Metal Armature Research Articles

The importance of the metal reinforcement of low voltage cables in the process of identifying defects

Regarding the identification of defect in the electrical energy cables, in exploatation, usual or high-performance methods are used, based in particular on the phenomenon of reflection and refraction of the impulse transmitted in the cable, phenomenon generated by the impedance change at the defect location. In order to identify the defect, an important role is played by the existence of a current path on the cable route between the ends of the electrical cable and the place where the defect occurred. In the case of low voltage cables, there are situations where, following the sleeve process the continuity of the mechanical protection armature of the steel strip or the copper screen has not been restored. To measure the distance to the defect location, location equipment uses low and high voltage pulses which moves to the defect site with a certain speed and which is repeated after a selected time interval. These impulses are transmitted to the location of the defect at one end of the cable, through the circuit generated by the short circuit between the faulted conductor and the metal armature, which is usually found at ground potential. At the same time, there is situations where the defect is difficult to identify precisely because of the continuity of the reinforcement or screen and their connection to ground potential. This paper describes the stages of fault identification in a low-voltage power cable and presents a case study that highlights the importance of the metal reinforcement in the case of the high-voltage impulse method. Ways to detect defects using the arc reflected method (ARM) using the shock wave generator as well as the inductive method are also briefly presented.

Carnival and the Theme of Migration

Carnival and the Theme of Migration

Design and optimization of a microfluidic-based inductor used as a multifunction-sensor

A planar miniaturized inductor has been designed in order to realize some transduction functions linked to the presence of fluids. Its electrical behaviour has been studied for two liquids: Galinstan and salted water. Their presence between metallic armatures modifies the inductance value at a nominal frequency, chosen at 2GHz. By using a FEM software, the spatial distributions of magnetic field and surface current density in the entire device have been modelized for six arbitrary positions of these liquids in inductor microchannels. The geometrical aspects of the device have been studied and their influence examined for each liquid. We show that the inductor performances are influenced by the spiral width variations and the inter-turn distances of the coil. Considering the device as a sensor, we have evaluated the variations of two parameters: inductance and quality factors, which can respectively attain 664% (for gallistan) and 175% (for salted water) from their nominal values.

ЭЛЕКТРОМАГНИТНАЯ КАТАПУЛЬТА ДЛЯ ЗАПУСКА ТЯЖЕЛЫХ ДРОНОВ С МАЛОРАЗМЕРНЫХ СУДОВ

The paper presents the results of mathematical modeling of the operation of a novel electromagnetic catapult design. The main elements of the latter are a single-section multi-rail accelerator with a metal armature and a pulsed energy source based on the powerful pulsed MHD generator and current-increasing transformer. The possibilities of such a scheme for accelerating bodies weighing 7 tons to speeds of about 150 km/h at a maximum permissible acceleration of 15 g are investigated. The mathematical model describes the coordinated operation of the device, starting with connecting of the pulsed MHD generator in idle mode to the primary winding of the transformer and up to the moment when the drone accelerates to a given takeoff speed. Using the proposed model, the efficiency of the electromechanical energy conversion in the developed catapult scheme is tested. The parameters of the main elements of the device, namely the length of the acceleration section of the catapult and the maximum acceleration of the drone, are determined.

Crack Resistance and Width of Crack Opening of Beams with Hybrid Reinforcement Using BFRP and Metal Armature

The sustainable development of industry and society requires new approaches to the building structures design. The article presents the indices of strength, crack resistance and width of crack opening obtained as a result of experimental testing of beams with hybrid reinforcement with basalt plastic and metal armature. The following beams were examined for comparison purposes: the ferroconcrete beams of the control-series, and the twin beams reinforced only with basalt-plastic reinforcement. It was found that the replacement of the metal armature with basalt plastics led to an increase in strength, on average, by 40%. Similar strength indices were obtained for hybrid reinforcement beams. Crack resistance indices of hybrid reinforcement beams were found to be close to ferroconcrete beams of the control series. Crack resistance indices for these beams were also by 84... 89% higher in comparison with beams reinforced with basalt-plastics. The width of crack openings in hybrid reinforced beams did not exceed the maximum permissible norms at the operational level of loads (70% of destructive) and were smaller than in beams reinforced with basalt plastic reinforcement. Hybrid reinforcement efficiency has been established to improve the performance criteria of beams reinforced with composite armature.

Influence of dry frictional heating on acceleration disruption in a railgun with a metal armature

The main problem associated with the realization of the concept of the electrodynamic accelerator with a metal armature (MA) is the complexity of providing metal contact MA/rail at the velocity over 1 km/s. Here, a complex of physical phenomena is analyzed, which leads to the destruction of the metal contact of the rail/armature due to its melting and the ignition of an electric arc. A mathematical model of the dry frictional heating of the contact zone is formulated and its analytical solutions are obtained using fractional calculus. The criterion of no melting of the contact zone is derived. The generalization of the experimental data showed that to ensure the metal contact, the choice of rail and armature materials is a dilemma. A possible way to resolve this dilemma has been proposed.

One: Egúngún curated by Kristen Windmuller-Luna

One: Egúngún curated by Kristen Windmuller-Luna

Research of the Deflections of Beams Reinforced with BFRP Armature and Hybrid Reinforcement Using Metal and BFRP Armature

It is presented the study of the beam samples reinforced with metal armature, BFRP armature and beams with hybrid reinforcement using metal and BFRP armature. Half of the tested samples of beams were manufactured on concrete with river sand, as a fine aggregate. The others were made on concrete with fractionated fine wastes of Mining and Beneficiary complex (MBC) instead of the river sand. The tests were carried out by static loading of the scheme of a single-run free beam loaded in the thirds of gear. It was established that the beams reinforced with BFRP armature and the beams with hybrid reinforcement showed an increase of strength, about 40%, compared with the beams reinforced with metal reinforcement. The deflections of the beams reinforced with BFRP armature were 315% -331% higher than the deflections of the beams reinforced with metal reinforcement and 165% -205% higher than it is allowed by standards. The use of hybrid reinforcement allowed reducing their deflections in two times compared to the beams reinforced with BFRP armature. At a load level of 60% of the destructive, the deflections of beams with hybrid reinforcement BFRP and metal armature did not exceed the maximum permissible norm. When concrete samples manufactured, the substitution of the river sand with fine fractionated wastes from the Mining and Beneficiary complex (MBC) did not affect their durability and deformability (the difference between the values according to these indicators is within the statistical error).

Визначення прогинів згинальних елементів армованих склопластиковою і металевою арматурою

Визначення прогинів згинальних елементів армованих склопластиковою і металевою арматурою

Виготовлення зразків балок зі змішаним армуванням базальтовою та металевою арматурою.

Виготовлення зразків балок зі змішаним армуванням базальтовою та металевою арматурою.

Виготовлення будівельних конструкцій армованих металевою і склопластиковою арматурою з бетонів на відходах гірничо-збагачувальних комбінатів

Виготовлення будівельних конструкцій армованих металевою і склопластиковою арматурою з бетонів на відходах гірничо-збагачувальних комбінатів

A Comparison of C-Shaped and Brush Armature Performance

The most important part of a railgun launch package is the armature where the electromagnetic force is generated leading to the acceleration of the launch package. In case of metal armatures, the most commonly used armature types are the C-shape and the multi-fiber brush technology. However, rarely both armature types were systematically compared under similar experimental conditions. That is why we constructed launch packages based on the C-shaped and brush armature technology with comparable armature and payload mass. With these launch packages a series of experiments were performed in an energy range between 0.8 MJ and 1.13 MJ corresponding to a speed range between 950 m/s and 1400 m/s. The results of the experiments were then analyzed qualitatively and quantitatively. On the one hand our results show that the total losses are higher for the C-shaped armature technology than for the brush aramture technology. On the other hand our results show that launch packages based on the C-shaped technology convert better electrical energy into kinetic energy.

Coilgun Velocity Optimization With Current Switch Circuit

An inductive coil gun is a solenoid surrounding a cylindrical metallic armature (the projectile), both electromagnetically coupled. One or more capacitors discharge a stored voltage quickly through the coil, configuring a kind of RLC circuit, with the pulse-shaped current generating a magnetic field inside the coil that accelerates the projectile. Once the projectile crosses an equilibrium point inside the coil, the existing magnetic field pulls the armature back, therefore reducing the final muzzle velocity and decreasing the efficiency-defined as the ratio between the available capacitor electrostatic versus the slug kinetic energies. This paper describes a system that monitors the armature position inside the coil, with a laser beam, and automatically cuts the current when the projectile reaches the equilibrium point. The system, named current switch circuit, enables higher velocities using the same set of coilgun and projectiles, providing a higher efficiency.

A new advanced railgun system for debris impact study

Abstract: The growing quantity of debris in Earth orbit poses a danger to users of the orbital environment, such as spacecraft. It also increases the risk that humans or manmade structures could be impacted when objects reenter Earth's atmosphere. During the design of a spacecraft, a requirement may be specified for the surviv-ability of the spacecraft against Meteoroid / Orbital Debris (M/OD) impacts throughout the mission; further-more, the structure of a spacecraft is designed to insure its integrity during the launch and, if it is reusable, during descent, re-entry and landing. In addition, the structure has to provide required stiffness in order to allow for exact positioning of experiments and antennas, and it has to protect the payload against the space environment. In order to decrease the probability of spacecraft failure caused by M/OD, space maneuver is needed to avoid M/OD if the M/OD has dimensions larger than 10cm, but for M/OD with dimensions less than 1cm M/OD shields are needed for spacecrafts. It is therefore necessary to determine the impact-related failure mechanisms and associated ballistic limit equations (BLEs) for typical spacecraft components and subsys-tems. The methods that are used to obtain the ballistic limit equations are numerical simulations and la-borato-ry experiments. In order to perform an high energy ballistic characterization of layered structures, a new ad-vanced electromagnetic accelerator, called railgun, has been assembled and tuned. A railgun is an electrically powered electromagnetic projectile launcher. Such device is made up of a pair of parallel conducting rails, which a sliding metallic armature is accelerated along by the electromagnetic effect (Lorentz force) of a cur-rent that flows down one rail, into the armature and then back along the other rail, thanks to a high power pulse given by a bank of capacitors. A tunable power supplier is used to set the capacitors charging voltage at the desired level: in this way the Rail Gun energy can be tuned as a function of the desired bullet velocity. This facility is able to analyze both low and high velocity impacts. A numerical simulation is also performed by using the Ansys Autodyn code in order to analyze the damage. The experimental results and numerical simulations show that the railgun-device is a good candidate to perform impact testing of materials in the space debris energy range.

Modelación y Validación en ATP de los Cables Subterráneo y Submarino del Sistema de Subtransmisión Baltra - Santa Cruz

En este trabajo, basados en el estado del arte, se presentan los criterios usados para la modelación y validación de los cables tripolares subterráneo y submarino del sistema de subtransmisión Baltra– Santa Cruz. Para modelar los cables en rutinas Cable Parameters incluida en programas del tipo EMTP, se realizó un tratamiento previo de los datos de diseño y constructivos de los cables; además, para analizar el cable tripolar subterráneo fue necesario agregar a su modelo una armadura ficticia de tal manera que se pueda modelar como un cable tipo “tubo” (Pipe).
 El estudio de transitorios electromagnéticos de energización de la línea se realizó usando el software ATP, pero debido a que el estado del arte indica limitaciones en el modelo de cables y líneas aéreas no simétricas cuando se usa Bergeron o JMarti, incorporados en ATP, se realizó un análisis que permitió determinar hasta qué punto es válido el modelo JMarti mediante una comparación de sus respuestas transitorias de voltaje con las ofrecidas por el modelo WideBand, incorporado en EMTPRV el cual es considerado el modelo más preciso de líneas y cables en la actualidad. Para este propósito los modelos JMarti de cable submarino y subterráneo fueron ajustados con un valor de frecuencia de acuerdo a lo sugerido por CIGRÉ.
 Los resultados indican que el modelo JMarti ofrece señales de voltaje aceptables únicamente para el conductor energizado, mientras que para voltajes inducidos en otros conductores de fase y pantallas y armaduras metálicas el modelo falla.

Monitoring the Degradation of UHPC Boards

In this article the hot water test is presented on thin UHPC slabs that are reinforced by a new type of armature. It is a textile armature, which should replace the classic metal (steel) armature. Textile armature should not only reduce the cost of production, but, because it is not susceptible to corrosion as conventional steel armature, panels can be designed with significantly less cover thickness in achieving similar or longer lifetime of these elements. The combination of UHPC concrete with a minimum thickness of cover and textile armature allows design elements weighing up to 70 % lower compared to conventional concrete elements with conventional armature. This can achieve significant savings and benefits not only in economic aspects, but also in environmental aspects.

To Monitoring the Degradation of UHPC Boards with Textiles Armatures

In this article the hot water test is presented on thin UHPC slabs that are reinforced by a new type of armature. It is a textile armature, which should replace the classic metal (steel) armature. Textile armature should not only reduce the cost of production, but, because it is not susceptible to corrosion as conventional steel armature, panels can be designed with significantly less cover thickness in achieving similar or longer lifetime of these elements. The combination of UHPC concrete with a minimum thickness of cover and textile armature allows design elements weighing up to 70 % lower compared to conventional concrete elements with conventional armature. This can achieve significant savings and benefits not only in economic aspects, but also in environmental aspects.

Ultimate kinematic characteristics of rail electromagnetic launchers with metal armatures in an external magnetic field

This paper presents the results of numerical simulation of the Joule heating of the armature and rails in rail launchers of metal bodies with one or two augmenting rails generating an external magnetic field. The ultimate projectile velocity is calculated under the assumption that the Joule heating of the armature and rails during acceleration does not exceed the melting temperature of the materials of which they are made. It is shown that, with an appropriate choice of the position of the coils generating the augmenting magnetic field with respect to the launcher channel and the current magnitude in them, the heat load on the rails and armature in electromagnetic launchers of solids can be substantially reduced and the ultimate kinematic characteristics of these launchers in crisis-free regimes can be considerably increased.

Investigation and conservation of Anne Marie Carl-Nielsen's wax models

The Danish sculptor Anne Marie Carl-Nielsen (1863–1945) often prepared three-dimensional models in wax before producing her works of art. The Carl Nielsen Museum in Odense keeps a unique collection of around 200 of the artist's fragile wax models. In 2008 the entire collection was examined, documented, X-ray radiographed, photographed, and conserved. Analyses of five figurines by attenuated total reflectance-Fourier transform infrared spectroscopy, optical microscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy showed two different kinds of wax mixtures, one containing beeswax and potato or maize starch as filler, and the other consisting of gypsum, zinc stearate, and a greasy substance. During the examination a specific deterioration phenomenon was noticed in the areas where the wax models had been strengthened with internal metal armatures. A chemical reaction between the wax mixture and the copper containing armature has caused an intense greenish colouring of the wax as well as creating a soft and almost liquid consistency and formation of copper(II) carboxylate salts. Based on an original recipe from Anne Marie Carl-Nielsen, a replica of one of the wax mixtures was produced and examined with respect to its infrared spectrum and its modelling properties.

Evaluation of a Novel Plasma Launcher Behavior Using Magneto Hydro Dynamic Modeling-Coupled Time Varying Electron Energy Distribution Function

An Electro Magnetic (EM) launcher can be used as an experimental tool to accelerate small-mass specimens up to 300 m/s to study impact phenomena. A plasma armature is employed to avoid the friction produced by a sliding metal armature and, in particular, to prevent high-Z impurities from entering the tokamak. High currents are used to achieve high accelerations, resulting in high plasma temperatures. For this purpose, 2-D and axisymmetric plasma models are widely used as these are less complicated and fairly available. The presented model solves the entire set of magneto hydro dynamic, including transport equations of mass, momentum, and energy along, with the vector potential form of Maxwell's equation-coupled time-varying electron energy distribution function for the novel EM launcher in axial symmetry domain. Radiation of the energy balance is calculated using the P-1 radiation method by dividing the electromagnetic spectrum into several gray bands. Simulations are performed using Comsol Multiphysics 4.2 software.