Special text: Unusual railways Special text: Underground railways
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Special text Unusual railways Special text Underground railway
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- THEME: POWER SUPPLY SYSTEM I
ESSENTIAL VOCABULARY
THEME: POWER SUPPLY SYSTEM I (1) Nowadays technical progress, including the progress in railway engineering, is unthinkable without the proper power supply system. (2) Till recent years, all electric energy has been generated by thermal and hydro-power stations. But the hydro-power stations are always tied to rivers As for the thermal power plants the supplies of fuel needed for their operation are not inexhaustible. So power engineers are now in search of new sources of energy. (3) The great efforts of scientists and engineers have resulted in discovering atomic energy which caused a revolution in energetics. (4) One of the most significant achievements in the development of atomic power engineering was made in the Soviet Union in 1954 with the construction of the world's, first atomic power plant (A-power plant). On being put into operation it opened up an epoch of peaceful uses of nuclear energy. [Now the atomic power stations have passed an experimental stage and successfully compete with the conventional power stations especially in the countries which experience the energy crisis. (5) The main and most remarkable feature of nuclear fuel is that it contains great thermal energy. Indeed, one ton of nuclear fuel is equal to more than 2.5 million tons of coal. Nuclear fuel reduces the cost of electric energy and saves valuable raw materials for other uses. (6) It goes without saying1 that nuclear energetics is faced with a bright future and very soon we may expect its being turned into the main source of power supply. II (7) However, there are a number of problems the scientists must solve in order to make the A-power plants still more attractive, one of these problems being the disposal of radioactive by-product should be placed in special containers and safely buried deep under the ground or on the ocean bottom. (8) While discussing of the A-power plants one should also mention the danger of accumulating radioactivity by the working personnel. (9) In order to provide greater reliability of operation and safety for people modern A-power plants are automatically controlled. Boilers, reactors, turbines and other equipments are operated from the plant's control room where there are batteries of dials and records giving the operators a second-by-second picture of everything what is happening. Electronic robots, manipulators and mechanical hands which are able to measure, could and touch are now indispensable for handling radioactive elements2 at A-power plants. Automatic sound warning is given as soon the slightest fault occurs, and light shows exactly where the fault is located. A special system enables the operator to direct all the processes any possible trouble. (10) After having been generated, the electric energy is sent to the electricity grid system3 of the country. It is the grid system that distributes the power to the consumers, including the electrified railways. (11) Both conventional and nuclear power stations generate a high voltage alternating current, (a. c.). The fact' is that the alternating current can be more economically transmitted over long distances than the , direct current, (d. c.) and higher the voltage the less energy is lost. (12) Although the alternating current, can be used to drive trains, in many countries it is converted to the direct current because d. с motors are simpler in construction than a. c. machines. (13) As is known, the conversion of а. с to d. с. takes place in railway substations. The first essential of a substation is a transformer in which the electric current taken from the transmission line is lowered in voltage. Another important instrument the substation is fitted with is a rectifier which converts a. c. to d. c, this one-way (i. e. direct) current being then fed to the overhead wire. (14) Electronics has found a wide application in railway substations, silicon rectifiers being one of the most commonly used electronic instruments. Due to electronics most substations are now operated by remote control. Download 0.85 Mb. Do'stlaringiz bilan baham: |
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