Electrodynamic Forces Research Articles

Electrodynamic Forces in a High Voltage Circuit Breakers With Tulip Contact System—FEM Simulations

Paper concerns the effects of electrodynamic forces that act on the contacts of the tulip contact system that is often implemented in high voltage circuit breakers. The high voltage circuit breaker often consists of two such systems. One of the systems is treated as an arcing one - made of tungsten coated elements. Capable of implementing the phenomenon of thermal-expansion. The second is made of one or two crown laces. The first system consists of a single piece of large mass, cut in such a way as to obtain the effect of increasing the contact surface. The second is a system, often of several dozen contacts, so as to increase the contact area and reduce the transition resistance. The main problem of actual validation through dynamic measurements (electrodynamic forces) is the specificity of the circuit breaker operation. The contact system is located directly in the switch chamber filled with CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> or SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas. Hence, tests under normal working conditions are very difficult - even impossible. Therefore, the authors proposed employment of FEM (Finite Element Method) in order to obtain values of electrodynamic forces acting on the contact system by executing the detailed 3D coupled simulation. The analysis of the results brought interesting conclusions that concerned operation of such contact layouts in short circuit conditions.

Reduction of the auto seismic component of error of a ballistic laser gravimeter by excitation of an induction-dynamic catapult from an AC voltage source

The purpose of the study is to analyse the influence of the excitation of an induction-dynamic catapult of a ballistic laser gravimeter from an AC voltage source at different frequencies on electromechanical indicators that provide a reduced value of the auto seismic component of error in measuring the gravitational acceleration g due to a decrease in the recoil force. A mathematical model of the gravimeter catapult when excited from an AC voltage source is proposed, taking into account the interrelated electrical, magnetic and mechanical processes. The nature of the electromechanical processes in the catapult of the gravimeter with such excitation has been established. It is shown that a phase shift occurs between the currents in active elements, as a result of which positive (repulsive) pulses of the electrodynamic force alternate with negative (attractive) pulses of force. A criterion for the efficiency of the gravimeter catapult has been introduced, taking into account the maximum value of push of the test body at the smallest values of the electrodynamic force and current of the inductor winding. It was found that the highest efficiency of the gravimeter catapult is provided at a frequency of 250 Hz, at which the catapult efficiency is 3.5 times higher than at a frequency of 50 Hz. It is shown that the transition from the method of excitation of an induction-dynamic catapult with one short pulse to excitation from an AC voltage source makes it possible to reduce the uncertainty in measuring the gravitational acceleration.

Experimental research of the influence of a ferromagnetic core on the speed of an induction-dynamic release with turning anchor type

Circuit breakers for overcurrent protection of semiconductor converters limit the duration and amplitude of the overcurrent at such a level that its thermal effect does not exceed the maximum allowable thermal protection index of the protected semiconductor device. The limitation of the thermal action of the short-circuit current is achieved by reducing the operation time of the circuit breaker. The design of the circuit breaker is changed in such a way that instead of the basic electromagnetic release is used an induction-dynamic release, which consists of an inductor with a ferromagnetic core and a rotary armature in the form of a copper disk. The electrodynamic force producing by the induction-dynamic release for quick operation is determined by the coefficient of mutual inductance of the inductor coil and the armature. Using of a ferromagnetic core entailed an increase in the coefficient of mutual inductance of the coil and armature, therefore, an increase in the electrodynamic force producing by the release, and a decrease in own tripping time of the circuit breaker. On a prototype, an experimental study of the proper operation time of the release was carried out at various values of the electrical parameters of the capacitor bank of the inductor power supply, the winding parameters of the inductor coil and the disk dimensions. The research results have proved both a decrease in the tripping time of the circuit breaker while conserving the energy of the capacitor bank of the inductor, and a decrease in the required energy of the capacitor bank to power the inductor while maintaining the minimum tripping time of the circuit breaker. Reducing the energy of the capacitor bank of the inductor made it possible to reduce the capacity and voltage of the capacitor bank of the supply of the release, and, consequently, its dimensions.

Influence of limiting the duration of the armature winding current on the operating indicators of a linear pulse electromechanical induction type converter

Introduction. Linear pulse electromechanical converters of induction type (LPECIT) are used in many branches of science and technology as shock-power devices and electromechanical accelerators. In them, due to the phase shift between the excitation current in the inductor winding and the induced current in the armature winding, in addition to the initial electrodynamic forces (EDF) of repulsion, subsequent EDF of attraction also arise. As a result, the operating indicators of LPECIT are reduced. The purpose of the article is to increase the performance of linear pulse electromechanical induction-type converters when operating as a shock-power device and an electromechanical accelerator by limiting the duration of the induced current in the armature winding until its polarity changes. Methodology. To analyze the electromechanical characteristics and indicators of LPECIT, a mathematical model was used, in which the solutions of equations describing interrelated electrical, magnetic, mechanical and thermal processes are presented in a recurrent form. Results. To eliminate the EDF of attraction between the LPIECIT windings, it is proposed to limit the duration of the induced current in the armature winding before changing its polarity by connecting a rectifier diode to it. It was found that when the converter operates as a shock-power device without limiting the armature winding current, the value of the EDF pulse after reaching the maximum value decreases by the end of the operating cycle. In the presence of a diode in the armature winding, the efficiency criterion, taking into account the EDF pulse, recoil force, current and heating temperature of the inductor winding, increases. When the converter operates as an electromechanical accelerator without limiting the armature winding current, the speed and efficiency decrease, taking into account the kinetic energy and voltage of the capacitive energy storage at the end of the operating cycle. In the presence of a diode in the armature winding, the efficiency criterion increases, the temperature rise of the armature winding decreases, the value of the maximum efficiency increases, reaching 16.16 %. Originality. It has been established that due to the limitation of the duration of the armature winding current, the power indicators of the LPECIT increase when operating as a shock-power device and the speed indicators when the LPECIT operates as an electromechanical accelerator. Practical value. It was found that with the help of a rectifier diode connected to the multi-turn winding of the armature, unipolarity of the current is ensured, which leads to the elimination of the EDF of attraction and an increase in the performance of the LPECIT.

A Bearingless Motor With Passive Electrodynamic Suspension in Axial Direction

This article presents a novel structure of a bearingless motor with integrated passive axial electrodynamic suspension. The simple initial structure has been improved in three steps. The structure was upgraded by including additional rings of permanent magnets and rotating back iron yokes in a double rotor structure that embraces the stator. Electrodynamic force generated in the final model was several times higher than that of the initial one. A prototype machine of the final structure was built. The suspension currents and axial electrodynamic forces were validated through an experiment under quasi-static condition, that is, constant rotational speed and fixed axial displacement. Theoretical equations for the axial electrodynamic force were derived. The force equation was compared to the finite-element analysis and experimental results.

The Influence of Second Air-Gap Length on the Performance of 10 kV, 1000 kW Permanent Magnet Synchronous Motor

Background: The influence of the second air-gap length on the performance of permanent magnet synchronous motor is usually ignored. A comparative analysis is made of line-start high-voltage permanent magnet synchronous motor in this paper. Objective: The purpose of this paper is to analyze the influence of the second air-gap length on the motor performance. Methods: A 10kV 1000kW permanent magnet synchronous motor is taken as an example and the model is established based on the finite element calculation method when the second air-gap length is different. The influence of the second air-gap length on the phasor diagram, no-load back electrodynamic force, starting performance and steady-state operation performance are studied. Based on the finite element calculation method, the torque angle, current, power factor, external power factor and d/q-axis current of the motor are analyzed, and the change of the motor phasor diagram is obtained. The influence of the second air-gap length on the no-load back electrodynamic force is studied. Results and Conclusion: The relationship between the no-load back electrodynamic force and the no-load air-gap fundamental magnetic field is determined, and the influence mechanism of the noload air-gap fundamental magnetic field on no-load back electrodynamic force is revealed. Furthermore, the influence of the no-load back electrodynamic force on the starting performance is studied. Finally, the influence of the second air-gap length on the 10kV 1000kW permanent magnet synchronous motor steady-state performance is obtained. Based on the above analysis, some references are given for the design of motor.

On the role of the energy loss function in the image force on a charge moving over supported graphene

We use a dielectric response theory to describe electrodynamic forces on a charged particle moving parallel to a supported two-dimensional layer. Using a Kramers–Kronig relation, we show that the image force on the particle can be expressed in terms of the energy loss function of the target materials. This enables us to analyze the stopping and the image forces on the particle on equal footing in the frequency–momentum domain encompassing all the energy loss channels in the target. Using the example of a graphene layer on a silicon carbide substrate, we show that both the image and stopping forces can be decomposed into contributions coming from two modes arising from hybridization of the sheet plasmon in doped graphene and a transverse optical phonon in the substrate.

Characteristics of Plasma Dynamics in Current Sheets Formed in Helium Plasma

The characteristic features of plasma acceleration in the current sheets are discussed on the basis of an analysis of the structure of electrodynamic forces at successive stages of the evolution of the current sheets formed in the plasma with helium ions. Of particular interest is the generation of reverse currents at the side edges of the sheet and the appearance of forces, which are braking previously accelerated plasma flows.

Influence of the initial winding displacement on the indicators of the electromechanical induction accelerator of cylindrical configuration

Purpose. The purpose of the article is to determine the influence of the initial displacement of the windings on the indicators of an electromechanical induction accelerator of a cylindrical configuration with pulsed excitation from a capacitive energy storage and with short-term excitation from an alternating voltage source. Methodology. To take into account the interrelated electrical, magnetic, mechanical and thermal processes, as well as a number of nonlinear dependencies, we use the lumped parameters of the windings, and the solutions of the equations describing these processes are presented in a recurrent form. The mathematical model of the accelerator takes into account the variable magnetic coupling between the windings during the excitation of the inductor winding. When calculating the parameters and characteristics of the accelerator, a cyclic algorithm is used. Results. At a frequency of an alternating voltage source of 50 Hz, the current amplitude in the armature winding is less than in the inductor winding. With an increase in the source frequency to 250 Hz, the phase shift between the winding currents decreases. The current in the inductor winding decreases, and in the armature winding it increases. The accelerating components of the force increase, and the braking ones decrease. With an increase in the source frequency to 500 Hz, the current density in the armature winding exceeds that in the inductor winding. In this case, the phase shift between the windings is further reduced. Originality. When a cylindrical accelerator is excited, the largest amplitude of the current density in the inductor winding occurs at the maximum initial displacement of the windings, but the amplitude of the current density in the armature winding is the smallest. The largest value of the current density in the armature winding occurs in the absence of an initial displacement. When excited from a capacitive energy storage, the electrodynamic force between the windings has an initial accelerating and subsequent braking components. As a result, the speed of the armature initially increases to a maximum value, but decreases towards the end of the electromagnetic process. When a cylindrical accelerator is excited from an alternating voltage source, a phase shift occurs between the currents in the windings, which leads to the appearance of alternating accelerating and decelerating components of electrodynamic forces. The accelerating components of the force prevail over the braking components, which ensures the movement of the armature. Practical value. At a frequency of an alternating voltage source of 50 Hz, the highest speed at the output of the accelerator vzf=0.5 m/s is realized at an initial displacement of the windings z0=6.2 mm, at a frequency of 250 Hz, the highest speed vzf=2.4 m/s is realized at z0=3.1 mm, and at a frequency of 500 Hz the highest speed vzf=2.29 m/s is realized at z0=2.3 mm.

Electrical Losses and Electrodynamic Forces in the Magnetic System of an Electric Generator with Windings Made of High-Temperature Superconducting Materials

Electrical Losses and Electrodynamic Forces in the Magnetic System of an Electric Generator with Windings Made of High-Temperature Superconducting Materials

Fuzzy-based continuous current control of electrodynamic tethers for stable and efficient orbital boost

This paper studies the control of libration stability of an insulated electrodynamic tether system in orbital boost. The electrodynamic tether is assumed rigid and the tethered spacecraft are modeled as lumped masses, while a complete electric circuit model is established by the Parker-Murphy model and Kirchhoff's first law. The electric current regulation is realized by adjusting the resistance of a resistor in the circuit. The impact of periodic variations of electrodynamic force on the libration of electrodynamic tether is minimized by a simple fuzzy-based continuous electric current control. The proposed controller maintains the merits of continuous electric current control and simplicity of on-off current control. The effectiveness of the fuzzy-based controller has been demonstrated by analyzing the libration dynamics of electrodynamic tether with continuous and discrete on-off current profiles in orbital boost. Numerical results show that the proposed approach is much effective than the on-off current control in stabilizing both in-plane and out-of-plane libration of the electrodynamic tether system subjected to periodic and non-periodic perturbations.

Mechanism of MRET Treated Water Inhibition Effect on Morphology of Pathogenic Microorganisms: A Review

We found the significant protective properties of MRET water confirmed by substantial decrease of Staphylococcus aureus CFU (colony forming units) in homogenate of kidneys of mice on MRET water compared to control group of mice on regular water following the intra-peritoneal staphylococcal infection. Another study relates to a detailed observation of the effect of MRET activated water with the modified molecular structure, physical and electrodynamic characteristics on metabolic activity and growth of conditionally pathogenic microbiological culture Escherichia coli K-12 (E.coli) and on metabolic activity of microbial associations (similar to microbial associations in the intestine). Activated (MRET) water produced significant changes of E.coli morphology: different shape, color and size of cells, disturbance of process of cellular division. We also observed positive results of MRET water complimentary treatment for HIV patients during the clinical trial. There are recent research data which allows pointing to a similar mode of action for the two viral proteins, suggesting that anti-viral strategy that targets the viral-induced membrane fusion step can be adapted from HIV-1 to SARS-CoV. The stability of virus spike protein structure is based on the overall interactions of van der Walls weak electrodynamic forces and hydrogen bonding. It is obvious, that all biochemical formations of proteins require presence of water molecules in biological systems. The overall observed research data suggest that modification of water - based medium electrodynamic parameters of the human tissues (that are favourable for the homeostasis of the body in the range of physiological “window”) can lead to significant change of van der Walls interactions and hydrogen bonding that result in the inhibition and interruption of virus spike proteins formation. Such scenario obviously disables virus life sequence of attachment and fusion with human cell membranes. The same type of mechanism can be adopted for the inhibition of other lines of pathogenic microorganisms. The studies conducted at AltheaDx Technology, USA confirm that MRET activated water based medium did not affect the morphology of normal PBMC cells on genetic level; it affected the morphology of normal PBMC cells in a positive way increasing their viability. MRET Activated Water is produced with the help of patented in the USA Molecular Resonance Effect Technology (MRET, US Patent # 6022479). We suggest that MRET water consumption by human subjects can lead to physiologically favorable modification of dielectric permittivity and hydrogen bonding of water –based medium in the human body tissues. It can provide the initial human body natural defence against intervention and spread of pathogenic microorganisms

Performance analysis of three-phase hybrid fault current limiter with one commutation circuit

This paper describes the development of a hybrid fault current limiter and interrupting device (HCLID) suitable for low and medium voltage AC or DC industrial installations. By substituting the three-commutation circuit on each phase in HCLID with one controlled commutation circuit, the commutation capacitance, let-through current, volume, and weight can be reduced. Reducing the number of commutations circuit aims at decreasing the initial cost of the (HCLID), which is mainly the focus of the commutation capacitors. The fault current commutation method is introduced as a new current limiting means. This technique is based on the injection of counter-current to the main contacts of the circuit breaker for very fast-breaking of fault currents. The HCLID consists of two electric circuits, one to force the fault current down to zero (commutation circuit) and the other to establish the electro-dynamic force to separate the main contacts. The proposed control method is easy to implement and has a low initial cost. The simulated results presented in the research confirm the validity of the new HCLID over traditional methods. Experimental tests were carried out to validate the proposed method. Simulations and experimental results prove the feasibility of the new HCLID.

Handheld Cleaning Tool for Lunar Dust Adhered to Spacesuits Using Magnetic and Electrodynamic Forces

AbstractThe removal of lunar dust adhered to spacesuits is indispensable for crewed lunar exploration. A handheld cleaning tool was developed using magnetic and electrodynamic forces. The tool comp...

Определение взаимных индуктивностей и электро- динамических сил между катушкой и соосным соленоидом при симметричном расположении

Object and purpose of research. Mutual inductances are among the main parameters of electrical circuits, and their determination is the most important task for studying the physical processes occurring in them, including the occurrence of electrodynamic forces. Coaxial coils and solenoids are very common part of electrical devices, and finding mutual inductances and electrodynamic forces in them has a great practical importance. Materials and methods. Methods of theoretical electrical engineering are used. Main results. Expressions for mutual inductance are obtained, and they are based on the decomposition of the solenoid into its external and internal parts relative to the end planes of the coil. Conclusion. On the basis of the undertaken analysis, alternative expressions for mutual inductances are obtained.

INFLUENCE OF AN EXCITATION SOURCE ON THE POWER INDICATORS OF A LINEAR PULSE ELECTROMECHANICAL CONVERTER OF INDUCTION TYPE

The purpose of the article is to evaluate the efficiency of an induction-type linear pulse electromechanical converter (LPEC) when operating in shock-power mode and excitation from an alternating voltage source (AVS) in comparison with excitation from a capacitive energy storage (CES). A mathematical model of an induction-type LPEC has been developed both when excited by a unipolar pulse from a CES and from an AVS using lumped parameters of the windings, which takes into account the interrelated electromagnetic, mechanical and thermal processes. It has been found that when the LPEC is excited from the AVS with a voltage frequency of 50 Hz, the electrodynamic force takes on a periodic decaying character with a significant prevalence of positive components of forces over negative ones. The maximum value of the force is much less, and the value of its impulse is much greater than in the LPEC, excited from the CES. With an increase in the frequency of the AVS voltage from 50 to 150 Hz, the highest value of the current density of the inductor winding decreases, and in the armature winding it increases. The greatest values of force and impulse of force are realized at a voltage frequency of 150 Hz. With an increase in the AVS frequency, the relative indicator of the efficiency of the LPEC increases. References 15, figures 4.

Consistency Analysis of a Dark Matter Velocity-dependent Force as an Alternative to the Cosmological Constant

Abstract A range of cosmological observations demonstrate an accelerated expansion of the universe, and the most likely explanation of this phenomenon is a cosmological constant. Given the importance of understanding the underlying physics, it is relevant to investigate alternative models. This article uses numerical simulations to test the consistency of one such alternative model. Specifically, this model has no cosmological constant; instead, the dark matter particles have an extra force proportional to the velocity squared, somewhat reminiscent of the magnetic force in electrodynamics. The constant strength of the force is the only free parameter. Because bottom-up structure formation creates cosmological structures whose internal velocity dispersions increase in time, this model may mimic the temporal evolution of the effect from a cosmological constant. It is shown that models with force linearly proportional to internal velocities, or models proportional to velocity to power 3 or more, cannot mimic the accelerated expansion induced by a cosmological constant. However, models proportional to velocity squared are still consistent with the temporal evolution of a universe with a cosmological model.

Aspects Regarding the Use of Electronic Power Devices in Power Grid

Abstract Custom power devices are generally used to power sensitive consumers who need higher energy quality. This paper will exemplify some of the custom power devices used in distribution networks. The case study will highlight the solid-state current limiter effects on an electrical network by simulating a medium voltage network. By installing a solid-state current limiter, the value of the short-circuit current decreases; thus, the electrodynamic forces and thermal stresses supported by the components of the electrical network are reduced.

Features of excitation of a linear electromechanical converter of induction type from an AC source

Purpose. The purpose of the article is to establish the basic laws of operation of induction-type linear electromechanical converter (LEMС) during operation in high-speed and shock-power modes and excitation from an AC source of increased frequency. Methodology. With the help of a mathematical model, the regularities of the course of processes in a LEMС, excited from an AC source, were established when working with shock-power and high-speed modes. The solutions of the equations of the mathematical model, which describe interrelated electrical, magnetic, mechanical and thermal processes, are presented in a recurrent form. Results. It was found that when the LEMC operates in the shock-power mode, the maximum value of the current in the inductor winding occurs in the first half-period, and in the inhibited armature winding in the second half-period. The electrodynamic force changes at twice the frequency, taking on both positive and negative values. Since the positive values exceed the negative ones, the magnitude of the impulse of the electrodynamic force increases with each period of the force. Depending on the initial voltage phase, the relative change in the magnitude of the force impulse is 1.5 %. It was found that when the LEMC operates in high-speed mode, the current in the inductor winding in the first half-period has the greatest value, but after several periods it takes on a steady state. The temperature rise of the inductor winding increases with the time of connection to the AC source, and the temperature rise of the armature winding has the nature of saturation. The electrodynamic force has an oscillatory character with strong damping and a significant predominance of the positive component. Depending on the initial phase of the voltage, the relative change in the maximum speed of the armature winding is 2.5 %. Originality. For the first time, a mathematical model of the LEMC, excited from an AC source, was developed, the solutions of the equations of which describe the interrelated electrical, magnetic, mechanical and thermal processes. For the first time, the regularities of the course of processes in LEMC were established when working with shock-power and high-speed modes. Practical value. The characteristics of LEMC are obtained, which determine the efficiency of work in shock-power and high-speed modes. It is shown that the initial voltage phase has no significant effect on the power, high-speed thermal performance of the converter excited from an alternating current source.

EXCITATION OF A PULSE ELECTROMECHANICAL CONVERTER OF ELECTRODYNAMIC TYPE FROM A TWO-SECTION CAPACITOR ENERGY STORAGE

A mathematical model of a pulsed electromechanical converter (PEC) of electrodynamic type has been developed, in which the solutions of the equations are presented in a recurrent form, which, when numerically implemented, allows taking into account the interrelated electrical, magnetic, mechanical and thermal processes and their nonlinear parameters. While maintaining the total energy of the pulsed source, the influence of the distribution of energy between the two sections of the capacitive energy storage (CES) and the voltage at which the additional section of the CES is connected was established. When operating in an accelerating mode, the largest amplitude of electrodynamic forces (EDF) and maximum speed occur in the basic version of the PEC, which is excited only from the main section of the CES, and the most effective is the PEC with the smallest capacity of the main section of the CES, and its maximum value is 2.61 higher than for the basic version of the PEC. When operating in the shock-power mode, compared with the basic version of the PEC, the amplitude of the EDF decreases. The most effective is the PEC with the smallest capacity of the main section of the CES, and its maximum value is 5.17 higher than that of the basic version of the PEC. Experimental studies of the PEC in the shock-power mode established that the oscillograms of the voltage of the CES and the current of the PEC correspond to the calculated characteristics, and their main indicators are consistent with each other with an accuracy of 5-7%. References 16, figures 6.