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Electric Lines and Their Efficiency
Wires are used to deliver electric power and to interconnect differed components of electrical installations. Conductors used for electr|
Answer these questions:
1. Why is aluminium widely used nowadays?
2. Is its cost very low or comparatively low?
I
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1796 - 6S -
| 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? 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 resis* tance 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. |
| a) Cover the right column and read the English words. Translate them into Russian and check your translation. b) Cover the left column and translate the Russian words back into English. |
area
distance
network
support
cord
bus
enterprise
to term
to divide
to support
to distribute
accordingly
as to
long distance
length of transmission lines
power consumption
distribution centre
citv area
.'eanaj площадь, область
расстояние
сеть электролиний
опора, мачта
провод
шина ['entapraiz] предприятие
| [di'vaid) |
называть, именовать
делить, разделять
поддерживать
распределять
соответственно
... что касается; ... что до!
большое расстояние
длина линий передачи
потребление энергии
распределительный центр
район городской застройки
2. Put down the Russian for:
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__________________________________________
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.
3* Complete these sentences using the correct variant.
1. Electric power is transmitted a) by electric lines.
b) by power networks.
-66
5*
-61-
2. Lines are divided into
3. An overhead line includes
4. The insulators are connected
5. Conductors consist of
6. Underground lines are used
a) overhead and underground.
b) overhead, indoor and underground.
a) conductors and supports.
b) conductors, insulators and supports.
a) to the buses.
b) to the supports.
a) bare wire.
b) insulated wire.
a) in cities.
b) in areas of enterprises.
c) in agricultural areas.
| danger | I'demdja] | опасность |
| strength | [strerj9] | сила |
| earth | [з:0] | заземление, земля |
| ground | земля, почва | |
| dead | [ded] | выключенный |
| dangerous | I'deir^ras] | опасный |
| strong | сильный, яркий (о свете) | |
| to save | спасать | |
| to disappear | исчезать | |
| to appear | появляться | |
| live | llaiv] | под напряжением |
| 4ГУ | сухой | |
| wet | сырой, мокрый |
4. Complete the sentences using while or as to. Follow the model on page
13.
1. The system is termed a power linein case it has no parallel branches
2. Transmission linesdeliver power from a station to distribution centres... .
3. Lowcurrent results in decreasedheating losses ....
4. Overheadlines are used in open areas ....
5. 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?
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| Electromagnetic Relay | | | B) Cover the left column and translate the Russian words back into English |
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