Published On: Thu, Jun 16th, 2022

© Electric machines through practical questions and answers – Part 1

© Electric machines through practical questions and answers  – Part 1

Introduction

Author: Radoje Jankovic.

In this, more extensive series of questions with answers in the field of electric machines, I tried to elaborate on this area from the point of view of practice and everyday use of rotating electric machines of all types in various fields today. I started, if you can say that from the beginning, from simpler things to more complex and complex problems from electric machines.

These are the types of questions with answers that are encountered for the first time in written and electronic educational and practical literature in the world. I believe that many colleagues, technicians, engineers, teachers, professors, service technicians, designers, master practitioners who work daily on the repair, maintenance, repair and rewinding of electrical machines will benefit from their daily work in this field. It will be especially useful for students of electrical engineering schools, students and beginners who meet for the first time in their career with different types, constructive solutions in rotating electrical machines.

There is almost no device, appliance or assembly of any system (our houses and apartments are full of various electrical appliances) that does not have some of the electric motors that operate on alternating and direct current of low voltages from a few volts to several tens of volts, low voltages of all sizes encountered and used worldwide whether internationally or locally standardized, high voltages from 1000 V to several tens of thousands of volts. Even, almost all mobile phones have a micromotor a few millimeters in size that drives a vibrator to let you know that someone is calling or sending you a message, right, I have a few pieces of such micromotors that can be put on top index.

To create these questions with answers I used my personal literature, documentation and archive as well as my original photos and photos with many details that I get from my friends and acquaintances who deal with servicing, repair and maintenance of various types and types of rotating electrical machines and more. them and other electrical devices and equipment, so I would like to take this opportunity to thank them. There are also photos that I downloaded from the Internet because it is impossible to take everything and every detail in person and I hope that colleagues who recognize their photos will not be angry since I use them exclusively for educational purposes, because many young colleagues around the world are eager for knowledge. they will need it in life and career and they do not get it from their schools and universities and their instructors enough.

In this series, I have included several hundred questions with answers illustrated with almost 3 times more very clear, understandable practical illustrations. This text entitled “Electric Machines through Practical Questions and Answers ©” can be a real handbook of electrical machines for all interested. On this occasion, I invite one of my colleagues from around the world (he can inform me by sending an e-mail) who can do something to print this manual and make it available to a wide range of students, professionals and others… The book would be large and large A4, no smaller, and with large clear photographs in which every detail can be clearly seen.

Osnov svih električnih rotacionih mašina

Before all…

Basic of all rotational electrical machines

NIKOLA TESLA U.S. PATENT 381,968 – ELECTRO-MAGNETIC MOTOR

UNITED STATES PATENT OFFICE.


NIKOLA TESLA, OF NEW YORK, N.Y., ASSIGNOR OF ONE-HALF TO CHARLES F. PECK, OF ENGLEWOOD, NEW JERSEY.

ELECTRO-MAGNETIC MOTOR.


SPECIFICATION forming part of Letters Patent No. 381,968, dated May 1, 1888.

Application filed October 12, 1887. Serial No. 252,132. (No model.)


To all whom it may concern:

Be it known that I, NIKOLA TESLA, from Smiljan Lika, border country of Austria-Hungary, residing at New York, N.Y., have invented certain new and useful Improvements in Electro-Magnetic Motors, of which the following is a specification, reference being had to the drawings accompanying and forming a part of the same.

The practical solution of the problem of the electrical conversion and transmission of mechanical energy involves certain requirements which the apparatus and systems heretofore employed have not been capable of fulfilling. Such a solution, primarily, demands a uniformity of speed in the motor irrespective of its load within its normal working limits. On the other hand, it is necessary, to attain a greater economy of conversion that has heretofore existed, to construct cheaper and more reliable and simple apparatus, and, lastly the apparatus must be capable of easy management, and such that all danger from the use of currents of high tension, which are necessary to an economical transmission, may be avoided.

My present invention is directed to the production and improvement of apparatus capable of more nearly meeting these requirements than those heretofore available, and though I have described various means for the purpose, they involve the same main principles of construction and mode of operation, which may be described as follows: A motor is employed in which there are two or more independent circuits through which alternate currents are passed at proper intervals, in the manner hereinafter described, for the purpose of effecting a progressive shifting of the magnetism or of the “lines of force” in accordance with the well-known theory, and a consequent action of the motor. It is obvious that a proper progressive shifting of the lines of force may be utilized to set up a movement or rotation of either element of the motor, the armature, or the field-magnet, and that if the currents directed through the several circuits of the motor are in the proper direction no commutator for the motor will be required; but to avoid all the usual commutating appliances in the system I prefer to connect the motor-circuits directly with those of a suitable alternate-current generator. The practical results of such a system, its economical advantages, and the mode of its construction and operation will be described more in detail by reference to the accompanying diagrams and drawings.

Figures 1 to 8 and 1a to 8a, inclusive, are diagrams illustrating the principle of the action of my invention. The remaining figures are views of the apparatus in various forms by means of which the invention may be carried into effect, and which will be described in their order.

Referring first to Fig. 9, which is a diagrammatic representation of a motor, a generator, and connecting-circuits in accordance with my invention, M is the motor, and G the generator for driving it. The motor comprises a ring or annulus, R, preferably built up of thin insulated iron rings or annular plates, so as to be as susceptible as possible to variations in its magnetic condition. This ring is surrounded by four coils of insulated wire symmetrically placed, and designated by C C C’ C’. The diametrically-opposite coils are connected up so as to co-operate in pairs in producing free poles on diametrically-opposite parts of the ring. The four free ends thus left are connected to terminals T T T’ T’, as indicated. Near the ring, and preferably inside of it, there is mounted on an axis or shaft, a, a magnetic disk, D, generally circular in shape, but having two segments cut away, as shown. This disk is mounted so as to turn freely within the ring R. The generator G is of any ordinary type, that shown in the present instance having field-magnets N S and a cylindrical armature-core, A, wound with the two coils B B’. The free ends of each coil are carried through the shaft a and connected, respectively, to insulated contact-rings b b b b. Any convenient form of collector or brush bears on each ring and forms a terminal by which the current to and from a ring is conveyed. These terminals are connected to the terminals of the motor by the wires L and L’ in the manner indicated, whereby two complete circuits are formed—one including, say, the coils B of the generator C’ C’ of the motor, and the other the remaining coils B’ and C C of the generator and the motor.

It remains now to explain the mode of operation of this system, and for this purpose I refer to the diagrams, Figs. 1 to 8, and 1a to 8a, for an illustration of the various phases through which the coils of the generator pass when in operation, and the corresponding and resultant magnetic changes produced in the motor. The revolution of the armature of the generator between the field-magnets N S obviously produces in the coils B B’ alternating currents, the intensity and direction of which depend upon well-known laws. In the position of the coils indicated in Fig. 1 the current in the coil B is practically nil, whereas the coil B’ at the same time is developing its maximum current, and by the means indicated in the description of Fig. 9 the circuit including this coil B’ may also include, say, the coils C C of the motor, Fig. 1a. The result, with the proper connections, would be the magnetization of the ring R’, the poles being on the line N S. The same order of connections being observed between the coil B and the coils C’, the latter, when traversed by a current, tend to fix the poles at right angles to the line N S of Fig. 1a. It results, therefore, that when the generator-coils have made one-eighth of a revolution, reaching the position shown in Fig. 2, both pairs of coils C and C’ will be traversed by currents and act in opposition, in so far as the location of the poles is concerned. The position of the poles will therefore be the resultant of the magnetizing forces of the coils—that is to say, it will advance along the ring to a position corresponding to one-eighth of the revolution of the armature of the generator. In Fig. 3 the armature of the generator has progressed to one-quarter of a revolution. At the point indicated the current in the coil B is maximum, while in B’ it is nil, the latter coil being in its neutral position. The poles of the ring R in Fig. 3a will, in consequence, be shifted to a position ninety degrees from that at the start, as shown. I have in like manner shown the conditions existing at each successive eighth of one revolution in the remaining figures. A short reference to these figures will suffice for an understanding of their significance. Figs. 4 and 4a illustrate the conditions which exist when the generator-armature has completed three-eighths of a revolution. Here both coils are generating current; but the coil B’, having now entered the opposite field, is generating a current in the opposite direction, having the opposite magnetizing effect; hence the resultant pole will be on the line N S, as shown. In Fig. 5 one-half of one revolution of the armature of the generator has been completed, and the resulting magnetic condition of the ring is shown in Fig. 5a. In this phase coil B is in the neutral position while coil B’ is generating its maximum current, which is in the same direction as in Fig. 4. The poles will consequently be shifted through one half of the ring. In Fig. 6 the armature has completed five-eighths of a revolution. In this position coil B’ develops a less powerful current, but in the same direction as before. The coil B, on the other hand, having entered a field of opposite polarity, generates a current of opposite direction. The resultant poles will therefore be in the line N S, Fig. 6a, or, in other words, the poles of the ring will be shifted along five-eighths of its periphery. Figs. 7 and 7a in the same manner illustrate the phases of the generator and rings at three-quarters of a revolution, and Figs. 8 and 8a the same at seven-eighths of a revolution of the generator-armature. These figures will be readily understood from the foregoing. When a complete revolution is accomplished, the conditions existing at the start are re-established and the same action is repeated for the next and all subsequent revolutions, and, in general, it will now be seen that every revolution of the armature of the generator produces a corresponding shifting of the poles or lines of force around the ring. This effect I utilize in producing the rotation of a body or armature in a variety of ways—for example, applying the principle above described to the apparatus shown in Fig. 9. The disk D, owing to its tendency to assume that position in which it embraces the greatest possible number of the magnetic lines, is set in rotation, following the motion of the lines or the points of greatest attraction.

The disk D in Fig. 9 is shown as cut away on opposite sides; but this, I have found, is not essential to effecting its rotation, as a circular disk, as indicated by dotted lines, is also set in rotation. This phenomenon I attribute to a certain inertia or resistance inherent in the metal to the rapid shifting of the lines of force through the same, which results in a continuous tangential pull upon the disk, causing its rotation. This seems to be confirmed by the fact that a circular disk of steel is more effectively rotated than one of soft iron, for the reason that the former is assumed to possess a greater resistance to the shifting of the magnetic lines.

In illustration of other forms of my invention, I shall now describe the remaining figures of the drawings.

Fig. 10 is a view in elevation and part vertical section of a motor. Fig. 12 is a top view of the same with the field in section and a diagram of connections. Fig. 11 is an end or side view of a generator with the fields in section. This form of motor may be used in place of that shown above. D is a cylindrical or drum-armature core, which, for obvious reasons, should be split up as far as practicable to prevent the circulation within it of currents of induction. The core is wound longitudinally with two coils, E and E’, the ends of which are respectively connected to insulated contact-rings d d d d, carried by the shaft a, upon which the armature is mounted, The armature is set to revolve within an iron shell, R’, which constitutes the field-magnet, or other element of the motor. This shell is preferably formed with a slot or opening, r, but it may be continuous, as shown by the dotted lines, and in this event it is preferably made of steel. It is also desirable that this shell should be divided up similarly to the armature and for similar reasons. As a generator for driving this motor I may use the device shown in Fig. 11. This represents an annular or ring-armature, A, surrounded by four coils, F F F’ F’, of which those diametrically opposite are connected in series, so that four free ends are left, which are connected to the insulated contact-rings b b b’ b’. The ring is suitably mounted on a shaft, a, between the poles N S. The contact-rings of each pair of generator-coils are connected to these of the motor, respectively, by means of contact-brushes and the two pairs of conductors L L and L’ L’, as indicated diagrammatically in Fig. 12. Now it is obvious from consideration of the preceding figures that the rotation of the generator-ring produces currents in the coils F F’, which, being transmitted to the motor-coils, impart to the core of the latter magnetic poles constantly shifting or whirling around the core. This effect sets up a rotation of the armature owing to the attractive force between the shell and the poles of the armature, but inasmuch as the coils in this case move relative to the shell or field-magnet the movement of the coils is in the opposite direction to the progressive shifting of the poles.

Other arrangements of the coils of both generator and motor are possible, and a greater number of circuits may be used, as will be seen in the two succeeding figures.

Fig. 13 is a diagrammatic illustration of a motor and a generator constructed and connected in accordance with my invention. Fig. 14 is an end view of the generator with its field-magnets in section. The field of the motor M is produced by six magnetic poles, G’ G’, secured to or projecting from a ring or frame, H. These magnets or poles are wound with insulated coils, those diametrically opposite to each other being connected in pairs so as to produce opposite poles in each pair. This leaves six free ends, which are connected to the terminals T T T’ T’ T”T”. The armature, which is mounted to rotate between the poles, is a cylinder or disk, D, of wrought-iron, mounted on the shaft a. Two segments of the same are cut away, as shown. The generator for this motor has in this instance an armature, A, wound with three coils, K K’ K”, at sixty degrees apart. The ends of these coils are connected, respectively, to insulated contact-rings e e e e e e. These rings are connected to those of the motor in proper order by means of collecting-brushes and six wires, forming three independent circuits. The variations in the strength and direction of the currents transmitted through these circuits and traversing the coils of the motor produce a steadily-progressive shifting of the resultant attractive force exerted by the poles G’ upon the armature D, and consequently keep the armature rapidly rotating. The peculiar advantage of this disposition is in obtaining a more concentrated and powerful field. The application of this principle to systems involving multiple circuits generally will be understood from this apparatus.

Referring, now, to Figs. 15 and 16, Fig. 15 is a diagrammatic representation of a modified disposition of my invention. Fig. 16 is a horizontal cross-section of the motor. In this case a disk, D, of magnetic metal, preferably cut away at opposite edges, as shown in dotted lines in Fig. 15, is mounted so as to turn freely inside two stationary coils, N’ N”, placed at right angles to one another. The coils are preferably wound on a frame, O, of insulating material, and their ends are connected to the fixed terminals T T T’ T’. The generator G is a representative of that class of alternating-current machines in which a stationary induced element is employed. That shown consists of revolving permanent or electro-magnet, A, and four independent stationary magnets, P P’, wound with coils those diametrically opposite to each other being connected in series and having their ends secured to the terminals t t t’ t’. From these terminals the currents are led to the terminals of the motor, as shown in the drawings. The mode of operation is substantially the same as in the previous cases, the currents traversing the coils of the motor having the effect to turn the disk D. This mode of carrying out the invention has the advantage of dispensing with the sliding contacts in the system.

In the forms of motor above described only one of the elements, the armature or the field-magnet, is provided with energizing-coils. It remains, then, to show how both elements may be wound with coils. Reference is therefore had to Figs. 17, 18, and 19. Fig. 17 is an end view of such a motor. Fig. 18 is a similar view of the generator with the field-magnets in section, and Fig. 19 is a diagram of the circuit-connections. In Fig. 17 the field-magnet of the motor consists of a ring, R, preferably of thin insulated iron sheets or bands with eight pole pieces, G’, and corresponding recesses, in which four pairs of coils, V, are wound. The diametrically opposite pairs of coils are connected in series and the free ends connected to four terminals, w, the rule to be followed in connecting being the same as hereinbefore explained. An armature, D, with two coils, E E’, at right angles to each other, is mounted to rotate inside of the field-magnet R. The ends of the armature-coils are connected ito two pairs of contact-rings, d d dd, Fig. 19. The generator for this motor may be of any suitable kind to produce currents of the desired character. In the present instance it consists of a field-magnet, N S, and an armature, A, with two coils at right angles, the ends of which are connected to four contact-rings, b b b’b’, carried by its shaft. The circuit-connections are established between the rings on the generator-shaft and those on the motor-shaft by collecting brushes and wires, as previously explained. In order to properly energize the field-magnet of the motor, however, the connections are so made with the armature coils or wires leading thereto that while the points of greatest attraction or greatest density of magnetic lines of force upon the armature are shifted in one direction those upon the field-magnet are made to progress in an opposite direction. In other respects the operation is identically the same as in the other cases cited. This arrangement results in an increased speed of rotation. In Figs. 17 and 19, for example, the terminals of each set of field-coils are connected with the wires to the two armature-coils in such a way that the field-coils will maintain opposite poles in advance of the poles of the armature.

In the drawings the field-coils are in shunts to the armature, but they may be in series or in independent circuits.

It is obvious that the same principle may be applied to the various typical forms of motor hereinbefore described.

Having now described the nature of my invention and some of the various ways in which it is or may be carried into effect, I would call attention to certain characteristics which the applications of the invention possess and the advantages which the invention secures.

In my motor, considering for convenience that represented in Fig. 9, it will be observed that since the disk D has a tendency to follow continuously the points of greatest attraction, and since these points are shifted around the ring once for each revolution of the armature of the generator, it follows that the movement of the disk D will be synchronous with that of the armature A. This feature by practical demonstrations I have found to exist in all other forms in which one revolution of the armature of the generator produces a shifting of the poles of the motor through three hundred and sixty degrees.

In the particular construction shown in Fig. 15, or in others constructed on a similar plan, the number of alternating impulses resulting from one revolution of the generator armature is double as compared with the preceding cases, and the polarities in the motor are shifted around twice by one revolution of the generator-armature. The speed of the motor will, therefore, be twice that of the generator. The same result is evidently obtained by such a disposition as that shown in Fig. 17, where the poles of both elements are shifted in opposite directions.

Again, considering the apparatus illustrated by Fig. 9 as typical of the invention, it is obvious that since the attractive effect upon the disk D is greatest when the disk is in its proper relative position to the poles developed in the ring R—that is to say, when its ends or poles immediately follow those of the ring—the speed of the motor for all the loads within the normal working limits of the motor will be practically constant. It is clearly apparent that the speed can never exceed the arbitrary limit as determined by the generator, and also that within certain limits at least the speed of the motor will be independent of the strength of the current.

It will now be more readily seen from the above description how far the requirements of a practical system of electrical transmission of power are realized in my invention. I secure, first, a uniform speed under all loads within the normal working limits of the motor without the use of any auxiliary-regulator; second, synchronism between the motor and generator; third, greater efficiency by more direct application of the current, no commutating devices being required on either the motor or generator; fourth, cheapness and simplicity of mechanical construction and economy in maintenance; fifth, the capability of being very easily managed or controlled; and, sixth, diminution of danger from injury to persons and apparatus.

These motors may be run in series, multiple arc or multiple series, under conditions well understood by those skilled in the art.

The means or devices for carrying out the principle may be varied to a far greater extent than I have been able to indicate; but I regard as within my invention, and I desire to secure by Letters Patent in general, motors containing two or more independent circuits through which the operating-currents are led in the manner described. By “independent” I do not mean to imply that the circuits are necessarily isolated from one another, for in some instances there might be electrical connections between them to regulate or modify the action of the motor without necessarily producing a new or different action.

I am aware that the rotation of the armature of a motor wound with two energizing-coils at right angles to each other has been effected by an intermittent shifting of the energizing effect of both coils through which a direct current by means of mechanical devices has been transmitted in alternately-opposite directions; but this method or plan I regard as absolutely impracticable for the purpose for which my invention is designed—at least on any extended scale—for the reasons, mainly, that a great waste of energy is necessarily involved unless the number of energizing-circuits is very great, and that the interruption and reversal of a current of any considerable strength by means of any known mechanical devices is a matter of the greatest difficulty and expense.

In this application I do not claim the method of operating motors which is herein involved, having made separate application for such method.

I therefore claim the following:

1. The combination, with a motor containing separate or independent circuits on the armature or field-magnet, or both, of an alternating-current generator containing induced circuits connected independently to corresponding circuits in the motor, whereby a rotation of the generator produces a progressive shifting of the poles of the motors, as herein described.

2. In a system for the electrical transmission of power, the combination of a motor provided with two or more independent magnetizing-coils and an alternating-current generator containing induced coils corresponding to the motor-coils, and circuits connecting directly the motor and generator coils in such order that the currents developed by the generator will be passed through the corresponding motor-coils, and thereby produce a progressive shifting of the poles of the motor, as herein set forth.

3. The combination, with a motor having an annular or ring-shaped field-magnet and a cylindrical or equivalent armature, and independent coils on the field-magnet or armature, or both, of an alternating-current generator having correspondingly independent coils, and circuits including the generator-coils and corresponding motor-coils in such manner that the rotation of the generator causes a progressive shifting of the poles of the motor in the manner set forth.

4. In a system for the electrical transmission of power, the combination of the following instrumentalities, to wit: a motor composed of a disk or its equivalent mounted within a ring or annular field-magnet, which is provided with magnetizing-coils connected in diametrically-opposite pairs or groups to independent terminals, a generator having induced coils or groups of coils equal in number to the pairs or groups of motor-coils, and circuits connecting the terminals of said coils to the terminals of the motor, respectively, and in such order that the rotation of the generator and the consequent production of alternating currents in the respective circuits produces a progressive shifting of the poles of the motor, as hereinbefore described.

NIKOLA TESLA.

Witnesses:

FRANK E. HARTLEY,

FRANK B. MURPHY.

NIKOLA TESLA U.S. PATENT 382,280 – ELECTRICAL TRANSMISSION OF POWER

UNITED STATES PATENT OFFICE.


NIKOLA TESLA, OF NEW YORK, N.Y.

ELECTRICAL TRANSMISSION OF POWER.


SPECIFICATION forming part of Letters Patent No. 382,280, dated May 1, 1888.

Original application filed October 12, 1887. Serial No. 252,132. Divided and this application filed March 9, 1888. Serial No. 266,755. (No model.)


To all whom it may concern:

Be it known that I, NIKOLA TESLA, from Smiljan, Lika, border country of Austria-Hungary, and residing in the city, county, and State of New York, have invented certain new and useful Improvements in the Transmission of Power, of which the following is a specification, reference being had to the drawings accompanying and forming part of the same.

This application is a division of an application filed by me October 12, 1887, No. 252,132.

The practical solution of the problem of the electrical conversion and transmission of mechanical energy involves certain requirements which the apparatus and systems heretofore employed have not been capable of fulfilling. Such a solution primarily demands a uniformity of speed in the motor irrespective of its load within its normal working limits. On the other hand, it is necessary, to attain a greater economy of conversion than has heretofore existed, to construct cheaper and more reliable and simple apparatus, and such that all danger from the use of currents of high tension, which are necessary to an economical transmission, may be avoided.

My present invention is a new method or mode of effecting the transmission of power by electrical agency, whereby many of the present objections are overcome and great economy and efficiency secured.

In carrying out my invention I employ a motor in which there are two or more independent energizing-circuits, through which I pass, in the manner hereinafter described, alternating currents, effecting thereby a progressive shifting of the magnetism or of the “lines of force,” which, in accordance with well-known theories, produces the action of the motor.

It is obvious that a proper progressive shifting of the lines of force may be utilized to set up a movement or rotation of either element of the motor, the armature, or the field-magnet, and that if the currents directed through the several circuits of the motor are in proper direction no commutator for the motor will be required; but to avoid all the usual commutating appliances in the system I connect the motor-circuits directly with those of a suitable alternating-current generator. The practical results of such a system, its economical advantages, and the mode of its construction and operation will be described more in detail by reference to the accompanying diagrams and drawings.

Figures 1 to 8 and 1a to 8a, inclusive, are diagrams illustrating the principle of the action of my invention. The remaining figures are views of the apparatus in various forms by means of which the invention may be carried into effect, and which will be described in their order.

Referring first to Fig. 9, which is a diagrammatic representation of a motor, a generator, and connecting-circuits in accordance with my invention, M is the motor, and G the generator for driving it. The motor comprises a ring or annulus, R, preferably built up of thin insulated iron rings or annular plates, so as to be as susceptible as possible to variations in its magnetic condition. This ring is surrounded by four coils of insulated wire symmetrically placed and designated by C C C’ C’. The diametrically-opposite coils are connected up so as to co-operate in pairs in producing free poles on diametrically-opposite parts of the ring. The four free ends thus left are connected to terminals T T T’ T’, as indicated. Near the ring, and preferably inside of it, there is mounted on an axis or shaft a magnetic disk, D, generally circular in shape, but having two segments, cut away as shown. This disk is mounted so as to turn freely within the ring R. The generator G is of any ordinary type, that shown in the present instance having field-magnets N S and a cylindrical armature-core, A, wound with the two coils B B’. The free ends of each coil are carried through the shaft a and connected, respectively, to insulated contact-rings b b b b. Any convenient form of collector or brush bears on each ring and forms a terminal by which the current to and from a ring is conveyed. These terminals are connected to the terminals of the motor by the wires L and L’ in the manner indicated, whereby two complete circuits are formed, one including, say, the coils B of the generator C C of the motor and the other the remaining coils B’ and C’ C’ of the generator and motor.

It remains now to explain the mode of operation of this system, and for this purpose I refer to the diagrams, Figs. 1 to 8 and 1a to 8a, for an illustration of the various phases through which the coils of the generator pass when in operation, and the corresponding and resultant magnetic changes produced in the motor. The revolution of the armature of the generator between the field-magnets N S obviously produces in the coils B B’ alternating currents the intensity and direction of which depend upon well-known laws. In the position of the coils indicated in Fig. 1 the current in the coil B is practically nil, whereas the coil B’ at the same time is developing its maximum current, and by the means indicated in the description of Fig. 9 the circuit including this coil may also include, say, the coils C C of the motor, Fig. 1a. The result, with the proper connections, would be the magnetization of the ring R, the poles being on the line N S. The same order of connections being observed between the coil B and coils C’, the latter when traversed by a current tend to fix the poles at right angles to the line N S of Fig. 1a. It results, therefore, that when the generator-coils have made one eighth of a revolution, reaching the position shown in Fig. 2, both pairs of coils C and C’, will be traversed by currents and act in opposition in so far as the location of the poles is concerned. The position of the poles will therefore be the resultant of the magnetizing forces of the coils—that is to say, it will advance along the ring to a position corresponding to one-eighth of the revolution of the armature of the generator.

In Fig. 3 the armature of the generator has progressed to one-fourth of a revolution. At the point indicated the current in the coil B is maximum, while in B’ it is nil, the latter coil being in its neutral position. The poles of the ring R in Fig. 3a will in consequence be shifted to a position ninety degrees from that at the start, as shown. I have in like manner shown the conditions existing at each successive eighth of one revolution in the remaining figures, A short reference to these figures will suffice for an understanding of their significance.

Figs. 4 and 4a illustrate the conditions which exist when the generator-armature has completed three-eights of a revolution. Here both coils are generating current; but the coil B’, having now entered the opposite field, is generating a current in the opposite direction having the opposite magnetizing effect; hence the resultant pole will be on the line N S, as shown.

In Fig. 5 one-half of one revolution of the armature of the generator has been completed, and the resulting magnetic condition of the ring is shown in Fig. 5a. In this phase coil B is in the neutral position, while coil B’ is generating its maximum current, which is in the same direction as in Fig. 4. The poles will consequently be shifted through one-half of the ring.

In Fig. 6 the armature has completed five-eighths of a revolution. In this position coil B’develops a less powerful current, but in the same direction as before. The coil B, on the other hand, having entered a field of opposite polarity, generates a current of opposite direction. The resultant poles will therefore be in the line N S, Fig. 6a; or, in other words, the poles of the ring will be shifted along five-eighths of its periphery.

Figs. 7 and 7a in the same manner illustrate the phases of the generator and ring at three-quarters of a revolution, and Figs. 8 and 8a the same at seven-eighths of a revolution of the generator-armature. These figures will be readily understood from the foregoing.

When a complete revolution is accomplished, the conditions existing at the start are re-established, and the same action is repeated for the next and all subsequent revolutions, and in general it will now be seen that every revolution of the armature of the generator produces a corresponding shifting of the poles or lines of force around the ring. This effect I utilize in producing the rotation of a body or armature in a variety of ways—for example, applying the principle above described to the apparatus shown in Fig. 9. The disk D, owing to its tendency to assume that position in which it embraces the greatest possible number of the magnetic lines, is set in rotation, following the motion of the line or the points of greatest attraction.

The disk D in Fig. 9 is shown as cut away on opposite sides; but this I have found is not essential to effecting its rotation, as a circular disk, as indicated by dotted lines, is also set in rotation. This phenomenon I attribute to a certain inertia or resistance inherent in the metal to the rapid shifting of the lines of force through the same, which results in a continuous tangential pull upon the disk, causing its rotation. This seems to be confirmed by the fact that a circular disk of steel is more effectively rotated than one of soft iron, for the reason that the former is assumed to possess a greater resistance to the shifting of the magnetic lines.

In illustration of other forms of apparatus by means of which I carry out my invention, I shall now describe the remaining figures of the drawings.

Fig. 10 is a view in elevation and part vertical section of a motor. Fig. 12 is a top view of the same with the field in section and a diagram of connections. Fig. 11 is an end or side view of a generator with the fields in section. This form of motor may be used in place of that shown.

D is a cylindrical or drum-armature core, which, for obvious reasons, should be split up as far as practicable to prevent the circulation within it of currents of induction. The core is wound longitudinally with two coils, E and E’, the ends of which are respectively connected to insulated contact-rings d d d’ d’, carried by the shaft a, upon which the armature is mounted.

The armature is set to revolve within an iron shell, R, which constitutes the field-magnet or other element of the motor. This shell is preferably formed with a slot or opening, r; but it may be continuous, as shown by the dotted lines, and in this event it is preferably made of steel. It is also desirable that this shell should be divided up similarly to the armature, and for similar reasons. As a generator for driving this motor, I may use the device shown in Fig. 11. This represents an annular or ring armature, A, surrounded by four coils, F F F’ F’, of which those diametrically opposite are connected in series, so that four free ends are left, which are connected to the insulated contact-rings b b b b. The ring is suitably mounted on a shaft, abetween the poles N S. The contact-rings of each pair of generator coils are connected to these of the motor, respectively, by means of contact-brushes and the two pairs of conductors L L and L’ L’, as indicated diagrammatically in Fig. 13.

Now, it is obvious from a consideration of the preceding figures that the rotation of the generator-ring produces currents in the coils F F’, which, being transmitted to the motor-coils, impart to the core of the latter magnetic poles constantly shifting or whirling around the core. This effect sets up a rotation of the armature, owing to the attractive force between the shell and the poles of the armature; but inasmuch as the coils in this case move relatively to the shell or field-magnet the movement of the coils is in the opposite direction to the progressive shifting of the poles.

Other arrangements of the coils of both generator and motor are possible, and a greater number of circuits may be used, as will be seen in the two succeeding figures.

Fig. 13 is a diagrammatic illustration of a motor and a generator connected and constructed in accordance with my invention. Fig. 14 is an end view of the generator with its field-magnets in section.

The field of the motor M is produced by six magnetic poles, G’ G’, secured to or projecting from a ring or frame, H. These magnets or poles are wound with insulated coils, those diametrically opposite to each other being connected in pairs, so as to produce opposite poles in each pair. This leaves six free ends, which are connected to the terminals T T T’ T’ T” T”. The armature which is mounted to rotate between the poles is a cylinder or disk, D, of wrought-iron, mounted on the shaft a. Two segments of the same are cut away, as shown. The generator for this motor has in this instance an armature, A, wound with three coils, K K’ K”, at sixty degrees apart. The ends of these coils are connected, respectively, to insulated contact rings e e e e e e. These rings are connected to those of the motor in proper order by means of collecting-brushes and six wires, forming three independent circuits. The variations in the strength and direction of the currents transmitted through these circuits and traversing the coils of the motor produce a steadily-progressive shifting of the resultant attractive force exerted by the poles G’ upon the armature D, and consequently keep the armature rapidly rotating. The peculiar advantage of this disposition is in obtaining a more concentrated and powerful field. The application of this principle to systems involving multiple circuits generally will be understood from this apparatus.

Referring now to Figs. 15 and 16, Fig. 15 is a diagrammatic representation of a modified disposition of my invention. Fig. 16 is a horizontal cross-section of the motor. In this case a disk, D, of magnetic metal, preferably cut away at opposite edges, as shown in dotted lines in the figure, is mounted so as to turn freely inside two stationary coils, N’ N”, placed at right angles to one another. The coils are preferably wound on a frame, O, of insulating material, and their ends are connected to the fixed terminals T T T’ T’. The generator G is a representative of that class of alternating-current machines in which a stationary induced element is employed. That shown consists of revolving permanent or electro-magnet, A, and four independent stationary magnets, P P’, wound with coils, those diametrically opposite to each other being connected in series and having their ends secured to the terminals t t t t. From these terminals the currents are led to the terminals of the motor, as shown in the drawings. The mode of operation is substantially the same as in the previous cases, the currents traversing the coils of the motor having the effect to turn the disk D. This mode of carrying out the invention has the advantage of dispensing with the sliding contacts in the system.

In the forms of motor above described only one of the elements—the armature or the field-magnet—is provided with energizing-coils. It remains, then, to show how both elements may be wound with coils. Reference is therefore had to Figs. 17, 18, and 19. Fig. 17 is an end view of such a motor. Fig. 18 is a similar view of the generator, with the field-magnets in section; and Fig. 19 is a diagram of the circuit-connections. In Fig. 17 the field-magnet of the motor consists of a ring, R, preferably of thin insulated iron sheets or bands, with eight pole-pieces, G, and corresponding recesses in which four pairs of coils, V, are wound. The diametrically opposite pairs of coils are connected in series and the free ends connected to four terminals, w, the rule to be followed in connecting being the same as hereinbefore explained. An armature, D, with two coils, E E’, at right angles to each other, is mounted to rotate inside of the field-magnet R. The ends of the armature-coils are connected to two pairs of contact-rings, d d d d. The generator for this motor may be of any suitable kind to produce currents of the desired character. In the present instance it consists of a field-magnet, N S, and an armature, A, with two coils at right angles, the ends of which are connected to four contact-rings, b b bb, carried by its shaft. The circuit-connections are established between the rings on the generator-shaft and those on the motor-shaft by collecting brushes and wires, as previously explained. In order to properly energize the field-magnet of the motor, however, the connections are so made with the armature-coils by wires leading thereto that while the points of greatest attraction or greatest density of magnetic lines of force upon the armature are shifted in one direction those upon the field-magnet are made to progress in an opposite direction. In other respects the operation is identically the same as in the other cases cited. This arrangement results in an increased speed of rotation.

In Figs. 17 and 19, for example, the terminals of each set of field-coils are connected with the wires to the two armature-coils in such a way that the field-coils will maintain opposite poles in advance of the poles of the armature.

In the drawings the field-coils are in shunts to the armature; but they may be in series or in independent circuits.

It is obvious that the same principle may be applied to the various typical forms of motor hereinbefore described.

Having now described the nature of my invention and some of the various ways in which it is or may be carried into effect, I would call attention to certain characteristics which the applications of the invention possess, and the advantages which it offers.

In my motor, considering, for convenience, that represented in Fig. 9, it will be observed that since the disk D has a tendency to follow continuously the points of greatest attraction, and since these points are shifted around the ring once for each revolution of the armature of the generator, it follows that the movement of the disk D will be synchronous with that of the armature A. This feature by practical demonstration I have found to exist in all other forms in which one revolution of the armature of the generator produces a shifting of the poles of the motor through three hundred and sixty degrees.

In the particular modification shown in Fig. 15, or in others constructed on a similar plan, the number of alternating impulses resulting from one revolution of the generator-armature is double as compared with the preceding cases, and the polarities in the motor are shifted around twice by one revolution of the generator-armature. The speed of the motor will therefore be twice that of the generator. The same result is evidently obtained by such a disposition as that shown in Fig. 17, where the poles of both elements are shifted in opposite directions.

Again, considering the apparatus illustrated by Fig. 9 as typical of the invention, it is obvious that since the attractive effect upon the disk D is greatest when the disk is in its proper relative position to the poles developed in the ring R—that is to say, when its ends or poles immediately follow those of the ring—the speed of the motor for all loads within the normal working limits of the motor will be practically constant.

It is clearly apparent that the speed can never exceed the arbitrary limit as determined by the generator, and also that within certain limits, at least, the speed of the motor will be independent of the strength of the current.

It will now be more readily seen from the above description how far the requirements of a practical system of electrical transmission of power are realized in my invention. I secure, first, a uniform speed under all loads within the normal working limits of the motor without the use of any auxiliary regulator; second, synchronism between the motor and the generator; third, greater efficiency by more direct application of the current, no commutating devices being required on either the motor or generator; fourth, cheapness and simplicity of mechanical construction; fifth, the capability of being very easily managed or controlled, and, sixth; diminution of danger from injury to persons and apparatus.

These motors may be run in series—multiple arc or multiple series—under conditions well understood by those skilled in the art.

I am aware that it is not new to produce the rotations of a motor by intermittently shifting the poles of one of its elements. This has been done by passing through independent energizing-coils on one of the elements the current from a battery or other source of direct or continuous currents, reversing, such currents by suitable mechanical appliances, so that it is directed through the coils in alternately opposite directions. In such cases, however, the potential of the energizing-currents remains the same, their direction only being changed. According to my invention, however, I employ true alternating currents; and my invention consists in the discovery of the mode or method of utilizing such currents.

The difference between the two plans and the advantages of mine are obvious. By producing an alternating current each impulse of which involves a rise and fall of potential I reproduce in the motor the exact conditions of the generator, and by such currents and the consequent production of resultant poles the progression of the poles will be continuous and not intermittent. In addition to this, the practical difficulty of interrupting or reversing a current of any considerable strength is such that none of the devices at present could be made to economically or practically effect the transmission of power by reversing in the manner described a continuous or direct current. In so far, then, as the plan of acting upon one element of the motor is concerned, my invention involves the use of an alternating as distinguished from a reversed current, or a current which, while continuous and direct, is shifted from coil to coil by any form of commutator, reverser, or interrupter. With regard to that part of the invention which consists in acting upon both elements of the motor simultaneously, I regard the use of either alternating or reversed currents as within the scope of the invention, although I do not consider the use of reversed currents of any practical importance.

What I claim is—

The method herein described of electrically transmitting power, which consists in producing a continuously-progressive shifting of the polarities of either or both elements (the armature or field-magnet or magnets) of a motor by developing alternate currents in independent circuits, including the magnetizing-coils of either or both elements, as herein set forth.

NIKOLA TESLA.

Witnesses:

FRANK B. MURPHY,

FRANK E. HARTLEY.

  1. I. FROM LARGE TO MICRO ELECTRIC MOTORS

Our Serbian and famous world scientist, Nikola Tesla, constructed his electric motor back in 1887. Tesla’s famous asynchronous electric motor can run on single-phase or three-phase electricity. The principle of operation was based on the electromagnetic rotating field discovered by Tesla in 1882. Further in the text you can learn more about the construction of the engine, its application and the principle of operation.

Asynchronous electric machine is a type of electric machine for alternating current, the very name of asynchronous was created by the speed of rotation of the rotor and the speed of rotation of the rotating magnetic field is synchronized already asynchronous. Asynchronous machines cannot produce reactive power, so they are mainly used as electric motors, which is their biggest application.

Electric machines are also called electric propulsion machines. They have penetrated practically all the pores of everyday life of modern man. Today, there are almost no devices that have a built-in electric motor to drive these / those devices.

Electric machines are operated by all categories of experts, as well as a huge number of lay people. All those who are in any way connected with the exploitation of electrical machines need to know what kind of machines they are, what they are used for and how they perform their basic functions, how they look, how they are maintained, how many are in standard design, and how many can be to be, which of them are commercial types for general purpose, and which are the possibility of their adaptation to special and special requirements of exploitation.

In this series, much of the above is dealt with in more detail through questions with answers richly illustrated with drawings, photographs and schemes. I hope that the texts in this series about rotating electric machines will be interesting, useful, saved for many of you, and also of an educational nature.

CONSTRUCTION OF ASYNCRONOUS ELECTRIC MOTOR

As we know, electric motors consist of stators and rotors. The stator of the asynchronous electric motor is made of ferromagnetic material in the form of sheets, and insulation is placed between the sheets. The stator consists of thin sheets to reduce losses due to hysteresis and eddy currents. Another way to increase the quality of the stator is to improve the material by alloying silicon to suppress losses due to hysteresis, since the addition of silicon narrows the hysteresis loop, and alloying increases the electrical resistance of sheets, which reduces eddy currents and losses due to them.

The grooves in which the stator windings are located can be semi-closed and open. For low power motors, up to 200 kW, semi-enclosed and open for higher power motors are used. Although open grooves are also used in low-voltage machines, their main application is in high-voltage asynchronous machines.

The rotor of the electric motor is also made of ferromagnetic material. The windings are placed on the rotor in two ways, which is why two subgroups of asynchronous motors are distinguished. Depending on the way the winding is placed, there are machines with wound rotor (machines with sliding rings) and cage asynchronous motors (motors with short-circuited rotor).

In motors with sliding rings, the rotor has a three-phase winding whose beginnings are performed on three sliding rings, while the ends are mostly connected to the star point. The purpose of the slip rings is the possibility of external access to the rotor winding. Brushes that are attached to the stator and whose leads are located on the connection plate of the machine slide on the rings.

In cage short-circuited motors, the rotor consists of massive conductors that are connected on both sides by short-circuit rings. The coil can be made of copper or aluminum. The cage winding is completely short-circuited, which means that there is no electrical access to the rotor winding, and thus there is no need for brushes, which are the most common cause of machine failure.

©Električne mašine kroz praktična pitanja i odgovore – Deo 1

Autor: Radoje Jankovic.

Uvod

U ovoj, obimnijoj seriji pitanja sa odgovorima iz oblasti električnih mašina, pokušao sam da što detaljnije obradim ovu oblast sa stanovišta prakse i svakodnevnog korišćenja rotacionih električnih mašina svih tipova u najrazlitijim oblastima današnjice. Počeo sam, ako se tako može reći od početka, od jednostavnijih stvari ka složenijim i najsloženijim problemina iz električnih mašina.

Ovo su tipovi pitanja sa odgovorima koji se prvi put susreću u pisanoj i elektronskoj obrazovnoj i praktičnoj literatururi u svetu. Verujem da će mnogim kolegama, tehničarima, inženjerima, nastavnicima, profesorima, serviserima, projektantima,  majstorima praktičarima  koji rade svakodnevno na remontu, održavanju, popravkama i premotavanju električnih mašina dobro doći u njihovim svakodnevnim poslovima iz ove oblasti. Posebno će dobro doći učenicima elektrotehničkih škola, studentima i početnicima koji se prvi put susreću u svojoj karijeri sa različitim vrstama, tipovima i konstruktivnih rešenja kod  rotacionih električnih mašina.

Skoro da ne postoji bilo koji uređaj, aparat ili sklop nekog sistema (naše kuće i  stanovi su puni najrazličitijih električnih aparata) koji nema u sebi neki od električnih motora koji rade na naizmeničnu i jednosmernu struju malih napona od nekoliko volti do nekoliko desetaka volti, niskih napona sviih veličina koji se susreću i koriste u celom svetu bilo da su međunarodno standardizovani ili standardizovani na lokalnom nivo, visokih napona od 1000 V do nekoliko desetina hiljada volti. Čak, skoro i svi mobilni telefoni u sebi imaju mikromotorčić veličine nekoliko milimetara u svojim dimenzija koji pogone vibrator da vam daju do znanja da vas neko poziva ili šalje neku poruku, zar ne, ja imam nekoliko komada takvih mikromotorčića koji mogu da se stave na vrh kažipsta. 

Za izradu ovih pitanja sa odgovorima koristio sam svoju ličnu literaturu, dokumentaciju i arhivu kao i moje originalne fotografije i fotografije sa mnoštvo detalja koje dobijam od svojih prijatelja i poznanika koji se bave serviseranjem, remontom i održavanjem  najrazličitijih tipova i vrsta rotacionih električnih mašina i ne samo njih već i ostalih elektro uređaja i opreme, pa im se ovom prilikom srdačno zahvaljujem. Ima i fotografija koje sam preuzimao sa interneta jer je nemoguće da sve i svaki detalj snimam lično a nadam se da se neće ljutiti kolege koje prepoznaju svoje fotografije s obzirom da ih koristim isključivo u obrazovne svrhe, jer su mnoge mlade kolege širom sveta željne znanja koje će im u životu i karijeri trebati a ne dobijaju ga od svojih škola i univerziteta i svojih instruktora u dovoljnoj meri.           

U ovoj seriji sam obuhvatio nekoliko stotina pitanja sa odgovorima ilustrovanih sa skoro 3 puta više veoma jasnih, razumljivih praktičnih ilustracija. Ovaj tekst pod naslovom “Električne mašine kroz praktična pitanja i odgovore© može biti pravi priručnik zanja iz električnih mašina za sve zainteresovane. Ovom prilikom, pozivam nekog od kolega iz sveta (može me obavestiti slanjem e-mail poruke ) koji može učiniti nešto da ovaj priručnik štampamo i učinimo dostupnim širokim masama učenika, studenata, profesionalaca i drugima… Knjiga bi bila obimna i velikog A4 formata, nikako manja, i sa velikim jasnim fotografijama na kojima se može jasno videti svaki detalj.

  1. OD VELIKIH DO MIKRO ELEKTROMOTORA

Naš Srpski i čuveni Svetski naučnik, Nikola Tesla, je konstruisao svoj elektromotor još davne 1887.godine. Čuveni Teslin asinhroni elektromotor može raditi na monofaznu ili trofaznu električnu energiju. Princip rada je zanovan na elektromagnetnom obrtnom polju koje je Tesla otkrio 1882.godine. Dalje u tekstu možete saznati više o samoj konstrukcji motora, njegovoj primeni i principu rada.

Asinhrona električna mašina je jedna vrsta električne mašine za naizmeničnu struju, sam naziv asinhrona je nastao tako što brzina obrtanja rotora i brzina obrtanja obrtnog magnetnog polja je sinhronizovana već asingrona. Asinhrone mašine ne mogu da proizvode reaktivnu snagu, pa se u glavnom koriste kao elektromotori, što im je i najveća primena.

Električne mašine nazivaju se i električne pogonske mašine. Prodrle su praktično u sve pore svakodnevnog života savremenog čoveka. Danas, skoro da nema uređaja koji u sebi ima ugrađen neki elektromotor za pogon tog/tih uređaja.

Električnim mašinama upravljaju sve kategorije stručnjaka, kao i ogroman broj laika. Svi oni koji su na bilo koji način povezani sa eksploatacijom električnih mašina potrebno je da znaju kakve su to mašine, čemu služe i na koji način obavljaju svoje osnovne funkcije, kako izgledaju, kako se održavaju, kolike su u standardnom izvođenju, a kolike mogu uopšte da budu, koje su od njih komercijalni tipovi za opštu namenu, a koje su mogućnost njihovog prilagođavanja posebnim i specijalnim zahtevima eksploatacije.

U ovoj seriji se mnogo od navedenog obrađuje detaljnije kroz pitanja sa odgovorima bogato ilustrovanih crtežima, fotografijama i šemama. Nadam se da će tekstovi u ovoj seriji o rotacionim električnim mašinama, mnogima od vas biti interesantni, korisni, savedovani a takođe i obrazovnog karaktera.   

Konstrukcija asinhronog elektromotora

Kao što znamo elektomotori se sastoje od statora i rotora. Stator asinhronog elektromotora se izrađuje od feromagnetnog materijala u obliku limova, a između limova postavlja se izolacija. Stator se sastoji iz tankih limova kako bi se smanjili gubici usled histerezisa i vrtložnih struja. Drugi način povećanja kvaliteta statora se vrši poboljšanjem materijala legiranjem silicijumom radi suzbijanja gubitaka zbog histerezisa, pošto dodatak silicijuma sužava histerezisnu petlju, a legiranjem se povećava električna otpornost limova zbog čega se smanjuju vrtložne struje i gubici usled njih.

Žlebovi u kojima se smeštaju namotaji statora mogu biti poluzatvoreni i otvoreni. Za motore malih snaga, do 200KW koriste se poluzatvoreni, a otvoreni za motore većih snaga. Mada se otvoreni žlebovi koriste i u niskonaponskim, ali njihova glavna primena je kod visokonaponskih asinhronih mašinama.

Rotor elektromotora se takođe pravi od feromagnetnog materijala. Namotaji se smeštaju na rotor na dva načina, zbog čega se razlikuju dve podgrupe asinhronih motora. U zavisnosti od načina smeštanja namotaja postoje mašine sa namotanim rotorom (mašine sa kliznim prstenovima) i kavezni asinhroni motori (motori sa kratkospojenim rotorom).

Kod motora sa kliznim prstenovima rotor ima trofazni namotaj čiji se počeci izvode na tri klizna prstena, dok se krajevi uglavnom vezuju u zvezdište. Svrha kliznih prstenova je mogućnost spoljnog pristupa namotaju rotora. Po prstenovima klize četkice koje su pričvršćene za stator i čiji se izvodi nalaze na priključnoj pločici mašine.

Kod kaveznih kratkospojenih motora rotor čine masivni provodnici koji su sa obe strane spojeni kratkospojnim prstenovima. Namotaj može biti od bakra ili od aluminijuma. Kavezni namotaj je potpuno kratko spojen, što znači da ne postoji električni pristup rotorskom namotaju, a time nema ni potrebe za četkicama, koje su najčešći uzrok otkazivanja mašine.

Slika A. Čovek trećeg milenijuma.
 
Figure A. The man of the third millennium.

Fig. B. New Definition of Tesla (T) units for the magnetic induction or magnetic flux density. 

1 T = 1 newton / ampere meter = 1 kilogram / ampere per second squared. 

Slika C. Veliki visokonaponski electromotor, 6 kV, 315 kW, težine (mase) od više tona
Figure C. Large high voltage electric motor, 6 kV, 315 kW, weight (mass) of several tons 


Slika D. Veliki trofazni asinhroni electromotor, 1250 kW, 690 VAC, kojim se upravlja pomoću frekventih regulatora odgovarajuće snage
Figure D. Large three-phase asynchronous electric motor, 1250 kW, 690 VAC, controlled by frequency regulators of appropriate power


Slika E. Razni trofazni asinhroni elektromotori
Figure E. Various three-phase asynchronous electric motors


Slika F. Dva visokonaponska 6 kV, 315 kW trofazna elektromotora sa namotanim rotorima pogone jedan  veliki trakasti transporter na površinskom kopu.
Figure F. Two high voltage 6 kV, 315 kW  three-phase slip-ring asynchronous electrical motors driving the large belt conveyor for dumping overburden in a open pit mine.


Slika G. Redni electromotor jednosmerne struje koji pogoni gusenični transport na jednom velikom rotacionom bageru zvani glodar.
Figure G. Series DC electrical motor driving a catterpilar of one large rotary excavator in a one open pit mine


Slika H. Jedan mali kolektorski jednofazni elektromotor otvorene konstrukcije koji se koristi kod raznih električnih aparata i uređaja
Figure H. One small collector single-phase electric motor of open construction used in various electrical appliances and devices

Slika I. Veliki trofazni elektromotor koji se koristi za pogon crpnih pumpi velikog kapaciteta crpljenja vode
Figure I. Large three-phase electric motor used to drive high-capacity water pumping pumps


Slika J. Veliki visokonaponski trofazni asinhroni elektromotor koji pogoni radni rotacioni točak kapaciteta kopanja jalovine od preko 8000 m3/hr na površinskim kopovima.
Figure J. Large high-voltage three-phase asynchronous electric motor that drives a working rotating wheel with a rotary excavator rodent digging capacity of over 8000 m3/h at one open pit mine


Slika K. Ova slika prikazuje dva elektromotora; u sredini, redni elektromotor jednosmerne struje 400 V za pogon guseničnog transporta jednog bagera; gore levo se vidi visokonaponski, 6 kV, motor sa namotanim rotorom i kliznim prstenovima, snage 315 kW koji pogoni radni točak rotacionog bagera glodar.  
Figure K. This figure shows two electric motors; in the middle, an in-line 400 V DC electric motor to drive the tracked transport of one excavator; at the top left you can see a high-voltage, 6 kV, motor with a wound rotor and slip rings, 315 kW, which drives the working wheel of a rotary excavator rodent. 


Slika L. Jedna fascinantna fotografija snimljena u vreme izlaska sunca jednog decembra na jednom površinskom kopu. Dubina kopa ispod jutarnje magle je od 20 do 100 m +. Na mnogobrojnim rudarskim mašina ovde rade hiljade i hiljade elektromotora različitih konstrukcija i snaga.
Picture L. One fascinating photograph taken at sunrise one December at a open pit surface mine. The depth of the excavation under the morning fog is from 20 to 100 m +. Thousands and thousands of electric motors of various constructions and powers work on numerous mining machines here.


Slika N. Fascinantni zalazak sunca na jednom površinskom ugljenokopu sa pogonskom stanicom trakastog transportera kapaciteta prenosa jalovine preko 8500 m3/hr.
Figure N. Fascinating sunset on a one surface coal mine with a belt conveyor drive station with a tailings transfer capacity of over 8500 m3 / hr.


Slika O. Mikro motor vibratora za mobilne telephone.
Uporedite masu (težinu) ovog motora sa motorima prikazanih na gornjim slikama čije se mase kreću i preko 10 tona (10000 kg)
 
Figure O. Micro vibrator motor for mobile telephone.
Compare the weight of this motor with the motors shown in the pictures above, which weigh over 10 tons (10000 kg)
– DC: 3.0V – 3.7V
– Current: 80mA
– Weight: 1.1g
 

Slika P. Još jedan od mikromotora za vibratore mobilnih telefona.
Figure P. Another of the micromotors for mobile phone vibrators.


Slika Q. Uporedite ovaj motor sa gore prikazanim velikim elektromotorima.
Figure Q. Compare this motor with the large electric motors shown above.
Voltage: 1.5VDC  Current: 60mA
Voltage: 2.0VDC  Current: 77mA
Voltage: 3.0VDC  Current: 110mA
Weight: 1g


Slika R. Šta mislite, da li biste mogli staviti na vaš kažiprst neki od elektromotora s početka ovog teksta?
Figure R. What do you think, could you put on your index finger some of the electric motors from the beginning of this text?

Second part coming soon.
 

About the Author

- Radoje - Rade Jankovic Electrician, Electrical Technician, Electrical Engineer, PhD, Ecologist, Environmentalist, Designer, Educator, Investigator... Today PROFESSIONAL TECHNICAL WRITER AND DOCUMENTATOR Massive practical experience in almost all fields of electrical engineering over 40 years. My International education group in Facebook: EEEW - ELECTRICAL & ELECTRONIC EDUCATION WORLD where published more than 8000 small or bigger articles, lessons, technical advice, projects, technical calculations, test questions with and without answers, illustrated test questions with and without answers; all my original works and few thousands of may original photos from practice, drawings, circuit diagrams, environmental lessons and examples from everyday practice etc., etc.

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  1. Dorthey Ancy says:

    Wonderful web site. Lots of helpful information here. I am sending it to several friends ans also sharing in delicious. And naturally, thanks on your effort!

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© Electric machines through practical questions and answers – Part 1