Lesson twenty

Read and translate the text

Transformers

The transformer is a device for changing the electric current from one voltage to another. As a matter of fact, it is used for increasing or decreasing voltage. A simple transformer is a kind of induction coil. It is well known that in its usual form it has no moving parts. On the whole, it requires very little maintenance if it is not mis­used and is not damaged by lightning.

We may say that the principal parts of a transformer are two windings, that is coils, and an iron core. They call the coil which is supplied with current the "primary winding", or just "primary" for short. The winding from which they take the current is referred to as the "secondary winding" or "secondary" for short. It is not new to you that the form­er is connected to the source of supply, the latter being connected to the load.

When the number of turns of wire on the secondary is the same as the number on the primary, the secondary vol­tage is the same as the primary, and we get what is called a "one-to-one" transformer. In case, however, the number of turns on the secondary winding is greater than those on the primary, the output voltage is larger than the input voltage and the transformer is called a step-up transformer. On the other hand, the secondary turns being fewer in number than the primary, the transformer is known as a step-down transformer.

The transformer operates equally well to increase the voltage and to reduce it. By the way, the above process needs a negligible quantity of power. It is important to point out that the device under consideration will not work on d.c. but it is rather often employed in direct-current circuits.

The transformers are used in stepping up the voltages for distribution or transmission over long distances and then in stepping these voltages down. For example, three large step-up transformers are used to increase the potential to 275,000 volts for transmission over long-distance transmission lines. At the consumer's end of the line, in some distant locality, three step-down transformers are made use of to reduce that value (i.e., 275,000 volts) to 2,300 volts. Local trans­formers, in their turn, are expected to decrease the 2,300 volts to lower voltages, suitable for use with small motors and lamps. One could have some other transformers in the systems that reduce the voltage even further. All radio sets and all television sets are known to use two or more kinds of transformers. These are familiar examples showing that electronic equipment cannot do without transformers. The facts you have been given above illustrate the wide use of transformers and their great importance.

Exercises

I. Learn the following words, groups of words. Translate the sentences.

1. consumer — потребитель. Power transmission system connects the power station to the consumer.

2. to damage — разрушать, повреждать. The nearest power station was damaged.

3. induction coil — индукционная катушка. The induc­tion coil is connected to the circuit in order to increase its inductance.

4. input — вход; подводимая мощность; входной. The input power of this substation is limited.

5. local — местный. The voltage is reduced at local sub­stations.

6. maintenance — техническое обслуживание, уход. The maintenance of this new equipment is expensive.

7. number — число; номер. The number of nuclear power plants has increased in this country. What is the num­ber of your telephone?

8. output — выходная мощность; выходной. The sci­entists try to increase the output power of the genera­tors.

9. to point out — указывать. The achievements of Russia in power engineering were pointed out in my report.

10. primary — первичный; первичная обмотка трансфор­матора; secondary — вторичный, вторичная обмотка трансформатора. A simple transformer has a prima­ry and a secondary winding.

11. source of supply — источник питания. A battery is a source of supply.

12. to step down — понижать. What device is used to step down the voltage?

13. to step up — повышать. A transformer is used to step up and down the voltage.

14. value — величина. Let us compare these two given values.

15. whole — целый, весь. The students have translated the whole article.

II. Learn to recognize the following international words.

globe, laser, quantum, theoretical, induction, electron­ic, plastics, asbestos, volt

III. Translate the following groups of words.

to damage by lightning, secondary distribution line, the number of windings, to step up the current, source of supply, the whole world

индукционная катушка, число потребителей, пони­жать напряжение, вся страна, местные фабрики, пер­вичная обмотка

IV. Form as many words as possible using suffixes and prefixes. De­fine the parts of speech of the new words and translate them.

engine, apply, differ, electric, value, oppose, transform, magnet, conduct, neglect

V. Translate the following sentences.

1. Говорят, что этот прибор описан в предыдущей статье. 2. Считали, что ток течет от положительного потенциала к отрицательному. 3. Говорят, что мой друг — хороший математик. 4. Известно, что М.В. Ломоно­сов основал Московский университет. 5. Кажется, что это вещество имеет некоторые другие свойства. 6. Из­вестно, что переменный ток меняет свое направление.

VI. Form nouns from the following words using suitable suffixes.

construct, develop, consider, distribute, deflect, equip, connect, require, produce, state, suit

VII. For the word combinations given in (a) find the Russian equiva­lents in (b).

a) 1. a number of; 2. as a matter of fact; 3. on the basis of; 4. for this reason; 5. it goes without saying; 6. at last; 7. on the whole; 8. to step up; 9. to increase current; 10. to offer resistance; 11. electrical engineering; 12. to step down

b) 1. наконец; 2. повышать (напряжение); 3. оказы­вать сопротивление; 4. понижать (напряжение); 5. ряд; 6. увеличить ток; 7. на основе чего-л.; 8. по этой при­чине; 9. в целом; 10. электротехника; 11. на самом деле; 12. само собой разумеется

VIII. Translate the following sentences and define the functions of the word but.

1. The Fahrenheit scale is mainly used in English speaking countries but it is not used in Russia. 2. His scientific activity lasted but twenty years, but in these twenty years he did very much. 3. Motors are widely em­ployed not only in industry but also in everyday life. 4. There is but one measuring scale in the instrument. 5. Every­one took an examination in physics but Novikov. 6. A simple transformer is but a kind of induction coil.

IX. Arrange the following words in the pairs of synonyms.

a) 1. amount; 2. big; 3. matter; 4. application; 5. at present; 6. tube; 7. research; 8. to step down; 9. appliance; 10. minute; 11. arrow

b) 1. investigation; 2. device; 3. needle; 4. quantity; 5. substance; 6. to lower; 7. small; 8. large; 9. new; 10. use; 11. pipe

X. Arrange the following words in the pairs of antonyms.

a) 1. left; 2. increase; 3. beginning; 4. d.c.; 5. above; 6. step-up; 7. at rest; 8. high; 9. short; 10. more

b) 1. end; 2. low; 3. long; 4. step-down; 5. in motion; 6. less; 7. decrease; 8. below; 9. a.c.; 10. right

XI. Answer the following questions.

1. What is a transformer? 2. What is a transformer used for? 3. Are there any moving parts in a transformer? 4. Can a transformer be damaged by lightning? 5. What are the principal parts of a transformer? 6. How many windings are there in a transformer? 7. What winding is connected to a load? 8. What is the purpose of a step-up transformer? 9. What is known as a step-down transformer? 10. Does a transformer work on d.c.? 11. In what circuits is the trans­former used? 12. For what purpose are step-down transform­ers used? 13. Is your radio set equipped with a transform­er? 14. Can we do without transformers? 15. Are transform­ers used both in industry and in our homes?

XII. Compare:

1. A solenoid and an electromagnet. 2. A direct current and an alternating current. 3. A step-up transformer and a step-down transformer. 4. A stator and a rotor. 5. A primary winding and a secondary winding.

XIII. Make up the annotation of the text and retell it.

ЧЕЛЯБИНСКИЙ ГОСУДАРСТВЕННЫЙ АГРОИНЖЕНЕРНЫЙ УНИВЕРСИТЕТ

МЕТОДИЧЕСКИЕ УКАЗАНИЯ

по английскому языку

для развития навыков работы со спецтекстами

для студентов I и II курсов

по специальностям ЭАСХП и Электроснабжение

Челябинск

2007

Составитель Халупо О.И.