Generators

 

The dynamo invented by Faraday in 1831 is certainly a primitive apparatus compared with the powerful, highly efficient generators and alternators that are in use today. Nevertheless, these machines operate on the same principle as the one invented by the great English scientist.

There are two types of dynamos, namely, the generator and the alternator. The former supplies d.c. which is similar to the current from a battery and the latter, as its name implies, provides a.c.

To generate electricity both of them must be continuously provided with energy from some outside source of mechanical energy such as steam engines, steam turbines or water turbines.

Both generators and alternators consist of the following principal parts: an armature and an electromagnet. The electromagnet of a d.c. generator is usually called a stator for it is in a static condition while the armature (the rotor) is rotating. Alternators may be divided into two types: 1. alternators that have a stationary armature and a rotating electromagnet; 2. alternators whose armature serves as a rotor (but this is seldom done). In order to get a strong e.m.f., the rotors in large machines rotate at a speed of thousands of revolutions per minute (r.p.m.). – The faster they rotate, the greater the output voltage the machine will produce.

In order to produce electricity under the most economical conditions, the generators must be as large as possible. In addition to it, they should be kept as fully loaded as possible all the time. It is interesting to note here that the biggest generators ever installed at any hydroelectric station in the world are those installed in the former USSR. As you are likely to remember the Bratskaya hydroelectric station is equipped with 225,000 kilowatt (kW) generators. Soviet scientists constructed more powerful generators which are installed at the Krasnoyarskaya station. The Konakovskaya, the Zaporoshskaya and the Uglegorskaya steam power-stations have large rated capacity. Our industry produces even greater power installations of 1,200 MW.

Notes on the text:

d.c. – direct current

a.c. – alternating current

e.m.f. – electromotive force

rafed capacity – номинальная мощность

VII. Письменно ответьте на вопросы по содержанию текста:

What do we need electricity for?

What are dynamo electric machines used for?

What are the principle parts of a generator?

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The scientific and technological progress of a country is determined by the qualification of specialists.

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A combination of electric lines and networks were set up throughout the country.

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It is considered that the development of the induction motor has become the most important technical achievement.

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This device does help them a lot in their work.

 

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V.V. Petrov was the first scientist to study the electrification of metals by rubbing them.

Laser and thermonuclear reaction can produce a limited source of energy.

When we are dealing with wires and fuses carrying an electric current, it is best to wear rubber gloves.

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Electromotive force is necessary for the current to flow along the circuit.

It is necessary to remember the term “circuit” as it is impossible to work with electricity without circuits.

Silver is the best conductor known since it offers the least resistance to the current flow.

Electricity is used both in industry and in everyday life.

Many lasers give off invisible radiation, either infrared or ultraviolet.

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