Power transmission

 

They say that about a hundred years ago, power was never carried far away from its source. Later on, the range of transmission was expanded to a few miles. And now, in a comparatively short period of time, electrical engineering has achieved so much that it is quite possible, at will, to convert mechanical energy and transmit the latter over hundreds of kilometres and more in any direction required. Then in a suitable locality the electric energy can be reconverted into mechanical energy whenever it is desirable. It is not difficult to understand that the above process has been made possible owing to generators, transformers and motors as well as to other necessary electrical equipment.

It goes without saying that as soon as the electric energy is produced at the power-station, it is to be transmitted over wires to the substation and then to the consumer. However, the longer the wire, the greater is its resistance to current flow. On the other hand, the higher the offered resistance, the greater are the heating losses in electric wires.

One can reduce these undesirable losses in two ways, namely, one can reduce either the resistance or the current. It is easy for us to see how we can reduce resistance: it is necessary to make use of a better conducting material and as thick wires as possible. However, such wires are calculated to require too much material and, hence, they will be too expensive. Can the current be reduced? Yes, it is quite possible to reduce the current in the transmission system by employing transformers. In effect, the waste of useful energy has been greatly decreased due to high-voltage lines.

It is well known that high voltage means low current, low current in its turn results in reduced heating losses in electrical wires. It is dangerous, however, to use power at very high voltages for anything but transmission and distribution. For that reason, the voltage is always reduced again before the power is used.

 

Notes on the text:

one cannot but – нельзя не, невозможно не

it goes without saying – ясно, само собой разумеется

on the other hand – с другой стороны

 

VII. Письменно ответьте на вопросы по содержанию текста:

What made it possible to transmit electric energy over hundreds of kilometres?

What are transformers used for?

In what way can the heating losses be reduced in transmission lines?

 

Вариант III

I. Перепишите предложения, подчеркните глагол-сказуемое в Passive

Voice. Переведите на русский язык.

The development of science is closely connected with the development of higher education.

These computers were programmed to provide an endless number of simple questions, and as the student answered these questions the facts were learned.

When the transformer was invented, the first electric lines and networks were set up.

It is known that much has been done in the world for the development of non- traditional sources of energy.

II. Определите функции глаголов to be, to have, to do. Предложения

переведите на русский язык.

Electricity has many important applications in industry as well as in our houses.

Some years later a motor with two speeds was designed.

Almost everything in the modern world is done with the help of computers – the complicated descendants (потомки) of the first calculating machine, invented by Ch. Babbage in 1812.

Computers do help students make a lot of calculations.

 

III. Перепишите предложения. Переведите на русский язык, обращая

внимание на функцию инфинитива (подлежащее, часть сказуемого,

дополнение, определение, обстоятельство).

The generator is the device to change mechanical energy into electric energy.

To design, construct and operate a laser system is a great technological achievement.

Lasers to be placed on Earth satellites will transform solar radiation into laser beams.

We must build as many power stations as possible to meet all the power needs in industry and agriculture.

To train highly scientific workers is extremely important for the development of science.

 

IV. Переведите предложения на русский язык, обращая внимание на

инфинитивные конструкции (Complex Subject, Complex Object).

The a.c. (alternating current) used for power and lightning purposes is assumed to go through 50 cycles in one second.

The students saw the thermometer mercury fall to the fixed point.

The latest achievements in the field of superconductivity are certain to make a revolution in technology and industry.

We want the atomic energy to be used for peaceful construction.

 

V. Переведите на русский язык, обращая внимание на значения слов: as,

because, because of, due to, for, since, either... or, neither... nor,

both... and.

As the devices were out of date it was decided not to install them.

Since the steam gives up its heat energy to drive the turbine its temperature and pressure fall.

The variety of purposes which electricity is used for nowadays is endless.

Both nuclear power and solar energy will be widely used in future.

Such satellites can contain either television cameras or photographic equipment for transmitting pictures to Earth.

The word “electricity” comes neither from English nor from Latin, it comes from the Greek word for “amber”.

Aluminium and its alloys are very useful due to good corrosion resistance combined with their light weight.

We could not continue our research because of the lack of data.

VI. Прочитайте текст, перепишите, письменно переведите на русский

язык.