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Кабiнет 45

Англiйська мова
 
Поточний час: 23 жовт 2017, 17:01

Часовий пояс: UTC + 2 години




   [ 1 повідомлення ] 
Автор Повідомлення
 Заголовок повідомлення: Заняття №57
ПовідомленняДодано: 27 квіт 2015, 12:15 
Адміністратор

Зареєстрований: 27 лип 2014, 11:21
Повідомлення: 203
Тема: Заземлення і заземлювальні пристрої.Технічні скорочення та одиниці вимірювання.



Методичні вказівки:

1. Знайти переклад слів та словосполучень у словнику.

2. Прочитати, перекласти текст та зробити лексичні вправи по темі.

3. Вивчити технічні скорочення та одиниці вимірювання.



Завдання І

Знайдіть переклад слів та словосполучень у словнику, запишіть та вивчіть їх:

groundbed [groundbed]
to install [tu ɪnˈstɔːl]
to provide ‘tə prəˈvaɪd]
ground rod [ ɡraʊnd rɒd]
to bond [tə bɒnd]
bare copper wire [beə ˈkɒpə ˈwaɪə]
path [pɑːθ]
resistance [rɪˈzɪstəns]
to retain [tə rɪˈteɪn]
to swell [tə swel]
sheathed type [ʃiːðd taɪp]
requirement [rɪˈkwaɪəmənt]



Завдання ІІ

Прочитати, перекласти текст та зробити лексичні вправи по темі.

GROUNDBED

A groundbed is an array of electrodes, installed in the ground to provide a low resistance electrical path to ground or earth. A groundbed is a component in an earthing system.

Each electrode is called a ground rod or a earth electrode.
Зображення
Grounding systems
Зображення
For building electrical grounding systems or earthing systems there is a low resistance conductor bonding the metalwork and this is connected to a groundbed. The electrodes for electrical grounding are often called ground rods and are often made from steel with a copper clad surface – typically 1 to 2m long and 20 millimetres in diameter. These are driven vertically into the ground and bonded together with bare copper wire.

Cathodic protection
Зображення
In cathodic protection, the anode groundbed is the arrangement of anodes in the ground or water and it provides the path for protective current to leave the anodes and enter to electrolyte.

Certain ground conditions make it difficult to obtain a reliable earth resistance, whilst particular installations may require a very low resistance. In such cases, Marconite provides a convenient and permanent solution.
Зображення
By adding Marconite in place of sand and aggregate, to cement, a conductive concrete is formed. This electrically conductive medium has many applications in the electrical/construction industry, including RF and microwave screening, static control and of course earthing, for which it was specifically developed.

When used as a backfill for earth electrodes, Marconite impregnated concrete greatly increases the electrodes surface area thus lowering its resistance to earth.

No other product can offer the same benefits as Marconite in earthing applications.

Used as an earth-electrode backfill to reduce soil resistivity by retaining moisture. The clay consists largely of sodium montmorillonite, which when mixed with water swells to many times its dry volume. It has the ability to hold its moisture content for a considerable period of time and to absorb moisture from the surrounding soil (e.g.from rainfall).

First copper bond earth rods probably offer to the installer the best and most economical earth rods available. They are made by molecularly bonding 99.9% pure electrolytic copper onto a low carbon steel core. First rods are not of the sheathed type. They are highly resistant to corrosion, and because the steel used has a very high tensile strength, they can be driven by power hammers to great depths.

The counter-bored couplings are made from high copper content alloy, commercial brass is not used. This again ensures excellent corrosion resistance and high strength.

How to apply earthing equipment

An effective earthing system is a fundamental requirement of any modern structure or system for operational and/or safety reasons. Without such a system, the safety of a structure, the equipment contained within it and its occupants is compromised.
Зображення

Earthing systems typically fall into (but are not limited to) one of the following categories:

-power generation, transmission and distribution
-lightning protection
-control of undesirable static electricity
-telecommunications.

Conductors and Earth Rods
Зображення
As with lightning protection, the first choice faced by the designer of an earthing system is the type of conductor to be used. The correct choice of conductor is extremely important, whether it be a simple below ground electrode or a complex computer room signal reference grid.

Conductors


There are three types of conductor: flat tape, solid circular and stranded cable.

A range of conductor materials are available. Above ground, copper, aluminium and steel may be used. Below ground, copper is the most common choice due to its high resistance to corrosion.

It is important that earthing conductors should be correctly sized for their application, as they may be required to carry a considerable current for several seconds. For specific information on conductor ratings see Conductor Ratings.
Зображення
Earth Rods and Plates
Зображення
In addition to the conductors outlined above, earth rods and plates or any combination thereof can be used to achieve an effective earth depending on the site conditions.

Earth rods take advantage of lower resistivity soils at greater depths than normal excavation will allow.
Зображення
Earth plates are used to attain an effective earth in shallow soils with underlying rocks or in locations with large amounts of buried services. They can also provide protection at potentially dangerous places e.g. HV switching positions.


Дайте відповіді на питання:

1. What is a groundbed?
2. How is it called each electrode?
3. What do you know about grounding systems?
4. What is cathodic protection?
5. What does Marconite provide?
6. What do you know about copper bond earth rods?
7. How can we apply earthing equipment?
8. What is the best earthing conductor?
9. What do you know about earth rods and plates?



Перекладіть речення:

1. An effective earthing system relies on joints and connections to have good electrical conductivity with high mechanical strength.
2. Poorly chosen or badly installed joints and connectors can compromise the safe operation of an earthing system.
3. A simple, self-contained method of forming high quality electrical connections which requires no external power or heat source.
4. Connections are made using the high temperature reaction of powdered copper oxide and aluminium.
5. They will never loosen, are highly conductive and have excellent corrosion resistance.
6. Compression connectors produce very robust joints which can be buried in the ground or in concrete.
7. Where permanent connections are not appropriate, mechanical clamps offer the ideal solution.
8. These are typically used on smaller scale installations where periodic disconnection for testing is required.
9. All Furse mechanical clamps are manufactured from high copper content alloy.
10. They have high mechanical strength, excellent corrosion resistance and conductivity.



Завдання ІІІ

Запишіть та вивчить технічні скорочення та одиниці вимірювання:

AC, ac (alternating current) змінний струм
AF (audio frequency) звукова частота
A (ampere) ампер
c (capacitance) ємність
cm (centimetre) сантиметр
cub (cubic) кубічний
dc (direct current) постійний струм
deg (degree) ступінь, градус
F (Fahrenheit) Фаренгейт
fig (figure) цифра, фігура (рисунок)
ft (foot) фут
HF (high frequency) висока частота
in (inch) дюйм
kg (kilogram) кілограм
km (kilometre) кілометр
kV (kilovolt) кіловольт
kW (kilowatt) кіловат
kWh (kilowatt-hour) кіловат-годин
lab (laboratory) лабораторія
lb (libra, pound) фунт
lg (length) довжина
lim (limit) межа
liq (liquid) рідина
meg (megohm) мегом
MeV (million-electronvolt) мільйон-електронвольт
MF (medium frequency) середня частота
mV (millivolt) мілівольт
mW (milliwatt) міліват
pc (per cent) процент, відсоток
psi (pounds per square inch) фунти на квадратний дюйм
r (R) (resistance) опір
ref (reference) посилання
rpm (revolutions per minute) оберти за хвилину
VHF (very high frequency) ультрависока частота
V (volt) вольт
vol (volume) обсяг, об’єм.


Завдання: розшифруйте скорочення:

ALU, CMEA, CRT, db, EPROM, FAB, FET, IC, J, kC, MC, MOSFET, mu, PROM, RAM, rf, ROM, VLSI.


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