Виконання вправ на закріплення граматичної теми

Вправа 11. Перекладіть речення з дієприкметниками.

1. The girl standing at the bus is my sister. 2. Having been sent to the wrong address the letter didn’t rich him. 3. He sat at the plant thinking. 4. She came up to us bringing the book on electronics. 5. The hall was full of laughing people. 6. The working electrician was about fourty-six. 7. Having repaired the electrical equipment I began testing it. 8. The large building being built in our street is a new laboratory. 9. Having finished the experiment the students left the laboratory.

Вправа 12. Перекладіть речення з дієприкметниками.

1.Обговорюючи електричні машини, ми звертали увагу на їхню будову. 2. Чоловік, що стоїть біля електричного щита, наш електрик. 3. Усі подивилися на схему провідника. 4.Небезпечно працювати біля оголених проводів. 5. Обговорюючи галузі сільського господарства, ми поділяємо їх на рослинництво і тваринництво.

Заняття 35

Тема: Кола синусоїдального струму. Коефіцієнт потужності

Граматичний матеріал: Вживання Participle II. Функції у реченні

Вправа 1. Прочитайте та перекладіть лексику за допомогою словника.

electromagnetic induction [ı͵lektrəmægʹnetık ınʹdʌkʃ(ə)n]

uninterrupted [͵ʌnıntəʹrʌptıd]

sinusoіdal form [sinusoіdal fɔ:m]

ease [i:z]

i.e. (that is)

compilation [͵kɒmpıʹleıʃ(ə)n]

voltage [ʹvəʋltıdʒ]

linear [ʹlınıə]

depict [dıʹpıkt]

rectangular [rekʹtæŋgjʋlə]

power factor [ʹpaʋə ʹfæktə]

convert [ʹkɒnvɜ:t]

promptly [ʹprɒmptlı]

artificial [͵ɑ:tıʹfıʃ(ə)l]

indicate [ʹındıkeıt]

full power [fʋl ʹpaʋə]

power receiver [ʹpaʋə] [rıʹsi:və]

insufficient [͵ınsəʹfıʃ(ə)nt]

inversely [ınʹvɜ:slı]

idling [ʹaıdlıŋ]

natural [ʹnætʃ(ə)rəl]

underloading ['ʌndə,ləudiŋ]

thoroughly [ʹθʌrəlı]

Вправа 2. Прочитайте та перекладіть текст українською.

Basic Сoncepts and Parameters of Sinusoidal Current

It is known that in industry, agriculture and everyday life mainly alternating current is used. The reason is that the use of AC allows greater use of the processes of energy conversion in comparison with direct current due to the electromagnetic induction.

Sinusodial form was selected among all possible forms of change of current. The advantages of this current form:

- technical ease of getting in an industrial environment;

- easy mathematical interpretation, i.e. the compilation of mathematical models of electromagnetic processes;

- repeatability of e.m.f. forms source in the currents and voltages in all areas of linear electric field.

Sinusoid currents, voltage and e.m.f. can be depicted with the help of the wave time graph in a rectangular coordinate system. The length of time for which one complete change of sinusoidal quantities is made called the period T and is measured in seconds.

Value equal to the number of periods per unit time is called the frequency f.

Power factor

Production as a rule consumes electrical energy of alternating current, which consists of active and reactive (inductive) energy. Active energy is converted into other forms of energy and is spent on useful work of the consumer and thermal losses. Reactive energy of the inductive nature, as it is known, is connected with the energy of the magnetic field. Uninterrupted exchange of reactive power flows between the source and the consumer with a double frequency. Power factor indicates what part of the full power of the field is the active power.

Any electrical equipment is characterized by:

1. Rated current;

2. Rated voltage;

3. Rated full power.

Full use of the generator power takes place at rated voltage and current and working with cos φ= 1, because in this case the active power is maximum and equal to the rated full power.

The generator operating at rated voltage and current, but when cos φ ≠ 1, generates the active power which is proportional to cos φ. It means that the reduction of cos φ, the value of which is determined by the power receiver, makes insufficient use of the generator.

At a constant power P of the receiver decreasing of cos φ leads to an increase of loss on heating, which increase inversely proportional to the square of the power factor.

It is necessary to increase cos φ of installations to the values close to unit (0,95-1) for full use of the rated installed capacity of the generator and reduce heat losses.

The most common in the production of three-phase asynchronous motors have a power factor of 0.83-0.92 at nominal loading and 0.2-0.3 at idling. Therefore, to improve cos φ of the consumers it is necessary to take certain technical measures.

All the ways to increase cos φ can be divided into natural and artificial. Natural methods include structural and technological.

Structural:

1. During the design of electrical installations, you should choose the most modern equipment (with high cos φ).

2. Motor power should choose the most close to the power of the working machine taking into account the mode of its operation.

Technological:

1. During operation to prevent idling of the electrical motors and to prevent their underloading.

2. To carry out technical maintenance of the electrical equipment promptly and thoroughly.

Artificial:

• connecting in parallel with the load of the compensative capacitor batteries or rotary reactors.

Вправа 3. Дайте відповіді на питання до тексту.

1. What is the reason of a.c. using in industry and agriculture?

2. What are the advantages of sinusoidal current form?

3. What is period? What is its unit of measuring?

4. What is frequency?

5. What Power factor indicates?

Вправа 4. Доберіть еквіваленти з колонки А до слів з колонки В.

A	B
1. електромагнітна індукція	1. e.m.f.
2. напруга	2. electromagnetic induction
3. електрорушійна сила	3. the length of time
4. частота	4. thermal losses
5. відрізок часу	5. voltage
6. теплові втрати	6. frequency
7. джерело	7. active power
8. номінальний струм	8. electrical installations
9. активна потужність	9. source
10. електроустановки	10.rated current

Вправа 5. Знайдіть англійські еквіваленти серед поданих українських словосполучень.

Переважно використовується змінний струм; причина полягає в тому, що ;

процеси перетворення енергії; явище електромагнітної індукції;

технічна простота одержання в промислових умовах; складається з активної та реактивної (індуктивного характеру) енергії; перетворюється в інші види енергії; обмін реактивною потужністю між джерелом і споживачем;

виробляє активну потужність; cos φ призво­дить до збільшення втрат на нагрів; асинхронні трифазні електро­двигуни; необхідно вживати певних технічних заходів; способи підвищення cos φ можна поділити на; природ­ні та штучні.

natural and artificial; the reason is that; cos φ leads to an increase of loss on heating; the processes of energy conversion; mainly alternating current is used; technical ease of getting in an industrial environment; consists of active and reactive (inductive) energy; exchange of reactive power between the source and the consumer; generates the active power; three-phase asynchronous motors; it is necessary to take certain technical measures; the ways to increase cos φ can be divided; the electromagnetic induction; is converted into other forms of energy.

Вправа 6. Прочитайте та перекладіть текст англійською.

Корекція коефіцієнта потужності за допомогою конденсаторів