The Topic: Electrical Machines The most prime governing thing that holds for the existence of mankind and the universe and beyond is Energy. From the dark ages, Humans have been trying to develop means and methods to produce energy and then to transform it into another usable form. Even today, our lives are based on Energy. Energy today is now available in many forms for different uses. The most significant type of Energy that has affected our lives in a huge way is the electrical energy. Just turn around your face and you will see electrical devices everywhere around you. Electricity or the popular name for electrical energy as we call it has transformed our lives in a significant way; it has made our lives quite easy and comfortable.  HOW IS ELECTRICITY PRODUCED? Electricity (the inevitable thing) is produced by different types of Electric Machines and that too in different forms. The electricity that reaches our home is not a novice task; many genius minds and lots of complex and bulky electric machines are involved behind it. Then an electric machine is not only used for generation purpose it can also be used as a source of mechanical energy that is motor may it be a juicer mixer in your kitchen or the conveyer belt system in large manufacturing plants. So in the next section we will try to explain briefly about basic principle of electric machines and their types.

The Topic: Electrical Machines What is an electrical machine? What are their principles of operation, construction? What are they used for? What are their types?

What is an electrical machine? An electrical machine converts energy from one category into another. Thereby at least one energy category features as electric power. They all comprise two electric circuits which have been coupled through a magnetic circuit. An electrical machine is an energy converter in which two electric circuits have been coupled by means of a magnetic circuit.

Figure: Tasks of electrical machines in power flow Going through the basic fundamentals about principle, construction and operation of electric machines Figure: Tasks of electrical machines in power flow

What are the principals of operation of electrical machines? Magnetic fields are the fundamental mechanism by which energy is converted from one form to another in motors, generators and transformers. Two related physical principles underline the operation of generators and motors. The electromagnetic induction The electromagnetic reaction discovered by Michael Faraday in 1831 discovered by André’ Ampere in 1820 If a conductor is moved through a magnetic field, or if the strength of a stationary conducting loop is made to vary, a current is set up or induced in the conductor. If a current is passed through a conductor located in a magnetic field, the field exerts a mechanical force on it.

Functional block diagram of electromechanical energy conversion devices as (A) motor, and (B) generator

Vocabulary: feature – особенность, характерная черта converter – преобразователь, конвертер commutator – коллектор armature – якорь to suggest – предлагать, предложить ring – кольцо, фланец, хомут bar – полоса (металла) to pull – тянуть, притягивать to switch – включать, выключать, переключать drive – передача, привод design – конструкция, чертёж, план, to power – снабжать энергией, to differ – различаться, отличаться to rotate – 1. вращаться; 2. чередоваться to create – творить, создавать

Motors and generators’ structure Motors, Generators The Armature a laminated soft-iron core around which conducting wires are wound in coils the electromagnet with its coils The Field

The Armature from a small DC fan motor A simple electromagnet consisting of a coil of insulated wire wrapped around an iron core The Armature  from a small DC fan motor

Electrical Machines Bearers of electric circuits to one another rigid flexible Stationary electrical machines Rotating electrical machines synchronous transformers asynchronous commutators DC Machines Single-phase Three-phase

What are these?

The subject: Transformers Lesson Tasks: To check up our homework; To get information about transformers; to find out what is a transformer; to learn about it’s construction; to know about the types of transformers;

Warming-up Column A Column B armature a device consisting of a core of magnetic material such as iron electromagnet a device that converts mechanical energy into electrical energy commutator the rotating part of a generator or motor rotor a laminated soft-iron core conductor a device for reversing the direction of a current motor a device that converts alternating current to direct current generator a device that converts electrical energy into mechanical energy converter a material allowing the flow of electric current induction the movement of an electric charge in a conductor current the excitation of the electric current in a conductor

Checking-up the h/w / Giving marks Number of mistakes Mark 0-3 Very Good 4-7 Good 8-15 Satisfactory 16, ˂ 16 Bad

Checking-up the Home work / Keys Column A Column B 1) electromagnetic 2) rotating 3) alternating 4) electrical 5) high 6) magnetic basic energy insulated conducting induction part current machine voltage field principle converter coil wires Column A Column B 1) electromagnetic 2) rotating 3) alternating 4) electrical 5) high 6) magnetic basic energy insulated conducting induction part current machine voltage field principle converter coil wires

Checking-up the h/w / Giving marks Number of mistakes Mark 0-3 Very Good 4-7 Good 8-15 Satisfactory 16, ˂ 16 Bad

Text working “Transformers” Vocabulary: winding [‘waɪndɪŋ] primary / secondary winding turn frequency [‘fri:kwənsɪ] open trouble (common trouble) short core to step up to step down to increase to decrease to substitute due to обмотка первичная / вторичная обмотка виток частота обрыв неисправность, (возможная неполадка) короткое замыкание сердечник повышать понижать увеличивать уменьшать заменить благодаря, из-за

What types of transformers are described in the text? Transformers’ Types What types of transformers are described in the text?

What is the work principle of a step-up transformer ?

What is the work principle of a step-down transformer ?

What is the work principle of an air-core transformer ?

What is the work principle of an iron-core transformer ?

The subject: Transformers Lesson Tasks: To check up our homework; To get information about transformers; to find out what is a transformer; to learn about it’s construction; to know about the types of transformers;

Transformers’ Application 1. Distribution transformers are generally used in power distribution and transmission systems. 2. Power transformers are used in electronic circuits and come in many different types and applications. 3. Control transformers are generally used in circuits that require constant voltage or constant current with a low power or volt-amp rating. 4. Auto transformers are generally used in low power applications where a variable voltage is required. 5. Isolation transformers are normally low power transformers used to isolate noise from or to ground electronic circuits. 6. Instrument potential and instrument current transformers are used for operation of instruments such as ammeters, voltmeters, watt meters, and relays used for various protective purposes.

Transformers’ Application

Complex Object Complex Object The Object (a Noun or a Pronoun in an Object case) The Infinitive (with or without to) The Rest Part of the Sentence The Subject The Predicate Complex Object She wants him to study English . an electrical machine. We consider a transformer to be

Complex Object to + The Infinitive The Infinitive После глаголов: желания (wish, want, like, would like), предположения (expect, seem, consider, appear, suppose, believe), сообщения/информации (know, think, claim, report, declare, show, find) После глаголов  физическое восприятия и ощущения  (notice, see, watch, hear, listen to, observe, feel, ), а также make и let to + The Infinitive The Object (a Noun or a Pronoun in an Object case) The Subject The Infinitive The Object (a Noun or a Pronoun in an Object case)

The Rest Part of the Sentence Complex Subject The Subject The Predicate The Infinitive The Rest Part of the Sentence Complex Subject She Is supposed to work at this plant. The current Is known to consist of moving electrons.

Complex Subject to + The Infinitive Сказуемое-глагол в пассивном залоге: to say, to report, to announce, to believe, to suppose, to think, to state, to expect, to know, to consider, to see, to hear Сказуемое в активном залоге: to seem, to appear, to prove, to turn out, to happen, to chance. 3) Сказуемое-глагол to be в выражениях: to be likely, to be unlikely, to be certain, to be sure to + The Infinitive The Subject

Complex Object / Complex Subject We suppose him to work at this plant. Complex Object He Is supposed to work at this plant. Complex Subject