Physics for Scientists and Engineers

Human civilization has always been caught between two forces̶chaos and order. Without order, society disintegrates into confusion; without structure, communities cannot grow, innovate, or sustain themselves. Yet, order does not arise by accident. It is designed, cultivated, and maintained by men and women who take upon themselves the responsibility to shape systems, laws, beliefs, and institutions. These are the Architects of Order̶the thinkers, leaders, innovators, and ordinary people who create frameworks that allow humanity to thrive. Like builders who draw blueprints for cities, these architects sketch invisible blueprints for society. Their work stretches across generations, influencing everything from governance to education, from science to spirituality. Chapter One: The Ancient Designers of Harmony The earliest civilizations understood the necessity of order. In Mesopotamia, King Hammurabi etched one of the first legal codes on stone tablets, declaring principles of justice and punishment. This was more than law; it was architecture for social stability. In Ancient Egypt, the concept of Ma at embodied truth, balance, and harmony. Pharaohs were seen not just as rulers, but as guardians of cosmic order. In China, Confucian teachings created a moral blueprint that shaped family life, government, and relationships for centuries. These ancient systems may differ in form, but they all reveal the same truth: societies cannot survive without an underlying structure of order. Chapter Two: Philosophers as Architects While rulers built order through power, philosophers built it through thought. Plato s Republic imagined the ideal city governed by justice and wisdom. Aristotle studied governance and declared that man is a political animal, destined to live in structured communities. In the East, Confucius emphasized respect, hierarchy, and harmony, while Lao Tzu encouraged balance through simplicity and nature s flow. These philosophers may not have held armies, but their ideas became the silent foundations upon which nations, laws, and ethics were constructed. Chapter Three: Kings, Lawgivers, and Statesmen Throughout history, some leaders transcended mere politics to become true architects of order. Augustus Caesar transformed Rome from chaos into the Pax Romana, an era of relative peace. Centuries later, leaders like George Washington, Kwame Nkrumah, and Nelson Mandela built nations by designing new systems of governance. Constitutions, treaties, and reforms are not simply documents; they are blueprints. A true statesman is not concerned with winning the next election but with building institutions that will outlast him. In this way, rulers who become architects of order transform personal power into lasting legacy.

Dowsing experimental technique (DET), also known as divination, has been used to serve human needs across different civilizations. A comprehensive review of the literature on DET indicates that scientists are divided into two groups, regarding DET's science and interpretation. One group believes that there is pure physics and chemistry behind DET and, therefore, it should be considered as one of the applied sciences used for materials' prospecting. The other group believes that identification of materials using DET can be explained as a psychological behavior. In this research paper, DET has been used to identify several materials, and the various possible mechanisms behind it also examined. Accordingly, 68 samples were collected from various locations in Jordan and Palestine to identify them using DET. The collected samples, including different kinds of minerals, metals, rocks, etc., were divided into 9 groups. Experiments were conducted on combinations of the collected materials, using wooden rods and two capsules filled with crushed materials and placed on the rods. It is believed that the materials were identified using DET because of energy radiation, thermal conduction, piezoelectric effects, and/or electrostatic forces. DET may be also interpreted in terms of psychological perspectives, as being a psychological kinesthetic sense. So that these forces may be able to move the rods towards the target material, identify it, and recognize its location. However, DET is still an open question for further research, including cyber-psychology and other digital tools. In short, DET has proven to be a successful, easy, cheap, applicable, and sustainable technique for identifying and locating various materials.

The economic and political changes in the world, from the 1970s, changed the political education of the Public Institutions of Higher Education in the world. The direction of these changes was clear: the university approachedthe market and the company and created interaction mechanisms that did not exist. The article therefore reviews the academic literature that interprets the relationship between university and market/company from two perspectives: approaches that positively position of interactions, exposing their motivations, interests and forms of interaction, especially the notions on Knowledge Economy and Entrepreneurial University; approaches that observe this interaction critically and reflectively, exposing the problems of interaction, its negative aspects and the reflection of the true role of the public university from the perspective of Academic Capitalism.

A review, study, and quick reference guide to partial differential equations from a science and engineering perspective. Included are fundamental concepts, descriptions of common solution techniques (separation of variables, integral transforms, etc.), and other supporting mathematical concepts.

Resumo: Nos últimos anos, vem ganhando força no Brasil a ideia do cientista/engenheiro inovador. Em um contexto onde a linha que separava empresas e universidades se torna cada vez menos perceptível, vozes de ambos esses mundos professam as vantagens atreladas a mudanças possíveis e desejáveis na formação desses profissionais. O discurso mais comum prega a necessidade de formar cientistas e engenheiros capazes de combinar profundo conhecimento técnico e científico a habilidades gerenciais, o que exigiria uma série de mudanças curriculares. Implícito nesse discurso está, obviamente, o diagnóstico de que o modelo vigente de formação desses profissionais tornouse inadequado à atual realidade brasileira. No presente artigo, expressamos nossa concordância em relação ao diagnóstico. De fato, o perfil dos cientistas e engenheiros formados atualmente no Brasil não é condizente com a realidade social brasileira. Contudo, discordamos completamente do modelo alternativo de formação que é frequentemente proposto, uma vez que, em nossa avaliação, esse modelo também provaria ser disfuncional. Encerramos este trabalho apresentando um outro modelo alternativo que pensamos ser mais adequado para o Brasil. Palavras-chave: Educação em ciência. Tecnologia e sociedade. Ciência e tecnologia. Cientistas e engenheiros. Modelo de formação.

This article presents the importance of analyzing the breakdown behaviour of high voltage fuses and highlights the pressure values at the fuse ends. The theoretical basis, test scheme structure, design and sizing elements of fuse components, and numerical simulations performed in Matlab/Simulink are presented. The extinguishing environment is not modelled as it is considered to be a vacuum Starting with the oldest overcurrent protection device and continuing with the importance of high voltage fuses for operational safety, the study presents the behaviour of high voltage fuses during short-circuit current interruption. The key element is the value of the pressure on the contacts of fuses, which is often ignored in favour of the pressure of the middle element. When fuses change from solid to liquid state the inner parts are hotter than the outer parts and melt first, and the melting zone extends to the periphery. The study found that the pressure is much higher and is an important value for designers. Experiments showed that the maximum pressure is reached during the arcing period, a significant finding for the design process of the contacts of a high-voltage fuse. The research was then extrapolated to check the pressure in metal enclosed switchgear containing fuse combinations.

Flow restrictions in the stator bar cooling channels are commonly caused by copper oxide deposits. The paper discusses the mechanisms of such flow restrictions: formation, release, migration and transport of copper oxides. These parameters can be controlled by water chemistry. Of the 1,600 water-cooled stators world-wide (excluding Russia, China and Japan), about half operate under high-oxygen chemistry, the other half under low-oxygen conditions. Alkaline treatment and "cationic purification" are promising options.

The shape of the free surface and the flow field of a simple fluid driven by the steadily rotating bottom cap of a cylindrical cup is investigated. A regular domain perturbation in terms of the angular velocity of the bottom cap is used. The velocity field is a superposition of a strong primary, azimuthal field and a weaker secondary meridional field. The effect of the aspect ratio and viscoelasticity of the fluid results in multiple cell structures in the meridional plane. The free surface shape determined at the lowest significant order in the perturbation algorithm, is similarly affected by the same factors. Both the flow field and the interface shape are determined for a wide range of aspect ratios and viscoelastic parameters.

Poiseuille flaw of an elastico-viscous liquid in a straight, circular pipe driven by a pressure gradient oscillating about a non-zero mean is ~~ves~~gat~. The simple fluid of the multiple integral type presents a flow enhancement which depends on the frequency and amplitude of the oscillation, magnitude of the mean pressure gradient and the material functions of the fluid. A closed form expression for the flaw rate alteration, independent of any explicit representations for the material functions, is developed at the lowest order in the perturbation algorithm where nonlinear effects appear. Asy~toti~ analyses of the flow rate ~o~a~~rne~t at small and large frequencies are presented.

This work aims to present the study of synchronous electrical machines with permanent magnets for use in wind turbines, where the rotor, usually built from laminated sheets of low carbon steel and FeSi, will be replaced by sintered alloys obtained from Powder Metallurgy. Thus, in this work, studies will be conducted in order to verify the feasibility of using pure iron and some sintered alloys, such as FeSi and FeNi, to construct the referred rotor. These materials will be characterized in terms of their physical properties as well as simulations of the machine will be carried out in three different topologies of the rotors. Two machines have the magnets bonded to the surface of the rotors, with two different configurations, namely straight poles and poles protruding, and the third one has the magnets inserted inside the rotor core. The simulations results of different topologies pointed out that for machines with rolled sheet, the best-sintered alloy in order to replace the rotor c...

statistical distributions of other parameters, for example the soil resistivity, are available, they can be incorporated in the evaluation of the withstand potential probability distribution. Probability of presence is also an important parameter. Therefore, this should be kept in mind when questions of public access and use of rights-ofway are being discussed.

This work aims to present the study of synchronous electrical machines with permanent magnets for use in wind turbines, where the rotor, usually built from laminated sheets of low carbon steel and FeSi, will be replaced by sintered alloys obtained from Powder Metallurgy. Thus, in this work, studies will be conducted in order to verify the feasibility of using pure iron and some sintered alloys, such as FeSi and FeNi, to construct the referred rotor. These materials will be characterized in terms of their physical properties as well as simulations of the machine will be carried out in three different topologies of the rotors. Two machines have the magnets bonded to the surface of the rotors, with two different configurations, namely straight poles and poles protruding, and the third one has the magnets inserted inside the rotor core. The simulations results of different topologies pointed out that for machines with rolled sheet, the best-sintered alloy in order to replace the rotor c...

The objective of this work was the development of a three-phase, six pole stepper motor with stator and rotor core built from Fe50%Ni alloy via powder metallurgy. The study involves analysis of the magnetic, electrical and mechanical properties, besides motor design and software simulation using finite elements. The Fe50%Ni alloy showed as result an electrical resistivity of 0.37 ˙m, relative permeability of 946 and maximum induction of 0.93 T. In the computational simulation, with the application of 1 A current per phase, the required voltage was 2.88 V, which resulted in a power of 2.88 W. In this condition the stepper motor generates a torque of 6.81.10-4 Nm with an air gap induction of 0.55 T.

The effect of silicon avalanche diodes (SADs) on the behavior of fuses in low-voltage (LV) power networks is shown, as well as the effect of the fuses on the energy dissipation in the SADs. In order to achieve this, an existing model developed for mediumvoltage fuses was adapted for LV fuses operating in the presence of SADs. An SAD model was also developed. Both models were validated by laboratory measurement. The effects of fault closing angle and fault level on SAD energy dissipation are shown, and a general method for determining the SAD energy rating for any given situation is derived.

Manual operations feature prominently in the manufacture of many electrical machines. Even though high-volume electrical machine manufacture is dominated by automation, several manufacturing operations continue to involve manual intervention because of the complexity of such operations makes them heavily reliant on high dexterity manual skills and experience. However, quality can be variable due to human involvement. Currently, in order to maintain a high precision of control and required tolerances of the final machine, inspection is performed at various steps during manufacturing and assembly. Detecting a defect at these end-of-line tests can result in significant wasted time and costs due to rework or scrappage. The solution to this problem lies in in-process monitoring particularly for error prone manual operations. This paper presents a literature review of the state-of-the-art available techniques and limitations in process monitoring within the context of electrical machine m...

This is a practical book on Power Distribution, focusing on medium voltage (1-36 kV) power considerations, switchgear, power cables, transformers, power factor correction, grounding/earthing, lightning protection and network studies. You will gain useful practical technical know-how in these areas, not always covered by university or college programs. Typical people who will find this book useful include: Critical medium-voltage (MV) distribution substations will generally also have two or more incoming supplies from different HV substations. Main distribution substations usually supply power to a clearly defined distribution network, for example, a specific plant or factory, or for town/city reticulation purposes. Power distribution is normally done on the medium-voltage level, in the range of 6.6-33 kV. Three-phase power is transferred, mostly via overhead lines or 3-core MV power cables buried in trenches. Single-core-insulated cables are also used, although less often. Low-voltage distribution is also done over short distances in some localized areas. Medium-voltage switchgear 2.1 Standards Standards in Europe and many other 50 Hz countries are governed by the IEC. The SA bureau of standards SABS has adopted many of the IEC standards e.g. SABS/IEC 87. In North America, the standards are set by ANSI and the IEEE. The standards and the way switchgear is tested vary from country to country. It is therefore important to verify what standard is being called for in a specification or is used by the manufacturer. Variations in standards also affect the price of equipment. 2.2 Switch board layout Switch boards can be designed to have various configurations. This depends on the reliability, fault level and the flexibility required. Examples: • Single busbar with only one busbar section (no flexibility and low reliability) • Single busbar with two sections (improved flexibility and reliability with highest fault level if section maker is closed) • Single busbar with three sections (excellent flexibility and reliability) • Double busbar with one or more sections (good flexibility and reliability). The busbar layout may require a break before transfer from one busbar to the next. 2.3 Ratings Manufactured medium-voltage (MV) switchgear panels are rated according to the following main specifications: Nominal voltage This is the designed average voltage of a system, e.g. 11 kV. The actual voltage will typically fluctuate between 10.5 and 11.5 kV (95-105%). Rated voltage This is the voltage level at which the equipment will be expected to perform at continuously under normal operating conditions, e.g. 12 kV for a system with a nominal voltage of 11 kV. Medium-voltage switchgear 29 Communications Communication capability of an IED is one of the most important aspects of the device today and is the one aspect that clearly separates the different manufacturers' devices from one another regarding their level of functionality. IEDs are normally able to communicate directly to a SCADA system, i.e. upper level communications. Different manufacturers use different communication protocols, and this will determine certain critical aspects, e.g. response times, possibility of direct relayto-relay communications, etc. An IED will, in addition to upper level communications, also have a serial port or optical interface to communicate directly to substation PC or laptop for configuration and data downloading purposes, should the SCADA link not be available or desirable in that instance. Comparison of electromechanical relays and digital relays Note 1 The cost will depend on the application. If a multi-function relay, like an intelligent feeder terminal, is used for only overcurrent protection, the cost for that function will be high. However, if a digital relay is fully utilized, for example a generator protection relay, the cost per function will be low. Note 2 Not all digital relays will comply with the features as in the table, depending on the type of relay. However, the table is an overview of what is possible with digital relays in general, compared to what could be achieved with electromechanical relays.

Current solutions for voltage regulation close to consumers usually require technicians for manually changing the taps of the transformer, which may imply in high maintenance costs and uncontrolled voltage levels. In this context, electronic onload tap changers (OLTC) are a prospective solution for the present and future power grids, since they can provide automatic voltage regulation. This paper presents the analysis and design guidelines for an electronic OLTC applied to a distribution transformer, encompassing the physical layout design for external access to the transformer tap terminals, the evaluation of current and voltage transients during the commutation process, and the dimensioning of the electronic switches and protection system. The dielectric withstand of the proposed physical layout is also analyzed through the finite elements method approach, guaranteeing adequate insulation for the electronic circuits located outside the transformer tank, which facilitates the circuitry maintenance and provides high modularity. The electronic switches and the protection circuit of the electronic OLTC are experimentally tested under normal and fault operational conditions in a 5 kVA, 7.69 kV/220 V, single phase earth return distribution transformer.

The transient fields generated during switching operations in gas-insulated substations (GIS) can have rise times in the order of a few nanoseconds. Transient fields, which are developed internally to the gas-insulated modules, leak into the external environment through discontinuities and interfere with nearby electronics. Depending on the configuration of the GIS and the observation point, amplitudes of the electric and magnetic fields could be of the order of a few tens of kilovolts per meter and a few hundreds of amps per meter, respectively. These transient fields, in turn, induce voltages in the control cables and secondary circuit of the instrument transformers, which result in malfunctioning of the primary equipment. In this paper, induced transient voltages in the control circuitry and their frequency spectra have been calculated due to the transient fields, leaking out from the gas-to-air bushing and the gas-insulated bus section of a 245-kV-rated GIS, during switching operations. The effect of the length of control circuit, type of grounding of the cable sheath (both-end/one-end), characteristics of the transient fields, type of secondary circuit (i.e., current transformer/potential transformer) and LC loading of the control circuitry on the induced voltages have been analyzed and reported.

Electrical energy losses in low-voltage devices can have a significant impact on the overall efficiency of an electrical system. In this research, a comprehensive comparative analysis of losses in electrical energy in low-voltage devices, including transformers, cables, and switchgear was presented. Experiments to measure the losses under varying operating conditions, such as loads, ambient temperatures, and frequencies were conducted. The data collected from the experiments were then analyzed to identify the major contributors to losses in each device with models for these devices to predict the losses accurately. The models were based on analytical and empirical approaches, considering various factors such as size, insulation type, and operating conditions. The models were validated using the data collected from the experiments, and the results showed good agreement between the predicted and measured losses. The findings show that losses in low-voltage devices depend on various fa...

The development of a dry-type transformer for pole mounted application and its major features allowing to use it as an outdoor transformer without need for an enclosure was presented at CIRED 2011 [1]. Meanwhile extensive testing of the outdoor performance of the transformer has continued and field installation of pilot units has taken place. Tests have been performed at both, the demanding KIPTS outdoor test station in South Africa and under controlled harsh conditions of a salt-fog chamber. The applied test conditions are used for proposing typical test procedures for such kind of transformers. Testing with respect to fire behavior was additionally performed.

Throughout introductory physics, students create and interpret free body diagrams in which multiple forces act on an object, typically at a single location (the object's center of mass). The situation increases in difficulty when multiple objects are involved, and further when electric and magnetic fields are present. In the latter, sources of the fields are often identified as a set of electric charges or current-carrying wires, and students are asked to determine the electric or magnetic field at a separate location defined as the observation location. Previous research suggests students do not always appropriately account for how a measurement or calculation depends on the observation location. We present preliminary results from a studio-style, algebrabased, introductory electricity and magnetism course showing the prevalence of correct and incorrect responses to questions about observation location by analyzing student written work involving vector addition of fields.

this paper describes the phenomena of propagation of common mode high-frequency currents (HF) in the metallic parts of AC machines supplied by pulse width modulation (PWM) inverters. A detailed analysis based on finite elements modeling is proposed to identify the privileged paths of these HF currents and parameters that rule this phenomenon.

The paper presents the procedure of electric arc furnace secondary circuit calculations. The separate parameters that form the furnace circuit impedance have been determined. The operating current for given power factor has been calculated and verified. To get better insight of the operating conditions of the arc furnace, thermal and stress analysis of the secondary delta closure have been performed. The procedure and the results are verified by measurements over 110 tone electric arc furnace with rated power of 110MVA. Streszczenie. W artykule przedstawiono procedurę obliczeń obwodu wtórnego elektrycznego pieca łukowego. Zostały określone poszczególne parametry, które tworzą impedancję obwodu pieca. Między innymi został obliczony i zweryfikowany prąd przy danym współczynniku mocy. W pracy przedstawiono wyniki przeprowadzonej analizy termicznej i naprężeń w przypadku zwarcia obwodu wtórnego, wykonane celem lepszego zrozumienia warunków pracy pieca łukowego. Procedura i wyniki pomiarów zostały zweryfikowane przez pomiary w ponad 110 tonowym piecu łukowym o mocy znamionowej 110MVA. (Obliczanie obwodu wtórnego elektrycznego pieca łukowego-podejście analityczne i numeryczne).

In September 1995, a project was initiated to replace the existing drive line at NASA's most unique transonic wind tunnel, the National Transonic Facility (NTF), with a single 101 MW synchronous motor driven by a Load Commutated Inverter (LCI). This Adjustable Speed Drive (ASD) system also included a custom four-winding transformer, harmonic filter, exciter, switchgear, control system, and feeder cable. The complete system requirements and design details have previously been presented and published [1], as well as the commissioning and acceptance test results [2]. The NTF was returned to service in December 1997 with the new drive system powering the fan. Today, this installation still represents the world's largest horizontal single motor/drive combination. This paper describes some significant events that occurred with the drive system during the first 15 years of service. These noteworthy issues are analyzed and root causes presented. Improvements that have substantially increased the long term viability of the system are given.

The use of non-linear devices causes unfavourable changes in the operation of the power system. First of all, they are a source of higher harmonics in network waveforms, which tend to increase the eddy currents. Their effect consists in raising the temperature of transformer cores. This, in turn, translates into their failure rate and fire safety, including reducing the actual value of rated power. The article describes the results of experimental studies carried out on a large scale. An analysis was performed of the quality of electric power depending on the type of network load. The results have shown that the increase in the use of non-linear receivers such as LED lighting, electronic chargers, inverters, etc. may have a tangible impact on the fire hazard of distribution transformers. Examples of calculations have been presented, which prove the necessity of taking into account the influence of higher harmonics on the reduction of the real rated power of power transformers.

Developed measurements system for evaluation of gas pressure value in direct vicinity of switching arc plasma was described in this paper. The system is resistant to heavy duty conditions present inside the MV switch quenching chamber and its functionality was verified during large scale functional tests. In this paper results of gas pressure measurements performed for a current interrupter equipped with an arc quenching system based on combination of forced air flow and gassing material ablation were presented. Gas pressure was measured by means of developed system, for several values of capacitive load current at 12/24 kV supplying voltage.

In this article a thermal modeling is developed for a double sided linear induction motor which is used to drive a power supply system for an electric locomotive. Two cases were considered for the linear motor, with full plate armature and with sectioned plate armature. The thermal model has been obtained with Pro/Engineering software package and the mesh of the 3D thermal model has been done using tetrahedron solid elements types. Experimental validation of the model has been realized too. Errors between the simulations and the experimental data (between 1% and 4%) show that the proposed model can be used for accurate precision of the heat distribution on the linear motor.

Several methods of attenuation of Very Fast Transient Overvoltages (VFTO) in Gas-Insulated Switchgear (GIS) are under development. An approach that is currently gaining high attention among researchers is based on the application of magnetic cores dissipating the energy associated with VFTO due to eddy current losses and magnetic hysteresis losses. This paper presents an advancement in this approach, by introducing a new material type (denoted in the present paper as "nanoflakes"). This new material comprises macro pieces of nanocrystalline ribbons (with the size ranged in square millimeters), acquired from crumbled nanocrystalline cores of a standard design. The material is characterized by relatively high magnetic permeability, poor electrical conductivity, and high saturation flux level. The material is suitable for application as a coating layer applied to the surfaces of an inner and/or an outer GIS conductor, as a fill-in material in the GIS shielding elements, or as a standard shaped core. The paper presents the material major features, outlines its development process, and reports on validation of the material effectiveness in real VFTO conditions. The validation is based on the measurement of VFTO attenuation in full-scale 550 kV GIS test setup .

The aim of this work was the development (design, construction and tests) of a Three-phase Synchronous Machine with permanent magnets and four poles to be used in small wind turbines, where the rotor and stator cores, usually constructed from laminated steel sheets, were replaced for massive blocks obtained from the Powder Metallurgy (PM) process. The other parts of the machine, such as housing, shaft, bearings and covers, were obtained from conventional three-phase induction motor of 10 HP. Initially, it was studied sintered alloys from pure iron, Fe-Si, Fe-P and Fe-Ni; eventually these alloys were analyzed in terms of magnetic and mechanical properties as well as electrical resistivity. From this study, it was chosen the use of sintered pure iron for the construction of the rotor and Fe1%P for the construction of the stator. The permanent magnets used were Nd-Fe-B, and the windings calculation was based on the coiling of the three-phase induction motor. According to the tests performed, it was observed the generation of a three-phase sinusoidal wave voltage of 242 VRMS, and the yield of 40.8%.

Insulation puncture on winding is a frequent failure of electrical motors. This consists of current shunt to ground which produces damage to the magnetic package and winding in a faulty zone, thus breaking the machine. Therefore, it was decided to conduct research in order to understand the phenomenon and propose improvements to avoid such failure. First, we looked for a relationship between the voltage surges the machine suffers and the failure. Then, we performed tests with different types of insulation, different construction conditions and state of the windings, in order to assess the value of the insulation resistance before and after the test. It was concluded that voltage surge was not the cause of the insulation puncture. As a future step, we propose to look for possible relationships with other variables which may attack the integrity of the insulation of electric motors. Keywords—Insulation puncture; electrical motors; voltage surges

This paper presents a design concept of an overcurrent protection for Li-Ion battery pack used in electric bicycles.  This overcurrent protection scheme is implemented as a part of the battery management system (BMS).  In addition to the conventional protection of the Li-Ion battery pack, the proposed concept extends the protection to cover also semiconductor devices in the motor converter from short-circuit fault and overloading. The protection scheme was developed based on i2t current-time protection characteristics in order to obtain interrupting characteristics in a similar way to conventional protection devices like circuit breaker or fuse.  The developed protection concept was implemented by adapting the software algorithm of a high-grade battery management system platform without any hardware adaptation.  The existing discharging MOSFETs are employed as the electronic circuit breaker mechanism for cutting-off the circuit.  The functionality of the proposed concept was success...

The manufacture of low voltage high current power supply using the MOT (Microwave Oven transformer) has been done. The purpose of this work is to convert low voltages into high currents by utilizing simple electrical equipment. This work use of varying voltages and different windings which are changed on the secondary winding section with a cable size of 240 mm 2, NYA cable type. The test is carried out with a series circuit, parallel circuit, and single circuit by utilizing a voltage of 30 V, 60 V, 90 V, 120 V and 5 different variations of winding. The results of this test provide knowledge of new methods that can be applied to iron smelting.

Unprecedented expansion of native direct current (DC) powered equipment (computers and consumer electronics) has increased household DC electricity consumption over the past decade. Since power utilities deliver alternating current (AC) rather than DC, the conversion process (rectifier) used to supply DC loads is very inefficient. The research investigates the suitability of employing conventional AC wiring to distribute DC power to supply loads directly, in particular around outlet/switch arcing issues. The problem of arcing in DC system is very predominant and needs to be addressed to meet safety requirements while improving the efficiency of the system. In order to overcome the arcing issues, an alternative flat DC wiring system is proposed which offers improved transient electrical and thermal characteristics for household wiring. The flat wire solution employs the same raw materials and provides improvements in parasitic values associated with arcing while reducing thermal resi...

Some new schemes using active circuits are proposed for realization of sinusoidal flux in a ferromagnetic core during loss testing. One of the suggested configurations facilitates the loss measurements to be made from the primary side itself. A few filter circuits enable the tests to be carried out on normal supply mains without the need for a calibration generator. Experimental results are reported to confirm the acceptability of the proposed schemes.

The mechanism of how and when an arcing short or a physical short occurs on a polyvinyl chloride (PVC)insulated cable when exposed to radiant heat flux has been found experimentally. How this mechanism acts on the size of the resulting arc beads is also considered. As a physical short usually changes into an arcing short in an instant, it is difficult to determine which type of short circuit occurs as the first phenomenon. To solve this difficulty, a short circuit current was limited to the order of an ampere, which is large enough to trigger an arcing short, and short circuit tests were conducted with a PVC-insulated cable. Before an arcing short, a small amount of leakage current in the order of milliamperes was observed flowing through PVC insulation, which gradually increased and finally turned into an arc. On the other hand, no leakage current was observed before a physical short. These results indicate the following mechanism: When PVC insulation between conductors in a cable melts when a heat flux is applied, conductors often come close to and into contact with each other. In this case, the leakage current is unrecognizably small because the PVC insulation is not yet carbonized and still has a high resistivity. Meanwhile, when conductors do not come into contact with each other, PVC insulation is gradually carbonized and the leakage current increases until an arcing-through-char occurs.

During the manufacture of cast coil transformers voids are occluded in the epoxy if the vacuum impregnation process is not carefully controlled. These voids may become the sites of partial discharges which will cause the transformer to fail. Partial discharge sites in cast coil transformers are often difficult to locate. One approach to locating partial discharges in these transformers is to use information contained in the electromagnetic signals generated by the partial discharges. Transformers are compact units often containing thousands of feet of wire and internally their structure is very complex and irregular. Partial discharge signals observed at the terminals of transformers are extremely distorted because the windings are not arranged in a manner which provides a good propagation path to the measurement point. A new method for determining the axial location of partial discharges in cast coils will be presented. A signal processing algorithm is used to determine the normalized energy as a function of position along the coil. The normalized energy is interpreted in terms of the attenuation of the electromagnetic emissions from the partial discharges along the axis of the transformer. A plot of the attenuation as a function of distance along the length of coil clearly indicates the location of the partial discharges.

This study proposed a novel travelling wave induction heating system with five-phase exciting current. The proposed system used special exciting current to obtain a homogeneous eddy current density, which affects the temperature pattern over the material surface. Fivephase system has been attracted from many industrial applications due to its inherent features compared to the three-phase system. An even number of phases is not preferred because the poles exchange with each other. A comparison investigation with other traditional methods is represented to realise the features of the proposed method. A finite-element method simulation is represented by using ANSYS 15 ® ; the simulation results show that the proposed system gives superior performance of energy transferred, uniform heat distribution and higher power factor over that of the traditional three-phase system. Moreover, it performs identical eddy current, power densities, temperature and efficiency to that of the six-phase system with profits of reduction in size, weight, cost and winding copper losses.

Some new schemes using active circuits are proposed for realization of sinusoidal flux in a ferromagnetic core during loss testing. One of the suggested configurations facilitates the loss measurements to be made from the primary side itself. A few filter circuits enable the tests to be carried out on normal supply mains without the need for a calibration generator. Experimental results are reported to confirm the acceptability of the proposed schemes.

A circuit employing a voltage follower is given for obtaining a sinusoidal flux in a ferromagnetic core. The amplifier just supplies the copper loss of the exciting winding. [4] G. W. Swift, "Realization of sinusoidal flux in a transformer iron sample,"

In this study, high-current-protecting multilayered thin film microfuses are designed and simulated using the MEMS-based tool of COMSOL multiphysics software and then fabricated and tested in the laboratory. Portable electronic devices are comprised of a secondary battery or DC charge source, and due to short circuit overcurrent, fire, and explosions can ensue. A protecting device should steadily cater to phenomena like overcurrent situations to avoid hazardous circumstances. The primary purpose of this investigation is to design a heater resistor with a negative temperature coefficient (NTC) to function as a low melting point-based alloy for the fuse element. A lead-tin (90Pb:10Sn wt.%) alloy has been employed as the low melting point-based fuse element, and tungsten oxide (WO3) is integrated with the layer as a heater resistor due to its negative temperature coefficient of resistance characteristics. The electro-thermo-mechanical behavior is assessed, and a three-dimensional struc...

A time domain model will be described for predicting transient bus currents, electromagnetic fields, and cable coupling effects caused by switching actions in high voltage substations. Having been validated against measured transient data, the model provides a basis for predicting EM1 effects resulting from abnormal switching actions, such as phase to ground faults, which are difficult to stage for measurement. From such worst case estimates, the adequacy of neu-generation, microprocessor-controlled substation protection standards can be assessed.

The aim of this work was the development (design, construction and tests) of a Three-phase Synchronous Machine with permanent magnets and four poles to be used in small wind turbines, where the rotor and stator cores, usually constructed from laminated steel sheets, were replaced for massive blocks obtained from the Powder Metallurgy (PM) process. The other parts of the machine, such as housing, shaft, bearings and covers, were obtained from conventional three-phase induction motor of 10 HP. Initially, it was studied sintered alloys from pure iron, Fe-Si, Fe-P and Fe-Ni; eventually these alloys were analyzed in terms of magnetic and mechanical properties as well as electrical resistivity. From this study, it was chosen the use of sintered pure iron for the construction of the rotor and Fe1%P for the construction of the stator. The permanent magnets used were Nd-Fe-B, and the windings calculation was based on the coiling of the three-phase induction motor. According to the tests performed, it was observed the generation of a three-phase sinusoidal wave voltage of 242 VRMS, and the yield of 40.8%.

Int. C. H02M 5/10 (2006.01) H02, 3/36 (2006.01) H02M 5/42 (2006.01) HOIF 3O/04 (2006.01) HO2H 9/OO (2006.01) U.S. C. CPC ................. H02M 5/10 (2013.01); H02J 3/36 (2013.01); H02M 5/42 (2013.01); HOIF 30/04 (2013.01); H02H 9/002 (2013.01); Y02E 60/60 (2013.01) Field of Classification Search CPC ...... H02M 7/268; H02M 7/7575: H02M 5/10; H02M 5/447; H02M 5/42; H02M 5/45; H02M 5/458; H02M 5/4585; H02M

An evaluation of insulation and switching media in medium voltage (1-52 kV) applications is presented in this paper. Special attention is given to motor switching and to distribution of electricity. The various insulating and/or switching media like oil, epoxy resin, air, SF6 and vacuum are discussed. The various arcing media in medium voltage grids have evolved to a mature situation nowadays, and the pro's and con's of the various media in different applications are presented. Key words are associated to the prevention of the various over voltages that might occur in industrial networks and their relation to the switching media. The basic phenomena, such as current chopping and restrikes are reviewed and the harm that overvoltages can cause either by amplitude or rising time to the equipment. Besides the overvoltage aspects, the operation & maintenance aspects related to different insulating and switching media are surveyed and discussed.

DC leakage current measurements on miniature cables are presented. Two approaches are proposed to deduce the DC electrical conductivity of the tested insulation material from these measurements: one approach based on an assumed electric field value in the insulation, and a coupled LMA-FEM approach which does not require this assumption. It is shown that using a-priori electric field values leads to significant mistakes on the identified DC conductivities, which can lead to underestimated DC conductivities.