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контрольная работа "The Principle of Transformer Action"
- 4 страниц
- 2016 год
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Задание 4
Перепишите и письменно переведите первые 2 абзаца текста.
The Principle of Transformer Action
A transformer is a simple device used in a.c. circuits for the purpose of changing voltage from one value to another. A transformer transfers electric energy from one electric circuit to another without a change in frequency. This energy transfer usually takes place with a voltage change. So transformers have to be generally used only with a.c.
A transformer may be defined аs an apparatus without moving parts. It means that mechanical losses are entirely absent. The action of a transformer is based on electromagnetic induction. What does it mean? Each transformer has а core on which the primary and the secondary are wound. The windings are linked magnetically.
The coil on which the a.c. is impressed on the input side of the transformer is called the primary, the one from which the induced e.m.f. is obtained on the output being known as the secondary. The coils may have air cores or they may be wound upon a laminated iron core. In the case of iron core transformers, the secondary voltage is very nearly equal to the primary voltage multiplied by the ratio of the number of the secondary to the number of the primary turns.
There is a limit to the frequencies that can be efficiently used in transformers with metallic cores. In case a very high frequency a.c. is used, air core transformers have to be used to eliminate core losses.
An a.voltage being applied to the terminals of the primary, the secondary is open-circuited. An a. magnetic flux is set up around the primary and this induces a back e.m.f. in the primary. A varying magnetic field is established between the two coils. The varying magnetic field will cut across the turns of the secondary and as the result of it an induced e.m.f. is produced across the secondary. This is the principle of a transformer action.
Задание 5
Ответьте письменно на следующие вопросы:
1. What is the function of a transformer?
2. When does the energy transfer take place between two coils?
3. What current is used in a transformer?
4. Why are mechanical losses absent in transformers?
5. What are the main parts of a transformer?
6. What types of transformer cores are there?
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Задание 1
Перепишите следующие предложения; подчеркните в каждом из них глагол-сказуемое и определите его видовременную форму и залог. Переведите предложения на русский язык. В разделе (б) обратите внимание на перевод пассивных конструкций.
а) 1) The engineers have refused from using these poor quality fuses.
2) Electricity is giving mankind efficient means for meeting the modern society requirements in energy.
b) 1) Today many highly conducting materials are produced on a massive scale.
2) This electric phenomenon was greatly influenced by these sets of external forces.
Задание 2
Перепишите следующие предложения; подчеркните Participle I и Participle II и установите функции каждого из них, т. е. укажите, является ли оно определением, обстоятельством или частью глагола-сказуемого. Переведите предложения на русский язык.
1) The chief engineer must give scantlings and drawings if required.
2) The amount of heat generated is very small.
3) The building of the first atomic power station was followed by the research work.
4) The pilot stood on the bridge giving orders to the helmsman.
Задание 3
Перепишите следующие предложения; подчеркните в каждом из них модальный глагол или его эквивалент. Переведите предложения на русский язык.
1) Repairs can be executed without special shop equipment.
2) Nowadays power stations should be connected into power grids.
3) The current must be as small as possible not to melt the wires.
4) A fast reactor has to be designed to produce more fuel than it consumes.
5) Considerable development may be done in the energy industry.
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