Виконання вправ на закріплення граматичної теми
Вправа 8. Перекладіть речення з безсполучниковими підрядними реченнями.
1. The heat the internal combustion engines produce inside the cylinder is converted into useful power. 2. Lubricating oil tractor-drivers use helps to cool the engine. 3. All the farmers know four-wheel drive tractors have an improved pulling power as compared with two-wheel drive. 4. Warning lights (сигнальні лампочки) on the instrument panel show there is a fault in the lubricating or ignition systems.
Вправа 9. Перекладіть речення з безсполучниковими підрядними реченнями.
1. Електрик повинен знати правила, які необхідні під час роботи з електроприборами. 2. Елементи, які потребує ґрунт, це азот, фосфор та калій. 3. Пристрій, який використовується для перетворення механічної енергії на електричну, трансформатор. 4. Людина, яка створила трьохфазний трансформатор, електротехнік Доліво-Добровольський М.О. 5. Струм, який виникає в електричному колі зі змінною напругою, змінний струм.
Заняття № 33
Тема: Однофазні кола змінного струму. Особливості електричних кіл змінного струму. Коло змінного струму з активним опором
Граматичний матеріал: Дієприкметники: утворення та форми
Вправа 1. Прочитайте та перекладіть лексику за допомогою словника.
distribution [͵dıstrıʹbju:ʃ(ə)n] interior [ınʹtı(ə)rıə]
supply [səʹplaı] motor stator [ʹməʋtə ʹsteıtə]
load [ləʋd] self-starting [self]-[ʹstɑ:tıŋ]
lighting [ʹlaıtıŋ] traction [ʹtrækʃ(ə)n]
heating [ʹhi:tıŋ] commonly [ʹkɒmənlı]
revolving [rıʹvɒlvıŋ] uncommon [ʌnʹkɒmən]
conductor [kənʹdʌktə] utility [ju:ʹtılıtı]
peak [pi:k] urban [ʹɜ:bən]
instantaneous [͵ınstənʹteınıəs] exceptional case [ıkʹsepʃ(ə)nəl keıs]
value [ʹvælju:] remote area [rıʹməʋt] [ʹe(ə)rıə]
sequentially [sıʹkwenʃ(ə)lı] converter [kənʹvɜ:tə] simultaneously [sım(ə)lʹteınıəslı] dedicated [ʹdedıkeıtıd]
waveform [weıvfɔ:m] densely [ʹdenslı]
be offset [bi: ʹɒfset]
multiple-unit apartment block [ʹmʌltıp(ə)l-ʹju:nıt əʹpɑ:tmənt blɒk]
Вправа 2. Чи знаєте ви про переваги постійного струму над змінним? Прочитайте та зробіть письмовий переклад на українську.
Advantages of AC system over DC system
1. AC voltages can be efficiently stepped up/down using transformer
2. AC motors are cheaper and simpler in construction than DC motors
3. Switchgear for AC system is simpler than DC system
Вправа 3. Прочитайте та перекладіть текст українською.
Single-phase Electric Power
In electrical engineering, single-phase electric power is the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, with few large electric motors. A single-phase supply connected to an alternating current electric motor does not produce a revolving magnetic field; single-phase motors need additional circuits for starting, and such motors are uncommon above 10 or 20 kW in rating.
In contrast, in a three-phase system, the currents in each conductor reach their peak instantaneous values sequentially, not simultaneously; in each cycle of the power frequency, first one, then the second, then the third current reaches its maximum value. The waveforms of the three supply conductors are offset from one another in time (delayed in phase) by one-third of their period. When the three phases are connected to windings around the interior of a motor stator, they produce a revolving magnetic field; such motors are self-starting.
Standard frequencies of single-phase power systems are either 50 or 60 Hz. Special single-phase traction power networks may operate at 16.67 Hz or other frequencies to power electric railways.
In some countries such as the United States, single phase is commonly divided in half to create split-phase electric power for household appliances and lighting.
Applications
Single-phase power distribution is widely used especially in rural areas, where the cost of a three-phase distribution network is high and motor loads are small and uncommon.
High power systems, say, hundreds of kVA or larger, are nearly always three phase. The largest supply normally available as single phase varies according to the standards of the electrical utility. In the UK a single-phase household supply may be rated 100 A or even 125 A, meaning that there is little need for 3 phase in a domestic or small commercial environment. Much of the rest of Europe has traditionally had much smaller limits on the size of single phase supplies resulting in even houses being supplied with 3 phase (in urban areas with three-phase supply networks).
In North America, individual residences and small commercial buildings with services up to about 100 square metres will usually have three-wire single-phase distribution, often with only one customer per distribution transformer. In exceptional cases larger single-phase three-wire services can be provided, usually only in remote areas where poly-phase distribution is not available. In rural areas farmers who wish to use three-phase motors may install a phase converter if only a single-phase supply is available. Larger consumers such as large buildings, shopping centers, factories, office blocks, and multiple-unit apartment blocks will have three-phase service. In densely populated areas of cities, network power distribution is used with many customers and many supply transformers connected.
Three-wire single-phase systems are rarely used in the UK where large loads are needed off only two high voltage phases.
Single-phase power may be used for electric railways; the largest single-
phase
generator in the world, at Neckarwestheim Nuclear Power Plant,
supplied a railway system on a dedicated traction power network.
Вправа 4. Дайте відповіді на питання до тексту.
What is a single-phase electric power?
When is a single-phase distribution used?
Does the electric motor produce a revolving magnetic field in a single-phase supply? What about a three-phase system?
What are standard frequencies of single-phase power systems?
Where is single-phase power distribution widely used? Why?
Are three-wire single-phase systems used in the UK?
Where can single-phase power be used?
Where is the largest single-phase generator used in the world?
Вправа 5. Знайдіть українські еквіваленти англійських словосполучень.
Resistors; electrical energy is converted into thermal; heating devices; DC circuit; capacity; changed voltage; resistance; current; power; inductance; incandescent lamps; rheostats; revolving magnetic field.
коло постійного струму; струм; потужність; змінна напруга; перетворення eлектричної енергії на теплову; опір; магнітне поле, що обертається; індуктивність; ємність; лампи розжарювання; нагрівальні прилади; реостати; резистори.
Вправа 6. Прочитайте та зробіть переклад без словника. Зробіть письмовий переказ.