UNIT 7

ELECTRIC POWER TRANSMISSION AND DISTRIBUTION

Active Vocabulary

bulk - величина, объем, масса substation - подстанция exploitation - использование, эксплуатация low-grade - низкого качества, имеющийся в незначительном количестве facility – возможность, благоприятные условия, устройство, установка facilities – оборудование, аппаратура, производственные мощности overhead transmission line - воздушная линия электропередачи underground transmission line - подземная линия, подземный кабель grid – электрическая сеть, (электро)энергетическая система redundant – избыточный, резервный route – путь, маршрут disastrous - бедственный, пагубный to alternate - периодически изменяться, чередоваться

to facilitate – содействовать, способствовать access – доступ to encourage – содействовать, стимулировать to enable - давать возможность expansion – распространение, развитие to step-up - повышать напряжение to step-down – понижать напряжение to enhance – усиливать, увеличивать, повышать to traverse – пересекать, проходить outlet – выход, вывод, розетка breaker – выключатель, прерыватель тока switch – выключатель, переключатель instrumentation - контрольно-измерительное оборудование apparatus - прибор, инструмент, оборудование pole – столб, стойка, свая, опора ЛЭП

1. Complete the sentences with the words from the box.

enable enhance step-down  facilitate traverse encourage

1. Transformers, which are often used to __________ voltage, work with AC voltages, not

DC voltages.

2. We are using technology to __________ our levels of service.

3. As estimated 250,000 cars __________ the bridge daily.

4. Recent innovations with computer aided design __________ us to produce magazines

which are more creative, efficient and cost effective.

5. A great deal can be done by the university authorities to help and __________ such

development.

6. Both centres are electronically linked to __________ communication.

Reading 1

2. Read the text about electric power transmission and distribution. Six sentences have

been removed from it. Choose from sentences A-F the one which fits each gap (1-6).

A Electricity is usually transmitted over long distance through overhead power transmission

lines.

B These circuits supply large commercial, institutional and some industrial consumers directly.

C Deregulation of electricity companies in many countries has led to renewed interest in

reliable economic design of transmission networks.

D Typically, power transmission is between the power plant and a substation near a

populated area.

E A power transmission system is sometimes referred to colloquially as a "grid".

F Basic equipment in a substation includes circuit breakers, switches, transformers and

protective devices.

ELECTRIC POWER TRANSMISSION AND DISTRIBUTION

Electric power transmission, a process in the delivery of electricity to consumers, is the bulk transfer of electrical power. 1_____________ Electricity distribution is the delivery from the substation to the consumers. Electric power transmission allows distant energy sources (such as hydroelectric power plants) to be connected to consumers in population centers, and may allow exploitation of low-grade fuel resources that would otherwise be too costly to transport to generating facilities.

Due to the large amount of power involved, transmission normally takes place at high voltage (110 kV or above). 2_____________ Underground power transmission is used only in densely populated areas due to its high cost of installation and maintenance, and because the high reactive power produces large charging currents and difficulties in voltage management.

3_______________ However, for reasons of economy, the network is not a mathematical grid. Redundant paths and lines are provided so that power can be routed from any power plant to any load center, through a variety of routes, based on the economics of the transmission path and the cost of power. Much analysis is done by transmission companies to determine the maximum reliable capacity of each line, which, due to system stability considerations, may be less than the physical or thermal limit of the line. 4______________ However, in some places the gaming of a deregulated energy system has been disastrous, such as that which occurred during the California electricity crisis of 2000 and 2001.

Power delivered by transmission circuits must be stepped down in facilities called substations to voltages more suitable for use in industrial and residential areas. On transmission systems, these facilities are commonly called bulk-power substations; on or near factories or mines, they are termed industrial substations; and where they supply residential and commercial areas, distribution substations. 5_______________ There is also instrumentation, control devices and other apparatus related to specific function in the power system.

That part of the electric power system that takes power from a bulk-power substation to consumers' switches, commonly about 40% of the total plant investment, is called distribution. Primary distribution circuits usually operate at 4,160-34,500 volts line-to-line and may be overhead open wire on poles, overhead or aerial cable, or underground cable. 6_____________ Smaller consumers are supplied through numerous distribution transformers. At conveniently located distribution transformers in residential and commercial areas, the voltage is stepped down again to 120 and 240 volts for secondary lines, from which service drops or loops extend to every consumer's lights and appliances. These low voltages are known as utilization voltages.

Use of English 1: vocabulary