1- Superconducting Power Generation Mario Rabinowitz Armor Research
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Transient Analysis of Three-Phase Wound Rotor (Slip-Ring) Induction Motor Under Operating Condition
International Journal of Recent Engineering Research and Development (IJRERD) ISSN: 2455-8761 www.ijrerd.com || Volume 02 – Issue 07 || July 2017 || PP. 19-32 Transient Analysis of Three-Phase Wound Rotor (Slip-Ring) Induction Motor under Operating Condition Obute K.C.1, Enemuoh F.O.1 1 – Department of Electrical Engineering Nnamdi Azikiwe University Awka, Anambra State Nigeria Corresponding Author - Obute Kingsley Chibueze Department of Electrical Engineering Nnamdi Azikiwe University Awka, Anambra State Nigeria Abstract: This work investigates the transient behaviours of a three phase wound rotor type induction motor, running on load. When starting a motor under load condition becomes paramount, obviously a wound rotor (slip ring) induction becomes the best choice of A.C. motor. This is because maximum torque at starting can be achieved by adding external resistance to the rotor circuit through slip-rings. Normally a face-plate type starter is used, and as the resistance is gradually reduced, the motor characteristics at each stage changes from the other (John Bird 2010). Hence, the three phase wound rotor (slip ring) induction motor competes favourably with the squirrel cage induction motor counterpart as the most widely used three-phase induction motor for industrial applications. The world-wide popularity and availability of this motor type has attracted a deep – look and in-depth research including its transient behavior under plugging (operating) condition. This paper unveils, through mathematical modeling, followed by dynamic simulation, the transient performance of this peculiar machine, analyzed based on Park’s transformation technique. That is with direct-quadrature-zero (d-q-o) axis based modeling in stationary reference frame. -
Electrical Machines
1 Electrical Machines 1. The left hand rule is applicable to (a) generator ( b) motor (c) transformer ( d) ( a) and ( b) both (e) ( a) or ( b) 2. The eddy current losses in the transformer will be reduced if (a) the laminations are thick (b) number of turns in the primary winding is reduced (c) the number of turns in the secondary winding is reduced (d) the laminations are thin 3. The speed of d.c. series motor at no load is (a) zero ( b) 1500 r.p.m. (c) infinity ( d) 3000 r.p.m. (e) none of the above 4. A sinusoidal voltage of frequency 1 Hz is applied to the field of d.c. generator. The armature voltage will be (a) 1 Hz square wave ( b) 1 Hz sinusoidal voltage (c) d.c. voltage ( d) none of the above 5. The function of the commutator in a d.c. machine is (a) to change alternating current to a direct current (b) to improve commutation (c) for easy control (d) to change alternating voltage to direct voltage 6. The phase sequence of voltage generated in the alternator can be reversed by reversing its field current. (a) true ( b) false 7. The rotation of three phase induction motor can be reversed by interchanging any two of the supply phases. (a) true ( b) false 2 ELECTRICAL ENGINEERING 8. The starting torque of the three phase induction motor can be increased by (a) increasing the rotor reactance (b) increasing the rotor resistance (c) increasing the stator resistance (d) none of the above 9. -
Applications of High Temperature Superconductors
FEATURES Applications of high temperature superconductors T.M. Silver, s.x. Dou and J.x. fin Institute for Superconducting and Electronic Materials, University ofWollongong, Wollongong, NSW2522, Australia ost ofus are familiar with the basic idea ofsuperconductivi magnetic separators, these losses may account for most of the M ty, thata superconductor can carrya currentindefinitely in a energy consumed in the device. Early prototypes for motors, closed loop, without resistance and with no voltage appearing. In transmission lines and energy storage magnets were developed, a normal metal, such as copper, the free electrons act indepen but they were never widely accepted. There were important rea dently. They will move under the influence of a voltage to form a sons for this, apart from the tremendous investment in existing current, but are scattered off defects and impurities in the metal. technology. In most superconducting metals andalloys the super This scattering results in energy losses and constitutes resistance. conductivity tends to fail in self-generated magnetic fields when In a superconducting metal, such as niobium, resistance does not the current densities through them are increased to practicallev occur, because under the right conditions the electrons no longer els. A second problem was the cost and complexity of operating act as individuals, but merge into a collective entity that is too refrigeration equipment near liquid helium temperatures large to 'see' any imperfections. This collective entity, often (4 K, -269°C). Removing one watt of heat generated at 4 K described as a Bose condensate, can be described by a single demands about 1000 W ofrefrigeration power at room tempera macroscopic quantum mechanical wave function. -
NNNNN May 19, 1970 A
May 19, 1970 A. D. APPLETON 3,513,340 HOMOPOLAR ELLCTRIC MACHINES Filed Jan. 6, 1967 2 Sheets-Sheet l -uo Lo NNNNN May 19, 1970 A. D. APPLETON HOMOPOLAR ELECTRIC MACHINES 3,513,340 Filed Jan. 6, 1967 2 Sheets-Sheet 2 222a1a1a2.1274.1444/4/14/a/ 244. A. ZZ 3,513,340 United States Patent Office Patented May 19, 1970 2 3,513,340 FIG. 1 shows diagrammatically a homopolar electrical HOMOPOLAR ELECTRIC MACHINES machine in accordance with the invention for use as a low Anthony Derek Appleton, Newcastle upon Tyne, Eng speed motor, land, assignor to International Research & Develop FIG. 2 is a longitudinal section of a typical machine of Company Limited, Newcastle upon Tyne, Eng the general form illustrated in FIG. 1, and FIG. 3 is a Filed Jan. 6, 1967, Ser. No. 607,784 detail of FIG. 2 on an enlarged scale. Claims priority, application Great Britain, Jan. 12, 1966, The homopolar machine shown in FIG. 1 comprises 1,530/66 two rotors 1 and 2. Int. Cl. H02k 31/00, 47/14 Each rotor is in the from of a disc of electrically con U.S. C. 310-13 10 Claims ducting material Such as copper. The copper discs may O each be mounted on a supporting disc of non-electrically conducting material. ABSTRACT OF THE DISCLOSURE Each rotor rotates within a magnetic field common to A homopolar machine is disclosed having two rotors both rotors and provided by a single superconducting coil in a common magnetic field, preferably provided by a 3, which surrounds the rotors. -
Hitachi's Leading Superconducting Technologies
Hitachi’s Leading Superconducting Technologies 290 Hitachi’s Leading Superconducting Technologies Shohei Suzuki OVERVIEW: Over 30 years have passed since Hitachi began researching Ryoichi Shiobara superconductors and superconducting magnets. Its scope of activities now encompasses everything from magnetically levitated vehicles and nuclear Kazutoshi Higashiyama fusion equipment to AC generators. Three big projects that use Hitachi Fumio Suzuki superconductors are currently underway in Japan: the Yamanashi Maglev Test Line, the Large Helical Device (LHD) for nuclear fusion and the 70- MW model of superconducting power generator. Hitachi has played a vital role in these projects with its materials and application technologies. In the field of high-temperature superconducting materials, Hitachi has made a lot of progress and has set a new world record for magnetic fields. INTRODUCTION is cryogenic stability because of the extremely low HITACHI started developing superconducting temperatures, but we have almost solved this problem technology in the late 1950’s. At first, it focused on by developing fine multiple-filament superconductors superconducting magnets for magneto-hydro- and various materials for stabilization matrixes, both dynamics (MHD) power generators, but eventually of which operate at liquid helium temperature (4 K), broadened its research to applications such as as well as superconductor integration technology and magnetically levitated vehicles, nuclear fusion precise winding technology. These new developments equipment, and high energy physics. Recently have led to a number of large projects in Japan. They Hitachi’s activities have spread to the medical field are (1) the world’s largest (70 MW) model super- (magnetic-resonance-imaging technology) and other conducting generator for generating electric power, (2) fields (AC power generators and superconducting the Yamanashi Maglev Test Line train, which may magnetic energy storage). -
Design of a Superconducting DC Wind Generator
Design of a superconducting DC wind generator zur Erlangung des akademischen Grades eines DOKTOR-INGENIEURS von der Fakultät für Elektrotechnik und Informationstechnik des Karlsruher Instituts für Technologie (KIT) genehmigte DISSERTATION von M. Eng. Yingzhen Liu geb. in: Hebei, China Tag der mündlichen Prüfung: 26. 01. 2018 Hauptreferent: Prof. Dr.-Ing. Mathias Noe Korreferent: Prof. Dr.-Ing. Martin Doppelbauer Acknowledgement This thesis was written at the Institute for Technical Physics at Karlruhe Institute of Technology and it cannot be finished without the help of my colleugues. I would like to thank my supervisor Prof. Dr.-Ing Mathias Noe, who provides me with the opportunity to pursue my PhD in Karlsruhe Institute of Technology. His continuous support, advice and insight have helped me to reach a higher research level. I highly appreciated the constructive feedback and helpful guaidance given by Prof. Noe at a regular meeting evey two to three weeks during my whole PhD period. In order to ensure the scientific quality of my work, Prof. Noe also encourages me to participate in interna- tional conferences, workshops and seminars, which benefit me a lot. My special gratitude goes to my second referee Prof. Dr.-Ing Martin Doppelbauer for his useful lessons, advice and discussions on electric machines, and the excellent and professional environment he offered to study the iron material properties. Specially, I would like to thank Prof. Doppelbauer for his scientific input and linguistic improve- ments, that helped a great deal to finish the final version of this thesis. I would like to thank my external referee Prof. Jean Lévêque for his scientific and practical comments which help me a lot to improve my thesis. -
Protection of Superconducting Magnet Circuits
Protection of superconducting magnet circuits M. Marchevsky, Lawrence Berkeley National Laboratory M. Marchevsky – USPAS 2017 Outline 1. From superconductor basics to superconducting accelerator magnets 2. Causes and mechanisms of quenching 3. Quench memory and training 4. Detection and localization of quenches 5. Passive quench protection: how to dump magnet energy 6. Active protection: quench heaters and new methods of protection (CLIQ) 7. Protection of a string of magnets. Hardware examples. 8. References and literature M. Marchevsky – USPAS 2017 Discovery of superconductivity H. K. Onnes, Commun. Phys. Lab.12, 120, (1911) M. Marchevsky – USPAS 2017 A first superconducting magnet Lead wire wound coil Using sections of wire soldered together to form a total length of 1.75 meters, a coil consisting of some 300 windings, each with a cross-section of 1/70 mm2, and insulated from one another with silk, was wound around a glass core. Whereas in a straight tin wire the threshold current was 8 A, in the case of the coil, it was just 1 A. Unfortunately, the disastrous effect of a magnetic field on superconductivity was rapidly revealed. Superconductivity disappeared when field Leiden, 1912 reached 60 mT. H. Kamerlingh Onnes, KNAWProceedings 16 II, (1914), 987. Comm. 139f. Reason: Pb is a “type-I superconductor”, where magnetic destroys superconductivity at once at Bc=803 G. Note: this magnet has reached 74% of its “operational margin” ! M. Marchevsky – USPAS 2017 First type-II superconductor magnet 0.7 T field George Yntema, Univ. of Illinois, 1954 • The first successful type-II superconductor magnet was wound with Nb wire It was also noted that “cold worked” Nb wire yielded better results than the annealed one… But why some superconductors work for magnets and some do not? And what it has to do with the conductor fabrication technique? M. -
Superconducting Magnets for Fusion
Magnets and magnetic materials Superconducting magnets for fusion The ITER's mission is to prove that magnetic confinement fusion will be a candidate source of energy by the second half of the twenty-first century. The tokamak, which is scheduled to begin operations in 2016 at the Cadarache site in the Bouches-du-Rhône, represents a key step in the development of a current-generating fusion reactor. ITER Considerable expertise acquired through its partnership with Euratom on the Tore Supra project has led the CEA to play a central role in the Overview of the magnetic design and development of the three field system equipping the ITER reactor. giant superconducting systems that will generate the intense magnetic fields vital to plasma confinement and stabilisation. he magnetic confinement fusion of thermo- magnetic field system comprises three giant super- Tnuclear plasmas requires intense magnetic fields. conducting systems: the toroidal magnetic field sys- The production of these magnetic fields in the large tem (TF), the poloidal magnetic field system (PF), and vacuum chamber (837 m3) of the ITER International the central solenoid (CS); Focus B, Superconductivity Thermonuclear Experimental Reactor, currently being and superconductors, p. 16. It could be said to repre- built at the Cadarache site in the Bouches-du-Rhône sent the backbone of the tokamak (Figure 1). is in itself a major technological challenge. The ITER's Superconductivity for fusion applications Up to the early 1980s, all magnetic confinement machines relied on resistive magnets, which were CS system generally built using silver-doped copper in order to TF system improve their mechanical properties. -
Superconducting Magnets for Accelerators Lecture
Superconductivity for accelerators - why bother? Abolish Ohm's Law • no power consumption (although do need refrigeration power) • high current density compact windings, high gradients • ampere turns are cheap, so don’t need iron (although often use it for shielding) Consequences • lower power bills • higher magnetic fields mean reduced bend radius smaller rings reduced capital cost new technical possibilities (eg muon collider) • higher quadrupole gradients higher luminosity Martin Wilson Lecture 1 slide 1 JUAS February 2013 Plan of the Lectures 1 Introduction to Superconductors 4 Quenching and Cryogenics • critical field, temperature & current • the quench process • superconductors for magnets • resistance growth, current decay, temperature rise • manufacture of superconducting wires • quench protection schemes • high temperature superconductors HTS • cryogenic fluids, refrigeration, cryostat design 2 Magnetization, Cables & AC losses 5 Practical Matters • superconductors in changing fields • filamentary superconductors and magnetization • LHC quench protection • coupling between filaments magnetization • current leads • why cables, coupling in cables • accelerator magnet manufacture • AC losses in changing fields • some superconducting accelerators 3 Magnets, ‘Training’ & Fine Filaments Tutorial 1: Fine Filaments • coil shapes for solenoids, dipoles & quadrupoles • how filament size affects magnetization • engineering current density & load lines Tutorial 2: Quenching • degradation & training minimum quench energy • current decay -
Mechanical Design and Construction of Superconducting E-Lens Solenoid Magnet System for RHIC Head-On Beam-Beam Compensation
1PoCB-08 1 Mechanical Design and Construction of Superconducting e-Lens Solenoid Magnet System for RHIC Head-on Beam-Beam Compensation M. Anerella, W. Fischer, R. Gupta, A. Jain, P. Joshi, P. Kovach, A. Marone, A. Pikin, S. Plate, J. Tuozzolo, P. Wanderer Abstract —Each 2.6-meter long superconducting e-Lens magnet assembly consists of a main solenoid coil and corrector coils mounted concentric to the axis of the solenoid. Fringe field and “anti-fringe field” solenoid coils are also mounted coaxially at each end of the main solenoid. Due to the high magnetic field of 6T large interactive forces are generated in the assembly between and within the various magnetic elements. The central field uniformity requirement of ± 0.50% and the strict field straightness requirement of ± 50 microns over 2.1 meters of length provide additional challenges. The coil construction details to meet the design requirements are presented and discussed. The e-Lens coil assemblies are installed in a pressure vessel cooled to 4.5K in a liquid helium bath. The design of the magnet adequately cools the superconducting coils and the power leads using the available cryogens supplied in the RHIC tunnel. The mechanical design of the magnet structure including thermal considerations is also presented. Index Terms —Accelerator, electron lens, solenoids, superconducting magnets. Fig. 1. Longitudinal section view of e-Lens solenoid II. MAIN SOLENOID DESIGN I. INTRODUCTION The main solenoid design is comprised of eleven “double To increase the polarized proton luminosity in RHIC, a layers” of rectangular monolithic conductor, 1.78 mm wide superconducting electron lens (e-Lens) magnet system is being and 1.14 mm tall, with a 3:1 copper to superconductor ratio. -
Superconductors: the Next Generation of Permanent Magnets
1 Superconductors: The Next Generation of Permanent Magnets T. A. Coombs, Z. Hong, Y. Yan, C. D. Rawlings fault current limiters, bearings and motors. Both fault current Abstract—Magnets made from bulk YBCO are as small and as limiters and bearings are enabling technologies and a great compact as the rare earth magnets but potentially have magnetic deal of successful research has been devoted to these areas[4- flux densities orders of magnitude greater than those of the rare 8]. With motors, though, we are seeking to supplant an earths. In this paper a simple technique is proposed for existing and mature technology. Therefore the advantages of magnetising the superconductors. This technique involves repeatedly applying a small magnetic field which gets trapped in superconductors have to be clearly defined before the superconductor and thus builds up and up. Thus a very small superconducting motors can become widely accepted. magnetic field such as one available from a rare earth magnet The principle advantages of a superconducting motor or can be used to create a very large magnetic field. This technique generator are size, weight and efficiency. Which of these is which is applied using no moving parts is implemented by the most important depends on the application. In a wind generating a travelling magnetic wave which moves across the turbine for example power to weight ratio is paramount. Any superconductor. As it travels across the superconductor it trails flux lines behind it which get caught inside the superconductor. weight in the nacelle has to be supported and considerable With each successive wave more flux lines get caught and the savings can be made if the machine is lighter especially if it field builds up and up. -
Design Considerations of the Superconducting Magnet
1 Electromagnetic, stress and thermal analysis of the Superconducting Magnet 1 1 , 2 Yong Ren *, Xiang Gao * 1 Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, PO Box 1126, Hefei, Anhui, 230031, People's Republic of China 2University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China *E-mail: [email protected] and [email protected] Abstract—Within the framework of the National Special but also to implement a background field superconducting Project for Magnetic Confined Nuclear Fusion Energy of China, magnet for testing the CFETR CS insert and TF insert coils. the design of a superconducting magnet project as a test facility During the first stage, the main goals of the project are of the Nb3Sn coil or NbTi coil for the Chinese Fusion Engineering composed of: 1) to obtain the maximum magnetic field of Test Reactor (CFETR) has been carried out not only to estimate the relevant conductor performance but also to implement a above 12.5 T; 2) to simulate the relevant thermal-hydraulic background magnetic field for CFETR CS insert and toroidal characteristics of the CFETR CS coil; 3) to test the sensitivity field (TF) insert coils. The superconducting magnet is composed of the current sharing temperature to electromagnetic and of two parts: the inner part with Nb3Sn cable-in-conduit thermal cyclic operation. During the second stage, the conductor (CICC) and the outer part with NbTi CICC. Both superconducting magnet was used to test the CFETR CS insert parts are connected in series and powered by a single DC power and TF insert coils as a background magnetic field supply.