The transformer effect can also be obtained with a single tapped winding instead of separate primary and secondary windings. The arrangement is called an auto-transformer. If the primary winding represents the whole coil, the secondary voltage will be substantially the same proportion of the applied voltage as the proportion between the turns up to the secondary tapping and the total number of turns. By interchanging the voltage so that the supply is connected to the smaller number of turns, a voltage larger than the supply voltage appears across the whole coil. The auto-transformers can thus be used to obtain a higher or lower voltage than the supply, as in the case of the conventional transformer with two separate windings.
In practice, the use of auto-transformers is limited to fairly small voltage ratios, one reason being that if a break occurs anywhere in the secondary section of the winding, the primary voltage is applied to the apparatus connected to the secondary. With a high primary voltage this would give dangerous conditions. The chief uses of auto-transformers, are in a. c. voltage regulation and for infrequent service such as the low-voltage starting of induction motors.
Notes and commentary
with a single tapped winding – на одной обмотке с отпайкой
up to – вплоть до
the total number of turns – общее число витков
across the whole coil – на всей катушке
one reason being – одной из причин является
if a break occurs – если происходит обрыв
low-voltage starting of induction motors – запуск асинхронных двигателей на низком напряжении
I. Переведите на английский язык следующие слова:
1. Автотрансформатор
2. Напряжение
3. Обмотка
4. Регулирование
5. Опасность
6. Подключить
7. Практика
8. Переключение
9. Первичный
10. Вторичный
II. Заполните пропуски в следующих предложениях, используя слова из текста:
a. Auto-transformers can be used to change the ________ of electrical devices.
b. If a ________ occurs in the secondary section, it can be dangerous.
c. The primary winding represents the whole ________.
d. Auto-transformers are often used for a.c. ________ regulation.
e. By interchanging the voltage, a higher ________ can be achieved.
III. Напишите ответы на следующие вопросы:
a. What is the primary purpose of auto-transformers?
b. How does an auto-transformer change voltage levels?
c. What are some common applications of auto-transformers?
d. Why is safety important when working with auto-transformers?
e. What happens if a break occurs in the secondary section of an auto-transformer?
