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.
| 1. Alternators which have high kilovolt-ampere ratings are of the ... | iron core turbine-driven type |
| 2. The windings of the rotor are excited by a ... ... | d.c. generator |
| 3. The stator of an alternator holds the ... | windings |
| 4. The stators consist of a laminated ... ... | coils |
| 5. In a single-phase alternator the stator winding is in two distinct ... |
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.
VI. Преобразуйте предложения так, чтобы глагол был употреблен в страдательном залоге.
Образец. Steam under high pressure drives the turbine. – The turbine is driven by steam under high pressure.
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1. The rotating magnetic fields cut the windings. 2. The poles of the rotor induce a.c. voltages in the stator windings. 3. Electric motors, geared turbines drive slower speed alternators. 4. The commutator converts the e.m.f. generated in the armature windings. 5. An alternator supplies the maximum current.
VII. Выразите согласие или несогласие с данными утверждениями, используя следующие фразы: You are quite right; I agree with you; I am afraid you are not right; On the contrary (напротив) (парная работа).
1. The rotor of the turbine-driven alternator is large in diameter. 2. The windings of the rotor form two or four distinct field poles. 3. The windings of rotors field are excited together. 4. The stators of all alternators are different. 5. In a single-phase alternator all the armature conductors are connected in series as one winding. 6. The windings are electrically separated from each other. 7. Each winding is made up of several parts which are not connected.
VIII. Расскажите: а) о конструкции генератора, б) об однофазном генераторе переменного тока, пользуясь набором слов и словосочетаний:
a) prime mover, windings, to be imbedded in slots, to withstand, salient-pole rotor, to be connected in series, slip rings, to be excited, rotating magnetic field, iron core;
b) single-phase alternator, output voltage, armature conductors, opposite polarity, to induce voltage, stator winding.
Text 3
Three-phase Alternator
The three-phase alternator, as the name implies, has three single-phase windings so spaced that the voltage induced in any one is phase-displaced by 120 degrees from the other two.
Instead of having six leads coming out of the three-phase alternator, three leads, one from each phase, are connected together to form what is called a "star" connection. The point of connection is called a neutral, and the voltage from this point to any one of the line leads will be the phase voltage. The total voltage, or line voltage, across any two line leads is the vector sum of the individual phase voltages. The line voltage is 1.73 times the phase voltage. Since the windings form only one path for current flow between phases, the line and phase currents are equal.
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A three-phase stator can also be connected so that the phases are connected end-to-end; it is then called "delta connected". In the delta connection the line voltages are equal to the phase voltage, but the line currents will be equal to the vector sum of the phase currents. Since the phases are 120 degrees out of phase, the line current will be 1.73 times the phase current. Both the "star" and the "delta" connections are used for alternators.
Most of the alternators in use today are three-phase-winding machines. This is because three-phase alternators are much more efficient than either two-phase or single-phase alternators.
It is common to use three-phase transformers in connection with three-phase alternators. Such a device may be made up of three single-phase transformers connected in the same way as the alternators. If both the primary and secondary are connected in star, the transformer is called a "star-star". If both windings are connected in delta, the transformer is called a "delta-delta".
Words and Word Combinations
| imply v | предполагать, подразумевать |
| to phase-displace | сдвигаться по фазе |
| instead adv | вместо |
| lead n | проводник |
| neutral n | нейтральная точка |
| total a | суммарный, общий |
| path n | путь |
| delta n | треугольник |
| common a | общепринятый |
| device n | устройство, прибор |
| primary n | первичная обмотка |
| secondary n | вторичная обмотка |
E x e r c i s e s
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I. Прочитайте слова и определите, к какой части речи они относятся. Переведите их на русский язык :
vector, imply, phase, connection, neutral, efficient, winding, equal, primary, secondary, alternator, transformer.
II. Найдите в тексте эквиваленты следующих слов и словосочетаний :
сдвигаться по фазе, проводник, фазовое напряжение, векторная сумма, равняться (быть равным), использоваться, первичная (вторичная) обмотка, устройство.
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