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Файл:Technical English for Electrical Engineers. Учебное пособие
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11
5. Why are different substances differ in their conductivity?
6. What instruments are used to measure the intensity and quality
of electrical energy?
3. Translate the text in written form.
V
1. Read the text.
NATURE OF ELECTRIC CURRENT
In the modern conception of the constitution matter is composed of
atoms. The atom is made up of a positive nucleus surrounded by negative
charges of electricity, called electrons, which revolve about the nucleus
at tremendous speed. The nucleus consists of a number of protons, each
with a single positive charge, and, except for hydrogen, one or more
neutrons, which have no charge. The atom is neutral when it contains
equal numbers of electrons and protons. A negatively charged body
contains more electrons than protons. A positively charged body is one
which contains fewer electrons than its normal number.
When the two ends of a conductor are connected to two points at
different potentials, such as the terminals of a battery, we say that there is
an electric current in the conductor. What actually happens?
The conductor has equal numbers of positive and negative charges in
its atoms, and we want to know how the charges can be made to produce a
current. The atoms in metals are packed so closely that they overlap to
some extent, so that it is comparatively easy for the outer electrons to pass
from one atom to another if a small force is applied to them. The
battery causes a potential difference between the ends of the wire, and
thus provides forces that make the negative electrons in the wire move
toward the point of higher potential. This electron flow toward the
positive electrode is the electric current. Naturally materials differ
considerably in the ease with which electrons can be made to migrate
from atom to atom.
12
The current will not flow unless there is an electric circuit. The
1) tremendous
a) same
2) modern
b) inner
3) positive
c) small
4) equal
d) hard
5) different
e) low
6) easy
f) negative
7) outer
g) artificial
8) high
h) unequal
9) natural
i) old
VERB
NOUN (ACTION)
NOUN (AGENT)
to compose
composition
composer
to revolve
revolution
conductivity
producer
to provide
applicator
reception
amplification
reflector
magnitude of the current depends simply on the rate of flow of electrons
along the conductor.
2. Match the columns:
3. Fill in the table:
4. Answer the questions:
1. What does atom consist of?
2. When is atom neutral?
3. What does a negatively charged body contain more?
13
4. What happens when two ends of a conductor are connected to
two points at different potentials?
5. What does the magnitude of the current depend on?
5. Speak on:
Modern conception of the constitution of matter.
VI
1. Read the text.
ELECTRONICS
Electronics is the science dealing with devices operated by control
of the movement of electric charges in a vacuum, in gases, or
semiconductors or with the processing of information or the control of
energy by such devices. This definition covers the whole complex family
of vacuum and gaseous electron tubes and their applications. It also
includes metallic contact or semiconductor rectifiers and the transistors
which utilize the control of electrons or positive charges (holes) to
process information or to convert energy.
Electronics was born in the 19th century. Like hydrolysis or
chemistry it has come into its own only recently. Electronics first
established itself, however, in wireless telegraphy. Industrial applications
of electronics include control gauging, counting, heating, speed
regulation, etc. But in a larger field, electronics leads to automatic control
of large-scale industrial operations.
Today, electronics has started a new era. Electronic devices are
doing simple, but human-like thinking. Some industries are controlled by
electronic robots. Automation is the industrial keynote of the day. Planes
and rockets are electronically controlled. Some radiotelescopes work
like radar to receive radio waves from outer space. Shortly speaking,
electronics is not so much a new subject as a new way of looking at
electricity.
14
2. Match the columns:
1) device
a) действие
2) semiconductor
b) выпрямитель
3) processing
c) волна
4) application
d) полупроводник
5) rectifier
e) заряд
6) charge
f) прибор, устройство
7) operation
g) применение
8) wave
h) определение
9) definition
i) обработка
3. Speak on:
Electronics in our life.
4. Give a list of modern gadgets you use.
VII
1. Read the text paying attention to the terms in bold.
TRANSFORMERS
A transformer consists of two insulated coils of wire linked with a
ring of iron. The coils are called high-voltage and low-voltage windings,
or primary and secondary windings. The primary winding is connected to
the source of energy, and the secondary is connected to the load. The high-
voltage winding is designed for the higher voltage, and has the greater
number of turns. The ring of iron is called the core.
Each coil consists of a number of loops of round or rectangular wire.
Several strands may be used in parallel but electrically insulated from
each other, from the core and from the other coil.
The core consists of thin sheets of high-grade silicon steel. The
thickness depends somewhat on the frequency at which the transformer
is to operate. The thickness commonly used for 60 cycles is
approximately 0. 014 in.
15
The primary function of a transformer is to transform electrical energy
1) core
a) a twisted length of wire through
which an electric current travels
2) frequency
b) the force of an electric current,
measured in volts
3) coil
c) the amount of electrical power that
is supplied
4) voltage
d) (a piece of) thin metal thread with
a layer of plastic around it, used for
carrying electric current
5) wire
e) the basic and most important part
of something
6) switch
f) the number of times something
happens within a particular period,
or the fact of something happening
often or a large number or times
7) battery
g) a transformer designed to lower
the voltage of alternating current
8) load
h) a transformer used to raise the
voltage
9) step-down transformer
i) a device for making, breaking or
changing the connections in an
electric circuit
10) step-up transformer
j) a group of two or more cells
connected together for generating
electric current by chemical
reactions
from one alternating voltage to another. To transform large amounts of
energy with maximum efficiency, many factors must be considered in
determining the materials, design, and arrangement of the primary and
secondary coils and the core.
2. Match the term with its definition:
16
3. Speak on:
Construction of a transformer.
Functions of a transformer.
4. Translate the text in written form.
VIII
1. Read the text.
TRANSISTORS
In 1948 a revolutionary concept was introduced to the electronics
world: the invention of a transistor, a crystal which amplified, was
announced. Nothing like this had happened in electronics since the
discovery of the triode vacuum tube in 1907; some years later radio
tubes replaced the crystal detectors of the wireless era.
Now a crystal amplifier, the transistor, challenges the vacuum tube
because transistors are smaller, simpler, more efficient, more rugged and
longer lived. Already transistors have replaced tubes in hearing aids, with
unheard-of battery economy. Moreover, many transistor circuits have
fewer components than the vacuum tube circuits, such as multivibrators.
For example, in switching circuits, such as multivibrators, one pointcontact transistor will do the work of two triode tubes.
The transistor is a current-operated device, whereas the vacuum tube
is a voltage-operated device. The transistor seems destined to become a
relatively high current, low-voltage device, although the vacuum tube is a
high-voltage, low current device. Transistors, because of their desirable
properties, shortly may replace electron tubes to a large extent in
communication equipment, computers, radio and television receivers.
2. Speak on:
The revolution transistor made in 1948.
Transistor’s advantages.
The difference between the transistor and vacuum tube.
17
MOTORS
I
1. Read the text paying attention to the underlined words and
word combinations.
ELECTRIC GENERATORS AND MOTORS
A device for converting mechanical energy into electric energy is
called a generator. The function of a motor is just the reverse, that is, it
transforms electric energy into mechanical energy. The enormous energy
of steam engines, gas engines, and water turbines can now be
transformed into electricity and transmitted for many miles. The generator
has revolutionized modern industry by furnishing cheap electricity.
The essential parts of a generator are: a) the magnetic field, which is
produced by permanent magnets or electromagnets; and b) a moving coil
of copper wire, called the armature, wound on a drum.
D. c. generators are used for electrolytic processes. Large d. с
generators are used in certain manufacturing processes, such as steel
making. Generators of small capacities are used for various special
purposes, such as welding, automobile generators, train lighting,
communication systems, etc.
2. Answer the questions:
1. How has a generator revolutionized industry?
2. What is a generator?
3. What are the essential parts of a generator?
4. What’s the difference between the use of d.c. generators of large
and small capacities?
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3. Make up your own sentences with the underlined words.
4. Speak on:
Electric generators, their use and role in modern industry.
5. Translate the text in written form.
II
1. Read the text paying attention to the terms in bold.
ELECTRIC MOTORS
There is a wide variety of d. c. and a. c. motors. There are shunt
motors, series motors, synchronous motors, induction motors, single-,
two-, and three-phase motors. They are used to drive various machines. A
ball-bearing fully-enclosed fan-cooled direct-current motor is shown in
Fig. 1.
Direct-current motors are of three principal kinds, and are named
according to the manner in which their field coils are connected to the
armature. They are named respectively: series, shunt, and compound.
In the series motors the field windings and armature are connected in
series with each other. All the current which passes through the armature
passes through the field coils. The field windings are therefore composed
of a few turns of thick wire. Starting under heavy load, a series motor will
take a large current to provide the huge torque required.
Fig. 1. A Ball – Bearing Fully – Enclosed Motor Fan – Cooled Direct
Current
19
1. field coil; 2. armature spider; 3. commutator key; 4. commutator sleeve;
1) conductor
a) a closed system of wires or pipes
through which electricity or
liquid can flow
2) lathe
b) a force that causes something to
rotate (= turn in a circle)
3) circuit
c) a tool that uses power to cut and
shape metal or other strong
materials
4) machine-tool
d) a machine for changing the
shape of a piece of wood, metal,
etc. which works by turning the
material while a sharp tool is
pressed against it
5. commutator mica V rings; 6. commutator bars; 7. commutator metal
ring; 8. front inner bearing cap; 9. bearing lock washer; 10. bearing
lock nut; 11. front outer bearing cap; 12. bearing assembly screw;
13. brush yoke; 14. brush stud insulation; 15. brush holder stud;
16. brush holder; 17. eye holt; 18. armature laminations; 19. frame;
20. armature coils; 21. armature end plate; 22. back inner bearing cap;
23. vellumoid gaskets; 24. ball bearing; 25. back outer bearing cap;
26. armature shaft; 27. grease seal; 28. armature key; 29. back bearing
bracket; 30. front bearing bracket
The field coils of shunt motors are connected direct across the
brushes, hence they have the full voltage of the mains applied to them.
The shunt motor may be called a constant speed motor, and is suitable for
driving machine tools, lathes, wood-working machines and any machines
requiring a steady speed.
A compound motor has both shunt and series field windings and
therefore partakes in the nature of both types of motors.
2. Match the term with its definition:
20
5) armature
e) a device that changes electricity
or fuel into movement and
makes a machine work
6) motors
f) a material through which a
current passes readily
7) potential energy
g) a movable piece of iron or other
magnetic material designed to be
acted upon by a magnetic force.
The part of a dynamo designed
to cut out lines of force by
rotating in a stationary magnetic
field or by remaining fixed in a
moving magnetic field; the
corresponding part of a motor
8) kinetic energy
h) a safety device used to protect
the line from overloading.
9) torque
i) energy of motion
10) fuse
j) energy of position
3. Answer the questions:
1. What kinds of motors are mentioned in the text?
2. What direct current motors do you know?
3. Where are motors used?
4. What are three principle kinds of d.c. motors?
5. How are the field windings and armature connected into series
motors?
6. Why does a series motor take a large current?
7. Why does a compound motor partake in the nature of types of
motors?
4. Name the main parts of the motor. Describe Figure I using
these verbs:
To connect
To pass
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