Electric Power Plants.
The two main types of power plants traditionally have been the fossil-fuel steam-electric plant and the hydroelectric plant. Other types, including internal-combustion-engine plants and nuclear plants also have been built. The selection of a particular type of generating plant and its locations involves consideration of a number of factors such as plant, fuel, and transmission line costs; availability of cooling water; and environmental considerations.
For several reasons, the relative importance of the various types of power plants has been shifting. Good sites for new hydroelectric plants have become scare in many countries. Distribution networks have been extended so that less expensive power from large steam-electric stations has been replacing power from smaller diesel-generator units. Nuclear-electric power plants have been built instead of fossil-fuel steam-electric plants because the cost of coal and oil has been increasing.
In the United States in 1970, fossil-fuel steam-electric plants accounted for 76% of the power generated, hydroelectric plants for 16%, and nuclear plants for 2%.
In 2000 45% of the electric power in the United States is generated from fossil-fuel steam- electric plants, 45% from nuclear plants, and 10% from hydroelectric plants.
Vocabulary
to generate- производить вырабатывать
to convert- преобразовывать, превращать
heat- теплота, тепло
heating- нагревание
to drive- приводить в движение
fuel- топливо, заправлять
to derive-происходить
steam- пар
combustion- сжигание
fission- распад
source- источник
to transmit- передавать
to count- считать
arailahility- наличие
consideration- вопрос
lead- свинец
furnance- печь
circuit-цепь
2. Выполните упражнения:
1) Распределите слова на 4 колонки:
Model: what? what king of? what to do? how?
use useful to use usefully
insulator, failure, fail, addition, additional, overestimate, equal, equalize, equality, equally, different, differ, difference, resist, resistance, resistivity, resistant, commonly, consumer, faulty, impossibility, carelessly, number, numerous, possible, clockwise
2) Поставьте всевозможные вопросы к предложениям, а так же дайте отрицательную форму:
1. Oxygen combines directly with nearly all elements.
2. Plastic materials are relatively new insulating materials.
3. Polythene cables have numerous advantages.
4. The importance of semiconductors for modern science cannot be underestimated.
5. Semiconductors conduct electricity less efficiently than metals.
6. The method proved to be efficient.
7. What resistance materials are in common use today?
3) Используя информацию текста, вставьте пропущенные слова:
а) The …. And energy balance is important for industry.
б) Conductirity increases with…
в) The amount of… used in the world in a year amounts to 12000 million tons of equivalent…
г)The wire and the… form a…
д) After the metal was heated it chamsed its colour to a red…
е) The heat is used to …. generate steam.
ж) Steam… a turbine generator
4) Составьте 7-8 вопросов по содержанию текста.
5) Перескажите текст .
3. Control text
Переведите текст и расположите абзацы в правильном логичном порядке
Testing Motors and Generators
It is of great importance, therefore, to make regular tests of insulation resistance of all machinery so as to detect possible faults. Different conditions may influence the value of the insulation resistance.
It is advisable, therefore, to make the test of the machine as soon after it has been shut down as possible, when the insulation resistance is likely to be lowest. If, after the motor has just been shut down the insulation resistance is found to be satisfactory, it may be assumed that it will be better at any other time provided that the machine does not stand idle for long in a humid atmosphere.
Faults on electrical machinery must be due to one pf two causes. One is the absence of continuity in the conductor which is supposed to be carrying the current. The other is the absence, or partial absence, of insulation. The latter is by far the more common and the more dangerous of the two. A burnt out armature, for example, is usually due to insulation failure.
A drop in insulation resistance may often be accounted for, for example, by damp weather.
As regards the effect of temperature it should be noted that the insulation resistance of motors and generators is generally lower when they are hot than when they are cold as the insulating varnishes used in the building of the machines have a lower resistance when hot than when cold.
Unit V
1. Прочитайте и переведите текст