scholarly journals Once again about the indivisibility of the scattered inductance of the transformer

2021 ◽  
pp. 8-17
Author(s):  
S.E. Zіrka ◽  
Y.I. Moroz ◽  
C.M. Arturi
Keyword(s):  
Equivalent Circuit ◽  
Physical Meaning ◽  
Magnetic Circuit ◽  
Finite Thickness ◽  
Equivalent Circuits ◽  
Leakage Inductance ◽  
The Core ◽  
Inrush Currents ◽  
Radial Thickness ◽  
Short Circuits

Purpose. The purpose of the article is to show the inadequacy of the traditional T-shaped equivalent circuit for modeling transformer operations with saturated core. The aim is to point out the unreasonableness of the separation of the transformer leakage inductance into components. The aim is also to explain the need to apply the П-shaped transformer equivalent circuits to transformers with two and three windings with finite radial thickness. Methodology. Analysis of magnetic fields in the transformer window and simulation of transient processes in equivalent circuits of the transformer using a preprocessor ATPDraw to the program ATP. Findings. The unfoundedness of the well-known T-shaped transformer equivalent circuit is shown. Differences in the processes in the core legs and yokes when transformer is connected to the network and during short circuits of the windings are noted. Equivalent circuits of a transformer with two and three windings of finite thickness are proposed, reproducing these differences. Originality. The absence of physical meaning in dividing the transformer leakage inductance into components is stated. The advantages of the П-shaped equivalent circuit are shown when calculating inrush currents accompanying the transformer switching to the network on its inner and outer windings. Practical value. We show theoretical insolvency and practical unsuitability of the Т-shaped equivalent circuit for studying transformer operations accompanied by saturation of the magnetic circuit. Advantages of the П-shaped equivalent circuit are clarified.

The Poynting Vector and the New Theory of a Transformer. Part 11. Three-Phase Three-Core Transformers without a Neutral Wire

2021 ◽  
Vol 1 (1) ◽  
pp. 23-34
Author(s):  
Mansur A. SHAKIROV ◽  
Keyword(s):  
Equivalent Circuit ◽  
Single Phase ◽  
Poynting Vector ◽  
Magnetic Circuit ◽  
Phase Zone ◽  
Field Patterns ◽  
Three Phase ◽  
Short Circuits ◽  
The Difference ◽  
Mathematical Relations

A topological equivalent circuit for a three-phase three-core transformer reflecting the spatial structure of its magnetic system is developed. Owing to this approach, it became possible to represent the magnetic fluxes of the magnetic circuit’s all main sections and the apertures for each of three phases directly in the circuit in the absence of the windings’ neutral wires. The circuit is constructed by stitching together the anatomical circuit models of single-phase transformers obtained in the previous parts with taking into account the relationships between the fluxes at the junctions of the phase zones in iron. Its validity is confirmed by the rigor nature of the physical and mathematical relations for idealized transformers with infinite magnetic permeability of iron and simplified magnetic field patterns, which corresponds to the generally accepted approach with neglecting the magnetization currents. The difference lies in the fact that the developed model takes into account the heterogeneity of magnetization in different parts of the magnetic circuit with allocating more than 30 sections in the iron and apertures. The transition to the model of a real three-core transformer is carried out by adding four nonlinear transverse magnetization branches in each extreme phase zone and eight branches in the central phase zone to the idealized equivalent circuit. It is shown that in cases of winding connections without neutral wires, there is no flux of the Poynting vector in interphase zones in any unbalanced mode. In this case, the problems connected with the occurrence of fluxes exceeding the no-load fluxes under the conditions of symmetric and asymmetric short circuits, as well as the occurrence of buckling fluxes in these modes in the region outside the transformer iron, are solved.

Prediction and Analysis of Reinforcement Corrosion in Simulated Concrete Pore Solution Based on Neural Network

2020 ◽  
Vol 34 (14) ◽  
pp. 2059047
Author(s):  
Fengjiao Jiang ◽  
Jinxin Gong ◽  
Jichao Zhu ◽  
Huan Wang ◽  
Weibo Song
Keyword(s):  
Neural Network ◽  
Equivalent Circuit ◽  
Pore Solution ◽  
Equivalent Circuit Model ◽  
Chloride Ion ◽  
Ion Concentration ◽  
Equivalent Circuits ◽  
Chromium Alloy ◽  
Ph Values ◽  
Impedance Characteristics

The corrosion of reinforcement has always been a problem to be solved in the field of architecture. In this paper, the corrosion characteristics of chromium alloy steel under different pH conditions are studied. The impedance characteristics and equivalent circuit are predicted by neural network model. First of all, in simulated pore solution with different pH values, the characteristics of Nyquist impedance spectroscopy of the whole chromium alloy under passivation stage and the damaged passivation film of reinforcing bars under initial corrosion stage have been found. Then, according to the difference of impedance characteristics under different pH values, different equivalent circuits have been established and [Formula: see text] values of different equivalent circuits under different chloride ion concentration have been calculated. By fitting the electrochemical parameters of the equivalent circuit with [Formula: see text] values, the equivalent circuit model which can be predicted by neural network has good consistency with the equivalent circuit which can be predicted by [Formula: see text] values.

A novel balanced-to-balanced power divider based on three-line coupled structure

2019 ◽  
Vol 11 (2) ◽  
pp. 139-142
Author(s):  
Zhen Tan ◽  
Qing-Yuan Lu ◽  
Jian-Xin Chen
Keyword(s):  
Equivalent Circuit ◽  
Design Procedure ◽  
Power Divider ◽  
Equivalent Circuits ◽  
Differential Mode ◽  
Detailed Design ◽  
Symmetrical Structure ◽  
The Common ◽  
First Time ◽  
Good Agreement

AbstractThis paper presents a novel balanced-to-balanced power divider (PD) based on a simple and compact three-line coupled structure for the first time. By bisecting the proposed symmetrical structure, the differential mode (DM) and the common mode (CM) equivalent circuits can be obtained for analysis. The DM equivalent circuit exhibits a three-line in-phase power dividing response, and then a resistor is added between the two outputs for achieving good isolation. Meanwhile, the CM equivalent circuit shows a three-line all-stop response so that the CM suppression in this design does not need to be considered. Accordingly, the detailed design procedure of the DM PD is given. For demonstration, a prototype centered at 1.95 GHz is designed, fabricated, and measured. The simulated and measured results with good agreement are presented, showing low DM loss and wideband CM suppression.

scholarly journals Partial Inductance Model of Induction Machines for Fault Diagnosis

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2340 ◽  
Author(s):  
Manuel Pineda-Sanchez ◽  
Ruben Puche-Panadero ◽  
Javier Martinez-Roman ◽  
Angel Sapena-Bano ◽  
Martin Riera-Guasp ◽  
...  
Keyword(s):  
Magnetic Circuit ◽  
Induction Machines ◽  
The Self ◽  
Magnetic Vector Potential ◽  
Diagnostic Systems ◽  
Magnetic Vector ◽  
Machine Model ◽  
Stator Current ◽  
Novel Approach ◽  
Short Circuits

The development of advanced fault diagnostic systems for induction machines through the stator current requires accurate and fast models that can simulate the machine under faulty conditions, both in steady-state and in transient regime. These models are far more complex than the models used for healthy machines, because one of the effect of the faults is to change the winding configurations (broken bar faults, rotor asymmetries, and inter-turn short circuits) or the magnetic circuit (eccentricity and bearing faults). This produces a change of the self and mutual phase inductances, which induces in the stator currents the characteristic fault harmonics used to detect and to quantify the fault. The development of a machine model that can reflect these changes is a challenging task, which is addressed in this work with a novel approach, based on the concept of partial inductances. Instead of developing the machine model based on the phases’ coils, it is developed using the partial inductance of a single conductor, obtained through the magnetic vector potential, and combining the partial inductances of all the conductors with a fast Fourier transform for obtaining the phases’ inductances. The proposed method is validated using a commercial induction motor with forced broken bars.

scholarly journals I. Note on induction coils or 'transformers.'

1887 ◽  
Vol 42 (251-257) ◽  
pp. 164-167 ◽  
Keyword(s):  
Magnetic Force ◽  
Magnetic Circuit ◽  
The Core ◽  
The Difference

The transformers considered are those having a continuous iron magnetic circuit of uniform section. Let A be area of section of the core, m and n the number of convolutions of the primary and secondary coils respectively, R, r , and ρ their resistances, ρ being the resistance of the secondary external to the transformer, x and y currents in the two coils, a induction per square centimetre, α the magnetic force, l the length of the magnetic circuit, E = B sin 2π ( t /T), the difference of potentials between the extremities of the primary, T being the periodic time.

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