V. Определите функцию слов с окончанием -ed: 1) определение; 2) составная часть сказуемого.

Образец. Is converted – составная часть сказуемого; converted e.m.f. – определение. The e.m.f. converted... – определение.

1. Owing to relative motion between a conductor and a magnetic field a voltage is generated. 2. The e.m.f. generated in the armature windings is converted into d.c. 3. In the alternators the generated a.c. is brought to the load unchanged. 4. The revolving-armature alternator is not generally used. 5. Fixed connections are easily insulated. 6. The voltage applied to the rotating field is low d.c. voltage. 7. Every alternator rating is expressed in volt-amperes.

VI. Найдите в упражнении V предложения, в которых глагол употреблен в страдательном залоге. Преобразуйте предложения так, чтобы действия относились к прошедшему и будущему времени.

Образец. The e.m.f. is converted …

The e.m.f. was converted into d.c.

The e.m.f. will be converted into d.c.

VII. Выразите свое согласие или несогласие с данными утверждениями, используя следующие фразы: You are quite right; I agree with you; I cannot agree with you; I am afraid you are not right (парная работа).

1. All electrical generators depend for their operation on the action of a magnetic field cutting through a coil. 2. In a d.c. generator the revolving part is always the winding. 3. The revolving-armature type alternator is similar in construction to the d.c. generator. 4. The revolving-armature alternator is found in alternators of large power rating and is widely used. 5. High-voltage alternators are usually of the rotating-field type.

VIII. Расскажите о типах генераторов переменного тока, пользуясь набором следующих слов и словосочетаний.

A.c. generator, d.c. generator, revolving-armature type, revolving-field type, armature, to rotate, to be converted, by means of advantage, stationary armature winding, high voltage alternators, heating loss, to be expressed.

Text 2

Alternator Construction

Alternators having high kilovolt-ampere rating are of the turbine-driven, high-speed type. The prime mover for this type of alternator is a high-speed steam turbine driven by steam under high pressure. The rotor of the turbine-driven alternator is cylindrical, small in diameter, and has windings firmly imbedded in slots in its face. The windings are arranged to form two or four distinct field poles. Only with this type of construction can the rotor withstand the terrific centrifugal force developed at high speeds without flying apart.

In slower speed alternators which are driven by engines, water power, geared turbines or electric motors, a salient-pole rotor is used. In this type the field windings are either connected in series, or in series groups connected in parallel. In either case, the ends of the windings connect to slip rings mounted on the rotor shaft. Regardless of the type of rotor field used, its windings are separately excited, usually by a d.c. generator called an "exciter".

The stationary armature, or stator, of an alternator holds the windings which are cut by the rotating magnetic field. The voltage generated in the armature as a result of this cutting action is applied to the load.

The stators of all alternators are essentially the same. They consist of a laminated iron core, with the armature windings embedded in this core. The core is secured to the stator frame.

A single-phase alternator has all the armature conductors connected in series as one winding, across which an output voltage is generated. If you understand the principle of the single-phase, you will easily understand multi-phase operation.

In a two-pole, single-phase alternator the stator winding is in two distinct coils, both being wound in the same direction round the stator frame. The rotor consists of two poles of opposite polarity.

As the rotor turns, its poles induce a.c. voltages in the stator windings. The two coils of the stator winding are connected to each other in such a way that the a.c. voltages induced in them are in phase, or "series-aiding".

Multi-phase (or "polyphase") alternators have two or more single-phase windings symmetrically spaced around the stator. The windings are electrically separated from each other.

In a two-pole, two-phase alternator the stator consists of two-phase windings completely separated from one another. Each winding is made up of two parts which are so connected that their voltages add. The rotor is identical to that used in the single-phase alternator.

Words and Word Combinations

E x e r c i s e s

I. Прочитайте следующие слова и определите, к какой части речи они относятся. Переведите их на русский язык:

turbine, pressure, cylindrical, diameter, winding, terrific, apart, apply, separately, secure, opposite, essentially.

II. Найдите в тексте эквиваленты следующих слов и словосочетаний:

высокоскоростная турбина, наружная поверхность, вставлять в паз, генератор с приводом от турбины, турбина с выдачей мощности через редуктор, по существу, соединяться последовательно, разноименные полюсы, магнитное поле, обмотка статора, отделять.

III. Заполните пропуски, выбрав нужный вариант.

1. The... of the turbine-driven alternator is cylindrical. 2. The rotor has... firmly imbedded in... in its face. 3. In slower speed alternators a...... rotor is used. 4. A single-phase alternator has the armature conductors connected...... as one winding. 5. The rotor consists of two poles of... polarity. 6. Multi-phase alternators have two or more single-phase windings... spaced around the stator.

(windings, opposite, symmetrically, rotor, in series, slots, salient-pole)

IV. Выберите из правого столбика слова или словосочетания, чтобы закончить предложения.

V. Найдите многокомпонентные определительные словосочетания в приведенных ниже предложениях и переведите их на русский язык.

1. The prime mover of this alternator is a high-speed steam turbine. 2. In slower speed alternators a salient-pole is used. 3. In a two-pole, single-phase alternator the stator winding is in two coils. 4. In a two-pole, two-phase alternator the stator consists of two single-phase windings separated from one another. 5. When the rotor turns, its poles induced a.c. voltages in the stator windings.

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