on the stator windings.

scholarly journals Anisotropy of Magnetic Properties in Non-oriented Electrical Steel Sheets

1989 ◽  
Vol 11 (2-4) ◽  
pp. 159-170 ◽  
Author(s):  
M. Shiozaki ◽  
Y. Kurosaki
Keyword(s):  
Magnetic Properties ◽  
Magnetic Induction ◽  
Crystallographic Orientation ◽  
Electrical Steel ◽  
Core Loss ◽  
Fluorescent Lamp ◽  
Steel Sheets ◽  
The Core ◽  
Texture Change ◽  
Electrical Steel Sheets

The anisotropy of magnetic properties in non-oriented electrical steel sheets can be evaluated by measuring Epstein specimens in the radial directions. The magnetic properties measured on ring cores are practically equal to the approximate values of magnetic properties determined by Epstein specimens in the radial directions. Non-oriented electrical steel sheets with anisotropy are not desirable for motors but are suitable for transformers and fluorescent lamp ballasts. The core loss and magnetic induction as measured with ring specimens are better with non-oriented electrical steel sheets with anisotropy than with non-oriented electrical steel sheets with random crystallographic orientation. This phenomenon depends on the texture change of the product.

Defects of Steel Sheets Joined by Laser Welding

2020 ◽  
Vol 405 ◽  
pp. 240-244
Author(s):  
Atila Drotár ◽  
Pavol Zubko ◽  
Alicia Mašlejová ◽  
Peter Kalmár ◽  
Peter Vranec ◽  
...  
Keyword(s):  
Quality Evaluation ◽  
New Technologies ◽  
Sheet Thickness ◽  
Relative Displacement ◽  
Point Of View ◽  
Cutting Edge ◽  
Butt Welding ◽  
Steel Sheets ◽  
Shear Edge

Introduction of new technologies demands a new access to quality evaluation of products. Joining of steel sheets with laser butt welding requires increased demand on precision of welded sheet ends alignment as well as condition of cutting edge. Moreover, increased requirements are placed on purity of environment, flatness of strips, gases, etc. The paper deals with evaluation of quality of laser butt welds of steel sheets and description of defects which could occur on welds from the metallographic point of view. The influence of relative displacement of welded strips ends alignment, different relative sheet thickness alignment, welding gap size and quality of sheet shear edge on quality of weld will be described. The most significant effect on quality of weld joints and their final mechanical properties has relative position of strip ends and geometry of cutting edge.

Study Status of Steel-Bamboo Composite Slabs

2014 ◽  
Vol 501-504 ◽  
pp. 727-730
Author(s):  
Jing Tang ◽  
Jun Guo ◽  
Gui Fen Hu ◽  
Yu Wen ◽  
Yu Shun Li
Keyword(s):  
Carrying Capacity ◽  
Steel Sheet ◽  
Light Weight ◽  
Building Structures ◽  
Steel Sheets ◽  
The Core ◽  
Composite Slabs ◽  
Steel Composite ◽  
Interface Slip ◽  
Core Part

At present, the development and application of new building structures are paid widely attention. In order to promote light-weight building slabs, different sections of steel-bamboo composite slabs are presented in this paper. Sandwiching thin-walled C-shaped steel or profiled steel sheet between two bamboo woods and bonding them with adhesive, a variety of different forms of steel-bamboo composite slabs are designed. For the C-shaped steel composite slabs, the reinforcement of self-tapping screws can effectively constraint interface slip between steel and bamboo plywood. It can also overcome the shortcoming of buckling which easily happen on C-shaped steel, ultimately, making the slabs have high stiffness and bearing capacity. The composite slabs with profiled steel sheets as the core part are strengthened by self-tapping screws and edge panels. And the global stability, deflection capacity and ductility performance of composite floors are significantly improved. Experimental results show that the reasonably combined composite slabs which have good combined effects, large carrying capacity and stiffness, can be used as architectural floors.

Noninvasive Measurement of Brachial Wall Mechanics During Flow-Mediated Vasodilation Using 2D Ultrasound Strain Tensor Imaging

2008 ◽  
Author(s):  
Ahmed M. Mahmoud ◽  
Phoebe A. Stapleton ◽  
Jefferson C. Frisbee ◽  
Osama M. Mukdadi
Keyword(s):  
Fluid Shear Stress ◽  
Low Cost ◽  
Measurement Techniques ◽  
Strain Tensor ◽  
Automatic Measurement ◽  
Relative Displacement ◽  
Contributing Factors ◽  
Arterial Diameter ◽  
Luminal Diameter

Atherosclerosis has become one of the contributing factors of cardiovascular diseases. Endothelial dysfunction is considered a key factor in the development of atherosclerosis [1]. Flow-mediated vasodilatation (FMD) measurement in brachial and other conduit arteries has become a common method to asses the endothelial function in vivo [2]. Fluid shear-stress increases due to blood flow increases, thus stimulating endothelial cell production and release of nitric oxide, a potent endogenous vasodilator. The mechanical behavior of the arterial wall during vasodilatation is considered an indication for endothelial health. In FMD measurement, the endothelium-dependent variation in arterial diameter in response to reactive ischemia-induced hyperemia is measured by comparing the luminal diameter of the brachial artery before and after the ischemia of the forearm induced by pressurizing a cuff [3]. Ultrasound imaging modalities has been widely used in the FMD analysis as a noninvasive low-cost tool, which can be used to track the arterial diameter change with time. Most of the FMD measurements in the literature are based on tracing the vessel wall boundary manually. Since this process is time consuming and may introduce human errors, automatic measurement techniques have been implemented [3,4]. These techniques utilize image processing algorithms to identify the edges of arterial walls, and then calculate the relative displacement change with time.

scholarly journals Sensitivity of Axial Velocity at the Air Gap Entrance to Flow Rate Distribution at Stator Radial Ventilation Ducts of Air-Cooled Turbo-Generator with Single-Channel Ventilation

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3442
Author(s):  
Yong Li ◽  
Weili Li ◽  
Ying Su
Keyword(s):  
Flow Velocity ◽  
Calculation Method ◽  
Air Gap ◽  
Test Method ◽  
Distribution Law ◽  
Stator Core ◽  
Flow Phenomenon ◽  
Turbo Generator ◽  
Ventilation Ducts ◽  
Ventilation Duct

In the design and calculation of a 330 MW water-water-air cooling turbo-generator, it was found that the flow direction of the fluid in the local stator radial ventilation duct is opposite to the design direction. In order to study what physical quantities are associated with the formation of this unusual fluid flow phenomenon, in this paper, a 100 MW air-cooled turbo-generator with the same ventilation structure as the abovementioned models is selected as the research object. The distribution law and pressure of the fluid in the stator radial ventilation duct and axial flow velocity at the air gap entrance are obtained by the test method. After the calculation method is proved correct by experimental results, this calculation method is used to calculate the flow velocity distribution of the outlets of multiple radial ventilation ducts at various flow velocities at air gap inlets. The relationship between the flow distribution law of the stator ventilation ducts and the inlet velocity of the air gap is studied. The phenomenon of backflow of fluid in the radial ventilation duct of the stator is found, and then the influence of backflow on the temperature distribution of stator core and winding is studied. It is found that the flow phenomenon can cause local overheating of the stator core.

Virtual Prototype and Modal Analysis of Stator System of Large Turbo-Generator

2012 ◽  
Vol 190-191 ◽  
pp. 232-236
Author(s):  
Yi Xuan Wang ◽  
Ying Wang ◽  
Li Lin
Keyword(s):  
Modal Analysis ◽  
Element Model ◽  
Virtual Prototype ◽  
Virtual Manufacturing ◽  
Prototype Model ◽  
Research Approach ◽  
Outer Diameter ◽  
Stator Core ◽  
Turbo Generator ◽  
On Line

The stator core is an important part of large turbo-generator .The its natural frequency must be to avoid the operating frequency and the double frequency. In this paper, stator core structure of 1000MW generator is considered as the research object. In the Pro / E software, its virtual manufacturing model is built for design and manufacture of stator core; In ANSYS software, a parametric finite element model is established for virtual experimental modal analysis; The virtual prototype model in the different constraints (free, and different constraints) and different core parameters (such as the core inner and outer diameter, length) is used to analyze and solve its natural frequencies and mode shape changes. For design, manufacturing and on-line monitoring and fault diagnosis of a variety of large-capacity turbine generator, the research approach and results provide an important basis.

Influence of interlocking dowels on motor core loss

2016 ◽  
Vol 35 (2) ◽  
pp. 808-820 ◽  
Author(s):  
Gui-Yu Zhou ◽  
He Hao ◽  
Meng-Jia Jin ◽  
Jian-Xin Shen
Keyword(s):  
Eddy Current ◽  
Simulation Analysis ◽  
Core Loss ◽  
Optimal Solution ◽  
Stator Core ◽  
Content Type ◽  
Steel Sheets ◽  
Electromagnetic Model ◽  
Proper Number ◽  
3D Finite Element Method

Purpose – The purpose of this paper is to investigate the effect of the interlocking process on the iron loss in the lamination core and to increase the efficiency of electrical machines. Design/methodology/approach – A 3D electromagnetic model of the interlocking dowels is proposed in order to simulate the eddy current distribution in the lamination core. Considering the time-consuming of the 3D finite element method (FEM), a 2D electromagnetic model is then proposed based on the 3D model. Influence of the interlocking process on the motor performances is analyzed with 2D FEM, considering the electrical connection of the dowels and the magnetic property deterioration of the electrical steel sheets. Findings – The interlocking process removes the insulation between the laminations at the cut-edges of the interlocking dowels, causing extra eddy current loss in the lamination core. The effect of the interlocking process is dependent on the number, location and size of the interlocking dowels. Practical implications – The interlocking dowel model is established in order to simulate the effects of the interlocking process. By using the FEM calculation, optimal solution is discussed to minimize the undesired effect of the interlocking dowels. Originality/value – In this paper, the FEM model of the induction motor with interlocked stator core is first established, then simulation analysis is implemented. Results shows that choosing a proper number of interlocking dowels with suitable location and size can reduce the extra loss.

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