И. А. Курбасова Е. И. Силантьева

TEXT A. POWER SUPPLY SYSTEM
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(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 seaVch 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 oL 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.
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(7) Hswever, th,ere 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 disoasal 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 radioactivrty by the working personnel.
(9) In order to provide greater reliabilty of opera­tion and safety for people modern A-power plants are automatically controlled. Boilers, reactors, turbines and other equipment are operated from the plant's control room where there are batteries of dials and recordes giv­ing the operators a second-by-second picture of every­thing what is happening. Electronic robots, manipulators and mechanical hands which are able to measure, cound and toush 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 cosumers, 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) Altraougn 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 lowerwd 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 cammonly used electronic instruments. Due to electronics most substations are now operated by remote control.