АНГЛИЙСКИЙ ЯЗЫК для энергетических специальностей

ДЕПАРТАМЕНТ ОБРАЗОВАНИЯ ИВАНОВСКОЙ ОБЛАСТИ

ОБЛАСТНОЕ ГОСУДАРСТВЕННОЕ БЮДЖЕТНОЕ ПРОФЕССИОНАЛЬНОЕ ОБРАЗОВАТЕЛЬНОЕ УЧРЕЖДЕНИЕ

«ИВАНОВСКИЙ ЭНЕРГЕТИЧЕСКИЙ КОЛЛЕДЖ»

Сорокина Е.А.

АНГЛИЙСКИЙ ЯЗЫК

для энергетических специальностей

Иваново, ОГБПОУ «ИЭК», 2015

Unit 1

Ohm's Law. Electric circuit.

I. Decimal fractions.

1. Translate into Russian

decimal fractions

numeration

denominator

O [ ou ]

Ohm

ampere

volt

point

Decimal fractions.

0.002- zero point two zeros two

1.1- one point one

5.36- five point three six

65.57- sixty-five point five seven

zero point seven

0.7 o point seven

point seven

2. Read these decimal fractions:

0.23 0.009 10.01 205.35 79.31 0.0003

II. Ohm's Law

1. Translate into Russian

current

resistance

voltage

law

times

to suppose

to equal

to divide

divided by

R Resistance equals voltage divided by current.

I Current equals voltage divided by resistance.

V = IR Voltage equals current times resistance.

3. Solve the following problems using the formulas of Ohm's Law.

Model: - Current equals 5 amp; resistance equals 10 ohms. How much is the voltage?

- Voltage equals current times resistance. 5 x 10 = 50 V

1) R = 80 ohms 2) R= 10.25 ohms 3) V = 50.05 V

V = 55 V I = 35 amp I = 120 amp

I = ? V = ? R = ?

4) 1= 10,500 amp 5) V = 20.05 V 6) I = 0.24 amp

V = 2,000 V R = 0.015 ohm R= 1.36 ohms

R = ? I = ? V = ?

III. Electric Circuit

1. Translate into Russian

circuit

conductor

function

difference

source

while

to reduce

to supply

to connect

to compare (with)

to pass through

to result in

to result from

to consist of

2. Translate the word - combinations:

Voltage source, to supply current, to reduce current, to connect the elements, to result from an open, to result in no current, trouble in a circuit.

3. Translate the sentence. Mind the word ,,while''

Current passes through circuit (a) while no current passes through circuit (b).

4. Translate into Russian

1. An open and a short are troubles in a circuit.

2. A trouble in a circuit results in no current in it.

3. What does an open in a circuit result in?

4. What does a short in a circuit result in?

5. What does a trouble in a circuit result from?

5. Read and translate the text

This is a circuit. Its elements are a voltage source, a resistor and a conductor. The circuit consists of a voltage source, a resistor and a conductor. A voltage source supplies current. A resistor reduces current. A conductor connects the elements of the circuit.

Compare circuit a with circuit b. What is the difference between them? Current passes through circuit a while no current passes through circuit b. Circuit b has an open. No current through circuit b results from an open. An open and a short are troubles in a circuit. A trouble in a circuit may result in no current in it.

a) b)

6. Complete these sentences, using the correct variant:

1.Circuit a consists of

a) resistors and conductors.

b) a voltage source and resistors.

c) a voltage source, a resistor and a conductor.

2. A voltage source

a) conducts current,

b) reduces current,

c) supplies current.

3. A conductor

a) connects the elements.

b) supplies voltage.

c) conducts current.

4. A resistor

a) connects the elements.

b) supplies current.

c) reduces current.

5. No current results from

a) an open.

b) a short.

7. Translate the words and distribute them into three columns. Mind the suffixes; the prefix:

Model: what? What kind of? What to do?

dependence dependent to depend on

difference, to differ, different, conductivity, to con­duct, conductor, to resist, resistant, resistance, resistor, resistivity, independent, independence

8. Answer the following questions:

1. What elements does a circuit consist of?

2. What is the function of a voltage source?

3. What is the function of a conductor?

4. What is the function of a resistor?

5. When is there no current in a circuit?

6. What does an open or a short result in?

7. What does no current in a circuit result from?

Unit 2

Series Circuit and Parallel Circuit

1. Translate into Russian

branch

line

value

voltage drop

series

parallel

main

in order (to)

(the) same

(the) whole

to use

2. Translate the word - combinations:

main line, parallel branches, the same value of voltage, different values of current, the whole circuit.

3. Translate the sentences. Mind the word ,,while''.

1.Circuit (a) is a series circuit while circuit (b) is a parallel circuit.

2.The value of voltage is the same in all the elements of a parallel circuit while the value of current is different .

3.The value of current is the same in all the elements of a series circuit while the value of current is different .

4. Fill in the verbs : "to connect", "consist of", "to equal", "to compare":

1. Resistance ... voltage divided by current. 2. See Fig 1; ... circuit (a) with circuit (b); are they different? 3. Circuit (a) ... a voltage source and two resistors. 4. The elements in circuit (b) are ... in parallel. 5.How many elements does circuit (b) ... ?

5. Read and translate the text

Series Circuit and Parallel Circuit

R1 R2 a) R1 b)

R2

c) d) R1 R2 R1

R2

Compare circuits a and b. Circuit a consists of a voltage source and two resistors. The resistors are connected in series. Circuit a is a series circuit. Circuit b consists of a voltage source and two resistors. The resistors are connected in parallel. Circuit b is a parallel circuit.

A parallel circuit has the main line and parallel branches.

In circuit b the value of voltage in R, equals the value of voltage in R₂. The value of voltage is the same in all the ele­ments of a parallel circuit while the value of current is different. A parallel circuit is used in order to have the same value of voltage.

In circuit a the value of current in R, equals the value of current in R₂. The value of current is the same in all the ele­ments of a series circuit while the value of voltage is different. A series circuit is used in order to have the same value of current. In R₁ V1=IR1 is the voltage drop in R1. In R₂ the voltage equals I*R₂; IR₂ is the volt­age drop in R₂. In circuit с a trouble in one element results in no current in the whole circuit. In circuit d a trouble in one branch results in no current in that branch only, a trouble in the main line results in no cur­rent in the whole circuit.

6 . Complete these sentences using the correct variant:

1. A parallel circuit has

a) parallel branches only.

b) the main line and parallel branches.

2. A parallel circuit is used in

a) to have the same value of current in order all the elements.

b) to have the same value of voltage in all the elements.

3. In a parallel circuit a trouble

a) results in no current in that branch in one branch only.

b) results in no trouble in the whole cir­cuit.

4. No current in a parallel cir-

a) results from a trouble in one branch.

b) results from a trouble in\he main

line.

5. The sum of IR voltage drops

a) equals the value of voltage in the circuit.

b) is less than the smallest voltage drop.

c) is more than the value of voltage in the circuit.

7. Complete the sentences using while. Follow the model:

Model: Resistors connected in series have the same value of current...

Resistors connected in series have the same value of current while resistors connected in parallel have the same value of voltage.

1. Resistors connected in series have different values of voltage while ....

2. A trouble in one element of a series circuit results in no current in the whole circuit while ....

3. In order to have the same value of current in all the elements, a series circuit is used while ....

4. No current in a parallel circuit results from a trouble in the main line while ….

8. Translate the words, mind the suffixes and the prefixes.

to differ- indifferent

equal- to equal

main- mainly

ampere +meter- ampermeter

conductor- semiconductor

use-to use

to connect- interconnection

to compare- comparative

supply+ water - water-supply

open- to open

9. Answer the following questions:

1. What type of circuit has the main line and parallel branches?

2. What type of circuit is used in order to have the same value of current in all the elements?

3. What type of circuit is used in order to have the same value of voltage in all the elements?

4. What does a trouble in the main line result in?

5. What does a trouble in a branch result in?

6. What does no current in a series circuit result from?

7. How much does the sum of IR voltage drops equal?

8. What is the difference between series and parallel circuits?

Unit 3

Meters

1. Translate into Russian

meter

battery

scale

readings

terminal

positive

negative

in this way

among

common

to calibrate

to measure

to take into

consideration

Функции местоимения ONE

Значения one

Примеры

Перевод

…один из…

(one of)

Nuclear energy is one of the forms of energy.

Ядерная энергия- одна из форм энергии.

Заменитель ранее упомянутого существительного (ones-мн.число)

The old turbine was a water turbine and the new one is a steam turbine.

Старая турбина бы­ла водной турбиной, а новая - паровая тур­бина.

One + модальный глагол

One can, one may-

можно

One must, one should-

нужно, следует

One should control the chain reaction

Следует контролировать цепную реакцию.

Неопределенно-личное подлежащее

(one -вы , тот)

One knows that these installations do not operate on nuclear power.

Вы, знаете что эти установки не работают на ядерной энергии.

2. Translate the sentences. Mind one.

1. The second sputnik was launched about a month after the first one.

2. There are many insulating materials from which one may choose.

3. Some substances are efficient conductors, others, poor ones.

4. One uses special devices to measure current, voltage, and resistance.

5. One should take into consideration the difference between these circuits.

6. One should take into consideration that the ammeter is connected to the circuit in series.

7. What should one take into consideration using the ohmmeter?

8. One must choose only one of those variants.

3. Translate the sentence. Mind Complex Subject, one.

The new method proved to be much more efficient that the old one.

4. Translate the word -combinations.

the most common, the value of resistance, the measured value, in order to measure, to be connected in series.

5. Read and translate the text.

Among the most common meters used there are the ohmmeter, the ammeter and the voltme­ter. The ohmmeter is used to measure the value of resistance. It consists of a milliammeter cali­brated to read in ohms, a battery and resistors. The meter is connected in parallel and the circuit is not opened when its resistance is measured. The readings on the scale show the measured value.

The ammeter is used to measure the value of current. When the ammeter is used the circuit should be opened at one point and

the terminals of the meter should be connected to it. One should take into consideration that the positive terminal of the meter is connected to the posi­tive terminal of the source; the negative termi­nal - to the negative terminal of the source.

The ammeter should be connected in series. The readings on the scale show the measured value.

Wattmeter

A wattmeter is used to measure the value of power. It is connected to the circuit directly. A wattmeter consists of coils: two fixed coils and a coil which moves in the magnetic field produced by the fixed coils. Wire used for the coils must have a high resistance; the fixed coils are in series with the load, the moving coil is connected across the line in series with a resistance. When a wattmeter is used, the readings on its scale show the value of power being used

6. Complete the sentences using the correct variant:

1. The ammeter is

a) a common meter.

b) an uncommon meter.

2. In order to measure the value of current

a) the ohmmeter is used.

b) the voltmeter is used.

c) the ammeter is used.

3. A meter has

a) positive terminals only.

b) negative terminals only.

c) positive and negative terminals.

4. When the ammeter is used

a) the circuit should be opened.

b) the circuit should not be opened.

5. The ammeter should be connected

a) in series,

b) in parallel.

6. One should take into consideration that

a) the positive terminal should be connected to the negative terminal.

b) the positive terminal should be con­nected to the positive terminal of

the source.

7. Complete these sentences using while. Follow the model.

Model: The ammeter is used to measure the value of current....

The ammeter is used to measure the value of current while the ohmmeter is used to measure the value of resistance.

1. The ohmmeter is used to measure the value of resistance……..

2. The ammeter is connected in series………

3. When the ammeter is used to measure the value of current the circuit
should be opened……..

4. A wattmeter consist of two fixed coils a coil which moves…

8. Translate the text in writing.

Meters

One of the important things that an engineer should take into con­sideration is "how much?" How much current is this circuit carrying? What is the value of voltage in the circuit? What is the value of resis­tance? In fact, to measure the current and the voltage is not difficult at all. One should connect an ammeter or a voltmeter to the circuit and read off the amperes and the volts.

Common ammeters for d. c. measurements are the ammeters of the magneto-electric system. In an ammeter of this type an armature coil rotates between the poles of a permanent magnet; but the coil turns only through a small angle. The greater the current in the coil, the greater the force, and, therefore, the greater the angle of rotation of the armature. The deflection is measured by means of a pointer connected to the armature and the scale of the meter reads directly in amperes.

When the currents to be measured are very small, one should use a galvanometer. Some galvanometers detect and measure currents as small as 10of an ampere per 1 mm of the scale.

A voltmeter is a device to be used for measuring the potential differ­ence between any two points in a circuit. A voltmeter has armatures that move when an electric current is sent through their coils. The deflection, like that of an ammeter, is proportional to the current flowing through the armature coil.

A voltmeter must have a very high resistance since it passes only very small currents which will not disturb the rest of the circuit. An , ammeter, on the other hand, must have a low resistance, since all the current must pass through it. In actual use the ammeter is placed in se­ries with the circuit, while the voltmeter is placed in parallel with that part of the circuit where the voltage is to be measured.

In addition to instruments for measuring current and voltage, there are also devices for measuring electric power and energy.

9. Answer the questions.

1. What is the ammeter used for?

2. What is the voltmeter used for?

3. What is the ohmmeter used for?

4. What terminals does a meter have?

5. Should the measured circuit be opened when the voltmeter is used?

6. Should the measured circuit be opened when the ammeter is used?

7. In what way should the voltmeter be connected to the circuit?

8. In what way should the ammeter be connected to the circuit?

9. What is the difference between a voltmeter and an ammeter?

10. What common meters are used to measure the values in a circuit?

11. What is the wattmeter used for?

12. What does it consist of?

13. In what way are the elements connected?

14. What do the readings on the scale show?

10. Describe these circuits
    
    

a) R1 R2 b) R1 R2

+ -

+ -

R1

R1

c) d) R2

R2 R2

+ - + -

Unit 4

Resistors.

1. Translate into Russian

capacity

power

heat

rate

low

high

fixed

in case

any

charge

pressure

protection in case

since

variable

the (more)

the (more)

to rise

to rate

to move

to left

to produce

to change

to vary

2. Translate the word- combinations:

Constant value, fixed resistors, high conductivity, free electrons, variable resistor, current- caring, capacity.

3. Translate into Russian using чем ... тем:

1. The more one studies nature, the better one knows its laws.

2. The longer one learns, the more one knows.

3. The higher the atmosphere, the less is its pressure.

4. The heavier the object, the more work one has to do in order to lift it.

5. The greater the number of free electrons in any metal, the higher is its conductivity.

4. Translate into Russian. Mind no.

1.There is no energy in this machine.

2. No charges move through an open circuit.

3. No material is a perfect conductor of electricity.

4. No electric machinery is used without protection.

5. No special material is needed in this case.

5. Read and translate the text.

Resistors

A resistor is one of the most common elements of any circuit. Re­sistors are used:

1. to reduce the value of current in the circuit;

2. to produce IR voltage drop and in this way to change the value of the voltage.

When current is passing through a resistor its temperature rises high. The higher the value of current the higher is the temperature of a resistor. Each resistor has a maximum temperature to which it may be heated without a trouble. If the temperature rises higher the resistor gets open and opens the circuit.

Resistors are rated in watts. The watt is the rate at which electric en­ergy is supplied when a current of one ampere is passing at a potential difference of one volt. A resistor is rated as a 1-W resistor if its resis­tance equals 1,000,000 ohms and its current-carrying capacity equals 1/1,000,000 amp, since P = E x I = IR x I = I²R where P - power is given in watts, R - resistance is given in ohms and I - current is given in amperes.

If a resistor has a resistance of only 2 ohms but its current-carrying capacity equals 2,000 amp, it is rated as a 8,000,000-W resistor.

Some resistors have a constant value - these are fixed resistors, the value of other resistors may be varied - these are variable resistors.

6. Complete the sentences using the correct variant:

1. A resistor is used a) to measure the resistance.

b) to reduce the current.

c) to change the resistance.

d) to produce IR voltage drop.

2. When current passes through a re­sistor a) its temperature drops.

b) its temperature rises.

3. Resistors are rated a) in ohms.

b) in volts.

c) in watts.

4. Power is given a) in amperes,

b) in watts.

5. Fixed resistors have a) a constant value.

b) a variable value.

6. The value of a variable resistor a) is fixed.

b) is varied.

7. A two-ohm resistor rated as a a) has a current-carrying capac­ity 8,000,000- W resistor equal to 2,000 amp.

b) has a current-carrying capac­ity equal to 200 amp.

7. Complete the sentences using while.

1. The value of a fixed resistor is constant..........

2. Current-carrying capacity is given in amperes..........

3. The lower the value of current, the lower is the temperature of a resis­tor ..........

4. An electric source produces energy..........

8. Translate the words. Mind the suffixed .

Activity, active, act, active by, additional, add, addition, additionally,

Equalize, equally, equality, equal, differ, different, difference, common,

commonly, use, usefully, useful, user.

9. Answer the questions:

1. What is a resistor used for?

2. When does the temperature of a resistor rise?

3. What element is used to change the value of voltage?

4. How are resistors rated?

5. What types of resistors do you know?

6. When does a resistor get open?

7. What does an open resistor result in?

8. What is the difference between a fixed resistor and a variable resistor?

9. How much is the current-carrying capacity of a two-ohm resistor?

10. What resistors have a variable value?

10. Translate the text in writing

Rheostat

A rheostat is a resistor whose resistance value may be varied. Thus,

a rheostat is a variable resistor.

It is used to change the resistance of circuits, and in this way to vary

the value of current.

A rheostat consists of a coil and a switch. Take into consideration

that wire used for the coil must have a very high resistance. When a

rheostat is used its terminals are connected in series with the load. The

switch is used to change the length of the wire through which the measured

current passes. The resistance may be changed to any value from

zero to maximum.

The longer the rheostat wire used in the circuit, the greater is the resistance.

1. What type of resistor is a rheostat?

2. What is a rheostat used for?

3. In what way does a rheostat vary the value of current?

4. What elements does a rheostat consist of ?

5. In what way are the terminals connected with the load?

6. What is the function of the switch?

Unit 5

Electric Cells

1. Translate into Russian.

cell

output

bulb

to light

to increase

to substitute

and so on=et cetera(etc)

2. Read the words and put down their Russian equivalents:

electrode

electrolyte

to start

to operate

to isolate

3. Translate the word - combinations . in writing.

current capacity

resistor temperature

voltage output

current value

to operate well

to operate badly

to increase the voltage output

to substitute the resistor

4. Translate into Russian. Say-ing forms are Participle I, Gerund or Verbal Noun

to start supplying energy

to stop operating

to start lightening

to stop lightening the bulbs

5. Read and translate into Russian. Mind one:

1. The element has a trouble. It operates badly. It should be substituted by a new one.

2. The element with a trouble was substituted with a new one and the cell started operating.

6. Read and translate the text.

Electric Cells

-An electric cell is used to produce and supply electric energy. It consists of an electrolyte and two electrodes. Electrodes are used as terminals, they connect the cell to the circuit - current passes through the terminals and the bulb lights.

Cells can be connected in series, in parallel and in series-parallel. In order to increase the current capacity cells should be connected in parallel. In order to increase the voltage output cells should be connected in series. In case a battery has a large current capacity and a large voltage output, its cells are connected in series-

parallel.

When cells are connected in series the positive terminal of one cell

is connected to the negative terminal of the second cell, the positive terminal of the second cell - to the negative terminal of the third ... and so on.

When cells are connected in parallel their negative terminals are connected together and their positive terminals are also connected.

In case a cell has a trouble it stops operating or operates badly. This cell should be substituted by another one.

7. Complete the sentences using the correct variant:

1. A cell is used

a) to increase the voltage output.

b) to reduce the current capacity.

c) to supply electric energy.

2. The terminals of a cell are used

a) to conduct current.

b) to increase voltage.

c) to connect the battery to a circuit

3. When cells are connected in series

a) all the positive terminals are

connected together.

b) all the negative terminals are

connected together.

c) the positive terminal of one cell is connected to the negative

terminal of the second.

4. Cells are connected in series in order

a) to increase the current capacity.

b) to increase the voltage output.

5. In order to increase the current capacity

1. cells are connected in series,

2. cells are connected in parallel.

8. Destitute the words into columns. Mind the suffixes and the prefixes.

Model: what? What kind of? What to do? How?

Failure, fail, faulty, overestimate, consumer, act, impossibility, carelessly, noisy, easily, numerous, possible, power, powerful, clockwise, superconductor, output, operate.

9. Answer the following questions :

1. What is a cell used for?

2. What does a cell consist of?

3. What is the function of the terminals?

4. In what way are cells connected in order to increase the voltage output?

5. In what way are cells connected in order to increase the current capacity?

6. In what way are the terminals of series cells connected?

7. In what case does a cell stop operating?

8. What should be done in case it stops operating?

Unit 6

Capacitors

1. Translate into Russian.

сapacitor

insulator

frequency

distance

advantage

disadvantage

plate

part

reason

besides

provided that

for this reason

c-centigrade

to store

to apply

to move

to prevent

2. Translate the word- combinations

paper insulators

air insulators

electrolyte capacitors

advantages of electrolyte capacitors

disadvantages of air insulators

cells under test

capacitors in common use nowadays

radio sets under test

PC in common use nowadays

a radioman

radio work

radio parts

telephone and radio work

3. Translate into Russian. Mind provided that.

1. A circuit operates well provided that it does not have any trouble.

2. The bulb lights provided that the circuit is connected to the cell.

3. A cell supplies energy provided that its electrodes are of different mate­rials.

4. Read and translate the text

Capacitors.

A capacitor is one of the main elements of a circuit. It is used to store electric energy. A capacitor stores electric energy provided that a voltage source is applied to it.

The main parts of a capacitor are metal plates and insulators. The

function of insulators is to isolate the metal plates and in this way to

prevent a short.

In the diagram one can see two common types of capacitors in use

nowadays: a fixed capacitor and a variable one. The plates of a fixed

capacitor cannot be moved; for this reason its capacity does not change.

The plates of a variable capacitor move; its capacity changes. The

greater the distance between the plates, the less is the capacity of a capacitor.

Variable capacitors are commonly used by radiomen; their

function is to vary the frequency in the circuit. Fixed capacitors are

used in telephone and radio work.

Fixed capacitors have insulators produced of paper, ceramics and

other materials; variable capacitors have air insulators. Paper capacitors

are commonly used in radio and electronics; their advantage is their

high capacity: it may be higher than 1,000 picofarad.

Besides, electrolyte capacitors are highly in use. They also have a

very high capacity: it varies from 0.5 to 2,000 microfarad. Their disadvantage is that they change their capacity when the temperature

changes. They can operate without a change only at temperatures not

lower than -40° C. ,

Common troubles in capacitors are an open and a short. A capacitor

stops operating and does not store energy in case it has a trouble. A capacitor

with a trouble should be substituted by a new one.

5. Complete these sentences using the correct variant

1. A capacitor is used

a) to supply voltage.

b) to increase the voltage output.

c) to store energy.

2. The main parts of a capacitor are

a) insulators only.

b) metal plates only.

c) metal plates and insulators between

them.

3. The function of insulators is

a) to store energy.

b) to isolate the metal plates.

c) to prevent a short between the

metal plates

4. The capacity of a capacitor depends

on

a) the size of the plates.

b) the distance between the plates.

c) the material of the insulators.

5. The capacity of a fixed capacitor

a) is constant,

b) is varied.

6. The plates of a variable capaci

tor

a) can be moved,

b) cannot be moved.

7. In order to charge a capacitor a

voltage source is applied

a) to the metal plates.

b) to the insulators.

8. The greater the distance between

the plates,

a) the greater is the capacity of a

capacitor.

b) the less is the capacity.

9. Variable capacitors have

a) air insulators.

b) paper insulators.

c) ceramic insulators.

10. Electrolyte capacitors have

a) a very low capacity.

b) a very high capacity.

11. In case a capacitor has a trouble a) it operates.

b) it stops operating.

6. Complete these sentences using while. Follow the model on page 13:

1. The plates of a fixed capacitor cannot be moved to vary the capacity ...

2. The capacity of a variable capacitor is varied.......

3. Electrolyte capacitors change their capacity when the temperature changes.......

4. The less the distance between the plates, the greater is the capacity ...

5. When a capacitor has no trouble it stores energy.......

7. How many parts does each word consist of? What are the stems? Translate the words and their stems.

Model: un-doubt-ed-ly

failure, indifferent, uncommonly, unequality, numerously, uselessly, noiseless, advantageous.

8. Pair work. Put these questions to your groupmate and ask him/her to answer them.

1. What is a capacitor used for?

2. What are the main parts of a capacitor?

3. What is the function of insulators?

4. What does the capacity of a capacitor depend on?

5. What is the difference between a fixed capacitor and a variable one?

6. What should be done in order to change a capacitor?

7. What is the relation between the value of capacity and the distance of plates?

8. What type of insulators have variable capacitors?

9. What should be done in case a capacitor has a trouble?

Unit 7

Conductors and Insulators

1. Translate into Russian.

carbon

enough

plastics

wise

cheap

copper

decrease

load

make smb (smth)

do smth

thus

difficulty

rubber

since

increase

to decrease

2. Translate the word- combinations

diagram

coefficient

function

transformer

to transfer

3. Translate into Russian. Mind provided that.

1. Copper conductors are widely used since they are much cheaper than silver ones.

2. A minimum voltage drop is produced in copper wire conductors since they have a low resistance.

3. A bulb connected to an open circuit does not light since an open circuit has no current.

4. Read and translate the text

Conductors and Insulators

Conductors are materials having a low resistance so that current easily passes through them. The lower the resistance of the material, the more current can pass through it.

The most common conductors are metals. Silver and copper are the best of them. The advantage of copper is that it is much cheaper than silver. Thus copper is widely used to produce wire conductors. One of

the common functions of wire conductors is to connect a voltage source to a load resistance. Since copper wire conductors have a very low re­sistance a minimum voltage drop is produced in them. Thus, all of the applied voltage can produce current in the load resistance.

It should be taken into consideration that most materials change the value of resistance when their temperature changes.

Metals increase their resistance when the temperature increases while carbon decreases its resistance when the temperature increases. Thus metals have a positive temperature coefficient of resistance while carbon has a negative temperature coefficient. The smaller is the tem­perature coefficient or the less the change of resistance with the change of temperature, the more perfect is the resistance material.

Materials having a very high resistance are called insulators. Cur­rent passes through insulators with great difficulty.

The most common insulators are air, paper, rubber, plastics. Any insulator can conduct current when a high enough voltage is applied to it. Currents of great value must be applied to insulators in or­der to make them conduct. The higher the resistance of an insulator, the greater the applied voltage must be.

When an insulator is connected to a voltage source, it stores electric charge and a potential is produced on the insulator. Thus, insulators have the two main functions:

1. to isolate conducting wires and thus to prevent a short between them and

2. to store electric charge when a voltage source is applied.

5. Complete these sentences using the correct variant

Insulators are materials having

a) low resistance.

b) high resistance.

Current passes through conductors

a)easily.

b) with great difficulty.

Copper and silver are

a) common conductors.

b) common insulators.

Air, paper and plastics are

a) common insulators.

b) common conductors.

In case a high voltage is applied to an insulator

a) it does not conduct current.

b) it conducts current.

Insulators are used

a) to store electric charge.

b) to reduce voltage.

c) to prevent a short between conducting wires.

Metals increase their resistance

a)when the temperature de­creases.

b)when the temperature in­creases.

Carbon decreases its resistance

a)when the temperature increases.

b) when the temperature de­creases.

Metals have

a) a positive temperature coefficient of resistance.

b) a negative temperature coef­ficient of resistance.

6. Complete the sentences using while.

1. Conductors have a low resistance……

2. Current passes through insulators with great difficulty….

3. Metals are common conductors…..

4. To make insulators conduct, currents of great value must be applied….

5. Carbon decreases its resistance when the temperature increases ....

6. Metals have a positive temperature coefficient of resistance ....

7. Which of the words are adjectives? adverbs? Why?

easily, equal, noisy, numerous, faulty, anticlockwise, eastwards well carelessly, powerful, traceable, good, simply, comfortable, useful, north­ward, dangerous, businesslike, naturally, inferior, bad

8. Pair work. Put these questions to your groupmate , and ask him/her to answer them.

1) What is the difference between conductors and insulators?

2)How does current pass through insulators?

3)What materials are commonly used to produce insulators?

4)What materials are commonly used to produce conductors?

5)In what case do insulators conduct current?

6)How does resistance change when the temperature decreases?

Unit 8

Transformers

1. Translate into Russian

iron

primary

frequency

due to

coil

time

device= instrument

core

winding

turn

to step up

to step down

to receive

2. Put down the Russian for:

iron core

closed core

input voltage

output voltage

primary winding

secondary winding

step-up transformer

step-down transformer

3. Read and translate the text.

Transformers

A transformer is used to transfer energy. Due to the transformer electric power may be transferred at a high voltage and reduced at the point where it must be used to any value. Besides, a transformer is used to change the voltage and current value in a circuit.

A two-winding transformer consists of a closed core and two coils (windings). The primary winding is connected to the voltage source. It receives energy. The secondary winding is connected to the load resis­tance and supplies energy to the load.

The value of voltage across the secondary terminal depends on the number of turns in it. In case it is equal to the number of turns in the primary winding the voltage in the secondary winding is the same as in the primary. In case the secondary has more turns than the primary the output voltage is greater than the input voltage. The voltage in the secondary is greater than the voltage in the primary by as many times as the number of turns in the secondary is greater than the number of turns in the pri­mary. A transformer of this type increases or steps up the voltage and is called a step-up transformer. In case the secondary has fewer turns than the primary the output voltage is lower than the input. Such a trans­former decreases or steps down the voltage, it is called a step-down transformer.

Compare T₁ and T₂ in the diagram. T1 has an iron core. For this rea­son it is used for low-frequency currents. T₂ has an air core and is used for high frequencies.

Common troubles in transformers are an open in the winding, a short between the primary and the secondary, and a short between turns. In case a transformer has a trouble it stops operating or operates badly. A transformer with a trouble should be substituted.

4. Complete the sentences using the correct variant:

A transformer is used

1. to store charge.

2. to prevent the change of energy.

3. to transfer energy.

4. to change the voltage and current value in a circuit.

Electric power is trans­ferred at a

high voltage and reduced to any value

1. due to resistors.

2. due to capacitors.

3. due to transformers.

A transformer consists of

1. cores only.

2. the primary and the secondary windings.

3. a core and the primary and the secon­dary windings.

The function of the pri­mary is

a. to prevent the change of voltage.

b. to supply energy .

c. to receive energy.

The function of the secondary is

a. to receive energy
b. to supply energy

c. to transfer energy.

A step-up transformer is used

a) to step down or decrease the secondary voltage.

b) to step up or increase the primary volt­age.

A step-down transformer is used

a) to step down the secondary voltage

b) to step down the primary voltage.

A transformer with an iron core

a) is used for high-frequency currents

b) is used for low-frequency currents.

A transformer with an air core is used

a) for high-frequency currents and for low frequency currents.

b) for high-frequency currents only.

In a step-up transformer

a) the number of turns of the secondary

winding is greater than the number of turns of the primary. b)the number of turns of the primary winding is greater than the number of turns of the secondary.

A transformer should be substituted

a) in case it has an open in the winding.

b) in case it has a short between the pri­mary and the secondary.

c) in case it has a short between turns.

5. Complete these sentences using while. Follow the model on page 13.

1. The secondary winding of a transformer is connected to the load re­sistance ....

2. The primary winding receives energy ....

3. A step-down transformer decreases the primary voltage ....

4. An air core transformer is used for high-frequency currents.......

5. In a step-up transformer the number of turns of the secondary winding is greater than the number of turns of the primary winding...... Look up the meanings of these words in a dictionary, if necessary. How are they translated in the sentences below? Mind the word order. place, iron, lift, house, light, heat, use, form, change, wire

1. The conductor wires are placed high up.

2. Electromagnets lift iron weights.

3. The plastic box houses the conducting and the insulating elements of the apparatus.

4. The house is lighted and heated by solar energy.

5. The light went out. Light the candle, please.

6. After the metal was heated it changed its colour to a red heat.

7. Numerous changes are taking place in the uses of atomic energy.

8. Electric power is used universally.

9. The newly made invention has a great number of uses.

10. The wire and the source form a circuit.

7. Pair work. Put these questions to your groupmate and ask him/her to answer them.

1. What is a transformer used for?

2. What does a transformer consist of?

3. What is the function of the primary winding?

4. What is the function of the secondary winding?

5. What type of transformer is called a step-up transformer?

6. What type of transformer is used for high-frequency currents?

7. What type of transformer is called a step-down transformer?

8. What type of transformer is used for low-frequency currents?

9. What is the relation between the number of turns in the windings and the value of current?

10. What are common troubles in a transformer?

11. What should be done in case a transformer has a trouble?

Unit 9

Types of Current

1. Translate into Russian

seldom

alternating

direct

direction

flow

necessary

to consider

use

2. Read the words and write down their Russian equivalents:

cycle

type

per second

3. Put down the Russian for:

one time

five times

sixty times

3. Read and translate the text

Types of Current

Current is a flow of electricity through a circuit. Let us consider two main types of current: direct and alternating. A direct current (d.c.) flows through a conducting circuit in one direction only. It flows pro­vided a direct voltage source is applied to the circuit.

An alternating current (a.c.) is a current that changes its direction of flow through a circuit. It flows provided an alternating voltage source is applied to the circuit. Alternating current flows in cycles. The number of cycles per second is called the frequency of the current. In a 60-cycle alternating current circuit the current flows in one direction 60 times and in the other direction 60 times per second.

It is easy to transform a.c. power from one voltage to another by a transformer. Transformers are also used to step down the voltage at the receiving point of the line to the low values that are necessary for use.

When necessary a.c. can be changed into d.c. but this is seldom nec­essary.

3. Complete the sentences using the correct variant:

D.c. is a current that

a) changes its direction of flow.

b) flows in one direction.

A.c. flows provided

a) a direct voltage source is applied.

b) an alternating voltage source is applied.

In an alternating cur-circuit second.

a) current flows in one direction 60 times per rent

b) current flows in one direction 60 times and in the other direction 60 times per second.

A.c.

a) can be changed into d.c.

b) cannot be changed into d.c.

3. Complete these sentences using while. Follow the model on page 13.

1. An alternating current changes its direction of flow….

2. A direct current flows provided a direct voltage source is applied…

3. Look up the meanings of these words in a dictionary, if necessary. How are they translated in the sentences below? Mind the word order.

balance, amount, water, fuel, control, measure, cause, increase

1. The fuel-and-energy balance is important for industry.

2. Conductivity increases with heating.

3. The machine should be re-fuelled.

4. The amount of power used in the world in a year amounts to 12,000 million tons of equivalent fuel.

5. Water barriers are crossed by submarine cables.

6. The instrument is foot-controlled by a pedal.

7. Force and motion go together; one is a cause, the other, a result.

8. An electromotive force causes the electrons to move.

9. Control of the apparatus is placed on the panel.
   10. The volt is a measure of electromotive force.

3. Answer the following questions:

1. What is current?

2. What types of current do you know?

3. When does a direct current flow?

4. What type of current is called an alternating current?

5. What type of current is called a direct current?

6. What is called the frequency of current?

7. What device is used to transform a.c. power from one voltage to another?

8. Is it often necessary to change a.c. into d.c?

Unit 10

Inductance and Mutual Inductance

1. Translate into Russian

inductance

close

coil

though

size

unit

fast

mutual

definite

that is

to induce

to provide

to touch

to bring

2. Translate into Russian and put down the Russian equivalents. Then translate them back into English (orally).

a. definite value

primary coil

wire coil

mutual inductance

varying current

one ampere per second

b. 1. Coils of wire are called inductors.

2. Two coils are brought close together.

3. A source of current is applied to one of the coils.

4. Mutual inductance is measured in henries.

3. Which of the words are nouns and which are verbs?

resistor, resist, resistance; induce, induction, inductor, inductance; conductor, conduct, conductance; compute, computer

4. Read and translate the text

Inductance and Mutual Inductance

Any conductor has some definite value of inductance. The induc­tance of a conductor shows how well it can provide induced voltage.

Elements of a circuit with a definite value of inductance are coils of wire called inductors. The inductance of a coil depends upon its size and material. The greater the number of turns of a coil, the higher is its inductance. An iron core also increases the value of inductance. Coils of this type are used for low-frequency currents while coils with an air core are used for high-frequency currents. Two coils A and В are brought close together and a source of vary­ing current is applied to coil A. If a measuring device is connected across the terminals of coil В it will be found that a voltage is induced in this coil though the two coils do not touch. The secondary voltage, that is the voltage in coil B, is called induced voltage and energy from one coil to the other transfers by induction. The coil across which the current is applied is called the pri­mary; that in which voltage is in­duced is called the secondary. The primary and the secondary coils have mutual inductance. Mutual induc­tance is measured in the same units as inductance, that is in henries.

Thus, when a rate of change of one ampere per second in the primary coil will produce one volt in the sec­ondary coil, the two coils have one henry of mutual inductance. It should be taken into consideration that induction by a varying cur­rent results from the change in current not in the current value. The faster the current changes, the higher the induced voltage.

5. Complete the sentences using the correct variant

Any conductor has

1. Some definite value of resistance.

2. Some definite value of inductance.

Any conductor can provide

1. Electric power

2. Induced voltage

Elements with a definite value of inductance

a) are called inductors.

b) are called coils.

c) are called sources.

The inductance of a coil de­pends upon

a) its size.

b) its core.

c) its material.

d) its number of turns.

An iron core

a) increases the value of inductance.

b) decreases the value of inductance.

The value of mutual induc­tance is measured

a) in watts.

b) in henries.

Induction by a varying current

a) results from the change in current.

b) results from the change in the cur­rent value.

The faster the current changes

a) the lower is the induced voltage.

b) the higher is the induced voltage.

6. Complete these sentences using while.

1. An air core decreases the value of inductance.......

2. An iron core is used for low-frequency currents.......

3. The coil in which voltage is induced is called the secondary......

7. Read the following words. What are their prefixes? stems? suffixes?

Translate the words into Russian:

generate, inefficient, abnormally, underproduction, anticlockwise, counter­action, demagnetize, superconductor, unequality, misunderstand, un­equally, equality, interrelation, non-conductor, input, simplify, waterless, irregularity, redden, enlargement, unreadable, southward, clockwise, fully, noisy, typically, impossible, superconductor

8. Answer the following questions:

1. What value of inductance do conductors have?

2. What is the function of inductors?

3. What are elements with a definite value of inductance called?

4. What does the inductance of a coil depend upon?

5. How does the inductance of a coil depend upon the material of its core?

6. In what units is the value of mutual inductance measured?

7. What does induction by a varying current result from?

8. What is the relation between the current changes and the value of in­duced voltage?

9. What is the unit of resistance?

10. What is the unit of potential difference?

11. For what type of current is an air core used?

12. What is the relation between the number of turns of a coil and its in­ductance value?

Unit 11

Components of Electric Circuits

Translate into Russian

1. Incandescence

2. incandescent lamp

3. switch

4. fuse

5. relay

6. copper

7. steel

8. according to

9. etc.= et cetera

10. to convert

11. to utilize

12. to deliver

Read the words and put down their Russian equivalents:

1. aluminium

2. chemical

3. generator

4. material

5. mechanical

6. thermal

7. motor

3. Translate into Russian:

a. convertible values, protected power source, various fuses, variable re­sistors, chemical cells

b. cells delivering electric power generator converting mechanical energy circuits utilizing common fuses

c. Primary cells deliver electric power.

Different kinds of energy can be converted into electric energy. Protection devices are utilized in any circuit.

4. Read and translate the text.

Components of Electric Circuits

The main components of any circuit are devices that produce and utilize electric energy. They are: 1. power sources, 2. utilizing loads, 3. connecting conductors.

The most common power sources are electric generators and primary cells. Electric generators convert chemical energy into electric energy.

Loads include electric heaters, electric motors, incandescent lamps, etc. Motors convert electric energy into mechanical, incandescent lamps and heaters convert electric energy into light and heat. Utilizing devices or loads convert electric energy into thermal, mechanical or chemical energy.

Electric power is delivered from power sources to loads by electric wires. According to their material, wires can be aluminium, copper, steel, etc.

Besides, electric circuits use different types of switches, protection devices (relays and fuses), and meters (ammeters, voltmeters, wattme­ters, etc.).

5. Complete the sentences using the correct variant:

1. The main components of electric circuits are

a) loads and wires.

b) power sources, load and wires.

2. Power sources are used

a) to produce electric energy.

b) to deliver it to the loads.

3. Electric conductors are used

a) to connect the circuit elements.

b) to deliver electric power.

4. Protection devices are utilized

a) in some circuits.

b) in any circuit.

5. A switch is utilized

a) in some circuits.

b) in any circuit.

6. Answer these questions:

1. What are the main components of an electric circuit?

2. What is the function of an electric source?

2. What is the function of a load?

2. What is the function of wire conductors?

2. What other devices are utilized in a circuit?

Unit 12

Power transmission

1. Translate into Russian

efficiency

ignorance

dependence

cost

installation

cross-section

loss

length

long

exceedingly per cent

to transmit

to offer

to ignore

to depend (on)

to exceed

2. Read the words and put down their Russian equivalents:

line

station

engineer

engineering

3. Translate into Russian:

a. line efficiency

voltage loss

power station

b. interdependent values

interconnected sources

changing power efficiency

c. exceedingly high power losses _

exceedingly inefficient energy sources _

d. One can ignore these exceedingly low power losses.

One should take into consideration the interdependence of these values.

One should not ignore the high cost of these installations.

4. Read and translate the text

Electric Lines and Their Efficiency

Wires are used to deliver electric power and to interconnect different components of electrical installations. Conductors used for electric wiring are commonly produced of copper and aluminium. Aluminium is widely used nowadays due to its low cost. Copper is also widely used in electrical engineering but its cost is much higher.

Wires connecting the components of various installations may be in­sulated. They may also be used without insulation. Since in short lengths of wire power loss is exceedingly low one can ignore it. In long wires (longer than 10 m), power loss cannot be ignored since it is rather high. Power loss in a line should not exceed a definite value. If this value is exceeded the line becomes inefficient.

One should know that the efficiency of a line is not constant - it may change. The value of the line efficiency depends on the load: the greater the load the lower is the line efficiency. At voltage losses of 2 to 5 per cent the efficiency of a line is 98-95 per cent. Protecting devices, fuses and relays are used to protect the circuit against overcurrents and short-circuits.

5. Complete the sentences using the correct variant:

1. Aluminium is used due to its

a) high cost.

b) low cost and high efficiency.

2. Cross-section of different conductors

a) varies.

b) is the same.

3. Power loss can be ignored

a) in short wires.

b) in long wires.

4. A definite value of loss

a) can be exceeded.

b) should not be exceeded.

5. Electric lines nowadays are

a) efficient.

b) inefficient.

6. Installations are protected

a) by switches.

b) by fuses.

6. Complete these sentences using while. Follow the model on page 13:

1. The cost of aluminium is comparatively low while ....

2. In a short length of wire power loss is extremely low while ....

3. The greater the load the lower is the efficiency of the line ....

7. Answer these questions:

1. Why is aluminium widely used nowadays?

2. Is its cost very low or comparatively low?

3. What is the cross-section of copper conductors?

4. May one ignore power loss in short wire? Why?

5. What does the efficiency of a line depend on?

6. What are fuses used for?

7. When does a line become inefficient?

8. Think of three questions about this extract and put them to your groupmate.

con'sumer - потребитель; relation - отношение

When electric energy is produced at the power station, it is to be trans­mitted over electric wires to the consumer. Wire conductors offer resis­tance to the current flow; the longer the wire, the greater is its resistance to the current flow. Accordingly, the higher the offered resistance, the greater are the heating losses in the wire.

Unit 12(продолжение)

Transmission Lines

1. Translate into Russian

area

network

support

cord

bus

enterprise

accordingly

as to

by means of

indoor

overhead

to serve

to baze

to term

to support

to distribute

2. Put down the Russian for:

long distance

length of transmission lines

power consumption

distribution centre

city area

interdependent city areas

interacting underground lines

interconnected overhead lines

transmitting power lines

transmission and distribution lines

overhead lines

step-down transformer

indoor lines

underground lines

3. Read and translate the text

Transmission Lines

A power system is an interconnection of electric power stations by high voltage power transmission lines. Nowadays the electricity is trans­mitted over long distances and the length of transmitting power lines varies from area to area.

A wire system is termed a power line in case it has no parallel branches and a power network in case it has parallel branches.^

According to their functions, power lines and networks are subdivided into transmission and distribution lines.

Transmission lines serve to deliver power from a station to distribu­tion centres. Distribution lines deliver power from distribution centres to the loads.

Lines are also classed into: 1) overhead; 2) indoor; 3) cable (underground).

Overhead lines include line conductors, insulators, and supports. The conductors are connected to the insulators, and these are connected to the supports. The greater the resistance, the higher are the heating losses in the conducting wires. In order to reduce the losses, a step-down trans­former can be used.

Indoor lines include conductors, cords, and buses. The conductor may include one wire or a combination of wires not insulated from one an­other. They deliver electric current to the consumers.

As to underground lines, they are used in city areas. Accordingly, they are used in cities and towns, and in the areas of industrial enterprises.

4. Complete these sentences using the correct variant.

1. Electric power is transmitted

a) by electric lines.

b) by power networks.

2. Lines are divided into

a) overhead and underground.

b) overhead, indoor and underground.

3. An overhead line includes

a) conductors and supports.

b) conductors, insulators and supports.

4. The insulators are connected

a) to the buses.

b) to the supports.

5. Conductors consist of

a) bare wire.

b) insulated wire.

6. Underground lines are used

a) in cities.

b) in areas of enterprises.

c) in agricultural areas.

5. Complete the sentences using while or as to. Follow the model on page 13.

1. The system is termed a power line in case it has no parallel branches

2. Transmission lines deliver power from a station to distribution cen­tres ....

3. Low current results in decreased heating losses ....

4. Overhead lines are used in open areas ....

6. Answer these questions:

1. By what means is electric power system transmitted?

2. Which system has no parallel branches?

3. Into what groups are all the transmitting lines classed?

4. What components does an overhead line have?

5. What elements do conductors consist of?

6. In what areas are overhead (underground) lines used?

7. Read the text and find in it the answers to the questions that follow it.

HV Power Transmission

A high-capacity hydrogenerator produces an a.c. current at 22,000 V. The current with the potential difference of 220,000 V is produced by means of the transformers at a step-up station and then transmitted over the power lines.

The current potential difference is lowered to medium 6,600 V at the main step-down substation at the end of the line. From here the power is transmitted to the next substations. Transformers stepping the voltage down from 6,600 V are installed at those substations.

Due to voltage conversion, alternating current is used widely in in­dustry. Direct current for battery charging for trams, trolleybuses and electric locomotives is changed from alternating current by means of rectifiers.

1. Where is the current potential difference lowered?

2. Where is the main step-down substation installed?

8. Read the text and find in it the answers to the questions that follow it.

Compressed-gas-insulated Transmission

Transmission lines in which compressed gas is used as insulator have a number of advantages. The main advantages are simplicity of construction and low cost.

What is the construction of compressed-gas-insulated transmission lines? It is rather simple. They comprise a number of phase conductors; each phase conductor is placed inside a tube and centered by means of cir­cular spacers. The tube space is filled with compressed gas - usually sul­phur hexofluoride. Each tube in a 345-kV line has a diameter about 50 cm.

The system including compressed-gas-insulated transmission has the following advantages: its losses are rather low, they are considerably lower than those of cable transmission. Unlike cables, compressed-gas-insulated transmission system can be designed for ultra high frequencies. No external electric field appears in the system. The shunt capacitance is considerably less for a gas-insulated line than for a cable. A gas-insulated line can thus transmit power over larger distances than cable lines.

The system should be protected against metallic particles. In case metallic particles get into the system, they cause a fault - a dielectric breakdown.

1. Does the system described have any advantages? What are they?

2. What gas is the space filled with?

3. Why should the system be protected?

9. Read and translate the text

POWER TRANSMISSION

A transformer is an electrical device by which the electromotive force of a source of alternating current may be increased or decreased. They are widespread in long-distance power transmission as well as in telephones, radio transmitters and receivers, television and etc. Nearly all transformers come under one of the two following classes: step-up, and step-down transformers. In the transmission of electrical energy over wires for long distance, transformers are practically indis­pensable. At the power house in the distant mountains, for example, electric current is generated by huge alternating current generators, at the relatively low voltage-of several thousand volts. Jf an attempt were made to transmit this electrical energy, at a voltage of say 2,200 volts, over many miles of wire cable to a distant city, the current would be so large that nearly all of the energy would be consumed in heating the power line. The heat generated (it should be remembered) is pro­portional to the square of the current (heat=0.24/² Rt).

To avoid large heat losses, transformers at the power house step the voltage up to some 220,000 volts before switching the current onto the power line. Since the voltage in the case cited is increased one-hun­dred fold, the current drops by the same proportion to one-hundredth. Since the square of ¹/₁₀₀ is ¹/_10*000the heat loss along the transmission line is only one ten thousandth of what it would have been had the trans­former not been used.

At the city end of , a transformer substation steps the voltage down to. Its original value, of 2,200 volts. From there branch lines distribute the power to various sections of the city where smaller transformers, one near each group of several houses, step it down again to the relatively safe voltage of 110 to 220 volts.

Unit 13

Safety Earthing System. Electric shock

1. Translate into Russian.

safe

safety

danger

strength

earth

ground

dead

dangerous

strong

live

dry

wet

to save

to disappear

to appear

2. Read the words and put down their Russian equivalents. Then trans­late them back into English (orally).

atmosphere

personnel

contact

regular

control

detect

3. Read and translate the text

Safety Earthing System. Electric Shock

The strength of current depends on both the voltage and the resis­tance in a circuit. A current of 50 mA is dangerous for a man and a cur­rent of 100 mA and higher is lethal.

Earthing system serves to protect attending personnel from electric shocks when voltage appears on parts that are normally dead. The risk of an electric shock decreases with decreasing voltage. In wet and hot atmosphere the risk of electric shock increases. Safe voltage for circuits used in dry atmosphere is under 36 V. When the power is on, contacts with live conductors are dangerous for life. Thus, measures are taken to protect attending personnel from contacts with live parts of installations under voltage.

The danger of an electric shock disappears provided the metal parts of installations under voltage are connected with ground by means of safety earthing.

Connecting to ground is made by means of earthing electrodes which are connected directly with ground.

The insulation resistance of any installation should be regularly controlled by means of measuring devices. The faulty parts should be detected, eliminated, and replaced by new ones.

4. Complete the sentences using the correct variant:

1. Earthing system serves

a) as protection from an electric shock.

b) as connection with ground.

2. Voltage appears on

a) dead parts.

b) live parts.

3. Contact with live conductors is

a) dangerous.

b) safe.

4. Connection to ground is made

a) dangerous.

b) safe.

5. Danger of an electric shock disappears if the frame

a) is earthed.

b) is unearthed.

5. Complete the sentences using while. Follow the model on page 13.

1. The insulation resistance of a faulty unearthed frame is extremely …..

2. Danger of an electric shock disappears when the faulty parts earthed ....

3. One should work on the circuit when the power is off. One should work on the circuit when the power is ....

4. Contact with dead conductors is safe ... .

5. In dry air the risk of an electric shock decreases ....

6. Answer these questions:

1. What does an earthing system serve for?

2. What parts are termed dead (live)?

3. In what air does the risk of an electric shock decrease?

4. By what means is connection to ground made?

5. What does an electric shock result from?

6. Is a current of 50 mA dangerous for a man?

7. Is wet and hot atmosphere dangerous for the attending personnel?

8. Does the risk of an electric shock decrease with increasing current?

7 Read the text and write four questions about it. Ask your groupmates to answer them.

A man can get an electric shock when he comes into contact with the electric fish. One of this kind is found in the tropical waters of South America: it is the electric eel. Small electric eels, one inch long, give a small shock. When the fish is 6 inches long its internal battery gives as much as 200 volts. A very big fish can generate 600 volts! When it is short-circuited, a current of one ampere can be obtained. A two-meter long eel can light a dozen 50 watt lamps. The eel's head is positively charged and the opposite end is negatively charged.

Unit 14

Electric Motors

1. Translate into Russian

condition

plant

pole

torque

poor

nameplate

2. Read the words and put down their Russian equivalents. Then trans­late them back into English.

industry

service

transport

motor

practical

potential

3. Read and translate the text

Electric Motors

Motors are used for converting different forms of energy into me­chanical energy.

The main part of a motor is a coil or armature. The armature is placed between the poles of a powerful magnet. When a motor is put into operation current starts flowing through the coil (armature) and the armature starts rotating.

Electric motors are used practically in every branch of industry, transport, and agriculture. Naturally, they are produced in many dif­ferent designs. They are used in industrial plants, and operate under dif­ferent conditions.

Each motor is supplied with a nameplate which bears machine ratings: output power, voltage, the rated current, the starting current, the power factor, the efficiency, and the rated torque.

These motor ratings should be taken into consideration since they are necessary for the users. On them depends the length of motors' service life, which is normally equal to about 10 years, provided that the operating conditions are normal. Naturally, under abnormal condi­tions the service life becomes much shorter: motors operate poorly and may have different faults.

4. Complete the sentences using the correct variant:

1. Motors are used

a) for transmitting energy.

b) for converting energy.

2. Motor's main part is

a) the frame.

b) the armature.

c) the stator.

3. The armature is placed

a) between the poles of the magnet.

b) about the poles of the magnet.

4. Motors' service life becomes shorter

a) under normal conditions,

b) under abnormal conditions

5. Faulty motors operate

a) normally.

b) poorly.

5 Answer these questions. Use them in a talk with your groupmate:

1. What are motors used for?

2. What is the motor's main part?

3. Where is the armature placed?

4. What ratings does the nameplate of a motor bear?

5. Under what conditions does a motor operate normally (poorly)?

Unit 15

Faults of Motors and Ways of Their Repair

1. Translate into Russian

brush

gap

spark

speed

noise

slow

excessive

check

to repair

to adjust

2. Read the words and put down their Russian equivalents:

commutator

stator

rotor

contact

to contact

process

3. Put down the verbs corresponding to the given nouns and translate them:

check to check проверять

spark

brush

repair

slow

4. Put down the Russian equivalents of these word combinations. Trans late them back into English (orally).

air gap

brush sparks

slow speed

excessive speed

safety devices

5. Answer these questions:

1. What do motors' faults result from?

2. Are there any faults that can be ignored?

3. What makes motors' service life shorter?

4. What does voltage supply stop result in?

5. What processes show the (dis)advantages of devices?

6. Are the words: spark, short, slow, brush, fault, load, test nouns? Are they verbs? Translate the sentences into Russian:

1. New motors are given a no-load and under a load tests.

2. When the motor is tested it should produce no abnormal noise.

3. In case this noise appears the motor must be disconnected.

4. This generator must be checked; one should give it a test.

5. The motor's brushes seem to be sparking. Can you see the sparks?

6. The windings of the coil are shorted. I have detected a short in the windings.

7. The armature rotates slowly; let's check it up!

8. The speed of rotation is too excessive; it must be slowed down.

9. In case the rotor brushes against the stator, the motor operates slowly. The faulty brushes should be replaced.

7. Read and translate the text

Faults of Motors and Ways of Their Repair

Motors may have different faults. A faulty motor does not start, or, when it is started, it operates at an excessive speed.

Its brushes may spark and its windings and the commutator may be overheated and burnt. Besides, a motor may produce an abnormal noise, etc. All these and other faults should be detected and repaired.

In case the motor does not start it may have different faults (see the ta­ble):

Possible causes of faults

Ways of repair

1. Fuses are faulty.

1. Replace the fuses.

2. Motor is overloaded.

2. Reduce motor load.

3. Circuit in armature winding has an open.

3. Repair the armature winding.

In case the motor, when started, stops:

1. Rheostat is shorted.

1. Check the rheostat and re­pair it.

2. Rheostat switches from one position to another.

2. Slow down operation of rheostat handle.

Brushes may spark in case:

1. Motor is overloaded.

1. Reduce the load and re­move overload.

2 Brushes are in poor condition.

2. Replace the brushes.

3. Pressure is low.

3. Adjust the pressure.

4. Pressure is excessive.

4. Adjust the pressure.

In case the armature winding is overheated:

1. Motor is overloaded.

1. Remove the overload.

2. Ventilation fails to operate properly.

2. Check for slowing down the speed of the motor.

In case of abnormal motor speed:

1. Motor is overloaded.

1. Reduce the load.

2. Rotor circuit has poor contact.

2. Repair the shorting mechanism.

In case rotor brushes against stator:

Rotor brushes against stator.

Adjust air gap.

8. Complete the sentences using the correct variant:

A motor with a fault a) operates normally.

b) operates poorly.

Motor brushes spark in case a) they are in normal conditions.

b) they are in poor conditions.

Burnt commutator should be a) replaced.

b) repaired.

Brushes may spark in case a) pressure is low.

b) pressure is excessive.

Air gap is adjusted in case a) the rotor brushes against the stator.

b) the stator brushes against the rotor.

9. Answer these questions:

1. When does a motor operate poorly?

2. What should be done in case the motor is overloaded?

3. What should be done in case the fuses are faulty?

4. What should be done in case the rheostat is shorted?

5. What should be done in case the brushes spark?

6. What should be done in case the pressure is low?

7. What should be done in case the ventilation does not operate?

8. What should be done in case the rotor brushes against stator?

Unit 16

Electric Power Consumers and Power Systems

1. Translate into Russian

predominant

graph

national economy

to achieve

to belong (to)

to feed

to determine

to relate

2. Read the words and put down their Russian equivalents. Then trans­late them back into English (orally).

characteristic-

municipal -

to electrify -

hydro -

period -

3. Distribute the words below into three columns:

action process doer

utilizer, protect, distribution, utilize, protection, distributor, consumption, consume, utilization, consumer

4. Put down the Russian equivalents of these word combinations. Trans­late them back into English (orally).

   1. load graph

lighting load

power load

1. 2. power utilizing devices

parallelly operating plants

enterprises utilizing power

5. Complete the sentences translating the words in brackets:

1. Water-turbine (заводы) are called hydroturbines.

2. Load graph (определяет) the operating load (условия).

3. Economical (потребление) of electric power (достигается) by inter­connected operation of power plants.

6. Read and translate the text

Electric Power Consumers and Power Systems

An electric power consumer is an enterprise utilizing electric power. Its operating characteristics vary during the hours of day, days and nights, days of week and seasons.

All electric power consumers are divided into groups with common load characteristics. To the first group belong municipal consumers with a predominant lighting load: dwelling houses, hospitals, theatres, street lighting systems, mines, etc.

To the second group belong industrial consumers with a predomi­nant power load (electric motors): industrial plants, mines, etc.

To the third group belongs transport, for example, electrified rail­ways. The fourth consists of agricultural consumers, for example, elec-trotractors.

The operating load conditions of each group are determined by the load graph. The load graph shows the consumption of power during dif­ferent periods of day, month, and year. On the load graph the time of the maximum loads and minimum loads is given.

Large industrial areas with cities are supplied from electric networks fed by electric power plants. These plants are interconnected for opera­tion in parallel and located in different parts of the given area. They may include some large thermal and hydroelectric power plants.

The sum total of the electric power plants, the networks that inter­connect them and the power utilizing devices of the consumers, is called a power system. All the components of a power system are inter­related by the common processes of protection, distribution, and con­sumption of both electric and heat power.

In a power system, all the parallelly operating plants carry the total load of all the consumers supplied by the given system.

The building up of a power system is of great importance for the na­tional economy. An economical utilization of the power plant installa­tions and of the sources of power is achieved by interconnected operation of a series of power plants in a common power distribution system.

7. Answer these questions:

1. What enterprises are called electric power consumers?

2. When do their operating characteristics vary?

3. What consumers belong to the four different groups?

4. What conditions does the load graph determine?

5. What type of system is called a power system?

6. What processes interconnect the components of a power system?

7. In what way is an economical utilization of power installations achieved?

Unit 17

Substantions

1. Translate into Russian

auxiliary

breaker

busbar

feeder

flexible

to comprise

to distribute

as ... to

as well as

2. Put down the Russian equivalents of these word combinations Trans­late them back into English (orally).

circuit breaker

auxiliary units

distribution centre

flexible construction

reliable operation

switch gear bus

hydraulic as well as solar sources of energy

as to phase-word motors

3. Read and translate the text

Substations

A substation is designed to receive energy from a power system, convert it and distribute it to the feeders. Thus a substation serves as a distribution centre. Substations feed (supply) various consumers pro­vided that their basic load characteristics are similar. Therefore the en­ergy is distributed without transformation of the voltage supplied.

Common substations comprise isolators, switchgear buses, oil cir­cuit breakers, fuses, power and instrument transformers and reactors.

Substations are classed into step up and step down ones. The step up substation includes transformers that increase the voltage. Connected to the busbars of the substation are the power transmission lines of power plants of the system.

As to step down substations, they reduce the voltage to 10 or 6 kV. At this voltage the power is supplied to the distribution centres and to the transformer substations of power consumers.

A transformer substation serves for transmitting and distributing electric power. It comprises a storage battery, control devices and aux­iliary structures.

Transformer substations are classed into indoor and outdoor; both types are used for feeding industrial enterprises. Compared to other types of substations, transformer substations have certain advantages. They have flexible construction and easy and reliable operation. In case of a fault in the left-hand section, the main circuit breaker opens while the normally open section circuit breaker closes and puts the voltage of the section to normal. Power from a substation is delivered to distribu­tion centres.

4. Complete the sentences using the correct variant:

1. A substation serves

a) to consume energy.

b) to distribute energy.

c) to convert energy.

2. A substation feeds consumers

a) with various load characteristics.

b) with similar load characteristics.

3. The lines of power plants are connected

a) to the busbars.

b) to the switchgear.

4. A substation comprises

a) the main elements.

b) the main and auxiliary elements.

5. Flexible construction is

a) an advantage.

b) a disadvantage.

5. Pair work. Put these questions to your groupmate, and ask him/her to answer them.

1. What does a substation serve for?

2. What type of consumers does a substation feed?

3. What parts are the power transmission lines connected to?

4. What components does a substation comprise?

5. What types are substations classed into?

6. What are advantages of a transformer substation?

Unit 18

Hydroelectric power plants

1. Translate into Russian

blade

level

magnitude

head

plant

runner

shaft

to rotate

to influence

to fluctuate

2. Put down the Russian equivalents of these word combinations. Then translate them back into English (orally).

runner blade

turbine runner

turbine shaft

water level

water head

large capacity power plant

magnitude of the water head

daily inflow of water

turbine runner shaft

3. Read and translate the text

Hydroelectric Power Plants

Hydroelectric power plants are built on rivers. Large-capacity hy­droelectric power plants are commonly located at considerable dis­tances from the consumers of electric power.

The production process at these plants is rather simple: the water flows into the hydroturbine runner, acts upon the runner blades and ro­tates the runner and the turbine shaft.

The generator shaft is connected to the turbine runner shaft. The dif­ference in the water level influences the power capacity of a plant, i.e. the magnitude of the water head and the daily inflow of water fluctuates considerably according to the season.

The production process is different at power plants of different con­structions and of different kinds. In atomic power plants, for example, it is not so simple as in hydroelectric plants.

4. Complete the sentences using the correct variant:

1. Hydroelectric power plants are built

a) on rivers, b) on waterfalls,

2. Large-capacity power plants located power.

a) at a short distance from consumers of power,

b) at a considerable distance from consumers of are

3. The production

a) is very complex, process at the

b) is rather simple, plants

4. The power ca­pacity of a plant

a) remains constant.

b) changes considerably.

c) is influenced by the difference in the water level.

5. The daily in­flow of water

a) fluctuates according to the consumption.

b) fluctuates according to the season.

6. The production process

a) depends upon the construction of the plant.

b) is the same at power plants of different construc­tions.

5. Pair work. Put these questions to your group mate and ask him/her to answer them:

1. On what sites are hydroelectric power plants built?

2. Are large-capacity plants located far from consumers of power?

3. Is the production process at the plants simple or is it complex? What influences the power capacity of a plant? According to what factors does the daily inflow of water fluctuate? Does the production process at the plant depend on its construction? Do you know that a thermal power plant seldom has an efficiency more than 40%?

Unit 19

Atomic Power Plant

1.Translate into Russian

exchanger

steam

tube

dust

attending personnel

to deliver

to pollute

to shield

1. Put down the Russian equivalents of these word combinations. Then translate them back into English (orally).

1. 1. auxiliary units

steam generator

heat exchanger

fuel consumption

1. 2. water to be heated in the reactor

water to be converted into steam

steam to be fed into the turbogenerator

1. 3. the polluted atmosphere

utilized nuclear fuel

shielded concrete walls

2. Read and translate the text

Ato Atomic power plants.

mic Power Plant

Atomic power plants are modern installations. They consist of sev­eral main units and a great number of auxiliary ones.

In a nuclear reactor uranium is utilized as a fuel. During operation process powerful heat and radioactive radiation are produced. The nu­clear reactor is cooled by water circulation. Cooling water circulates through a system of tubes, in which the water is heated to a temperature of 250-300°C. In order to prevent boiling of water, it passes into the re­actor at a pressure up to 150 atmospheres.

A steam generator includes a series of heat exchangers comprising tubes. The water heated in the reactor is delivered into the heat ex­changer tubes. The water to be converted into steam flows outside these tubes. The steam produced is fed into the turbogenerator.

Besides, an atomic power plant comprises a common turbogenera­tor, a steam condenser with circulating water and a switchboard.

Atomic power plants have their advantages as well as disadvantages. The reactors and steam generators operate in them noiselessly; the at­mosphere is not polluted by dust and smoke. As to the fuel consump­tion, it is of no special importance and there is no problem of fuel transportation.

The disadvantage of power plants utilizing nuclear fuel is their ra­diation. Radioactive radiation produced in the reactors is dangerous for attending personnel. Therefore, the reactors and steam generators are installed underground. They are also shielded by thick (up to 1.5 m) concrete walls. All their controls are operated by means of automatic devices. These measures serve to protect people from radioactive ra­diation.

3. Complete the sentences using the correct variant

1.A nuclear reactor is used in

a) wind-power plants.

b) atomic power plants.

2. A nuclear reactor is cooled by

a) water circulating in tubes.

b) oil circulating in tubes.

3. Water is passed into the re­actor

a) at a low pressure.

b) at a high pressure.

4. High pressure

a) activates boiling of water.

b) prevents boiling of water.

5. Atomic power plants

a) pollute the air with dust and smoke.

b) do not pollute the air with dust and smoke.

6. Circulating water flows

a) inside the heat exchangers.

b) outside the heat exchangers.

7. Attending personnel is shielded by

a) thick concrete walls.

b) thick metal walls.

5. Pair work. Put these questions to your groupmate and let him/her an­swer them:

1. What are the main units of an atomic power plant?

2. By what means is the nuclear reactor cooled?

3. At what pressure does the water pass into the reactor?

4. What types of power plants pollute the air with dust and smoke?

5. Why is it necessary to protect attending personnel?

6. By what means is it done?

Unit 20

Protection Against Environmental Pollution

1. Translate into Russian

concrete

environment

fission

(stainless) steel

vessel

waste

to confine

to release

to withstand

to dispose

2. Put down the Russian equivalents of these word combinations. Then translate them back into English (orally):

nuclear fuel

nuclear fission

steel vessel

reactor vessel

fission release

sealed tubes

concrete housing

waste products

nuclear waste

shielded cylinders

3. Read and translate the text

Protection Against Environmental Pollution

Any operating nuclear power plant releases fission products into the environment, which causes environmental pollution.

To prevent the harmful effects of nuclear power release, the nuclear power plants are supplied with protective installations that serve as bar­riers to the pollution.

First, the nuclear fuel and the fission products are confined within sealed tubes made of stainless steel or zirconium. Then the assembly of tubes is placed in a steel reactor vessel. And finally the steel reactor vessel is placed in a large steel and concrete housing.

As to the hot radioactive waste products they are disposed in heavily shielded cylinders. The cylinders are buried 305 to 610 metres under­ground.

4. Complete the sentences using the correct variant:

1. A nuclear power plant

a) liquid products, releases

2. fission products.

1. Operating nuclear power plants

a) pollute the environment.

b) prevent the pollution.

3. The protective power plant installations

a) produce the release of fission products.

b) prevent the release of fission products.

4. The sealed tubes are made of

a) bronze.

b) stainless steel.

5. The fission products are confined

a) within sealed tubes.

b) within open tubes.

6. The steel reactor vessel is placed

a) in a concrete housing.

b) in a zirconium housing.

7. The waste products are disposed

a) in an open vessel.

b) in shielded cylinders.

5. Pair work. Put these questions to your groupmate and let him/her an­swer them:

1. What kind of products does the operating nuclear power plant release?

2. What installations are used to prevent the harmful effects of a nuclear power plant operation?

3. What material are the tubes made of?

4. Where are the fission products confined?

5. In what part of the installation is the reactor vessel placed?

6. In what way are the hot radioactive waste products disposed?

66