Перегрузка электрической сети является одной из самых распространенных причин короткого замыкания. Короткое замыкание может произойти и из-за воздействия влаги.

Электроустановочные устройства – розетки и выключатели также должны быть влагозащищенными. Внутренняя проводка, а если это невозможно, то внешняя проводка должна быть хорошо изолирована.

 III. Fill in the blanks with the necessary forms of Modal Verbs:

(must, should, would, ought to, needn't, can, could, may, might)

1. They...not do this work themselves. 2. You...take my dictionary. 3. You don't look well, you... consult the doctor. 4. Why... I give you my money? 5. She... not speak any foreign language. 6. He...to help them, they need his help. 7....you tell me the time?  

 

 

 

Контрольная работа №20

I. Translate the text:

Care of the electrical equipment

As a rule electrical equipment operates reliably. Still it does not mean that it deserves no attention. It is necessary to give the equipment frequent inspections, keep it well cleaned, lubricated and repaired. Undue heating, vibration, sparking should be immediately removed.

Heating may be due to overload or to a short circuit between turns, lack of oil in bearings. Vibration may be due to unproper foundation, unbalance in the moving parts of the machine.

Conductors may get heated because of overload or by reason of damage of the insulation of the conductor.

An electrical machine of any kind requires certain conditions under which it may operate reliably: temperature and freedom of access of surrounding air, need for protection against dirt, dust, type and duration of load, etc.

Rotating machines should be placed on solid foundations.

Conductors should be protected against mechanical damage.

All measures of safety precaution must be undertaken.

 II. a) Find in the text English equipments:

- короткое замыкание между витками

- чрезмерное нагревание

- меры по технике безопасности

b) Translate into English:Техника безопасности:

Ни в коем случае нельзя одновременно дотрагиваться до бытовых приборов и заземленных предметов (водопроводные трубы, батареи центрального отопления и т. д.). Вполне возможно, что на корпус бытового прибора пробивает электричество. В последнее время все больше и больше приборов имеют заземление. Это делается для обеспечения безопасности потребителей. Такие бытовые приборы имеют трехжильный шнур и вилку с тремя контактами.

IV. Fill in the blanks with the articles a, an, the and prepositions, where necessary:

When Mary was to open a meeting... the first time... her life, her voice shook... excitement. The young scientist shook hands... his friends who had come... the airport to see him.... I wonder why Bob is such an ill-natured boy. It's a pity he takes... his mother only... appearance! Ask Kate to join... our party. She looks serious, but I know she is very gay... nature and is fond of... singing and dancing.

V. Put the verbs in brackets into the correct voice and tense-forms:

1. Don't let the boy stay out so long. He (to run about) for three hours, and may catch cold. 2. That young singer has had very good training. He (to sing) for half an hour and never (to stop) for a moment's rest. 3. It is unfair of you to be so cross with the man. He (to be) away for two weeks and you can't blame him for few mistakes that (to make) during his absence. 4. Our reply (to send) to you as soon as all the dates (to fix) finally. At the moment some of them (to consider) still.

VI. Fill in the blanks with prepositions and adverbial particles where necessary:

1. Instead  ... buying something... everyday wear, as she had first intended, Mary bought a... sleeveless dress... better wear. 2. I don't advise you to buy this pair... shoes. I am afraid they'll soon wear.... 3.1 wonder why the water has set the table... two persons instead... three.

4. Speaking at the production meeting, the director... the factory pointed... that each... the workers and engineers was responsible... carrying... the plan. 5. She said that the new film was worth seeing, but there was such an expression... her face that I thought she was saying it only... fun.

Контрольные работы для студентов специальности техник-механик

Контрольная работа №1

I. Translate the text.

Types of Loading

   As to the manner in which loads are applied or transmitted to a structure of machine they may be considered as static loads, repeated loads, impact and energy loads.

  1.In static, steady or dead loads are forces that are applied slowly and remain nearly constant after being applied to the body such as the loads on most buildings or the load applied to a bar in the usual type of testing machine.

Repeated loads are forces that are applied a very large number of times causing a stress in the material that is continually changing, usually through some definite range. Such are the loads applied to the connecting rod of an engine is running, the wheel loads on a railroad rail as a train passes over the rail and similar ones.

Impact loads are forces that are applied to the resisting body in a relatively short period of time. An impact load, in general, is applied by a moving body when it comes in contact with the resisting body. The force exerted by the moving body and the period during which it acts in general cannot be determined. For this reason in some problems it is more satisfactory to calculate the stress and strain produced by an impact load from the energy delivered to the resisting body by the moving body.

  Other Classifications of Loads.-Loads may be classified as distributed loads and concentrated loads. A distributed load may be uniformly distributed or non-uniformly distributed. A concentrated load is one whose area of contact with the resisting body is negligible in comparison with the area of the resisting body.

11. Translate the text.

Зимние шины не рекомендуется эксплуатировать при температуре выше +5 по Цельсию. Они мало того, что становятся мягче и буквально «плавятся», но кроме того еще и не выполняют в полной мере своих функций, устойчивость автомобиля на дороге при этом становится большим вопросом.

 

 

Контрольная работа №2

I.  Translate the text.

Four-stroke engine

    The internal combustion engine is a machine that develops power from the combustion of fuel within a cylinder. The cycle of operation is as follows:

  a) Suction Stroke- Just before the piston reaches the inner dead-centre, a valve, usually of the "poppet" type, is opened.

   On its outward stroke, the piston draws into the cylinder an explosive mixture of air and fuel vapour.

Shortly before the piston reaches the outer dead-centre, the inlet valve is closed and the compression stroke begins.

b) Compression stroke- During this stroke, the whole of the gas in the cylinder is compressed into the free space at the head of the cylinder.

c) Explosion, or Working Stroke- When the compression stroke is almost complete, the explosive mixture is ignited by an electric spark or by other suitable means. The gases reach their maximum pressure almost immediately, and work is done until the piston has again reached a position just before the outer dead- centre, when a second exhaust valve is opened.

   If the ignition takes place too late, the piston begins its outward journey before the maximum pressure is developed and power is lost.