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Документ Application of Vyshnegradky's diagrams for transient analysis in electric discharge installations with stochasticload(Національний технічний університет "Харківський політехнічний інститут", 2018) Suprunovska, N. I.; Shcherba, M. A.Purpose. To analyze the transient processes in the discharge circuit of reservoir capacitor of electric discharge installationsat a change in the circuit configuration duringthe discharge as well as to determine the appropriate circuit parameters for which the discharge process described by the third-order differential equation remains a dampedoscillatory process. Methodology. We have applied the concepts of theoretical electrical engineering, the principles of theory of electrical circuits, theory of automatic control systems and mathematical simulation in the software package MathCAD 12. Results. We have obtained the analytical expressions and graphical dependenciesthat allow us to determine a relationship between the value of the element parameters of the discharge circuit of installations with anadditional active-inductive chain and the character ofthe transient discharge process without solving a third-order differential equation. Originality. Using Vyshnegradsky's criteria and their graphical representations in the form of diagrams,we have proposed the procedure for determining the inductance value in additional chain shunting the capacitor of electric discharge installation in order to avoid the undesirable aperiodic discharge transient process in the stochastic load. Practical value. The use of this approach makes it possible to determine the ranges of the expedient change in the additional inductance at different load resistances for the realization of transient process required by the technology – the oscillatory discharge of the reservoir capacitor trough the load.Документ Method for voltage control in charge circuit of electric discharge installations with two capacitors under nonzero initial conditions(НТУ "ХПИ", 2018) Suprunovska, N. I.; Shcherba, M. A.To analyze the transient processes in the charge circuit of electric discharge installations with two capacitors, taking into account the change in the initial conditions of such processes (initial voltage on the capacitors and the initial current in the charge circuit) as well as to develop the method for charge voltage control of such installations using purposeful change of these initial conditions. We have applied the concepts of theoretical electrical engineering, the principles of theory of electrical circuits, and mathematical simulation in the software package MathCAD 12. We have obtained analytical expressions and graphical dependencies establishing a quantitative relationship between the value of the maximum charge voltage of an electric discharge installation and the values of the initial voltage on its capacitors and the initial current in the circuit. This allows us to propose the method for the charge voltage control of electric discharge installations with two reservoir capacitors, using a purposeful change in their initial voltages and initial current in the chargecircuit. For the first time, we have found that the charge voltage of the installation can be controlled using two influence mechanisms – either changing the initial current in the charge circuit (by interrupting the transient process of the first capacitor charge at a certain time) or using a nonzero initial voltage on the charged second capacitor. In this case the charge voltage can be varied by 2 times. The use of this method makes it possible to obtain discharge pulses of complex shape in the technological load, since the maximum charge voltages of the first capacitor and second one can differ by a factor of 1.5.Документ Calculation of the equivalent electrical parameters of the inductor of induction channel furnace with defects in its lining(НТУ "ХПИ", 2018) Podoltsev, O. D.; Zolotaryov, V. M.; Shcherba, M. A.; Belyanin, R. V.The aim of the paper is to determine a quantitative relationship between measured impedance of the inductor and the electrical characteristics of the separated melt circuit parts for the determination of the place of a liquid metal leakage andfor the improvement in such way the diagnostic system of lining state of induction channel furnaces. The study was performed on the basis of the concepts of theoretical electrical engineering, mathematical physics, and mathematical modeling. Using two equivalent electrical circuits of the inductor the analytical expressions and graphical dependencies, which determine a quantitative relationship between the parameters of the separated parts of a liquid-metal circuit and the impedance of the whole inductor measured in practice, for the presence of different lining defects, were found. The method for calculating the increments of equivalent electrical parameters of the inductor as a function of increments of the parameters of the secondary liquid-metal circuit was proposed. It is proved that for small changes (less than 10 %) of the parameters of the liquid-metal circuit, it is expedient to use a linear relationship between its increments and to create the sensitivity matrix, which clearly shows the presence of a strong or weak interrelation between the disturbed values of the parameters of the secondary circuit and the inductor. The use of this technique allows to develop the database for various types of lining defects for a given furnace and on itsbasis to predict the places of a melt leakage and the state of furnace lining owing to periodical measurements of the inductor parameters.Документ Electromechanical transient processes during supply voltage changing in the system of polymer insulation covering of the current-carrying core ofultra high voltage cables(НТУ "ХПИ", 2018) Zolotaryov, V. M.; Shcherba, M. A.; Belyanin, R. V.; Mygushchenko, R. P.; Korzhov, I. M.The article is devoted to the analysis of the electromechanical transient processes in a system of three frequency-controlled electric drives based on asynchronous motors that control current-carrying core motion, as well asto the study of the effect of such processes on the modes applying three-layer polymer insulation to the current-carrying core. The study was conducted based on the concepts of electromechanics, electromagnetic field theory, mathematical physics, mathematical modeling. A mathematical model has been developed to analyze transients in an electromechanical system consisting of three frequency-controlled electric drives providing current-carrying core motion of ultra-high voltage cables in an inclined extrusion line. The coordination of the electromechanical parameters of the system drives has been carried out and the permissible changes in the supply voltage at the limiting mass while moving current-carrying core of ultra-high voltage cables with applied polymer insulation have been estimated. For the first time it is determined that with the limiting mass of the current-carrying core, the electromechanical system allows to stabilize the current-carrying core speed with the required accuracy at short-term decreases in the supply voltage by no more than 27 % of its amplitude value. It is also shown that this system is resistant to short-term increases in voltage by 32 % for 0.2 s. Using the developed model, it is possible to calculate the change in the configuration and speed of the slack current-carrying core when applying polymer insulation, depending on the specific mass of the current-carrying core per unit length, its tension atthe bottom, the torque of the traction motor and the supply voltage to achieve stable operation of the system and accurate working of the set parameters.Документ Comparative analysis of electrical and thermal control of the lining state of induction apparatus of copper wire manufacture(НТУ "ХПИ", 2018) Zolotaryov, V. M.; Shcherba, M. A.; Belyanin, R. V.; Mygushchenko, R. P.; Kropachek, O. Yu.This article is intended to develop a technique for monitoring the lining state of induction channel furnaces for melting oxygen-free copper by monitoring changes in the distribution of thermal fields in their lining and carrying out a comparative analysis of the developed technique with the existing one that controls the electrical resistance of the melting channel of the furnaces. For carrying out the research, the theories of electromagnetic field, thermodynamics, mathematical physics, mathematical modeling based on the finite element method were used. A technique for diagnosing the lining state of the induction channel furnaces for melting oxygen-free copper has been developed, which makes it possible to determine the dislocation and the size of the liquid metal leaks by analyzing the temperature distribution over the body surface both the inductor and the furnace. The connection between the temperature field distribution on the surface of the furnace body and the dislocation and dimensions of the liquid metal leaks in its lining is determined for the first time. Using the proposed technique will allow to conduct more accurate diagnostics of the lining conditions of the induction channel furnaces, as well as to determine the location and size of the liquid metal leaks, creating the basis for predicting the working life of the furnace.