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Ex. 6. Match the halves of the sentences together.

	A		B
1.	The wire must be able to ...	a)	like 3rd rail systems.
2.	The wire is zigzagged ...	b)	a single wire hung directly from insulated
			supports.
3.	Overhead lines are normally fed ...	c)	can represent a safety hazard.
4.	A tram depot may have ...	d)	to reduce interference in communications
			cables.
5.	Third rail routes need special	e)	withstand wind, extreme cold and heat.
	protection ...
6.	Special precautions are taken ...	f)	connected to the running rail at intervals
7.	Unequal voltages ...	g)	relative to the centre line of the track
8.	The return conductor is ...	h)	to be completely safe.

Ex. 7. Go to the text and complete the sentences.

1.Overhead catenary systems have a complex geometry ....

2.The contact wire tension is about ....

3.The wire length is usually ….

4.The tension of the wire is maintained by ....

5.Each length is overlapped by its neighbour to ….

6.A waving wire can cause the dropper wires to …

7.Each subsection is isolated from its neighbour by …

8.An alternator consists of …

9.To reduce the arcing at a neutral section some systems use ...

10.Simple catenary is slightly sagged to ...

11.The third rail is inconvinient because of ...

12.If a communications cable is laid alongside rails carrying the return it can ...

13.Booster transformers are positioned ...

14.Booster transformers are connected to ...

15.The return conductor is connected to ....

Ex. 8. Translate the following sentences from Russian into English.

1. Контактная сеть − это техническое сооружение электрифицированных железных дорог и других видов транспорта (метро, трамвая, троллейбуса). 2. Контактная сеть служит для передачи электроэнергии с тяговых подстанций на электроподвижной состав.

3.Контактная сеть бывает двух типов: воздушная контактная сеть и контактные рельсы.

4.Несмотря на то, что ходовые рельсы обычно применяются для отвода обратного тягового тока, они не являются частью контактной сети. 5. Воздушная контактная сеть подвешивается на различных опорах. 6. В момент отрыва между токоприёмником и проводом образуется электрическая дуга. 7. Восстановление контакта происходит с ударом токоприёмника о провод. 8. Также происходит раскачивание токоприёмников.

9.Эти явления ускоряют износ контактного провода и токоприёмников, ухудшают качество токосъёма, а также создают радиопомехи. 10. Для обеспечения возможности питания контактной сети от нескольких тяговых подстанций, а также для ремонта отдельных участков без отключения всей контактной сети, применяется секционирование контактной сети. 11. Контактная сеть разбивается на участки, так

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называемые секции. Каждая секция запитывается отдельным фидером от тяговой подстанции. 12. В случае неисправности фидера обычно есть возможность запитать секцию от другой тяговой подстанции. 13. Таким образом, секционирование повышает надёжность контактной сети, обеспечивая бесперебойную подачу электроэнергии. 14. Для обеспечения надёжной изоляции секций и предотвращения образования дуги, которая может нарушить изоляцию между секциями при прохождении токосъёмников из одной секции в другую используются секционные изоляторы.

A d d i t i o n a l t e x t

Read the text and translate it using a dictionary. Check your translating speed.

P A N T O G R A P H S

Current is collected from overhead lines by pantographs. Pantographs are easy in terms of isolation - you just lower the pan to lose the power supply to the vehicle. However, they do provide some complications in other ways.

Since the pantograph is usually the single point power contact for the locomotive or power car, it must maintain good contact under all running conditions. The higher the speed, the more difficult the maintenance of good contact. We have already mentioned the problem (above) of a wave being formed in the wire by a pantograph moving at high speed.

Pantograph contact is maintained either by spring or air pressure. Compressed air pressure is preferred for high speed operation. The pantograph is connected to a piston in a cylinder and air pressure in the cylinder maintains the pantograph in the raised condition.

Originally, pantographs were just that, a diamond-shaped "pantograph" with the contact head at the top. Two contact faces are normally provided. More modern systems use a single arm pantograph - really just half of the original shape - a neater looking design (photo above).

The contact strips of the pantograph are supported by a lightweight transverse frame which has "horns" at each end. В. These are turned downwards to reduce the risk of the pantograph being hooked over the top of the contact wire as the train moves along. This is one of the most common causes of wires "being down". A train moving at speed with its pantograph hooked over the wire can bring down several kilometres of line before it is detected and the train stopped. The most sophisticated pantographs have horns which are designed to break off when struck hard, for example, by a dropper or catenary support arm.В These special horns have a small air pressure tube attached which, if the pressure is lost, will cause the pan to lower automatically and so reduce the possible wire damage.

Some train services operate over lines using more than one type of current. In cities suchВ as London, New York City and Boston, the same trains run under overhead wires for part of the journey and use third rail for the remainder. In Europe, some locomotives are equipped to operate under four voltages - 25 kV AC, 15kV AC, 3,000 V DC and 1,500 V DC. Modern electronics makes this possible with relative ease and cross voltage travel is now possible without changing locomotives.

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U N I T 4

Ex. 1. Copy and memorize the following terms.

Glossary

bundle conductor − многожильный провод cross beam −траверса

electrolysis − электролиз pylon − опора

rapid-transit system − метрополитен

rotary transformer − вращающийся трансформатор

static inverter − преобразователь переменного тока в постоянный voltage spike −выброс напряжения

Ex. 2. Copy the following words and memorize their meanings:

9to adopt − принимать

9cross section − поперечное сечение

9dedicated to … − предназначенный для …

9to disintegrate − разделять

9to embarrass − смущать

9manhole − люк

9medium − средство

9to neglect − пренебрегать

9nevertheless − тем не менее

9to overcome − преодолеть

9peril − опасность

9structure − сооружение

9tendency − тенденция

Ex. 2. Translate the following sentences from English into Russian.

1. The revelations in the press have embarrassed the government. 2. A manhole is a hole in the surface of a road covered by a lid used to examine underground pipes and wires. 3. They saw a high wooden structure with a curved roof at a distance. 4. The disintegration of the Soviet empire into separate republics happened in 1991. 5. The company dedicated $50,000 for the study. 6. Many of these ideas have been neglected by modern historians. 7. Congress finally adopted the law after a two-year debate. 8. The Woodland Trust is dedicated to preserving our native woodland. 9. This incident is deeply embarrassing for the government. 10. The drug is effective but has a tendency to cause headaches. 11. English is still the main medium of instruction in Nigeria. 12. He knows them to be evil, nevertheless he indulges in them. 13. Her financial problems could no longer be overcome. 14. The roof beams were 50 centimetres square in cross-section. 15. Politicians ignore this issue at their peril.

Ex. 3. Match the phrases in column A with their definitions in column B.

	A		B
1.	bundle conductor	a)	an upright structure that is used for support
2.	cross beam	b)	an electric passenger railway in an urban area with a high
			capacity and frequency, and grade separation from other
			traffic
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3.	electrolysis	c)	a specialized transformer used to couple electrical signals
			between two parts which rotate in relation to each other
4.	pylon	d)	serves to provide an insulating spacing and wire support
5.	rapid-transit	e)	consist of several conductor cables connected by
			non-conducting spacers
6.	rotary transformer	f)	short duration electrical transients in voltage
7.	static inverter	g)	a method of using a DC to drive an otherwise
			non-spontaneous chemical reaction
8.	voltage spike	h)	an electrical device that converts DC to AC

Ex.4. When you add a second piece of information in a sentence to support the first piece of information, you often use a n d .

The food is excellent and very good value.

When you put this information in two sentences, the following link words and phrases are common:

The food is ususally very good. Furthermore, it is one of the cheapest centres in town.

The set menu is £10, which is excellent value. In addition, you get a free glass of wine.

The restaurant has a reputation for excellent food. It's also a very good value.

The food is excellent in that restaurant. It's very good value as well.

You get very good food in that place. What's more, it's excellent value.

Fill in the blanks with the words given in the box. Sometimes more than one variant is possible. Translate the sentences into Russian.

furthermore in addition	and	also	what’s more	as well
1

. By 1940, there were 19 systems, ... by 1984, there were 66. 2. The technology swiftly spread to other cities in Europe, as in Budapest, Hungary in 1896, and then to the United States .... 3. At the same time, technological improvements have allowed new driverless lines ... systems. 4. Hybrid solutions have ... evolved, such as tram-train and premetro, which have some of the features of rapid transit systems. 5. Transit maps may show only the rapid transit. ... they include other modes of public transport. 6. Compared to other modes of transport, rapid transit has a good safety record. ... they have few accidents. 7. ..., rail transport is subject to strict safety regulations, with requirements for procedure and maintenance to minimize risk. 8. The semiconducting glaze ... ensures a more even distribution of voltage along the length of the chain of insulator units.

Ex. 5. When you want to contrast two pieces of information in a single sentence and say that the second fact is surprising after the first, you can use the following link words:

She still won the game although / though / even though she had a bad knee.

They still went for a walk in spite of the fact that it was raining.

The service is worse despite the fact that they have more staff.

Marcel thought it was it was a good idea. Joe, however, thought it was stupid.

Most big cats, such as tigers and leopards, are very solitary creatures. Lions, on the other hand, spend much of their time in groups.

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Translate the following sentences.

1. Service on rapid transit systems is provided on designated lines between stations using electric multiple units on rail tracks, although some systems use guided rubber tyres, magnetic levitation, or monorail. 2. The biggest metro system in the world by length of routes and number of stations is the New York Subway, however by length of lines the largest are the London Underground and Shanghai Metro. 3. Today overhead lines are routinely operated at voltages exceeding 765,000 volts between conductors, though higher voltages are possible in some cases. 4. More recently the growth of new systems has been concentrated in Southeast Asia and Latin America. However, Western Europe and North America have seen a revival of the tram, with light rail systems supplementing full scale urban railways, and less focus on building rapid transit. 5. Many cities have chosen to operate a tram system in the city core with the metro expanding beyond it, though many cities chose to close this system in the 1950s and 60s. 6. The systems in Moscow and St. Petersburg are widely regarded as some of the most beautiful in the world, however, several other cities such as Stockholm, Montreal, Lisbon, and Los Angeles have also focused on art. 7. Railway electrification has many advantages, on the other hand, it requires significant capital expenditure for installation. 8. Even though during the mid-20th century, rotary converters or mercury arc rectifiers were used to convert AC power to the required DC voltage at feeder stations, today, this is usually done by semiconductor rectifiers. 9. Some voltage spikes may be created by current sources in spite of the fact that the effect of a voltage spike is to produce a corresponding increase in current.

Read the text and translate it using a dictionary if necessary.

A C O R D C T R A C T I O N

(1)A traction network or traction power network is an electricity grid for the supply of electrified rail networks. The installation of a separate traction network generally is only done if the railway in question uses alternating current (AC) with a frequency lower than that of the national grid, such as in Germany, Austria and Switzerland.

(2)Alternatively, the three-phase alternating current of the power grid can be converted in substations by rotary transformers or static inverters into the voltage and type of current required by the trains. For railways which run on direct current (DC), this method is always used, as well as for railways which run on single-phase AC of decreased frequency

(3)Dedicated traction current lines are used when railways are supplied with low frequency alternating current. The traction current supply line is connected to substations along the line of the railway and is usually run separately from the overhead catenary wire from which the locomotives are fed.

(4)In countries in which the electric trains run with direct current or with single phase AC current with the frequency of the general power grid, the required conversion of the current is performed in the substations, so again no traction current lines are required.

(5)Traction current supply lines are not usually laid parallel to the railway line, in order to allow a shorter line length and to avoid unnecessary influences to the electrical system near the railway line; this also is applied to the current supply of some rapid-transit railways operating with alternating current in Germany.

(6)It is also possible to lay out the traction current supply on special cross beams right on the overhead wire pylons above the catenary wire. Because the overhead line pylons have a smaller cross section than traction current supply masts the cross beams cannot be too wide, so the standard arrangement of four conductor cables in one level cannot be used. In this case a

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two-level arrangement is used, or with two electric circuits for double-railed lines the overhead line pylons for both directions are equipped with cross beams for their own traction current system of two conductor cables each.

(7)In densely populated areas there are pylons, which carry circuits for both traction current and for three-phase alternating current for general power. Such lines are found where right of ways are rare. In particular the parallel route of 110 kV and 220 kV three-phase AC is common. The use of 380 kV-power lines on the same pylon requires 220 kV insulators for the traction current line, because in case the 380 kV line fails, voltage spikes can occur along the traction current line, which the 110 kV insulators cannot handle.

(8)As a rule traction current lines use single conductors, however for the supply of railways with high traffic and in particular for the supply of high speed railway lines, two bundle conductors are used.

(9)It doesn’t really matter whether you have AC or DC motors, nowadays either can work with an AC or DC supply. You just need to put the right sort of control system between the supply and the motor and it will work. However, the choice of AC or DC power transmission system along the line is important. Generally, it’s a question of what sort of railway you have. It can be summarised simply as AC for long distance, however DC for short distance.

(10)It is easier to boost the voltage of AC than that of DC, so it is easier to send more power over transmission lines with AC. This is why national electrical supplies are distributed at up to 765,000 volts AC. As AC is easier to transmit over long distances, it is an ideal medium for electric railways. Only the problems of converting it on the train to run DC, on the other hand was the preferred option for shorter lines, urban systems and tramways. However, it was also used on a number of main line railway systems, and still is in some parts of continental Europe, for example. Apart from only requiring a simple control system for the motors, the smaller size of urban operations meant that trains were usually lighter and needed less power. Of course, it needed a heavier transmission medium, a third rail or a thick wire, to carry the power and it lost a fair amount of voltage as the distance between supply connections increased. This was overcome by placing substations at close intervals – every three or four kilometres at first, nowadays two or three on a 750 volt system – compared with every 20 kilometres or so for a 25 kV AC line.

(11)It should be mentioned at this point that corrosion is always a factor to be considered in electric supply systems, particularly DC systems. The tendency of return currents to wander

away from the running rails into the ground can set up electrolysis with water pipes and similar metallics. This was well understood in the late 19th century and was one of the reasons why London’s Underground railways adopted a fully insulated DC system with a separate negative return rail as well as a positive rail − the four-rail system. Nevertheless, some embarrassing incidents in Asia with disintegrating manhole covers near a metro line as recently as the early 1980s means that the problem still exists and isn’t always properly understood. Careful preparation of earthing protection in structures and tunnels is an essential part of the embarrassing incidents and is neglected at one’s peril.

Ex. 1. Go back to the text and translate the following phrases into Russian:

traction power network, the railway in question, dedicated traction current lines, laid parallel to, double-railed lines, preferred option, fair amount of voltage, separate negative return rail, embarrassing incidents.

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Ex. 2. Go back to the text and using the paragraph reference find words which are similar to:

¾detached, commonly (paragraph 1);

¾kind, way (paragraph 2);

¾meant, linked (paragraph 3);

¾done, demanded (paragraph 4);

¾permit, elude (paragraph 5);

¾support (paragraph 6);

¾uncommon, breaks down, manipulate (paragraph 7);

¾especially (paragraph 8);

¾essential (paragraph 9);

¾means, except for, considerable, arranging, at the present time (paragraph 10);

¾thought over, ramble, perplexing (paragraph 11).

Ex. 3. Answer the following questions to the text.

1.What is a traction network?

2.How can the three-phase alternating current of the power grid be converted?

3.When are dedicated traction current lines used?

4.Where is the required conversion of the current performed in the substations?

5.Why are not traction current supply lines laid parallel to the railway line?

6.What is the other method to lay out the traction current supply?

7.What is used in densely populated areas?

8.What conductors do traction current lines use as a rule?

9.What distances are AC and DC supply used for?

10.How was the loss of a fair amount of voltage on a number of main line railway

systems overcome?

11.What can set up electrolysis with water pipes and similar metallics?

A d d i t i o n a l t e x t

Read the text and translate it using a dictionary. Check your translating speed.

S T A N D A R D F R E Q U E N C Y A C

Only in the 1950s after development in France (20 kV then 25 kV) and former Soviet Union countries (25 kV) did the standard-frequency single-phase alternating current system become widespread, despite the simplification of a distribution system which could use the existing power supply network.

The first attempts to use standard-frequency single-phase AC were made in Hungary since 1923, by the Hungarian Kálmán Kandó on the line between Budapest-Nyugati and Alag, using 16 kV at 50 Hz. The locomotives carried a four-pole rotating phase converter feeding a single traction motor of the polyphase induction type at 600 to 1,100 V. The number of poles on the 2,500 hp motor could be changed using slip rings to run at one of four synchronous speeds. The tests were a success so, from 1932 until 1960s, trains on the Budapest-Hegyeshalom line (towards Vienna) regularly used the same system. A few decades after the Second World War, the 16 kV was changed to the Russian and later French 25 kV system.

Today, some locomotives in this system use a transformer and rectifier to provide lowvoltage pulsating direct current to motors. Speed is controlled by switching winding taps on the

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transformer. More sophisticated locomotives use thyristor or IGBT circuitry to generate chopped or even variable-frequency alternating current (AC) that is then supplied to the AC induction traction motors.

This system is quite economical but it has its drawbacks: the phases of the external power system are loaded unequally and there is significant electromagnetic interference generated as well as significant acoustic noise.

The United States commonly uses 12.5 and 25 kV at 25 Hz or 60 Hz. 25 kV, 60 Hz AC is the preferred system for new high-speed and long-distance railways, even if the railway uses a different system for existing trains.

To prevent the risk of out-of-phase supplies mixing, sections of line fed from different feeder stations must be kept strictly isolated. This is achieved by Neutral Sections, usually provided at feeder stations and midway between them although, typically, only half are in use at any time, the others being provided to allow a feeder station to be shut down and power provided from adjacent feeder stations

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G L O S S A R Y

A

alternator – генератор переменного тока armature – якорь

appliance – аппарат, прибор attract – притягивать attraction – притяжение

B

branch – ветвь на схеме разводки blower – воздухозаборник

booster transformer – вольтодобавочный трансформатор

brushed DC motor – щёточно-коллекторный электродвигатель постоянного тока brushless DC motor – бесщёточный электродвигатель постоянного тока

bulb– лампочка

C

cable – кабель

capacitance – ёмкость, емкостное сопротивление capacitor – конденсатор

carburetor – [kɑbə'reɪtə] карбюратор cell – гальванический элемент

dry-cell battery – галетная сухая батарея (из плоских элементов) chamber – камера

charge – заряжать, заряд clearance – зазор controller – контроллер

circuit – цепь, контур; схема

return circuit – цепь обратного тока coil – катушка

primary coil – первичная обмотка secondary coil – вторичная обмотка conductor – проводник nucleus (мн.nuclei) – ядро

bundle conductor − многожильный провод return conductor – обратный провод

conductivity – электропроводность, удельная проводимость; conduit – изоляционная трубка

crankshaft – коленчатый вал cross beam −траверса

cross section – поперечное сечение current – ток

et current – результирующий поток, полный ток current source – источник тока

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D

density – плотность; концентрация depot – станция, депо

device – устройство, прибор dioxide – двуокись

doping – допирование (введение примесей) drift – смещаться, смещение

distribution grid – распределительная сеть drive – привод

drive circuit – возбуждающий контур

Earth potential – потенциал Земли

E electric battery – гальванический элемент, аккумулятор electric power – электроэнергия

electric traction – электрическая тяга electrolysis − электролиз

electromotive force (emf) – электродвижущая сила engine – двигатель

four-stroke engine – четырёхтактный двигатель equation – уравнение

F

feeder station – питающая станция ferromagnetic – ферромагнитный frequency – частота

friction – трение

G

grid – сеть

I

impurity – примесь incandescent – раскалённый inductance – индуктивность insulator – диэлектрик; изолятор

inductor – катушка индуктивности

L

layer – слой

lead-acid storage battery – батарея свинцово-кислотных аккумуляторов leads – электропроводка

M

mains – сеть электроснабжения mast – мачта

matter – вещество

measure – измерять, единица измерения

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