Exercise 2. Translate into English

Exercise 2. Translate into English

1. Линии электропередачи используют трехфазный переменный

ток.

2. Линии электропередачи связаны в региональные, националь-

ные или континентальные сети.

3. Высоковольтные воздушные линии электропередачи исполь- зуют алюминиевые провода, не покрытые изоляцией.

4. Подземные линии электропередачи более дорогие, но часто используются в городах.

5. Гирлянда подвесных изоляторов висит на поперечине вышки или на столбе и поддерживает линейный провод.

6. Воздушные выключатели используются для прерывания цепи, когда в них течет ток.

 

Unit 2. Transformers

Vocabulary

to convert                             преобразовывать

core                                       сердечник

due to                                    благодаря; из-за

electric power                      электроэнергия

primary winding                  первичная обмотка

regulator                               стабилизатор

secondary winding               вторичная обмотка

smoothing                            сглаживающая фильтрация

to step down                         понижать

step-down transformer         понижающий трансформатор

to step up                              повышать

step-up transformer             повышающий трансформатор

to supply                               снабжать; поставлять; подавать; питать

to transfer                             передавать, переносить

two-winding transformer     двухобмоточный трансформатор

turn                                       виток

while                                     тогда как

winding                                обмотка

 

Text

There are many types of power supply. Most are designed to convert

high voltage AC mains electricity to a suitable low voltage supply for elec- tronics circuits and other devices. A power supply can be broken down into a series of blocks (e.g. transformer, rectifier, smoothing, regulator), each of which performs a particular function.

A transformer is a static device which transfers AC electrical power from one circuit to the other at the same frequency, but the voltage level is usually changed. For economical reasons, electric power is required to be transmitted at high voltage while it has to be utilized at low voltage from a safety point of view.

Due to the transformer electric power may be transferred at a high voltage and reduced at the point where it must be used to any value.

A two-winding transformer consists of a closed core and two coils (windings). The primary winding is connected to the voltage source. It re- ceives energy. The secondary winding is connected to the load resistance and supplies energy to the load.

The value of voltage across the secondary winding depends on the

number of turns in it. In case it is equal to the number of turns in the primary winding, the voltage in the secondary winding is the same as in the primary. In case the secondary has more turns than the primary, the output voltage is greater than the in- put voltage. The voltage in the sec- ondary is greater than the voltage in the primary by as many times as the number of turns in the secondary is greater than the number of turns in

the primary. A transformer of this type increases or steps up the voltage and is called a step-up transformer. In case the secondary has fewer turns than the primary, the output voltage is lower than the input. Such a trans- former decreases or steps down the voltage; it is called a step-down trans- former.

Common troubles in transformers are an open in the winding, a short between the primary and the secondary, and a short between turns. In case a transformer has a trouble it stops operating or operates badly. A trans- former with a trouble should be substituted.