Answer the questions. 1) What does a transformer consist of?

1) What does a transformer consist of?

2) What is the function of a coil?

3) Why are transformers sometimes used to isolate one circuit from another electrically?

4) What winding is connected to the source of power?

5) What winding is connected to the load?

6) What transformer is called a step-up transformer?

7) What transformer is called a step-down transformer?

8) What should be done to make transformers as close to 100 percent efficient?

Complete the following sentences.

1) A transformer consists of … .

2) The core of a transformer is … .

3) The coupling between the primary and secondary is … .

4) Transformers are sometimes used … .

5) The winding that is connected to the source of power is … .

6) The winding connected to the load is … .

7) The load may be … .

8) If the secondary has more turns than the primary, the transformer is … .

9) If the secondary has fewer turns than the primary, the transformer is … .

Retell the text.

UNIT 17 (PART 3). TRANSFORMERS

Words to remember.

nameplate – табличка

maintenance – техническое обслуживание

capacity – емкость

rating – номинальный режим, номинальные параметры

a tank – корпус

frequency – частота

drain – капля, водопровод

a gag – заглушка

Read the text.

Transformer rating

The nameplate on a transformer gives all the pertinent information required for the proper operation and maintenance of the unit. The capacity of a transformer (or any other piece of electrical equipment) is limited by the permissible temperature rise during operation. The heat generated in a transformer is determined by both the current and the voltage. Of more importance is the kilovolt-ampere rating of the transformer. This indicates the maximum power on which the transformer is designed to operate under normal conditions (when the current and voltage are “in phase”). Other information generally given is the phase (single-phase, three-phase, etc.), the primary and secondary voltages, frequency, the permitted temperature rise, and the cooling requirements – which include the number of gallons of fluid that the cooling tanks may hold. Primary and secondary currents may be stated at full load.

Depending on the type of transformer and its special applications, there may be other types of identifications for various gages, temperature indication, pressure, drains, and various valves.

Thus, it can be seen that while the transformer consists primarily of a primary and a secondary winding, there are many other points to take into consideration when selecting a transformer for a particular use.