2832

5.What type of a dry-cell battery is the most commonly used?

6.How can a zinc packaged serve?

7.What kinds of batteries are rechargeable?

8.What are the benefits that nickel-cadmium batteries have?

A d d i t i o n a l t e x t Read the text and translate it using a dictionary. Check your translating speed.

The fuel cell is actually quite an old technology having been invented by the British scientist William Grove in 1843. In this apparatus, electrical power is produced in a simple yet intriguing way. There are two electrodes, the anode and the cathode, and in the middle of both there is a membrane ion conductor or electrolyte. Hydrogen gas is fed continuously over the anode while oxygen from the air passes over the cathode. The electrolyte is the partition which ensures that the two gases do not come into direct contact with each other. Through the chemical process in the fuel cell, hydrogen splits into hydrogen ions and electrons. The electrons then pass through an external circuit to the cathode depicted by the glowing bulb. Electrical current is produced in this way.

The hydrogen ions meanwhile pass through the membrane. They and the electrons then react with oxygen at the cathode to produce water or steam. Thus heat is also produced, and this too can be utilized.

The electricity produced is direct current, which can be converted into alternating current if required. In order to create large volumes of power, fuel cells are connected in series to form a stack.

The advantage of the fuel cell is that the only waste product is water although it should be stressed that the waste depends on how hydrogen is obtained. If it is derived from sources, such as natural gas CO2 will also be produced.

Fuel cells can primarily be used where there is no connection to the grid. But developments in this technology could mean that heat and electrical power from fuel cells will also be harnessed in the future in cities, in decentralized energy-supply systems for homes, offices and factories. We could even have them in our cellars.

So is this the key to a vision clean, cheap plentiful energy supply? Does it spell the end for the power plant as we know it? This is unlikely as the volumes of power needed cannot be generated by the fuel cell alone. But there will be changes, and in twenty to thirty years’ time fuel cells could be common in energy supply as well as in vehicles.

31

Ex.1. Read the text again and complete the flow chart.

1.An interrupted stream of ______ passes over the anode while the

1.comes into contact with oxygen from the air.

2.Hydrogen is divided into ______ and ______ as the result of the chemical process

3.An ______ then conducts the electrons to the cathode.

4.______ pass through the membrane.

5.There is a ______ between the hydrogen ions, electrons and

oxygen at the cathode and		or	is produced.
	6. The type of electricity	produced	is DC which can be turned
into.	.

Ex.2. How would you answer the following questions in a discuss forum? Use the information from the text and Ex.1.

1.I still don’t really understand how it works. Can you explain in simple language?

2.So what exactly are the advantages, and are there any disadvantages?

3.Is this the answer to all our needs? Can you produce a large volume of energy like this?

Here are some useful phrases to describe a process:
Firstly / First of all…	The next step / stage is …	Then …
After that…	Following that …	Finally …
	The final step is ….

Ex.3. Speak on the advantages and disadvantages of fuel cells.

U N I T 2

Ex. 1. Copy and memorize the following terms.

Glossary

alternator – генератор переменного тока appliance – аппарат, прибор

armature – якорь carburetor – карбюратор

32

chamber – камера crankshaft – коленчатый вал

four-stroke engine – четырёхтактный двигатель mains – сеть электроснабжения

piston – поршень valve – клапан winding – обмотка

Ex. 2. Copy the following words and memorize their meanings:

9cord – шнур

9core – сердечник

9fuel – топливо, горючее

9fumes – дым, газы

9spark – искра

9to descend– опускаться

9to ignite – воспламенять, зажигать

Ex.3. Translate the following sentences from English into Russian

1. I heard his footsteps descending the stairs. 2. Scientists could not explain why the gas had suddenly ignited. 3. The scrape of metal on metal sent up a shower of sparks. 4. An engine failure forced a jetliner to crash-land in a field. 5. The winding is an electrical conductor that is wound round a core. 6. The cord is an electrical wire or wires with a protective covering, usually for connecting electrical equipment to the supply of electricity. 7. There’s plenty of space for all the usual kitchen appliances. 8. Another area of expertise is the repair of combustion chambers, used in both aviation and industrial gas turbines. 9. Coal is one of the cheapest fossil fuels of all. 10. Investigators concluded damaged wiring may have provided the spark that ignited fumes in the fuel tank. 11. The core is the inner strand of an electric cable or rope. 12. The accident, which occurred in August did not involve the release of radiation or damage to the reactor core.

Ex.4. Practice the reading of the following word combinations. You are to copy them and memorize their meaning

Power stations, convert motion into electricity, run on petrol, air inlet valve, fuel mixture, compression stroke, exhaust valve, sets of windings, stator windings, armature windings, iron core, electromagnetic induction, emergency power, sucked in through a carburetor.

Ex.5. Translate the phrases into Russian paying attention to Participles I and II. Model: regulated power supply – регулируемый источник электропитания;

performing the task – выполняя задание

the door leading to the library – дверь, ведущая в библиотеку

controlled value, electrochemical cells connected in series, desired voltage, stabilized against fluctuations, protecting the power supply, applications requiring a pulsed output, wire wound closely around an iron core, shaped like a broad ring, a portion of unused alternating current, charging a storage battery, fuel-based electricity generation, interconnected networks.

Ex.6. Translate the following sentences paying attention to Participles I and II.

33

1. Electrical power storage and recovery using pumped storage methods are normally carried out by the electric power industry. 2. Electricity is most often generated at a power station by electromechanical generators, primarily driven by heat engines fueled by chemical combustion or nuclear fission but also by other means such as the kinetic energy of flowing water and wind. 3. Centralised power generation became possible when it was recognised that alternating current power lines can transport electricity at very low costs across great distances. 4. All turbines are driven by a fluid acting as an intermediate energy carrier. 5. Small electricity generators are often powered by reciprocating engines burning diesel, biogas or natural gas.

6.Fuel cells can be used to extract power either from natural fuels or from synthesized fuels.

7.While calculating costs, several internal cost factors have to be considered. 8. Electricity is generated from the reaction between a fuel supply and an oxidizing agent. 9. At the anode a catalyst oxidizes the fuel, usually hydrogen, turning the fuel into a positively charged ion and a negatively charged electron. 10. In 1827, Hungarian Anyos Jedlik started experimenting with electromagnetic rotating devices which he called electromagnetic self-rotors. 11. Homopolar generators would solve this problem by using an array of magnets arranged around the disc perimeter to maintain a steady field effect in one current-flow direction. 12. The magnetic field of the dynamo or alternator can be provided by either electromagnets or permanent magnets mounted on either the rotor or the stator.

Read the text and translate it using a dictionary if necessary.

P O R T A B L E G E N E R A T O R

Although most electricity comes from power stations, power can also be generated by far smaller means. Nowadays, electricity generators can be small enough to hold in the hand.

Portable generators are made up of two main parts: an engine, which powers the equipment, and an alternator, which converts motion into electricity.

The engine runs on petrol. It is started by pulling a cord. This creates a spark inside which ignites the fuel mixture.

In a typical four-stroke engine, when the piston descends, the air inlet valve opens and a mixture of air and petrol is sucked in through a carburetor.

The valve closes, the piston rises on the compression stroke and a spark within the upper chamber ignites the mixture. This mini-explosion pushes the piston back down, and as it rises again the fumes formed by the ignition are forced out through the exhaust valve.

This cycle is repeated many times per second. The moving piston makes the crankshaft rotate at great speed.

The crankshaft extends directly to an alternator, which consists of two main sets of windings – coils of insulated copper wire wound closely around an iron core. One set, called stator windings, is in a fixed position and shaped like a broad ring. The other set, the armature windings, is wound on the rotor which is fixed to the rotating crankshaft. The rotor makes about 3,000 revolutions per minute.

The rotor is magnetized and as it spins round, electricity is generated in the stator windings through the process of electromagnetic induction. The electric current is fed to the output terminals or sockets.

A portable generator can provide electricity to power lights and other appliances no matter how far you are from the mains. It works by turning the movement of a piston into electrical energy.

34

This type of generator can produce a 700 watt output, enough to operate lights, television, and some domestic appliances. Larger versions provide emergency power to hospitals and factories.

Ex. 7. Match the halves of the sentences together.

	A		B
1.	Portable generators are made up of …	a)	the air inlet valve opens and a mixture of
			air and petrol is sucked in.
2.	An engine …	b)	the crankshaft rotate.
3.	An alternator …	c)	an engine and an alternator.
4.	When the piston descends …	d)	electricity is generated in the stator
			windings.
5.	When the piston rises …	e)	through the process of electromagnetic
			induction.
6.	The moving piston makes …	f)	converts motion into electricity.
7.	The rotor is magnetized and …	g)	a spark ignites the mixture.
8.	Electricity is generated in the stator	h)	powers the equipment.
	windings …

Ex.2. Answer the following questions to the text.

1.What are the main parts of a portable generator?

2.What does the engine run on?

3.What are the four strokes called?

4.What is the function of the crankshaft?

5.What do both stator and rotor have?

6.What is the difference between stator and rotor?

Ex. 3. Match the words in column A with their definitions in column B.

	A		B
1.	winding	a)	stationary part around which rotor turns
2.	rotor	b)	a piece of a metal connected to the engine
3.	stator	c)	movement of piston
4.	crankshaft	d)	button controlling electrical circuit
5.	exhaust	e)	wire coil carrying electricity
6.	switch	f)	rotating part of a machine
7.	stroke	g)	a valve which let out waste gases

Ex. 4. Fill in the blanks with the words given in the box. Translate the sentences.

motor	induction	generator
magnetic	current	conductor
	convert

Electric motors and generators are group of devices used to (1)… mechanical energy into electrical energy, or electrical energy into mechanical energy, by electromagnetic means. A machine that converts mechanical energy into electrical energy is called a (2)… and a machine that converts electrical energy into mechanical energy is called a (3)….

35

Two related physical principles underlie the operation of generators and motors. The first is the principle of electromagnetic (4)… discovered by the British scientist Michael Faraday in 1831. If a conductor is moved through a (5)… field, or if the strength of a stationary conducting loop is made to vary, a (6)… is induced in the conductor. The converse of this principle is that of electromagnetic reaction, first observed by the French physicist André Marie Ampère in 1820. If a current is passed through (7)… a located in a magnetic field, the field exerts a mechanical force on it.

Ex.5. Transform the sentences according to the model:

Model: The gas expands. This drives the piston down. →

The gas expands, driving the piston down.

1.The piston moves down the cylinder. This creates a partial vacuum.

2.The piston creates a vacuum. This draws in fuel from the carburetor.

3.The piston moves up the cylinder. This compresses the mixture.

4.The gas expands quickly. This pushes the piston down.

5.The piston moves up and down. This rotates the crankshaft.

6.The crankshaft spins round. This turns the rotor at 3,000 rpm.

7.The armature of the alternator rotates. This induces a current in the stator windings.

8.The alternator runs at a steady 3,000 rpm. This generates around 700 watts.

Ex.5. Go back to the text and complete the sentences.

1.The gas expands so….

2.The expanded gas drives ....

3.The piston ascends and ….

4.The piston forces the products ….

5.The rotor is magnetized so ….

6.A portable generator can provide electricity to ….

7.A portable generator works by turning ….

8.An alternator consists of ….

Ex.6. Translate the following sentences from Russian into English.

1. Электрический генератор – это устройство, в котором механическая энергия, химическая энергия, тепловая энергия преобразуются в электрическую энергию. 2. Генератор постоянного тока преобразует механическую энергию в электрическую.

3.Большинство генераторов переменного тока используют вращающееся магнитное поле.

4.Принцип действия генератора основан на явлении электромагнитной индукции – возникновении электрического напряжения в обмотке статора, находящейся в переменном магнитном поле. 5. Электрическое напряжение создается с помощью вращающегося ротора при прохождении по его обмотке постоянного тока. 6. Генератор переменного тока используется на современных автомобилях для заряда батареи аккумуляторов и для энергоснабжения автомобильной электрической системы. 7. Генераторы переменного тока имеют большое преимущество над генераторами постоянного тока из-за не использования коммутатора, что делает их проще, легче и дешевле, чем генераторы постоянного тока.

8.Большой двухфазный генератор переменного тока был построен британским электриком Джеймсом Эдвардом Генри Гордоном в 1882 году.

36

U N I T 3

Ex. 1. Copy and memorize the following terms.

Glossary

blower – воздухозаборник

brushed DC motor – щёточно-коллекторный электродвигатель постоянного тока brushless DC motor – бесщёточный электродвигатель постоянного тока controller – контроллер

distribution grid – распределительная сеть drive – привод

drive circuit – возбуждающий контур

permanent magnet motor – электродвигатель с постоянными магнитами shaded-pole motor – электродвигатель с расщеплёными полюсами

slip – сдвиг; скольжение

split-phase induction motor – двухфазный двигатель со сдвигом фазы во второй обмотке stepper motor – шаговый двигатель

torque - вращающий момент

traction motor – тяговый электродвигатель

Ex. 2. Copy the following words and memorize their meanings:

9mutual – взаимный

9requisite – необходимый, нужный, требуемый

9to accomplish – выполнять; достигать;

9ubiquitous – повсеместный

9vice versa – наоборот; противоположно

9vs (versus) – против, относительно

Ex.2. Translate the following sentences from English into Russian

1. We have accomplished all we set out to do. 2. He lacks the requisite qualifications. 3. The tires were bald and lost traction on the wet road. 4. She slipped into the driving seat and closed the door. 5. It was just a slip of the tongue. 6. A rotational force down a shaft forms a couple, so the resulting moment is called a "torque". 7. If we'd all work together, I think we could accomplish our goal. 8. Electricity distribution is the final stage in the delivery of electricity to end users. 9. A leaf blower is a gardening tool that propels air to move yard debris such as leaves. 10. Coffee shops are ubiquitous these days. 11. Energy-and water-saving technologies are ubiquitous. 12. The boys may refuse to play with the girls, and vice versa. 13. Stepper motor performance is strongly dependent on the drive circuit. 14. Science must be at the service of human, and not vice versa. 15. Servo controllers use position feedback to close the control loop. 16. A partnership should be based on mutual respect and understanding.

Ex. 3. Practice the reading of the following word combinations. You are to copy them and memorize their meaning

Current-carrying conductors interaction of magnetic fields, reverse process asynchronous motor, synchronous motor, standardized dimensions and characteristics, industrial use, to induce current, mutual inductance.

37

Ex. 4. Match the halves of the sentences together.

	A		B
1.	A brushed DC	a)	a brushless, synchronous electric motor that can divide a full
	motor is …		rotation into a large number of steps.
2.	A brushless DC	b) an AC motor distinguished by a rotor spinning with coils
	motor is …		passing magnets at the same rate as the alternating current and
			resulting magnetic field which drives it.
3.	A stepper motor is	c)	an electric motor that produces a straight-line force along its
	…		length by setting up a traveling electromagnetic field.
4.	An asynchronous	d) powered by DC and which has an electronically controlled
	motor is …		commutation system.
5.	A synchronous	e)	has two independent multiphase windings that actively
	electric motor is		participate in the energy conversion process.
	…
6.	A linear motor	f)	an AC motor where power is supplied to the rotor by means of
	is …		electromagnetic induction.
7.	A doubly-fed	g)	an internally commutated electric motor designed to be run
	electric motor …		from a DC power source.

Ex. 5. Translate the following sentences from English into Russian paying attention to the forms of participles used.

1. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a circular magnetic field around the wire. 2. These were demonstration devices only, unsuited to practical applications due to their primitive construction 3. A rotor consists of one or more coils of wire wound around a core on a shaft. 4. At higher speeds, brushes have increasing difficulty in maintaining contact. 5. Depending on the commutator design, this may include the brushes shorting together adjacent sections. 6. A specialized class of brushless DC motor controllers utilize EMF feedback through the main phase connections. 7. Optimized for rapid acceleration, these motors have a rotor that is constructed without any iron core. 8. A third design has the windings shaped as a disc running between arrays of high-flux magnets facing the rotor and arranged in a circle. 9. Operating at normal power line frequencies, universal motors are very rarely larger than one kilowatt. 10. Slip rings are metal rings rigidly mounted on the rotor, and combined with brushes (as used with commutators), provide continuous unswitched connection to the rotor windings.

Read the text and translate it using a dictionary if necessary.

E L E C T R I C M O T O R

An electric motor is a motor that uses electrical energy to produce mechanical energy, usually through the interaction of magnetic fields and current-carrying conductors. The reverse process, producing electrical energy from mechanical energy, is accomplished by a generator or dynamo. A motor converts electrical energy to mechanical power by using current to make a metallic loop ("the rotor" or "armature") spin around a central shaft.

Traction motors used on vehicles often perform both tasks. Electric motors can be run as generators and vice versa, although this is not always practical. Electric motors are ubiquitous,

38

being found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives. They may be powered by direct current (for example a battery powered portable device or motor vehicle), or by alternating current from a central electrical distribution grid. The smallest motors may be found in electric wristwatches. Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses. The very largest electric motors are used for propulsion of large ships, and for such purposes as pipeline compressors, with ratings in the thousands of kilowatts. Electric motors may be classified by the source of electric power, by their internal construction, and by their application.

The classic division of electric motors has been that of Alternating Current (AC) types vs Direct Current (DC) types. But many classic DC motors run on AC power, these motors being referred to as universal motors.

Considering all rotating (or linear) electric motors require synchronism between a moving magnetic field and a moving current sheet for average torque production, there is a clearer distinction between an asynchronous motor and synchronous types. An asynchronous motor requires slip between the moving magnetic field and a winding set to induce current in the winding set by mutual inductance; the most ubiquitous example being the common AC induction motor which must slip in order to generate torque. In the synchronous types, induction (or slip) is not a requisite for magnetic field or current production (eg. permanent magnet motors, synchronous brushless wound-rotor doubly-fed electric machine).

Ex. 6. Choose the best alternative to complete the sentences.

1.A motor converts electrical energy to mechanical power …

a)to make an armature spin around a central shaft.

b)to make a stator spin around a central shaft.

2.Motors may be powered …

a)by direct current.

b)by either direct current or alternating current

3.Medium-size motors provide convenient mechanical power

a)for household uses.

b)for industrial uses.

4.Electric motors may be classified …

a)by the source of electric power.

b)by the source of electric power, by their internal construction, and by their application.

5.Electric motors require synchronism between …

a)a moving magnetic field and a moving current for torque production.

b)a moving rotor and a fixed stator for torque production.

6.An asynchronous motor requires slip …

a)between a moving rotor and a fixed stator to induce current

b)between the moving magnetic field and a winding set to induce current.

7.In the synchronous types, induction …

a)is not a requisite for magnetic field or current production.

b)is a requisite for magnetic field or current production.

39

Ex. 7. Translate the text using a dictionary if necessary and read the table

A company is going to buy some items of equipment for their engineering department. They need to compare all the characteristics of motors on offer and make a choice. Compare the given motors using the given adjectives in the appropriate form of comparison. Make as many sentences as possible.

long

low

high

precise

man

much

expensive

Example: AC synchronous motors have more applications than AC induction motors.

C o m p a r i s o n o f M o t o r T y p e s

Type		Advantages	Disadvantages	Typical	Typical
				Application	Drive
AC Induction		Least expensive	Rotation slips
			from frequency	Fans	Uni/Poly-
(Shaded Pole)		Long life	Low starting		phase AC
		High power
			torque
AC Induction		High power	Rotation slips	Appliances	Uni/Poly-
(split-phase		High starting torque	from frequency		phase AC
capacitor)
AC		Rotation in-		Industrial motors	Uni/Poly-
		syncchronous with	More expensive	Clocks
Synchronous		frequency		Audio turntables	phase AC
		Long-life (alternator)		tape drives
Stepper DC		Precision positioning	Requires a	Positioning in	Multiphase
				printers and floppy
		High holding torque	controller		DC
				drives
Brushless DC		Long lifespan	High initial cost	Hard drives	Multiphase
		Low maintenance	Requires a	CD/DVD players
					DC
		High efficiency	controller	electric vehicles
Brushed DC		Low initial cost	High maintenance	Treadmill
			(brushes)	exercisers	Direct PWM
		Simple speed control
			Low lifespan	automotive starters

Ex.8. Fill in the blanks with the words given in the box. Translate the text.

DC	AC	electrodynamics	equal
charge	current	amperes	conductors

Electric … flows because atoms and molecules contain two types of electrical, … positive and negative, and they attract each other. If there is a difference in the overall charge of atoms between two points – for example, between two ends of a wire – the negatively charged electrons will flow toward the positively charged end of the wire, creating electric current. … is the flow of electricity in one direction. … intermittently reverses direction because of the way it is generated. Electric current flows easily in some substances but not at all in others. Solids, liquids, and gases that carry electric currents are called …. The rate at which electric charge flows in a current is measured in …. The unit is named for French physicist Andre Marie Ampere, who contributed to the study of ….in the early 19th century. One ampere of electric current is … to about 6 billion billion electrons per second flowing past a point.

40