Electrical Power : Обучение профессионально-ориентированному чтению
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Английский язык
Издательство:
ФЛИНТА
Год издания: 2012
Кол-во страниц: 104
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Вид издания:
Учебное пособие
Уровень образования:
ВО - Бакалавриат
ISBN: 978-5-89349-651-2
Артикул: 620675.01.99
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Настоящее учебное пособие предназначено для развития на- выков чтения оригинальной литературы, получения нужной ин- формации, умения побеседовать по прочитанному тексту и де- лать сообщения на английском языке. Для студентов электромеханических и электроэнергетических специальностей технических вузов.
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Г.К. Кушникова ELECTRICAL POWER Обучение профессионально-ориентированному чтению Учебное пособие 3-е издание, стереотипное Москва Издательство «Флинта» 2012
УДК 811.111(075) ББК 81.2Англ-923 К96 Кушникова Г.К. К96 Electrical Power : Обучение профессионально-ориентированному чтению [Электронный ресурс] : учеб. пособие / Г.К. Кушникова. – 3-е изд., стер. – М. : Флинта, 2012. – 104 с. ISBN 978-5-89349-651-2 Настоящее учебное пособие предназначено для развития навыков чтения оригинальной литературы, получения нужной информации, умения побеседовать по прочитанному тексту и делать сообщения на английском языке. Для студентов электромеханических и электроэнергетических специальностей технических вузов. УДК 811.111(075) ББК 81.2Англ-923 ISBN 978-5-89349-651-2 © Издательство «Флинта», 2012
Contents Ïðåäèñëîâèå ........................................................................................... 5 Ðàçäåë I Text One. Generation of Electricity ......................................... 7 Text Two. Resistance ................................................................... 8 Text Three. Electromagnetism .................................................... 10 Text Four. Electromagnetic Induction .................................... 12 Text Five. Alternating Current Generator ............................. 14 Text Six. Three-Phase Generator .......................................... 16 Text Seven. Transmitting Alternating Current......................... 17 Text Eight. Alternating Current Motors .................................. 19 Text Nine. Induction Motor...................................................... 20 Text Ten. Single-Phase Motors............................................... 22 Text Eleven. Induction Motors .................................................... 23 Text Twelve. Direct-Current Generators.................................... 24 Text Thirteen. Difference between Alternating- and Direct-Current Generators.................................... 26 Text Fourteen. Types of Direct-Current Generators ................... 27 Text Fifteen. Compound Generators........................................... 29 Text Sixteen. Direct-Current Motors........................................... 31 Text Seventeen. Types of Direct-Current Motors .......................... 32 Text Eighteen. Uses of DC Machines ............................................ 33 Text Nineteen. Compound Motors.................................................. 35 Ðàçäåë II Supplementary Texts Dry-Type Transformers........................................................................ 37 In Coal Mines ........................................................................................ 39 Practical Tests ........................................................................................ 40 Lightning ................................................................................................. 41
Types of Armature Windings .............................................................. 42 AC Generators in Parallel ................................................................... 43 Future Power Sources Introducion ............................................................................................. 49 Thermoelectric Generators.................................................................. 49 The Basic Phenomenon ....................................................................... 50 Materials and Their Parameters......................................................... 50 Devices and Design .............................................................................. 52 Thermionic Generators ........................................................................ 54 Principle of Operation ......................................................................... 55 Magnetohydrodynamic Generators Power from High-Temperature Gas ................................................. 58 The MHD Generator ........................................................................... 58 MHD Generator Cycles...................................................................... 60 Research in MHD ................................................................................. 62 Fuel Cells ... Electrical Energy from Electrochemical Process....... 62 Operating Characteristics and Properties ......................................... 63 Ðàçäåë III Ñëîâàðü-ìèíèìóì äëÿ ÷òåíèÿ íàó÷íîé ëèòåðàòóðû íà àíãëèéñêîì ÿçûêå ......................................................................... 65
Ïðåäèñëîâèå Íàñòîÿùåå ïîñîáèå ïðåäíàçíà÷åíî äëÿ ñòóäåíòîâ ýëåêòðîìåõàíè÷åñêèõ è ýëåêòðîýíåðãåòè÷åñêèõ ñïåöèàëüíîñòåé è ðàññ÷èòàíî íà âòîðîé ýòàï îáó÷åíèÿ àíãëèéñêîìó ÿçûêó â òåõíè÷åñêîì âóçå. Îñíîâíîé çàäà÷åé ïîñîáèÿ ÿâëÿåòñÿ íàó÷èòü ñòóäåíòîâ ÷èòàòü îðèãèíàëüíóþ ëèòåðàòóðó ïî ñïåöèàëüíîñòè ñ öåëüþ ïîëó÷åíèÿ íóæíîé èíôîðìàöèè, âåñòè áåñåäó ïî ïðî÷èòàííîìó òåêñòó è äåëàòü ñîîáùåíèÿ íà àíãëèéñêîì ÿçûêå. Ïîñîáèå òàêæå ïîìîãàåò ñòóäåíòàì îâëàäåòü ðÿäîì òåõíè÷åñêèõ òåðìèíîâ ýëåêòðîìåõàíè÷åñêèõ è ýëåêòðîýíåðãåòè÷åñêèõ ñïåöèàëüíîñòåé. Ïîñîáèå ñîñòîèò èç òðåõ ðàçäåëîâ. Ïåðâûé ðàçäåë ñîäåðæèò 19 òåêñòîâ è óïðàæíåíèé ê íèì. Êàæäûé òåêñò îõâàòûâàåò ïðèáëèçèòåëüíî 1500–2000 ïå÷àòíûõ çíàêîâ. Òåêñòû ïîäîáðàíû èç îðèãèíàëüíîé òåõíè÷åñêîé ëèòåðàòóðû. Äëÿ áîëüøåé íàãëÿäíîñòè òåêñòû ñíàáæåíû ðèñóíêàìè è ÷åðòåæàìè. Âî âòîðîì ðàçäåëå äàíû òåêñòû äëÿ âíåàóäèòîðíîãî ÷òåíèÿ.  òðåòüåì ðàçäåëå äàí ñëîâàðü-ìèíèìóì. Ñëîâàðü èìååò öåëü îáëåã÷èòü è óíèôèöèðîâàòü ïðîöåññ îáó÷åíèÿ ÷òåíèþ, ïåðåâîäó è ðåôåðèðîâàíèþ íàó÷íûõ òåêñòîâ ïî ñïåöèàëüíîñòè. Îí ìîæåò áûòü èñïîëüçîâàí è êàê ñïðàâî÷íèê ïðè ñàìîñòîÿòåëüíîé ðàáîòå. ßçûê, ñ ïîìîùüþ êîòîðîãî èçëàãàþòñÿ íàó÷íûå è òåõíè÷åñêèå ôàêòû, ñòàâèò ïåðåä ñòóäåíòàìè ðÿä ïðîáëåì, è îäíîé èç ñàìûõ âàæíûõ ÿâëÿåòñÿ «âîêàáóëÿð». Íàó÷íûå è òåõíè÷åñêèå òåêñòû ñîäåðæàò áîëüøîå êîëè÷åñòâî òåðìèíîâ. Ýòà ïðîáëåìà ðåøàåòñÿ ñ ïîìîùüþ ñóùåñòâóþùèõ ðàçëè÷íîãî ðîäà îòðàñëåâûõ ñëîâàðåé, êðîìå òîãî, áîëüøîå êîëè÷åñòâî ñëîâ ÿâëÿþòñÿ ìåæäóíàðîäíûìè. Íàèáîëüøóþ æå òðóäíîñòü ïðåäñòàâëÿþò ïîëóíàó÷íûå, ïîëóòåõíè÷åñêèå ñëîâà (íåêîòîðûå ìåòîäèñòû íàçûâàþò èõ îáùåíàó÷íûìè ñëîâàìè), êîòîðûå õàðàêòåðíû äëÿ âñåõ îòðàñëåé íàóêè, èìåþò ðÿä çíà÷åíèé è ÷àñòî èñïîëüçóþòñÿ èäèîìàòè÷åñêè. Ñóùåñòâóåò òàêæå ðÿä ãëàãîëîâ, ïðèëàãàòåëüíûõ, íàðå÷èé, êî
òîðûå, ïî ñóùåñòâó, íå ÿâëÿþòñÿ íàó÷íûìè, íî ïðèíàäëåæàò ê íàó÷íîé ôðàçåîëîãèè. Ìàêñèìàëüíîå êîëè÷åñòâî òàêèõ ñëîâ è âîøëî â äàííûé ëåêñè÷åñêèé ìèíèìóì. Âñå ñëîâà ðàñïîëîæåíû â àëôàâèòíîì ïîðÿäêå. Êàæäîå îòäåëüíîå ñëîâî, áóäü òî îñíîâíîå èëè ïðîèçâîäíîå, äà¸òñÿ êàê ñàìîñòîÿòåëüíàÿ ëåêñè÷åñêàÿ åäèíèöà. Ñëîâà, îäèíàêîâûå ïî íàïèñàíèþ è ïðîèçíîøåíèþ, íàïðèìåð ñóùåñòâèòåëüíîå è ãëàãîë, äàþòñÿ îäèí ðàç. Ñëîâî, îäèíàêîâîå ïî íàïèñàíèþ, íî èìåþùåå äðóãîå ïðîèçíîøåíèå, âûäåëÿåòñÿ â îòäåëüíóþ ñëîâàðíóþ ñòàòüþ. Ïðåäëîã, õàðàêòåðíûé äëÿ äàííîãî ãëàãîëà, ñòàâèòñÿ â ñêîáêàõ ïîñëå ïåðåâîäà ýòîãî ãëàãîëà. Íåïðàâèëüíî îáðàçóþùèåñÿ ôîðìû ãëàãîëîâ ïðèâîäÿòñÿ â ñêîáêàõ. Åñëè â ñêîáêàõ äàíà îäíà ôîðìà ãëàãîëà, çíà÷èò Past è Participle II ñîâïàäàþò.  ñëîâàðíûõ ñòàòüÿõ ïðèâîäÿòñÿ íåêîòîðûå ôðàçåîëîãè÷åñêèå ñî÷åòàíèÿ, êîòîðûå ÷àñòî âñòðå÷àþòñÿ â àíãëèéñêîé íàó÷íîé ëèòåðàòóðå.
Ðàçäåë I TEXT ONE GENERATION OF ELECTRICITY Our study of electricity will bå limited to methods of generation, distribution and application in furnishing motive power for machinery. As this is not a highly technical study, the electron theory of the nature of electricity will not be discussed. Historically, knowledge of electrical manifestation goes back to the early Greeks who noticed that amber, after being rubbed, had the power to attract feathers or small bits of straw. Through the ages many people have experimented with and studied the nature of this strange power, and by their efforts it has been brought under control and made one of man’s most useful servants. Before studying the way in which electrical power is generated, certain terms must be explained and certain manifestations must be discussed in order to make the study meaningful. The explanations given here are made as simple and nontechnical as possible. Electromotive force (emf) is the force or pressure that causes electric current to flow. The unit of measure of this force is the volt. Electromotive force is sometimes called “potential” or “voltage”. Electric current will flow in a wire when sufficient voltage is present. The unit of measurement of electric current flow is the ampere. Volts and amperes are measured by dial instruments called voltmeters and ammeters. The amount of electric power that is delivered bó à generator or is consumed by a motor or other power device is the product of the pressure and the flow. Thus, power = volts x amperes. The unit of measure of power is the watt. Therefore, watts = volts x amperes. Instruments for indicating or recording watts are called wattmeters. For designating large amounts of power the term “kilowatt” or kw, which means one thousand watts, is used.
EXERCISES I. Read and translate the text. Remember the words which are new for you. II. Give Russian equivalents. Electromotive force; the measure of electric power; wattmeter; dial instrument; voltmeter; ammeter. III. Give Russian equivalents, paying attention to the suffixes in English words: to explain-explanation; to consume-consumer-consumption; to indicate-indicator-indication; to generate-generator-generation. IV. Answer the following questions: 1. What is electromotive force? 2. What electrical units do you know? 3. What is the volt? 4. What is the ampere? 5. What is the watt? 6. What instruments are used for measuring emf and the electric current flow? 7. What is the kilowatt and when is it used? V. Speak on: 1) electromotive force; 2) the measure of electric power. TEXÒ TWO RESISTANCE Resistance is the property of any material to oppose the flow of electricity through it. The unit of measure of this resistance is the ohm. The resistance of a conductor varies directly to its length and inversely to its cross-sectional area. Thus a long thin wire would have a high resistance in ohms and a short thick wire would have a low resistance. The voltage required to make a current flow in a conductor depends upon the resistance. A pressure of 1 volt will make a current of 1 ampere flow through a resistance of 1 ohm. This relationship is expressed in the formula I = U/R,
where I is the current in amðåres, U — pressure in volts and R – resistance in ohms. This formula may be transposed U = IR or R = U/I, so that when any two of the values in the formula are known the other may be found. This formula is known as Ohm’s Law. Electric conductors usually consist of wires or cables made of copper. Copper is used because it is the best conductor and relatively cheap. Every substance is a conductor to some degree, but the metals are the best. Electric insulators are materials that allow almost no electricity to pass through them. These materials are also called nonconductors. Typical commercial insulators are rubber, silk, cotton, mica, porcelain, glass, dry paper and etc. Dry air and oils are good insulators too. Wire conductors are usually covered with insulation. Electric circuits. – In order to use electric currents for transmitting power they must be sent through insulated conductors arranged to form complete paths. That is, the conductor must start at the generator, go to the motor, through it and return to the generator. If there is a break in the path, current will not flow. These paths are called electric circuits. Circuits may be series, shunt or compound. (For example, see diagrams shown in Figure 1.) Fig. 1. Circuits COMPOUND OR SERIES PARALLEL SHUNT LAMPS SERIES
EXERCISES I. Read and translate the text. II. Give Russian equivalents: cross-sectional area, to be directly proportional to, to be inversely proportional to, relationship, in order to, the arrangement of conductors, series circuit, shunt circuit, compound circuit. III. Answer the following questions: 1. What is the resistance? 2. In what units is the electrical resistance measured? 3. How does the resistance of a conductor vary? 4. We have two wires. One of them is long and thin. The other is short and thick. Which of them will have higher resistance? 5. What is Ohm’s Law? 6. What is a conductor? 7. What is an insulator? 8. What substance is widely used as a conductor? 9. What substances are used as insulators? 10. What is an electric circuit? 11. What kinds of electric circuits do you know? IV. Speak on: 1. resistance; 2. electric conductors; 3. electric insulators; 4. electric circuits. V. Look at Fig. 1 and describe three kinds of electric circuits. TEXT THREE ELECTROMAGNETISM We are all familiar with permanent magnets. Permanent magnets, however, are not suitable for use in large electric generators, and so the electromagnets must be used. Magnetism can be produced by electric currents. In fact every current-carrying conductor has a magnetic field about it. When a current-carrying wire is formed into a coil the magnetic field, which is the space occupied by magnetic lines of force, passes through the coil and around the outside, as shown in Fig. 2.
If a bar of iron or steel is placed within the coil, the field is concentrated in it and it becomes a magnet, or, more properly, an electromagnet. If the iron or steel core and the coiled wire are arranged as shown in Fig. 3, the magnetism follows the core and is concentrated at the gap G. This concentrated form of the magnet field is very useful in generators, as will be shown. The strength of any magnetic field thus produced depends on the amount of current flowing in the wire, and the number of turns of wire. Many turns of wire and a strong current will produce a strong electromagnet and thus a strong field. EXERCISES I. Read and translate the text. II. Read the words and give Russian equivalents: magnet, magnetic, magnetism, electromagnetism, electromagnet, magnetic field, magnetic lines of force, current-carrying conductor, the number of turns of wire. III. Speak on electromagnetism using Figs. 2 and 3. Fig. 3. Electromagnet with concentrated field N S G Fig. 2. Electromagnet S N
TEXT FOUR ELEÑTROMAGNETIC INDUCTION If a conductor (wire) is moved across this magnetic field so that, in effect, it cuts across “the lines of magnetic force” a voltage will be produced in it. This action is illustrated in Fig. 4. The effect would be the same if the conductor were stationary and the field were moved. This phenomenon illustrates the principle of electromagnetic induction which is stated as follows: “When a conductor cuts or is cut by a field of magnetic force an electromotive force is produced in that conductor”. The direction in which the current will flow in the conductor is determined by the direction of motion of the conductor. As shown in Fig. 4, the field direction is from N to S (north to south pole of the magnet); the direction of the motion of the conductor is down and the current direction is as shown by the arrows. If the movement of the conductor were upward the direction of the current would be the opposite of that shown in the illustration. The voltage produced in the conductor depends on the strength of the field and the speed of the conductor. The stronger the field and the faster it is cut by the conductor the greater will be the voltage. Fig. 4. Principle of electromagnetic induction VOLTMETER A N S A
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