Vocabulary.

Voltage ratings – номинальное напряжение

To expect – ожидать

Rather than – а не

Across the terminals – через клеммы

Wind (wound, wound) – наматывать

Rare – редко

In addition – кроме

Pole face – рабочая поверхность полюса, поверхность полюсного башмака

Amortisseur winding – демпферная обмотка

Current-carrying conductor – проводник, несущий ток

To cause – приводить к, вызывать

Conventional right-hand rule – обычное правило правой руки

Counter-clockwise direction – в направлении против часовой стрелки

Start from the rest – запускать с состояния покоя

Simultaneously – одновременно

In order to maintain rotation – чтобы поддерживать вращение

One pole pitch – однополюсное деление

Repelling force – обратная сила

Running torque – крутящий момент при установившемся режиме работы

Relative to – относительно

Line frequency – частота сети

Allow for slip – поправка на смещение

Across the line starting – запуск при полном напряжении

Breakup switch – размыкатель, переключатель

To short-circuit the field on itself – замкнуть накоротко обмотку возбуждения

The rotor is accelerated – ротор набирает обороты

5. Answer the questions.

1. What is a dc shunt motor electrically and magnetically identical with?

2. What are two modes that the shunt dynamo may be operated?

3. Will changes in mechanical load cause a change in speed?

4. What can the construction of a polyphase synchronous motor be compared with?

5. What does the type of armature depend on?

6. Are the poles different from those of the alternator?

7. What type of winding is used in the rotor? How is it called?

8. With three-phase voltage applied to the armature, what kind of field id produced?

9. What does the speed of the field depend on?

10. What does the synchronous-motor operation depend on?

11. In which case there is no starting torque?

12. What does the speed of the rotor depend on?

13. What are the methods of starting of synchronous motor?

14. Why should the auxiliary induction motor have two poles fewer than the synchronous motor?

15. When does the squirrel-cage winding develop torque?

16. What causes the great initial current inrush?

17. What is the function of the breakup switch?

6. Never looking into the text try to complete the following sentences:

1. Since a dc shunt motor is electrically and magnetically identical with a _____, the shunt dynamo may be operated either as a _____ or a ______. 2. When an ас supply is connected across the _____ terminals, _____ will be developed. 3. Changes in mechanical load within the machine’s rating will not cause u change in _____. 4. Essentially, the construction of a polyphase synchronous motor is the same as that of a _____.

5. In large machines the _____ is on the stator and is wound for the same number of _____ as the rotor. 6. The slots of this winding are on the pole faces and are parallel to the _____ . 7. This _____ winding on the rotor is known as the cage winding. 8. Since the conductor is stationary and the field is on the shaft, motion is produced in a _____ direction. 9. If both rotor and stator are simultaneously energized from rest, there is no _____ . 10. With a reversal of both current and magnetic field _____ of the con­octor remains in the same direction. 11. The _____ induction motor should have two poles fewer than the syn­chronous motor.

12. The synchronous motor, now operating as a generator, can be _____ with the supply lines. 13. The squirrel-cage winding embedded in the pole faces develops _____ when a three-phase supply is connected across the armature ter­minals and sets up a _____ in the stator. 14. Another preventive method is to short-circuit the field on itself or close it through an external resistor, thereby providing an _____ drop in either case. 15. After the rotor is _____to its constant induction motor speed, the stator field is moving rather _____ relative to the rotor field. 16. The effect of _____ may at some point magnetize each pole in only one di­rection.