DOCSLIB.ORG

Alternating Current Loss Measurement of Power Cable

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Alternating Current Loss Measurement of Power Cable ALTERNATINGCURRENTLOSSMEASUREMENTOFPOWER CABLECONDUCTORSWITHLARGECROSSSECTIONSUSING ELECTRICALMETHODS vorgelegt von Master of Science René Suchantke geboren in Berlin von der Fakultät IV - Elektrotechnik und Informatik der Technischen Universität Berlin zur Erlangung des akademischen Grades Doktor der Ingenieurwissenschaften - Dr.-Ing. - genehmigte Dissertation Promotionsausschuss: Vorsitzender: Prof. Dr.-Ing. Kai Strunz Gutachter: Prof. Dr.-Ing. Ronald Plath Gutachter: Prof. Dr.-Ing. Steffen Großmann Gutachter: Prof. Dr.-Ing. Rolf Schuhmann Tag der wissenschaftlichen Aussprache: 13. Juli 2018 Berlin 2018 René Suchantke: Alternating Current Loss Measurement of Power Cable Conduc- tors with Large Cross Sections Using Electrical Methods © July 2018 Dedicated to my beloved wife and biggest critic Isabell. You, the people, have the power, the power to create machines, the power to create happiness! You, the people, have the power to make this life free and beautiful, to make this life a wonderful adventure. [...] Let us fight for a world of reason, a world where science and progress will lead to all men’s happiness. Charlie Chaplin ABSTRACT High voltage power cables for bulk AC power transport use the Milliken conductor design from a certain cross section up to decrease transmission losses. It is not possible to reliably assess their AC losses by simulation or other calculation methods in advance, as the performance of this complex design strongly depends on manufacturing processes and quality. The exact knowledge of the AC resistance is important, because it is a critical design parameter for the thermal dimensioning of the cable and whole cable systems. Therefore, it is necessary to accurately determine the AC losses by measurement using the electrical or the calorimetric method. This work focuses on the electrical method solely, as it can be performed much faster with less logistical effort. The goal is to have a measurement setup, where the measured losses are as close as possible to the true losses. The true losses result in conductor heating, which limits the transmission power. They are also called Joule losses. Theoretical calculations, FEM simulations in Comsol Multiphysics and mea- surements have been used in combination to evaluate different, possible influences in AC resistance measurements. After the problem definition and the presentation of the methodology, past advances and concepts focusing on AC resistance determination were shown. Then, after the basics were made clear to the reader, the measurement circuit was defined and different error sources in measurement setups were evaluated. These included the influence of the sheath and return conductor position upon true and measured losses, the influence of current homogenization and placement of voltage tap-offs. A recommendation for the preparation, setup and measurement procedure was given. At the end, multiple Milliken conductors were measured using the proposed method and compared to the IEC standard. It was shown that the electrical measurement method is able to measure the true AC losses of complex conductors consisting of insulated wires. One important requirement is that the voltage pick-up loop is large enough to capture enough complex magnetic field originating from the conductor under test. On the other side, complex magnetic fields caused by eddy currents in adjacent conductors should not be captured by the pick-up loop as they also affect the measured losses. Using 2 equally spaced return conductors in the same plane as the conductor under test and the average of at least 4 evenly distributed voltage pick-up loops located at the surface of the insulation of the cable, will deliver results of sufficient accuracy. The findings of this thesis indicate that great care must be taken for multiple aspects in the AC resistance measurement of complex conductors. Engineers performing AC resistance measurements have to be aware of error sources, specifically the interplay between conductor positions and apparent losses. The electrical measurement method needs to be thoroughly prepared, espe- cially regarding the contacting of current path and voltage tap-offs. Never- theless, the effort concerning time and logistics is still significantly smaller compared to a calorimetric measurement. ZUSAMMENFASSUNG Hochspannungskabel für die Übertragung großer Mengen elektrischer Energie verwenden ab einem bestimmten Querschnitt die Millikenleiter- Bauweise zur Senkung der Wechselstromverluste. Es ist nicht möglich, die Verluste dieser komplexen Leiter verlässlich vorab zu berechnen, da die Performance dieses Leiterdesigns unter anderem stark von Einflüssen der Fertigung abhängt. Eine genaue Kenntnis der Wechselstromverluste ist allerdings zwingend notwendig, da diese zur thermischen Dimensionie- rung des Kabels und ganzer Kabelsysteme genutzt werden. Es ist daher erforderlich, die Verluste durch Messungen zu bestimmen. Zur Auswahl stehen die elektrische und die kalorimetrische Messmethode, wobei sich diese Arbeit exklusiv auf erstere fokussiert. Diese ermöglicht eine schnellere Messung der Verluste mit geringerem logistischen Aufwand. Das Ziel jeder Messung sollte sein, dass die Diskrepanz zwischen gemessenen und den echten Wechselstromverlusten des Innenleiters so gering wie möglich ist. Die echten Verluste sind unbekannt und tragen in Betrieb maßgeblich zur Erwärmung des Innenleiters bei, was gleichzeitig die Übertragungsverluste des Kabels senkt. Um verschiedene mögliche Einflüsse in Wechselstromwiderstandsmessun- gen zu evaluieren, wurden Theorie, FEM Simulationen in Comsol Multiphysics und Messungen in Kombination eingesetzt. Nach der Definition des Pro- blems und des Ziels wurde die Methodik vorgestellt. Anschließend wurden relevante Konzepte zur Ermittlung von Wechselstromverlusten aufgezeigt. Darauf folgt die Definition des Messaufbaus und das Herausstellen rele- vanter Einflüsse auf die Messungen. Als am relevantesten stellten sich der Einfluss von Kabelschirm und Rückleiter auf die gemessenen und echten Verluste des Kabels heraus. Hinzu kommt ein signifikanter Einfluss der Stromhomogenisierung und der Positionierung der Spannungsabgriffe auf dem Leiter. Danach wurde eine Empfehlung für die Vorbereitung, den Aufbau und die Durchführung der Messung gegeben. Am Ende wurden verschiedene Millikenleiter-Designs mit den vorgeschlagenen Methoden vermessen und mit der aktuellen IEC Norm verglichen. Die Untersuchungen haben gezeigt, dass die elektrische Methode unter gewissen Voraussetzungen dazu im Stande ist, die echten Wechselstrom- verluste von komplexen Leitern mit isolierten Einzeldrähten zu messen. Eine Anforderung ist beispielsweise, dass die Spannungsmessschleife groß genug ist, um komplexe Magnetfelder, die vom zu untersuchenden Leiter erzeugt werden, einzufangen. Allerdings darf die Messschleife nicht so groß sein, dass andere komplexe Magnetfelder, erzeugt von Wirbelströmen in umgebenden Leitern, in die Messschleife einkoppeln. Diese können die gemessenen Verluste sonst direkt beeinflussen. Der empfohlene Aufbau zur Messung der Wechselstromverluste von Millikenleitern verwendet 2 äquidi- stant platzierte Rückleiter, die in einer Ebene mit dem zu untersuchenden Leiter liegen. Die Messung der Spannung erfolgt aus dem Mittelwert von mindestens 4, gleichmäßig um die Oberfläche der Isolation des Kabels verteilten, Spannungsmessschleifen. Die Analyse des Problems hat gezeigt, dass die Wechselstromverlustmes- sung von komplexen Leitern genauer Kenntnisse über mögliche Störeinflüs- se bedarf. Die Auswirkung der Positionierung der Leiter auf die gemessenen Verluste sollten vom Anwender verstanden sein und in der Versuchsvor- bereitung und Ausführung weitestgehend eliminiert werden. Auch für die elektrische Methode müssen daher einige Maßnahmen und Vorbereitungen — insbesondere hinsichtlich der Kontaktierung der Spannungsabgriffe und Strompfadkontaktierung — zur akkuraten Messung getroffen werden. Im Vergleich zur kalorimetrischen Methode sind diese vorbereitenden Maßnah- men allerdings wesentlich weniger zeitintensiv. PUBLICATIONS It takes many good deeds to build a good reputation, and only one bad one to lose it. Benjamin Franklin In the following, publications related to the topic of this thesis are listed, where the author took direct part during his research activity at Technische Universität Berlin: [CIG18] CIGRE, ed. Basic principles and practical methods to measure the AC and DC resistance of conductors of power cables and overhead lines. D1.54. CIGRE, 2018. [Sch+14] Gero Schröder, René Suchantke, Hendrik Just, Rolf Schuhmann, and Ronald Plath. “Maßnahmen zur Reduzierung des Skin- Effekts bei Energiekabeln durch optimierte Leiterkonstruktio- nen und deren messtechnische Bewertung.” In: Diagnostik elek- trischer Betriebsmittel 2014. ETG-Fachbericht. Berlin u.a.: VDE- Verl., 2014. isbn: 978-3-8007-3648-5. [Sch+15] Gero Schröder, Volker Waschk, Ronald Plath, Rolf Schuhmann, and René Suchantke. “Measures to reduce skin-effect losses in power cables with optimized conductor design and their evalu- ation by measurement.” In: Jicable 2015 - 9th International Confer- ence on Insulated Power Cables. Paris, France, 2015. [SPS16] René Suchantke, Ronald Plath, and Rolf Schuhmann. “Beson- derheiten bei der Messung von Wechselstromwiderständen von kurzen Leitern und kurzen Kabelstücken mit großen Quer- schnitten: Difficulties with AC resistance measurements of short conductor- and cable samples with large cross-sections.” In: VDE-Hochspannungstechnik 2016. ETG-Fachbericht. Berlin: VDE- Verlag,
Load more

Recommended publications
  • A Novel Solid State Ultracapacitor
    National Aeronautics and NASA/TM—2017–219686 Space Administration IS02 George C. Marshall Space Flight Center Huntsville, Alabama 35812 A Novel Solid State Ultracapacitor A.Y. Cortés-Peña Johnson Space Center, Houston, Texas T.D. Rolin and S.M. Strickland Marshall Space Flight Center, Huntsville, Alabama C.W. Hill CK Technologies, Meridianville, Alabama August 2017 The NASA STI Program…in Profile Since its founding, NASA has been dedicated to the • CONFERENCE PUBLICATION. Collected advancement of aeronautics and space science. The papers from scientific and technical conferences, NASA Scientific and Technical Information (STI) symposia, seminars, or other meetings sponsored Program Office plays a key part in helping NASA or cosponsored by NASA. maintain this important role. • SPECIAL PUBLICATION. Scientific, technical, The NASA STI Program Office is operated by or historical information from NASA programs, Langley Research Center, the lead center for projects, and mission, often concerned with NASA’s scientific and technical information. The subjects having substantial public interest. NASA STI Program Office provides access to the NASA STI Database, the largest collection of • TECHNICAL TRANSLATION. aeronautical and space science STI in the world. English-language translations of foreign The Program Office is also NASA’s institutional scientific and technical material pertinent to mechanism for disseminating the results of its NASA’s mission. research and development activities. These results are published by NASA in the NASA STI Report Specialized services that complement the STI Series, which includes the following report types: Program Office’s diverse offerings include creating custom thesauri, building customized databases, • TECHNICAL PUBLICATION. Reports of organizing and publishing research results…even completed research or a major significant providing videos.
    [Show full text]
  • TION GALVANOMETERS in the Vibration Galvanorneter
    A paper to be presented at the 29th Annual Con* vention of the American Institute of Electrical Engineers, Boston, Mass., June 25, 1912. Copyright, 1912. By Α. I. Ε. E. (Subject to final revision for the Transactions.) CHARACTERISTICS AND APPLICATIONS OF VIBRA- TION GALVANOMETERS BY FRANK WENNER In the vibration galvanorneter we have a type of synchronous motor which is distinctly different from all the ordinary types of dynamo electric machines. Further it does not have any of the characteristics of any of the ordinary galvanometers and except for the fact that it is used in the detection or measure­ ment of small currents and voltages, it should not be called a galvanometer. In galvanometers, except when used in the measurement of transient currents or quantity of electricity, the moving system is displaced until we have an equality of static couples acting on it. In the vibration galvanometer the equilibrium condition is an equality between integral values of the product of the current and generated voltage and the mechanical power dissipated in various ways as in ordinary electric motors when operated without a load. It therefore behaves more like an electric motor than like a galvanometer. Further, since it is used only with alternating currents and op­ erates in synchronism with the current it must necessarily have some of the characteristics of a synchronous motor. As a motor the efficiency of conversion was found in a particular case to be as high as 97J per cent while the power required to maintain an easily discernable amplitude of vibration was of the order of 10-11 watts.
    [Show full text]
  • HOW the SCIO TECHNOLOGY WORKS Many Have Asked What Is
    HOW THE SCIO TECHNOLOGY WORKS Many have asked what is measured by the SCIO/QXCI medical device. This incredible advancement in medicine measures subtle electrical factors of the body. The history of alternative medicine has been dominated by old style resistance measuring devices. These antique devices depended on the operator to apply the probe to the acupuncture point. By subtle changing the speed of probe delivery (not the pressure), the operator could influence the outcome. This prevented true results. The other complication was the limits of just resistance testing. The body is much more complicated than just resistance. The electrical factors of the body include voltage, amperage, capacitance, inductance, frequency, and many others. The basics of bio-electrical medicine lie in the voltage, amperage, and resistance. The only thing that can truly be measured in electricity is the voltage and amperage. Everything else is a mathematical variation of voltage and amperage. So the QXCI device starts by measuring multiple channels of this information. Multiple channels are needed so that we can see variations in the electrical potential and flow of the body total. So we measure the extremities and the head. This direct measurement is of four channels of voltage, four of amperage, and four of resistance. These come into the computer for amplification and the computer acts as a frequency counter for receiving this data. This makes an active twelve channel measuring device. Other calculations are made mathematically. Resistance cannot be measured directly. It must be calculated from an amperage or voltage meter. Same as that any capacitance meters cannot directly measure capacitance it must do a mathematical adjustment of voltage and amperage flow.
    [Show full text]
  • Arxiv:1708.02856V1 [Cond-Mat.Mes-Hall] 9 Aug 2017 Systems Close to Equilibrium
    Probing the energy reactance with adiabatically driven quantum dots Mar´ıaFlorencia Ludovico,1, 2 Liliana Arrachea,1, 3 Michael Moskalets,4 and David S´anchez5 1International Center for Advanced Studies, UNSAM, Campus Miguelete, 25 de Mayo y Francia, 1650 Buenos Aires, Argentina 2The Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, I-34151 Trieste, Italy 3Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universit¨atBerlin, 14195 Berlin, Germany 4Department of Metal and Semiconductor Physics, NTU "Kharkiv Polytechnic Institute", 61002 Kharkiv, Ukraine 5Institute for Cross-Disciplinary Physics and Complex Systems IFISC (UIB-CSIC), E-07122 Palma de Mallorca, Spain The tunneling Hamiltonian describes a particle transfer from one region to the other. While there is no particle storage in the tunneling region itself, it has associated certain amount of energy. We name the corresponding flux energy reactance since, like an electrical reactance, it manifests itself in time-dependent transport only. Noticeably, this quantity is crucial to reproduce the universal charge relaxation resistance for a single-channel quantum capacitor at low temperatures. We show that a conceptually simple experiment is capable of demonstrating the existence of the energy reactance. PACS numbers: 73.23.-b, 72.10.Bg, 73.63.Kv, 44.10.+i Motivation. A very exciting experimental activity is lately taking place in search of controlling on-demand quantum coherent charge transport in the time domain. The recent burst of activity started with the experimen- Floating contact tal realization of quantum capacitors in quantum dots under ac driving [1], single particle emitters [2], and was followed by the generation of quantum charged solitons over the Fermi sea (levitons) [3].
    [Show full text]
  • Hypothesis of the Hidden Multiverse Explains Dark Matter and Dark Energy
    Journal of Modern Physics, 2016, 7, 1228-1246 Published Online June 2016 in SciRes. http://www.scirp.org/journal/jmp http://dx.doi.org/10.4236/jmp.2016.710111 Hypothesis of the Hidden Multiverse Explains Dark Matter and Dark Energy Alexander Alexandrovich Antonov Research Center of Information Technologies “TELAN Electronics”, Kiev, Ukraine Received 12 May 2016; accepted 24 June 2016; published 28 June 2016 Copyright © 2016 by author and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Analysis of WMAP and Planck spacecraft data has proved that we live in an invisible Multiverse, referred to as hidden, that has a quaternion structure. It explains the reason for the mutual invisi- bility of parallel universes contained in the hidden Multiverse. It is shown that the hidden Multi- verse includes most likely twenty parallel universes from different dimensions, six of which are adjacent to our universe. Besides, edges of the hidden Multiverse are connected to other (from one to four) Multiverses, which are observable neither by electromagnetic nor by gravitational ma- nifestations. The Multiverse described contains four matter-antimatter pairs, annihilation of which is prevented by relative spatial position of the universes. The experimental proof of exis- tence of the hidden Multiverse is explained to be the phenomenon of dark matter and dark energy that correspond to other invisible parallel universes, except ours, included in the hidden Multi- verse. General scientific principle of physical reality of imaginary numbers, refuting some of the statements of the existing version of the special theory of relativity, is a physical and mathematical foundation of the outlined conception of the hidden Multiverse.
    [Show full text]
  • Capacitive Reactance This Worksheet and All Related Files Are Licensed
    Capacitive reactance This worksheet and all related files are licensed under the Creative Commons Attribution License, version 1.0. To view a copy of this license, visit http://creativecommons.org/licenses/by/1.0/, or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. The terms and conditions of this license allow for free copying, distribution, and/or modification of all licensed works by the general public. Resources and methods for learning about these subjects (list a few here, in preparation for your research): 1 Questions Question 1 As a general rule, capacitors oppose change in (choose: voltage or current), and they do so by . (complete the sentence). Based on this rule, determine how a capacitor would react to a constant AC voltage that increases in frequency. Would an capacitor pass more or less current, given a greater frequency? Explain your answer. file 00579 Question 2 R f(x) dx Calculus alert! We know that the formula relating instantaneous voltage and current in a capacitor is this: de i = C dt Knowing this, determine at what points on this sine wave plot for capacitor voltage is the capacitor current equal to zero, and where the current is at its positive and negative peaks. Then, connect these points to draw the waveform for capacitor current: e C e 0 Time How much phase shift (in degrees) is there between the voltage and current waveforms? Which waveform is leading and which waveform is lagging? file 00577 Question 3 You should know that a capacitor is formed by two conductive plates separated by an electrically insulating material.
    [Show full text]
  • Electromagnetic Modeling of Open Cell Conductive Foams for High Synchrotron Radiation Rings
    Proceedings of IPAC2014, Dresden, Germany TUPRI047 ELECTROMAGNETIC MODELING OF OPEN CELL CONDUCTIVE FOAMS FOR HIGH SYNCHROTRON RADIATION RINGS S. Petracca∗ , A. Stabile, University of Sannio, Benevento, INFN, Salerno, Italy Abstract Electrical Properties of Conducting Foams Open cell conductive foams (OCMF) have been recently Electromagnetic modeling of OCMFs has been studied suggested as a possible alternative to perforated metal by several Authors during the last decade. A numerical ap- patches for efficiently handling gas desorption from the proach based on Weiland finite integration technique (FIT, beam pipe wall in high synchrotron radiation machines, in [4]) has been proposed by Zhang et al. [5] to compute the view of its superior performance in terms of residual gas (frequency, thickness and angle of incidence dependent) re- concentration and beam shielding. Here we discuss the flection coefficient of SiC foam. In the quasi-static limit λ 0, the conductivity of OCMFs can be computed us- electromagnetic properties (characteristiuc impedance and −→ propagation constant) of OCMFs and how they affect the ing effective medium theory (EMT), for which several for- beam coupling impedance. mulations exist giving comparable results (see, [6],[7] for a review), e.g., ν σeff = σ0(1 p) , (1) OPEN CELL METAL FOAMS − where σ0 is the bulk metal conductivity, p the porosity, and ν a morphology-dependent factor. Open cell metal foams (OCMF) are highly gas- Measurements of the microwave electromagnetic shield- permeable reticular materials, consisting of a 3D web of ing efficiency of OCMF panels [8] indicate that a simple thin conducting ligaments (Fig. 1), whose typical struc- Drude model ture is shown in Figure 1.
    [Show full text]
  • ELTR 110 (AC 1), Section 1 Recommended Schedule Day 1
    ELTR 110 (AC 1), section 1 Recommended schedule Day 1 Topics: Basic concepts of AC and oscilloscope usage Questions: 1 through 20 Lab Exercise: Analog oscilloscope set-up (question 81) Day 2 Topics: RMS quantities, phase shift, and phasor addition Questions: 21 through 40 Lab Exercise: RMS versus peak measurements (question 82) and measuring frequency (question 83) Day 3 Topics: Inductive reactance and impedance, trigonometry for AC circuits Questions: 41 through 60 Lab Exercise: Inductive reactance and Ohm's Law for AC (question 84) Day 4 Topics: Series and parallel LR circuits Questions: 61 through 80 Lab Exercise: Series LR circuit (question 85) Day 5 Exam 1: includes Inductive reactance performance assessment Lab Exercise: Oscilloscope probe ( 10) compensation (question 86) £ Practice and challenge problems Questions: 89 through the end of the worksheet Impending deadlines Troubleshooting assessment (AC bridge circuit) due at end of ELTR110, Section 3 Question 87: Troubleshooting log Question 88: Sample troubleshooting assessment grading criteria 1 ELTR 110 (AC 1), section 1 Skill standards addressed by this course section EIA Raising the Standard; Electronics Technician Skills for Today and Tomorrow, June 1994 C Technical Skills { AC circuits C.01 Demonstrate an understanding of sources of electricity in AC circuits. C.02 Demonstrate an understanding of the properties of an AC signal. C.03 Demonstrate an understanding of the principles of operation and characteristics of sinusoidal and non- sinusoidal wave forms. C.05 Demonstrate an understanding of measurement of power in AC circuits. C.11 Understand principles and operations of AC inductive circuits. C.12 Fabricate and demonstrate AC inductive circuits.
    [Show full text]
  • Low Frequency Bio-Electrical Impedance Mammography and Dielectric Measurement
    Western University Scholarship@Western Electronic Thesis and Dissertation Repository 10-21-2016 12:00 AM Low Frequency Bio-Electrical Impedance Mammography and Dielectric Measurement Seyyed Hesabgar The University of Western Ontario Supervisor Dr. Samani The University of Western Ontario Graduate Program in Medical Biophysics A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Seyyed Hesabgar 2016 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Biomedical Devices and Instrumentation Commons Recommended Citation Hesabgar, Seyyed, "Low Frequency Bio-Electrical Impedance Mammography and Dielectric Measurement" (2016). Electronic Thesis and Dissertation Repository. 4208. https://ir.lib.uwo.ca/etd/4208 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Abstract Assessment of electrical impedance of biological tissues at low frequencies offers a great potential for a safe, simple, and low-cost medical breast imaging techniques such as mammography. As such, in this dissertation a mammography method which uses tissue electrical impedance to detect breast malignancies was developed. The dissertation also introduces a new technique for measuring the dielectric properties of biological tissues at low frequencies. The impedance mammography technique introduced in this study is founded on the assumption that dielectric values of breast malignancies are significantly higher than the dielectric values of normal breast tissues. While previous studies have shown that this assumption is valid at high frequencies (50MHz-20GHz), less research efforts have been dedicated to ascertain the validity of such assumption at low frequencies (<1MHz).
    [Show full text]
  • United States Patent [191 [II] Patent Number: 4,575,690 Walls Et Al
    * "4 United States Patent [191 [II] Patent Number: 4,575,690 Walls et al. [45] Date of Patent: Mar. 11, 1986- [54] ACCELERATION INSENSITIVE 4,453,141 6/1984 Rosati .................................. 32 1/1 LS OSCILLATOR Primary Exatnitrer-Eugene R. LaRoche [75] Inventors: Fred L. Walls, Boulder, Colo.; John Assislatrr Exatttitrer-Jnnies C. Lee R. Vig, Colts Neck, N.J. Attorney, Agent, or Finn-Anthony T. Lane; Jeremiah G. Murray; John T. Rehberg I731 Assignee: The United Stated of America 81 represented by the Secretary of the P71 ABSTRACT Army, Wildiiligt(w, D.C. A crystiil oscill:itor, iiiclutliiig Itvo cryst:tls 01' uticq~i;il [21] Appl. No.: 715,862 acceleration sensitivity niiigiiitude illid mounted such 1 that their respective acceleration sensitivity vectors are [22] Filed: Mar. 25, 1985 aligned in an anti-parallel relationship, further includes at least one electrical reactance, such as a variable CB- [51] Int. c1.4 ............................................... H03B 5/32 [52] US. C1. ................................ 331/162; 331/116 R; pacitor, coupled to one of the crystals for providing 331/158 cancellation of acceleration sensitivities. After the ac- I581 Field of Search ....................... 310/311, 360, 361; celeration sensitivity vectors of the two crystals are 331/116 R, 158, 160, I62 aligned anti-parallel, the variiible capacitor is ad.jiisted until the iict or result;int accclcr:itioii sciisitivity vccior ~561 References Cited of the pair of resonators is reduced to zero. A second U.S. PATENT DOCUMENTS electrical reactance, such ils a vari;ible capacitor, is utilized as a tuning capacitor for adjusting the oscilla- 3,978,432 8/1916 Onw ..................................
    [Show full text]
  • Modelling of Distorted Electrical Power and Its Practical Compensation in Industrial Plant
    MODELLING OF DISTORTED ELECTRICAL POWER AND ITS PRACTICAL COMPENSATION IN INDUSTRIAL PLANT By JAN HARM CHRISTIAAN PRETORIUS THESIS presented in partial fulfilment of the requirements for the degree DOCTOR 1NGENERIAE ' (D. Ing) in the FACULTY OF ENGINEERING of the RAND AFRIKAANS UNIVERSITY SUPERVISOR: PROF. J.D. van WYK CO-SUPERVISOR: DR. P.H. SWART DECEMBER 1997 11 PREFACE Alternating current systems employing single-frequency sinusoidal waveforms render optimal service when the currents in that system are also sinusoidal and have a fixed phase relationship to the voltages that drive them. Under unity- power factor conditions, the currents are in phase with the voltages and optimal net-energy transfer takes place under minimum loading conditions, i.e. with the lowest effective values of current and voltage in the system. The above conditions were realised in the earlier years, because supply authorities generated 50 Hz sinusoidal voltages and consumers drew 50 Hz sinusoidal currents with fixed phase relationships to these voltages. Static and rotating electrical equipment like transformers, motors, heating and lighting equipment were equally compatible with this requirement and well-behaved AC networks were more the rule than the exception. The fact that three-phase systems conveyed the bulk of the power from one topographical location to the next did not constrain the utilisation of that concept at all, even though poly-phase transmission systems were necessary to increase the economy of transmission and to furnish non-pulsating power transfer. Also, additional theory had to be developed to handle unbalanced conditions in these multi-phase systems and to take care of complex network analysis and fault conditions.
    [Show full text]
  • Title Electrical Reactance and Its' Correlates In
    TITLE ELECTRICAL REACTANCE AND ITS' CORRELATES IN BIOLOGICAL SYSTEMS BY NELSON W. C. NMD LPCC AND NIEBER, JOZSEF HIPPOCAMPUS INSTITUTE BUDAPEST , HUNGARY 1995 ABSTRACT: In this short paper we review some of the basic principle of reactance and draw correlates to reactivity in biological systems. Biological organisms indeed have electrical capacities. Electronic stability is important for every cell in maintaining its' life. Reactance is one way that the cell could react with its external environment. This article draws correlates to cell membrane capacitance and inductance changes as possible ways of understanding the electronic function of a cell . Thus classical electronic theory could be used to describe the phenomena of cell reactivity. This has offered potentials for deeper development of bio electronic device interface, and diagnostic medical instrumentation. page 1 REVIEW OF ELECTRONIC REACTIVITY INTRODUCTION: Reactance was first described as the ability of an electronic circuit to react to voltage and amperage changes. Reactance allows us to understand the range of responsiveness of a circuit as well as its sensitivities. In fact Reactance is a correlate to sensitivity in a circuit. The voltage and amperage changes applied to a circuit effect and are effected by the capacitance and inductance of the circuit. These determine the then the reactance or range of sensitivity of the circuit and set response characteristics of the circuit. In the Handbook of Electronic Tables and Formulas (Sams & Co.) (ref. 1986 ), reactance is defined now as opposition to the flow of alternating current by the inductance or capacitance of a component or circuit. The handbook further defines capacitance reactance differing from inductance reactance.
    [Show full text]