Hydroelectric Power-Station

 

Water power was used to drive machinery long before Polzunov and James Watt harnessed steam to meet man’s needs for useful power.

Modern hydroelectric power-stations use water power to turn the machines which generate electricity. The water power may be obtained from small dams in rivers or from enormous sources of water power. However, most of our electricity, that is about 86 per cent, still comes from steam power-stations.

The locality of a hydroelectric power plant depends on natural conditions. The hydroelectric power plant may be located either at a dam or at a considerable distance below. That depends on the desirability of using the head supply at the dam itself or the desirability of getting a greater head. In the latter case, water is conducted through pipes or open channels to a point farther downstream where the natural conditions make a greater head possible.

The design of machines for using water power greatly depends on the nature of the available water supply. In some cases great quantities of water can be taken from a large river with only a few feet head. In other cases, instead of a few feet, we may have a head of several thousands of feet. In general, power may be developed from water by the action of its pressure, of its velocity, or by a combination of both.

A hydraulic turbine and a generator are the main equipment in a hydroelectric power-station. Hydraulic turbines are the key machines converting the energy of flowing water into mechanical energy. Such turbines have the following principal parts: a runner composed of radial blades mounted on a rotating shaft and a steel casing which houses the runner. There are two types of water turbines, namely, the reaction turbine and the impulse turbine. The reaction turbine is the one for low heads and a small flow. Modified forms of the above turbine are used for medium heads up to 500-600 ft, the shaft being horizontal for the larger heads. High heads, above 500 ft, employ the impulse- type turbine.

Hydropower engineering is developing mainly by constructing high capacity stations integrated into river systems known as cascades. Such cascades are already in operation on the Dnieper, the Volga and the Angara.

 

VI. Письменно ответьте на вопросы по содержанию текста:

What does the locality of a hydroelectric power plant depend on?

What is the key machine for converting the energy of water into mechanical energy?

 

Вариант III

I. Перепишите предложения. Переведите на русский язык, обращая

внимание на перевод герундия. Подчеркните герундий в предложениях.

 

Protecting buildings from strokes of lighting was a great achievement in the field of electricity.

Supercomputers are used for calculating complex problems.

His taking part in the development of the new semiconductor device was of great help to us.

Besides using optical telescopes scientists are extensively employing radio telescopes, which are huge antennae, and constantly listening to the radio signals coming from our distant neighbours in the Universe.

II. Перепишите предложения. Подчеркните причастия. Переведите

предложения на русский язык. Укажите № предложения, в котором

употреблен независимый причастный оборот.

 

In future, the nuclear reactor will be one of the most reliable “furnaces” producing atomic energy.

Atomic energy being developed in a reactor in the form of heat, we can get both heat and electrical energy.

Having been translated into a machine language any high level programming language can be used by any computer.

Knowing how to detect radio signals emitted by the Sun and other heavenly bodies people can greatly enlarge their possibilities of observing the universe.

When passed through the reading equipment (устройство ввода) the characters are read into the memory of a PC (Personal Computer).

The students heard the professor speaking about his experimental work.

III. Перепишите предложения и переведите их на русский язык, обращая

внимание на глаголы в сослагательном наклонении.

Without radioelectronics there would be no cybernetic, cosmonautic or nuclear physics.

The electrons move round the nucleus as if they were the planets of the solar system moving round the sun.

It is essential that a superconductor should be cooled to - 273˚C.

The substance should be purified so that it might be used for this purpose.

IV. Перепишите предложения. Переведите на русский язык, обращая

внимание на условные придаточные предложения.

If there were no computers, space flights would be impossible.

If atomic energy replaces the present sources of energy, we shall get more energy than we produce at present.

Had there been no Earth`s gravitational, the artificial satellites would have moved through airless space in a straight line at a uniform speed.

V. Прочитайте текст, перепишите его и письменно переведите на

русский язык.