2. Complete the sentences with words given in previous exercise and translate them into Russian.

1. The most widely used electromechanical device is the magnetic_____.

2. The main purpose of most rotating machines is electro­ mechanical ­­­­_____.

3. All rotating machines operate on the same principle, namely, the tenden­cy of two magnets to _____ .

4. The study of electric machines is based on the _____viewpoint.

5. The _____ between the inner surface of the stator and the outer surface of the rotor is known as the _____

6. The field structure can be physically situated on either the stationary member (stator) or the rotating member (rotor) of the machine, depending on_____.

7. Two different types of construction are used for the field circuit: the _____ and the _____.

3. Write down from the text 5 words corresponding to one of following parts of speech. Complete the table.

noun	verb	adjective	preposition	adverb

4. Give adequate Russian equivalents of the italicized words.

Proper, property - общий элемент смысла: присущее, неотъемлемое. Частотные русские эквиваленты: proper присущий, свойственный; правильный, надлежащий, должный, уместный и т.д.; property - свойство, качество; собственность и т.д.

1. It is only proper to begin consideration of the issue with some facts of common knowledge. Each atom has the proper number of electrons to make it neutral and it is this number that determines its chemical and physical properties. Yet, properly speaking, there are electrons which do not belong to the atom proper. These are called free electrons. 2. It is often very difficult to do things properly: to pay proper attention to one's job, to give the proper interpretation of one's results or even to say the proper thing at the proper moment.

5. Read and translate the text.

The most widely used electromechanical device is the magnetic field type rotating machine. The main purpose of most rotating machines is electro­ mechanical energy conversion, i.e., to convert energy between electrical and me­chanical systems, either for electrical power generation (as in generators or sources) or for the production of mechanical power to do useful tasks (as in motors or sinks). These machines range in size and capacity from small motors that con­sume only a fraction of a watt to large generators that produce several hundreds of megawatts. In spite of the wide variety of types, sizes, and methods of con­struction, all these machines operate on the same principle, namely, the tenden­cy of two magnets to align themselves. Thus, an analysis of an idealized struc­ture of one electric machine will provide the essential concepts necessary to un­derstand the operation of most practical electric machines.

The study of electric machines from the coupled-circuit viewpoint is based on the fundamental consideration that machines can be viewed in terms of sets of linear lumped circuits in relative motion. Relative motion exists be­tween the two magnetic members of the electric machine, namely, the stator, which is the stationary member, and the rotor, which is the rotating member. In general, electrical machines consist of two sets of windings (or coils) in which one set of coils can rotate with respect to the other. The mechanical motion between these two sets of coils is generally restricted to one degree of freedom, which, in most instances, is rotary motion. The annular space between the inner surface of the stator and the outer surface of the rotor is known as the air gap. The radial length of the air gap is always kept very small compared to the radial dimension of the outer surface of the rotor in order to produce a large magnetic field for a given current. The two windings in relative motion are known as the field winding, which produces the flux density, and the armature wind­ing in which the working emf is induced. The field structure in which the field circuit is located can, in general, be physically situated on either the stationary member (stator) or the rotating member (rotor) of the machine, depending on constructional convenience.

While permanent magnets can be used in the small machines as the primary sources of flux, in the majority of machines the field is electromagnetic and field coils carrying the field current are wound on a magnetic structure. The iron core forming this structure is laminated in order to reduce the field iron losses if the field current is alternating or contains an alternating component.

Two different types of construction are used for the field circuit. One type is the salient-pole arrangement, in which the field coils are concentrated and wound around the protruding poles; this form of construction is used only for machines with direct-current field supply. The air gap around the periphery of the machine is characteristically non-uniform in this arrangement. The second type is the non-salient-pole construction for smooth (or uniform) air-gap ma­chines, in which the field coils are distributed in slots cut into a cylindrical mag­netic structure; this arrangement is commonly used on certain forms of large ac generators known as turbo-alternators.