III. Заполните пропуски, выбрав нужный вариант.
1. The voltage induced in the loop ... its polarity every time the loop goes through 0 and 180 degrees points (reverses, switches).
2. The only way that d.c. can be obtained from the generator is ... the generated a.c. into d.c. (to induce, to convert).
3. It would be ... to operate a switch manually at such a high speed (impossible, exactly).
4. The polarity of the induced e.m.f. ... the direction a conductor moves through a magnetic field (generates, depends on).
IV. Вставьте нужный предлог: of, to, along, opposite, at, through.
1. ... these points the conductors of the loop reverse their direction ... the magnetic field.
2. The other slip ring is split ... its axis.
3. The brushes are now positioned ... each other.
4. The ends of the coil are then connected one ... each of the segments ... the slip ring.
V. Переведите предложения на русский язык, обращая внимание на время сказуемого в пассивной форме.
1. A solution has been found in the slip rings of the elementary generator.
2. One of the slip rings is eliminated.
3. The segments were insulated so that there was no electrical contact between segments, the shaft or any other part of the armature.
4. As the loop rotates each conductor will be connected by means of the commutator, first to the positive and then to the negative brushes.
VI. Запомните и воспроизведите диалог.
A: Do you know that since the loop continues rotating through the field the conductors of the loop will always have an alternating e.m.f. induced in them?
B: Yes, that is quite right.
A: And how can d.c. be obtained from the generator?
B: To obtain d.c. from the generator one must convert the generated a.c. to d.c.
A: What device converts the generated a.c. to d.c.?
B: To my mind the commutator does.
A: And how is the action of converting a.c. to d.c. called?
B: It is called commutation.
VII. Просмотрите текст и расскажите о коллекторе, употребив следующие слова:
one of the slip rings, the other slip ring, along its axis, the ends of the coil, each of the segments of the slip ring, no electrical contact, the shaft, any other part of the armature, the entire slip ring, commutator, its action of converting, commutation, between, is eliminated, is split, are connected to, are insulated, there is, is known as.
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Text 4
D.C. Generator Construction and Operation
Now you will learn about actual generators and how they are constructed.
There are several components essential to the operation of a generator. Once you learn to recognize these components and become familiar with their function, you will find it much easier to do fault-finding and maintenance work on generators.
All generators – whether a.c. or d.c. – consist of a rotating part and a stationary part. In most d.c. generators the armature coil is mounted on the rotating part, which is then referred to as the "armature". The field coils are mounted on the stationary part which is then referred to as the "field". In most a.c. generators the field is mounted on the rotating part – the rotor and the armature winding on the stationary part – the stator.
In either case there is relative motion between the armature and field coils, so that the armature coils cut through the magnetic lines of force of the field. As a result, an e.m.f. is induced in the armature, causing a current to flow through the outside load.
Since the generator supplies electrical power to a load, mechanical power must be put into the generator to cause the rotor to turn and to generate electricity. The generator itself simply converts mechanical power into electrical power. Consequently, all generators must have machines associated with them which will supply the mechanical energy necessary to turn the rotors. These machines are called "prime movers", and may be steam engines, electric motors and so on.
In assembling the generator, the fields are mounted in the stator and one end housing is bolted to the stator frame. The armature is then inserted between the field poles and the housing end, with the brush assemblies mounted last.
Generator assembly and disassembly varies depending on the size, type and manufacturer.
The field windings, when mounted on the pole pieces, form electromagnets which provide the magnetic field necessary for generator action. Field windings can be connected either in series or in parallel (or shunt, as the parallel connection is often called) with the armature. Shunt field windings consist of many turns of fine wire, while series field winding are composed of fewer turns of fairly heavy wire.
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Words and Word Combinations
| actual a | фактически существующий |
| A.C., a.c. – alternating current | переменный ток |
| D.C., d.c. – direct current | постоянный ток |
| essential to a | необходимый для |
| recognize v | узнавать |
| become familiar | познакомиться |
| do fault-finding | находить повреждения |
| do maintenance-work | осуществить техническое обслуживание и ремонт |
| armature coil | катушка обмотки якоря |
| refer to v | зд. называть |
| field coil | катушка возбуждения |
| mount v | устанавливать, монтировать |
| field n | индуктор |
| rotor n | ротор |
| stator n | статор |
| in either case | в любом случае |
| relative a | относительный |
| as a result | в результате |
| cause v | заставлять |
| outside a | наружный, внешний |
| load n | нагрузка |
| put into v | вложить |
| consequently adv | следовательно |
| associate with v | соединять с |
| necessary a | необходимый |
| prime mover | первичный двигатель |
| assemble v | монтировать, собирать |
| assembly n | монтаж, сборка |
| end housing | подшипниковый щит |
| bolt to v | скреплять болтами, привинчивать |
| insert v | вставлять |
| field pole | полюс с катушкой возбуждения |
| stator frame | станина статора |
| brush assembly | щеточное устройство, щеточный узел |
| disassembly n | разборка, демонтаж |
| size n | размер |
| manufacturer n | изготовитель |
| field winding | обмотка возбуждения |
| connect in series | соединять последовательно |
| connect in parallel (shunt) | соединять параллельно |
| shunt (field) winding | шунтовая (параллельная) обмотка |
| fine wire | тонкая проволока |
| fairly adv | довольно |
| heavy wire | толстая проволока |
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Note: with the brush assemblies mounted last – ..., а щеточные устройства устанавливаются последними.
E x e r c i s e s
I. Прочитайте и переведите слова и словосочетания :
essential, maintenance, stationary, referred to as, motion, function, outside (load), mechanical, to cause, consequently, associated with, necessary, assembling, size, to insert, assemblies, winding, fault-finding, turn, components.
II. Найдите в тексте эквиваленты следующих словосочетаний:
работа генератора, вращающаяся часть, неподвижная часть, в любом случае, относительное движение, в результате, сам генератор, при сборке генератора, в зависимости от размера и типа, тонкая проволока, толстая проволока.
III. Вставьте нужное слово.
1. Several components are ... to the operation a generator (essential, stationary).
2. As a result an e.m.f. ... in the armature causing a current to flow through the outside load (is mounted, is induced).
3. The armature coil ... on the rotating part (is mounted, is called).
4. The generator itself simply ... mechanical power into electrical power (supplies, converts).
5. These ... are called "prime movers" (stators, machines).
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