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2) Ответьте на вопросы:

1. What does a substation serve for?

2. What type of consumers does a substation feed?

3. What parts are the power transmission lines connected to?

4. What components does a substation comprise?

5. What types are substations classed into?

6. What are advantages of a transformer substation?

7. On what sites are hydroelectric power plants built?

8. Are large-capacity plants located far from consumers of power?

9. Is the production process at the plants simple or is it complex?

10. What influences the power capacity of a plant?

11. According to what factors does the daily inflow of water fluctuate?

12. Does the production process at the plant depend on its construction?

13. Do you know that a thermal power plant seldom has an efficiency more

than 40%?

3) Поставьте вопрос к предложению начиная с вопросительного слова, стоящего в скобках:

1) Hydroelectric power plants are built on rivers. (Where)

2) Large- capacity power plants at a short distance from consumers of power. (What)

3) The power capacity of a plant is influenced by the difference in the water level. (What by)

4) The daily inflow of water fluctuates according to the season. (How)

5) The production process depends upon the construction of the plant. (How)

3. Control text.

Переведите текст и найдите ответы на следующие вопросы

HV Power Transmission

A high-capacity hydrogenerator produces an a.c. current at 22,000 V. The current with the potential difference of 220,000 V is produced by means of the transformers at a step-up station and then transmitted over the power lines.

The current potential difference is lowered to medium 6,600 V at the main step-down substation at the end of the line. From here the power is transmitted to the next substations. Transformers stepping the voltage down from 6,600 V are installed at those substations.

Due to voltage conversion, alternating current is used widely in in­dustry. Direct current for battery charging for trams, trolleybuses and electric locomotives is changed from alternating current by means of rectifiers.

Superconductivity

In the electric generating field, as well as in the electric-transmission and storage-technology areas, considerable attention is focused on the use of superconductivity conductors. Cooling an electric conductor to temperatures close to absolute zero (-273°C) results in the conductors' losing their resistance to electric current. Accordingly, their ohmic losses also drop greatly. Current densities of tens of millions amperes per sq cm can be tolerated in such conductors.

Cryogenic technology being now mastered, one can foresee the pos­sibility of supercooling not only generators but also underground transmission lines and storage coils.

  1. Where is the current potential difference lowered?

  2. Where is the main step-down substation installed?

  3. Conductors can never lose their resistance to the flow of electric current?

  4. Generators and underground transmission lines can be supercooled?

Unit III

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