Step 2. Electrical drive

Task 1. Pronounce correctly the following words and word combinations. Learn them by heart.

Electrical drive – электропривод

power rating – максимально допустимая мощность

conversion – превращение, преобразование

to estimate – оценивать

constant-speed drive – двигатель с постоянной частотой вращения

predominance – превосходство, преобладание

steam turbine – паровая турбина

hydraulic drive system – гидропривод

pneumatic drive system – пневмопривод

pump – насос

hydrostorage plant – гидроузел

torque – вращающий момент

forced air ventilation – принудительная вентиляция

to enclose – окружать, обрамлять, ограждать

to submerge – погружать под воду, затоплять

to expose – выставлять, подвергать себя

hazardous fuel – опасные виды топлива

to emit – излучать, выпускать, извергать

exhaust fumes – отработавшие газы, выхлопные газы

at a moment’s notice – немедленно, сразу

service requirements – техническое обслуживание

modest – скромный, умеренный

high dynamic performance – высокие динамические характеристики

considerable short-time overload capacity – чрезвычайно высокая способность выдерживать перегрузки в течение короткого промежутка времени

elevated temperature – повышенная температура

fatigue – усталость (металлов)

compatible with – совместимый с

foot-mounted – смонтированный на полу

flange-mounted – прифланцованный двигатель

outer rotor – внешний ротор

to supplement – пополнять, добавлять

propulsion – толчок, тяга

on-board – встроенный

storage battery – аккумуляторная батарейка

fuel and solar cells – топливные и солнечные элементы

power-to-weight ratio – удельная мощность

Task 2. Read and translate the text.

Electrical drive

The mechanical form of energy is particularly important. It is needed in widely varying power ratings wherever physical activities take place, involving the transportation of goods and people or industrial production processes. For this final conversion at the point of utilization, electromechanical devices in the form of electrical drives are well-suited. It is estimated that about half the electricity generated in an industrial country is eventually converted to mechanical energy.

Most electrical motors are used in constant-speed drives that do not need to be controlled except for starting, stopping or protection.

The predominance of electrical drives (as compared with steam turbines, hydraulic drive system, diesel engines, pneumatic drive system) is caused by several aspects:

1. Electrical drives are available for any power (from the power in electronic watches to the power for driving pumps in hydro storage plants).

2. They cover a wide range of torque and speed.

3. Electrical drives are adaptable to almost any operating conditions such as forced air ventilation or totally enclosed, submerged in liquids, exposed to explosive or radioactive environments. They do not require hazardous fuels and do not emit exhaust fumes. The noise level is low compared, for instance, with combustion engines.

4. Electrical drives are operable at a moment’s notice and can be fully loaded immediately. There is no need to refuel, nor warm-up the motor. The service requirements are very modest, as compared with other drives.

5. Electrical drives are easily controllable. The steady state characteristics can be reshaped almost at will. High dynamic performance is achieved by electronic control.

6. Electrical drives have a considerable short-time overload capacity.

7. Since there are no elevated temperatures causing fatigue, long operating life can be expected.

8. Electrical motors are built in a variety of designs to make them compatible with the load; they may be foot-or flange-mounted, or the motor may have an outer rotor etc.

Machine tools can now be driven by a multitude of individually controlled motors producing the mechanical power exactly where, when and in what form it is needed. As would be expected, this long list of remarkable characteristics is to be supplemented by disadvantages of electrical drives which limit their use.

1. The dependence on a continuous power supply causes problems with vehicle propulsion. An electric energy source must be carried on-board, which is usually bulky, heavy and expensive (storage battery, rotating generator with internal combustion engine, fuel or solar cells).

2. Electrical motors are likely to have a lower power-to-weight ratio than, for instance, high pressure hydraulic drives.

Task 3. Find in the text the English equivalents for the following.

1. техническое обслуживание;

2. высокие динамические характеристики;

3. повышенная температура;

4. срок службы;

5. ограничивать использование;

6. аккумуляторная батарейка;

7. удельная мощность;

8. уровень шума;

9. непрерывный источник энергии;

10. взрывоопасная среда.

Task 4. Think of the best translation to the following words and word combinations.

1. warm-up the motor;

2. radioactive environment;

3. emit exhaust fumes;

4. submerged in liquids;

5. adaptable to almost any operating conditions;

6. long operating life can be expected;

7. an electric energy source must be carried on-board;

8. remarkable characteristics;

9. high pressure hydraulic drives;

10. rotating generator.

Task 5. Arrange synonyms given in columns I and II in pairs.

1. to estimate 2. to generate 3. protection 4. to require 5. for instance 6. immediately 7. to achieve 8. characteristics 9. disadvantage 10. eventually

a. features b. to reach c. at a moment’s notice d. finally e. to calculate f. drawback g. to produce h. for example i. defence j. to demand

Task 6. Put in the missing prepositions.

1. It is estimated that about half the electricity generated in an industrial country is eventually converted … mechanical energy.

2. The predominance of electrical drives is caused … several aspects.

3. Electrical drives are adaptable … almost any operating conditions.

4. Electrical motors are built in a variety of designs to make them compatible …the load.

5. Most electrical motors are used in constant-speed drives that do not need to be controlled except … starting, stopping or protection.

6. Electrical drives are operable … a moment’s notice.

Task 7. Fill in the gaps using words and word combinations from the text.

1) About half the electricity generated in an industrial country is eventually … .

2) Electrical drives are adaptable to … .

3) The service requirements are very … .

4) High dynamic performance is achieved by … .

5) The dependence on … causes problems with vehicle propulsion.

6) An electric energy source must be carried on-board, which is usually … .

Task 8. Answer the questions.

1) What types of drives do you know?

2) Why are electrical drives so important? Where are they used?

3) In what conditions can electrical drives operate?

4) What are the service requirements of electrical drives?

5) In what designs are electrical motors built?

6) Are there any disadvantages of electrical drives?

Task 9. Give the summary of the text.