 Vol: 45 Issue: 1
 Vol: 45 Issue: 2
 Vol: 45 Issue: 3
 Vol: 45 Issue: 4
 Vol: 45 Issue: 5
 Vol: 45 Issue: 6
 Vol: 45 Issue: 7
 Vol: 45 Issue: 8
 Vol: 45 Issue: 9
 Vol: 45 Issue: 10
 Vol: 45 Issue: 11
 Vol: 45 Issue: 12
 Vol: 46 Issue: 1
 Vol: 46 Issue: 2
 Vol: 46 Issue: 3
 Vol: 46 Issue: 4
 Vol: 46 Issue: 5
 Vol: 46 Issue: 6
 Vol: 46 Issue: 7
 Vol: 46 Issue: 8
 Vol: 46 Issue: 9
 Vol: 46 Issue: 10
 Vol: 46 Issue: 11
 Vol: 46 Issue: 12
 Vol: 47 Issue: 1
 Vol: 47 Issue: 2
 Vol: 47 Issue: 3
 Vol: 47 Issue: 4
 Vol: 47 Issue: 5
 Vol: 47 Issue: 6
 Vol: 47 Issue: 7
 Vol: 47 Issue: 8
 Vol: 47 Issue: 9
 Vol: 47 Issue: 10
 Vol: 47 Issue: 11
 Vol: 47 Issue: 12
 Vol: 48 Issue: 1
 Vol: 48 Issue: 2
 Vol: 48 Issue: 3
 Vol: 48 Issue: 4
 Vol: 48 Issue: 5
 Vol: 48 Issue: 6
 Vol: 48 Issue: 7
 Vol: 48 Issue: 8
 Vol: 48 Issue: 9
 Vol: 48 Issue: 10
 Vol: 48 Issue: 11
 Vol: 48 Issue: 12
 Vol: 43 Issue: 1
 Vol: 43 Issue: 2
 Vol: 43 Issue: 3
 Vol: 43 Issue: 4
 Vol: 43 Issue: 5
 Vol: 43 Issue: 6
 Vol: 43 Issue: 7
 Vol: 43 Issue: 8
 Vol: 43 Issue: 9
 Vol: 43 Issue: 10
 Vol: 43 Issue: 11
 Vol: 43 Issue: 12
The Journal of the American Institute of Electrical Engineers (AIEE) contains articles published between 1924 and 1930. Contents are devoted to the advancement of theory and practice of electrical engineering and the allied arts and sciences.
This Journal ceased publication in 1930. The current retitled publication is IEEE Spectrum.
Latest Published Articles

Discussion at Winter convention: The M. M. F. wave of polyphase windings
Jun24 2013 
Electrical measurement of physical values: The determination by electrical and magnetic means of quantities not in themselves of an electrical nature
Jun24 2013 
Condenser shunt for measurement of highfrequency currents of large magnitude
Jun24 2013 
The possibilities of flashovers
Jun24 2013 
Italian electric power industry
Jun24 2013
Popular Articles

Power limitations of transmission systems
Jun24 2013 
A twospeed salientpole synchronous motor
Jun24 2013 
Fundamental considerations of power limits of transmission systems
Jun24 2013 
Abridgment of generalized theory of electrical machinery
Jun24 2013 
Abridgment of tworeaction theory of synchronous machines generalized method of analysis — Part I
Jun24 2013
Publish in this Journal
Popular Articles (November 2014)
Includes the top 50 most frequently downloaded documents for this publication according to the most recent monthly usage statistics.
1. Power limitations of transmission systems
Page(s): 45  51Review of the Subject — Several independent studies have been made recently to determine the economies of a large, uniform power system. The two studies of more general interest were those conducted by the Department of the Interior, under the direction of W. S. Murray, for the Superpower Zone, and by F. G. Baum for the United States. Both of these investigations are available in published form. During the progress of the Superpower Survey, one of the longest transmission lines proposed was that extending 350 miles from the Niagara Falls Development to New York City. Under emergency conditions on this line, the power limit for the maximum amount of power was approached by two twincircuit lower lines with three circuits carrying the emergency load. The maximum power limit would have been exceeded if two singlecircuit tower lines had been employed, even though the transmission voltages and the total copper crosssection were the same as with the two twincircuit lower lines. Similarly, several long, highvoltage lines will be required in a nationwide system, especially through the middle western region as shown by Mr. Baum's report. The tendency to extensive transmission systems has emphasized the necessity of considering the factors which will limit the amount of power that can be transmitted any distance with the highest practical transmission voltage. On account of the transmission line characteristics, the power limits will be greater when the system is regulated by synchronous apparatus than when those such apparatus is used so that two power limits will be considered in this paper; first, for an unregulated system; and second, for a regulated system. However, while we are primarily interested in highvoltage systems in this paper, it should be kept in mind that these same methods of calculation may be applied to lower voltages in determining the power limitations of station tie lines. It is commonly accepted that different types of networks have cer ain power limitations. For example, a very simple case quite generally known is that of a simple resistance circuit in which the power delivered is a maximum when the resistance of the load is equal to that of the line. Another familiar case is that of the electric arc furnace where the maximum power occurs when the resistance of the furnace arc is equal to the reactance of the electric furnace leads. The general phenomenon of maximum power limit in circuits of fixed reactance and variable resistance or load has been recognized and Us theory worked out for numerous cases, such as short transmission lines, rotating machines, and transformers. A power transmission system may be regarded as a special type of network. Ordinarily it consists of long, hightension transmission lines and apparatus connecting generating stations with distant load centers which may be either at the terminus or at intermediate points on the hightension lines. In large systems, the hightension lines may form a network similar to an ordinary local distribution system. Where synchronous condensers are not installed, the problem of the maximum amount of power which may be delivered through the system is similar to the simple resistance and reactance cases cited above in that additional load or shunt impedance simply alters the load and voltage in accordance with the relative impedances of the system. The employment of synchronous condensers at the load centers or along the transmission lines to alter the power factor and maintain the voltage at the load materially increases the maximum amount of power that may be desired over a given transmission network. The theoretical maximum amount of power however, cannoi be obtained under operating conditions because the synchronous equipment at the receiver drops out of step with the supply. Also, fluctuations in load will produce unstable conditions, which may accumulate sufficiently to cause the momentary swings in load to exceed the power limit, resu View full abstract»

2. A twospeed salientpole synchronous motor
Page(s): 339  346The design features and performance characteristics of salientpole synchronous motors are well known and have been thoroughly covered in the technical press. The synchronous motor has been handicapped in the past because it is inherently a singlespeed machine, and a change in speed could be obtained only by a change in the frequency of the power supply. Changing the frequency, however, is not practical in most applications. The special pole described in this paper which allows twospeed operation of a synchronous motor to be obtained at high efficiency is a new feature^{2}. The same principle applied to a generator enables two frequencies to be obtained at the same speed or the same frequency at two different speeds. All that is necessary to change the speed (or frequency) is a polechanging switch for the stator winding and a reversing switch for the rotor winding. A 5000/2500h. p., 600/300rev. per min., twospeed synchronous motor was built without having first constructed a model of any kind. This motor proved to be entirely satisfactory and its characteristics obtained by test agreed very closely with the calculated characteristics. At either speed the twospeed synchronous motor functions exactly as the ordinary synchronous motor. There is nothing special or complicated about its construction, it does not require any more attention than the ordinary synchronous motor, and its expense of maintenance is just the same. The first cost of such a motor is only slightly more than that of the ordinary synchronous motor whose rating is equal to the lowspeed rating of the twospeed motor. Therefore, the twospeed synchronous motor is a practical machine and it should open a new field for synchronous motor application. View full abstract»

3. Fundamental considerations of power limits of transmission systems
Page(s): 1045  1057At this time the power limit of transmission lines is a live subject and presents such complications as to require very careful analysis. The paper points out the essential features to be considered in a study of the problem, and calls attention to some outstanding results of an experimental investigation of the subject with a view to clarifying some of the points that have been under discussion in the past two years. It is shown that the problem of stability is not necessarily confined to longdistance, highvoltage transmission, but may be present in any system where the impedance of the transmitting circuit is high compared with the load to be carried. While the impedance of the transmission line and transformers plays an important part in establishing the breakdown point of a system, the characteristics of synchronous apparatus with the method of voltage regulation used are of equal importance. It is shown that the synchronizing power of synchronous apparatus is largely dependent upon the field excitation at the time excess load is applied; that field excitation is determined by the circuit conditions under steady load, and, in order to provide for increase of excitation with increasing loads of considerable magnitude, some automatic means of controlling the field is essential. The rate at which mechanical load in large quantities can be added to a system is limited on account of the necessity of change in angular displacement between the generators and receiving bus; this changing angle requires relative speed change, which takes time. This fact, together with the inherent tendency of synchronous machines to “stiffen” under sudden applications of load, makes it possible to rely on the usual vibratingtype voltage regulator working on the field of the exciter to provide the necessary field change. It is brought out that the maximum load that a system can carry under steady conditions at normal voltage can be suddenly thrown on, and the voltage r gulator, with the assistance of the factors mentioned, will provide the necessary excitation. Voltage regulators are practically a necessity where it is desired to approach, under operating conditions, the ultimate maximum power of the system. Transient load changes that occur on the usual system, such as throwing on or off load, cutting in or out transmission circuits, etc., can be easily taken care of, providing such changes do not exceed the steady state limits of the system. The effect of short circuits depends upon their nature, whether threephase or singlephase, and upon the location and duration. This subject is discussed briefly and the conclusion drawn that successful operation can be obtained under usual shortcircuit conditions if adequate relaying is provided. The possibility is discussed of increasing the limit of power transmission by improving the apparatus and the characteristics of the transmission circuits, and it is pointed out that no great development may be expected from any scheme yet proposed regarding a modification in line characteristics. With reference to the apparatus, it is possible to make some changes in the design of synchronous machines tending to “stiffen” them, such as higher saturation, larger airgap, etc., but in general no radical improvement may be expected here that does not materially increase the cost and decrease the efficiency of the machine. Attention is turned therefore toward such schemes of regulation, or compensation, of the synchronous apparatus as would increase the maximum power. Among these is the use of reactors for locally controlling power factor and thus too the field excitation of the more important synchronous machines. However, the possible additional power thus obtained is limited, and, as it now appears, other methods which have greater promise will be resorted to. The use of a mercuryarc rectifier in the alternator field circuit seems to have great possibilities. By varying the fiel View full abstract»

4. Abridgment of generalized theory of electrical machinery
Page(s): 302  305In the following pages, electrical machinery is analyzed from a new point of view. Analytical quantities, like magnetizing current, armature reaction, leakage flux, transient reactance are not introduced; only such quantities are used as actually exist in the machine at one particular load. Thereby the theory of electrical machinery is expressed in terms of the minimum possible number of quantities. No hypothetical currents or fluxes are used and no actual physical quantity is left out. The concept of “free energy,” used in thermodynamics, is introduced and generalized. The criterion of good design of all electrical machines is expressed by a constant, the “thermodynamic efficiency” which gives a measure of the effective utilization of iron and space for the transformation of energy. This constant plays a most fundamental role in the steady and transient behavior of the machine. A method is given by which the direction of flow of energy between different parts of any complicated machine can easily be read from the diagrams. The theory of constantpotential and constantcurrent electromagnets is used as a stepping stone to show that the theory of the polyphase alternator is identical with the theory of the constantpotential polyphase transformer if flux linkages and magnetomotive forces are interchanged. The circle diagrams of the transformer and the alternator are developed, as well as the elliptical locus diagram of the alternator with salient poles. Problems in the sudden short circuit and the sudden load variation of the polyphase alternator are also solved. Blondel's diagram for the circular locus of the synchronous motor is derived in a more extended form together with its elliptical locus with salient poles. The elliptical loci of the reaction machine and the synchronous converter are also developed. The circular locus for the polyphase induction motor, the singlephase induction motor and the repulsion motor are derived. The method of attack used in the paper is applicable not only to circular and elliptical loci, but also to loci of higher curves. The method is used to develop the complete theory and locus diagram of the double squirrelcage induction motor and the splitphase induction motor with or without condenser (or the socalled condenser motor). Besides those mentioned above, the writer has also developed with this method the loci of commutator machines such as the polyphase induction motor with commutator rotor, the series polyphase and the shunt polyphase commutator motors, and the compensated series motor, including the effect of the shortcircuited brush currents, also the locus of induction motors in cascade. An extension of the concept of free energy establishes the fourline vector diagram and the locus characteristics of any transmission system or any fourterminal network, showing the voltages and currents at both sending and receiving ends. Due to the length of the article, however, their discussion does not appear here. All locus diagrams show the speed and the torque at all loads. They also show the magnitude and phase relation of all actual currents, fluxes, and e. m. fs. A relation of the form r/x is found for the ratio of the work done to the free energy and this one simple formula is sufficient to find the locus diagram and the complete performance of all electrical machinery and transmission lines. It is the only formula used in the paper. In the appendix, the relation of the design constants used to the constants of other methods is shown. View full abstract»

5. Abridgment of tworeaction theory of synchronous machines generalized method of analysis — Part I
Page(s): 194STARTING with the basic assumption of no saturation or hysteresis, and with distribution of armature phase m. m. f. effectively sinusoidal so far as regards phenomena dependent upon rotor position, general formulas are developed for current, voltage, power, and torque under steady and transient load conditions. Special detailed formulas are also developed which permit the determination of current and torque on threephase short circuit during starting, and when only small deviations from an average operating angle are involved. View full abstract»

6. Synchronous machines I — An extension of Blondel's tworeaction theory
Page(s): 974  987Blondel treated salient pole machines by resolving the fundamental space component of m. m. f. along the two axes of symmetry the direct axis of the pole, and the quadrature axis between poles. Using this idea and applying harmonic analysis, Blondevs theory has been extended in the present paper to a comprehensive system of treatment in which the effect of harmonic m. m. fsy as well as the fundamental and also of field m. m. f. in the quadrature axis, as well as in the direct have been taken into account. It is shown that the “armature leakage flux” which causes reactance voltage drop in synchronous operation comprises all fluxes due to armature currents which generate fundamental voltage except the space fundamental component, the latter constituting the total flux of “armature reaction.” Impressing upon the variable airgap permeance those space harmonics of m. m. f. which are due to the fundamental time component of current and which therefore rotate at various fractional speeds produces odd space harmonics of flux rotating at many different speeds and in opposite directions. Some of these listed in Table I produce fundamental voltage, but most of them generate time harmonics. The former, which are reactive voltages, are only those of the nth space order rotating at one nth speed that is, those which correspond in space order and speed to the harmonic m. m. fs. The corresponding reactances are definitely defined in Appendix C in terms of permeance coefficients, and means are outlined for quantitative determination of such coefficients from graphically constructed field plots. Although, strictly, there areas many field plots required as there are significant m. m.f. harmonics, an approximation, developed in Appendix B, is given in which only one plot is necessary, other permeance waves being derived therefrom. It is shown that only the average term and the second space harmonic of the permeance series affect the fundamental voltage Hence, unless it is required to calculate the harmonic voltages, only those two terms of the permeance series need to be determined. In the application of the results, the fundamental voltages thus produced by the armature currents are superposed upon that due to current in the field winding, which latter has been previously treated. This gives the vector diagram, Fig. 19, from which the steady state relations are set down in equations. In Part II, the steadystate anglepower relations are developed, including an interpretation of the “reluctance term11 in the power or torque equation. In Appendix D, the vector diagram for salient pole machines is interpreted in terms of the wellknown Potier diagram for cylindrical rotor machines. Also the effect of saturation both on anglepower relation and on the value of excitation required under load is discussed. Subsequent papers in the near future will present results which have been obtained from the application of the method and point of view here outlined to the solution of problems relating to abnormal operating conditions of synchronous machines. View full abstract»

7. Effects of time and frequency on insulation test of transformers
Page(s): 145  155Permanently grounded transformers must be given the insulation lest by inducing the necessary voltage across the windings. The A. I. E. E. Standards specify that the time of induced voltage tests be the same as for high potential test. In certain cases where the transformers are of very large capacity the induced voltage must be made at a frequency several times higher than normal. Since the dielectric strength of most insulating materials decreases with an increase in the frequency, an investigation has been made to determine the proper and fair length of time to make induced voltage test when the frequency is higher than normal. Following are the main points brought out in the investigation. Above a certain voltage, time of voltage application as well as voltage causes failure of insulation. The dielectric strength can be expressed as a function of both time and voltage by an equation of the form
$Kv. = A(a + {1a over root {1} of T})$ in which A is the kilovolts necessary to cause failure in one minute, “a” is a constant representing the ratio of strength for infinite time to the one minute strength and T is time in minutes. The value of “a” varies for different materials apparently depending mostly on the dielectric loss. The breakdown by creepage over solid insulation with the electrodes either on the same side or on opposite sides of the sample (arranged in such a manner that the solid insulation is under considerable stress) is not affected by time nearly so much as is the puncture voltage of solid insulation. The behavior of oil without barriers is so erratic that no very definite relation can be obtained between time and dielectric strength. In general time decreases the strength quite rapidly for the first few seconds after which the effect decreases and probably disappears entirely after two or three minutes. The momentary strength ranges from 25 to 30 per cent higher than the one minute strength. The effect  f time on the strength of solid insulation and oil in series is about the same as for solid insulation alone until the oil distance exceeds the solid insulation thickness after which it begins to be the same as for oil without barriers. The strengthtime curves for solid insulation are of approximately the same shape for all frequencies from 60 to 420 cycles, although the strength decreases with an increase in frequency F approximately in accordance with the formula kv. = 1.75/ F^{0·137} Failure by creepage over the surface of solid insulation which is under no stress (i. e., with the electrodes on the same side of the barrier) takes place at approximately the same voltage for all frequencies from 60 to 420 cycles; but if the electrodes are so arranged (on opposite sides) that the insulation is under considerable stress the failure voltage decreases with an increase in frequency in about the same order as the puncture voltage of solid insulation does. The rupture voltage of oil is the same for both 60 and 420 cycles. The effect of frequency on the puncture voltage of solid insulation and oil in series is the same as for solid insulation until the oil distance exceeds the thickness of solid insulation, after which the effect decreases and as the oil distance increases the effect approaches that for oil without barriers. By considering the effects of both time and frequency on dielectric strength it is shown how to determine the proper length of time to make the voltage strain at higher frequencies equal to the strain at 60 cycles for one minute. 8. ACKNOWLEDGEMENTS It is desired to acknowledge the valuable assistance rendered in the Testing Department by Messrs. N. M. Albert, H. L. Garver, C. F. Green, L. D. Martin and W. F. Weikel in carrying on the long and tedious tests, covering a period of three to four months. View full abstract» 
8. Abridgment of development of the porcelain insulator
Page(s): 796  799Porcelain insulators have been manufactured and used for the transmission of highvoltage electric power for forty years. The first designs were of the single piece and multipart cemented pin type. Necessity of higher safety factors against flashover and increase in operating voltages demanded a rapid increase in the size of the insulators. This reached an economic limit at the operating voltage of 66 kv. The suspension unit overcame this temporary check of increased operating voltage. Further study of the electrostatic capacitance of the various parts and consequent voltage distribution, made marked refinements in the pin type insulator possible. During this time the single piece porcelain suspension unit took practically its present form. Early improvements were the provision of proper expansion joints and the separation of the lip of the cap from the porcelain hood. Gradual improvements have since been made resulting in a great increase in mechanical strength. These changes have been principally of hardware design. By experiment and analysis the shapes of the cap and pin have been determined to give a uniform distribution of load from the pin to the cap. Constant check tests by the quick pull and time loading methods have shown, that the suspension insulator with properly designed hardware and a suitable coating on the cap to prevent the cement from adhering to the metal, to have a high strength associated with electrical reliability. Ceramic research and exact manufacturing control has made possible the production of nonabsorbent, thoroughly vitrified porcelain of consistent strength. This has centered largely about the proper firing of the clay. Recent experiments upon the properties of the combination of porcelain and glaze has eliminated surface stress and consequently assured stronger, longer lived porcelain. Still greater uniformity has been gained by glazing the sanded surfaces. The elimination of the abutting joint and the proper design of the cemented  oint has stopped expansion troubles. Proper use of Portland cement has resulted in insulators able to withstand drastic temperature changes without harm. A recent improvement in the pin type insulator is the metal threaded pin hole. This has lessened manufacturing and construction difficulties and in addition due to the exact fit of the insulator on the pin, overcomes hidden corona and the consequent radio interference. View full abstract»

9. Currentlimiting reactors
Page(s): 1050  1054Currentlimiting reactors are desirable only insofar as they are strictly reliable protective devices. In this paper general considerations of the factors affecting reliability are outlined, and some of the early weaknesses and the means taken to eliminate them are enumerated. Modern reactors are considered to be reliable and on large systems are considered practically indispensable. The thermal duty of a currentlimiting reactor is a consideration affecting the reliability which has been the subject of considerable discussion. Various opinions have been expressed ranging from the idea that a reactor should fail first and open the circuit in the event of short circuit, to the idea that it should have enough thermal capacity to withstand shortcircuit currents for long periods of time. A middle ground is suggested in this paper where recognition is given both to the protective function of the reactor and to the practical consideration of dimensions and cost. View full abstract»

10. Abridgment of additional losses of synchronous machines
Page(s): 573  582In the case of highspeed turbine generators, the most reliable means of determining the losses under actual operating conditions is to measure the weight and temperature rise of the cooling medium and to estimate the small part of the losses which is dissipated from the frame to the surrounding medium. The temperature rise of the cooling medium can be obtained by means of temperature detectors located at the inlet and outlet sections of the generator. In order to obtain reliable values of the average temperature rise for the machine, it is necessary to have approximately uniform velocities at both inlet and outlet sections and to measure the temperature rise at a large number of incremental sections. The volume of cooling medium passing through the machine can be determined by (a) introducing a definite amount of heat energy into the cooling medium and measuring its temperature rise, or (b) measuring the mean velocity head at the outlet section of a properly designed stock. Loss tests were made on five 3600rev. per. min. turbine generators when operated as synchronous condensers. In the case of these machines, the additional losses including the increase in core loss at full kva. and zero per cent powerfactor load varied from 3 to 22 per cent of the total losses. This corresponds to approximately 0.14 to 1.0 per cent of the generator input. The additional losses as measured under sustained shortcircuit conditions were from 5 to 10 per cent less than the corresponding values for full kva. at zero per cent power factor. It is suggested that data can be obtained for predetermining the magnitude of the total additional losses by measuring the loss in each structural part and determining graphically the magnetizing flux which produces it. The magnetizing flux distributions at different parts of the machine were plotted for different ampereturn relations. Additional studies are being made on methods of calculating the magnitude of the additional losses and the inc ease in core loss with load. View full abstract»

11. 2,000,000Volt, hightension, laboratory at Stanford university
The highest voltage yet obtained by man was demonstrated in the new laboratory of Stanford University, California, on Friday, September 17, before an assemblage of eminent men of science including Cummingb C. Chesney, president of the Institue educators, and the press, a ribbon of living flame, more than 20 ft. long, leaped between two points high into the air above six giant transformers, marking the highest voltage yet attained at commercial frequency. — 2,100,000 volts. View full abstract»

12. Abridgment of long telephone lines in Canada
Page(s): 1005  1008This paper describes the development of the long distance telephone service in Canada, historically, from its inception and the installation of the nucleus of 360 mi., up to and through the present status and lines listed in Table I, to the proposed development represented by Table II, the result of a careful study of calls per day to be expected by 1932. This effort is to provide for traffic requirements in a manner most suitable from a transmission point of view, and to accomplish it with a minimum amount of switching. Much of the engineering work for this is already actively under way and certain work of construction actually commenced. A survey of existing routes and the matter of transmission maintenance discussed. View full abstract»

13. Design of nondistorting power amplifiers
Page(s): 490  498The paper deals with the problem of obtaining the maximum output possible from a given amplifier tube, while keeping the distortion down to a negligible amount. A tube can be rated for this purpose in terms of the watts output obtainable, when a sine wave voltage of as great an amplitude as can be advantageously utilized, is applied to the grid. This maximum sine wave output is very much less than the rating of the same tube for oscillator purposes. Starting with a set of static characteristics for a given lube, the dynamic characteristics for any resistance load is readily plotted, and the power output and distortion can be read from the dynamic characteristic. A simple rule has been given by Mr. W. J. Brown for determining the best conditions of load resistance and grid bias for a given plate supply voltage. The best load resistance is shown to be twice the internal plate resistance of the tube. If the supply voltage exceeds a certain value, the application of the rules just mentioned would lead to excessive healing of the anode, and therefore a different procedure is followed, calling for greater grid bias and higher load resistance. There is an advantage in using low impedance tubes. The balanced or pushpull circuit, while reducing distortion, will not make up for failure to operate the tubes under proper conditions, nor will it greatly increase the permissible output per lube. The dynamic characteristic for a reactive load is not readily plotted, but for design purposes it is sufficient to determine the best operating conditions for a resistance load, and then make the impedance of the reactive load high enough to keep the plate current variations within the same limits as for the resistance load. An important application of the principles outlined here, is the design of radio telephone transmitters where serious distortion results from overworking the modulator tubes. For moderately deep modulation there should be from two to four modulating tubes for each o cillator tube. Certain details of design are discussed in the closing paragraphs. View full abstract»

14. Studies of transmission stability
Page(s): 374  383Stability may be defined as the capacity of a power system to remain in equilibrium under steady load conditions, and its ability to regain a state of equilibrium after a disturbance has taken place. The lack of stability first manifested itself in the cases of overloaded machines and high impedance tie lines. The transmission of large blocks of power over long distances has presented the problem in a new form. Attention was directed to this problem in a group of papers before the Institute at the Midwinter Convention of 1924. These papers gave a general discussion of the stability problem and pointed out the necessity of considering the limitations imposed not only by the line alone but by the transformers, rotating machines and load. Extensive and pertinent discussions followed which emphasized the importance of the limitations imposed on power transmission by stability conditions. The papers and discussions at the 1924 Midwinter Convention established a method for the determination of power limits under steady load conditions assuming fixed excitation. The limit so determined is due to the inherent characteristics of machines and does not take into account the possibility of changes in excitation due to the action of voltage regulators. The possibility of exceeding the “inherent stability limits” by the operation of the voltage regulators and exciters was pointed out. This condition of “artificial stability” was not at that time believed to be attainable. It was recognized that under the actual operating conditions on a transmission system instability would occur because of short circuits or other disturbances at a point considerably below the maximum static limit. Subsequently extensive studies of stability conditions were made to determine the feasibility and economics of a number of large transmission projects. These studies emphasized the necessity of determining the maximum permissible load under the most severe operating con itions which obviously arise at the time of system disturbances, such as switching operations or flashovers with the attendant switching. Transmission stability has been the subject of a number of articles in the technical press and of papers before the Institute, the principal ones of which are listed in the bibliography. C. L. Fortescue's paper before the Seattle Convention in September 1925 serves as an introduction to the present paper, presenting in a qualitative manner results of recent investigations whereas this paper presents methods for the quantitative determination of system oscillations. During the early part of 1925 extensive stability tests including switching operations and single phase faults to ground were conducted on the system of the Pacific Gas and Electric Company. These tests will be described in a companion paper by Roy Wilkins. The present paper first deals with the principal elements entering into the stability problem, such as the action of generators and exciters during disturbances, effect of dissymmetry produced by singlephase short circuits, simplification of the load end network and methods for combining these various factors in the determination of the electromechanical oscillations of the system following major disturbances. Results of calculations by these methods are compared with the results of tests on the system of the Pacific Gas and Electric Company. The paper concludes with a discussion of various methods of improving stability. View full abstract»

15. Street lighting began in 1414
Street lighting began in 1414 when a city ordinance in London required every house and store owner on certain streets to hang out at least one hornsided lantern at sunset. Paris, in 1558, led the world in municipal street lighting when it installed tall vases at important street corners in which pitch was burned each night with flickering, sooty results. These various crude outdoor lighting methods strove ineffectually for more than 450 years to achieve what the electric carbon and filament lamps have done in the last 40 years. View full abstract»

16. The rotating magnetic field theory of AC. motors
Page(s): 170  178The predetermination of the performance of a polyphase ac. machine is greatly facilitated by the fact that at constant voltage and frequency its magnetic field is of constant intensity and rotating with uniform velocity. It is easy to form a mental picture of lines of ferce moving in space and being cut by conductors, which may be moving or stationary. Furthermore, the rate of cutting, and therefore the generated voltages, which form the basis for quantitative analysis, are readily determined by the relative motion of the flux and the conductors. Because of the ease with which a physical conception can be formed of a rotating magnetic field, the idea of considering a singlephase alternating field as made up of two oppositely rotating fields has been found very useful. In a paper entitled “A Physical Conception of the Operation of the Singlephase Induction Motor” Transactions A. I. E. E., Vol. XXXVII), Mr. B. G. Lamme has given an excellent description of singlephase induction motor operation based on a conception of two oppositely rotating magnetic fields. From the discussion of Mr. Lamme's paper, it appears to be the concensus of opinion that the method he uses furnishes the simplest and clearest physical conception of the singlephase motor. However, this is not the method usually employed in the quantitative analysis. Reference to text books will show that the mathematical treatment is usually based on the so called “cross field” theory. In this method the secondary induced voltage is considered made up of two components, one the voltage induced by transformer action of the alternating field and the other the voltage generated by rotation of the secondary conductors in the magnetic field. It has been argued against the method based on two oppositely rotating fields, also known as the “Rotating Field” theory, that it is more apt to lead to erroneous results, requires more expert handling and that it is an indir ct method, being based on the previously determined performance of the polyphase motor. However, the main argument against it seems to be its limitation to induction motors only, and that it must be abandoned when we come to motors of the commutator type. Even those who otherwise favor the method appear to agree that it is not applicable to commutator motors as we are then no longer dealing with induction machines, but with shunt or series motors, as the case may be. The objection to the rotating field theory, that it is applicable to induction motors only, would be a serious one if it were valid. However, it will be shown in this paper that the theory can be readily applied to commutator machines also, and that so far from being more apt than other methods to lead to erroneous results, it undoubtedly furnishes the simplest and most direct means for mathematical deductions in the more complicated problems where three or more circuits are inductively related and moving with respect to one another. View full abstract»

17. Equivalent singlephase networks for calculating shortcircuit currents due to grounds on threephase star grounded systems
Page(s): 1014  1020This paper presents a method for calculating the steady state value of the shortcircuit current in a fault to ground on a power system operated with grounded neutral, and the distribution of this current throughout the system. Constant impedances and electromotive forces in the system, and electrically short lines, are assumed, and line capacitance is neglected. If, at the time the fault to ground occurs, the distribution of the load current in the system is known, the total current in any portion of the system under the short circuit condition may be calculated by means of this method. By “total current” is meant here the sum of that part of the fault current which appears in the branch considered, and the normal current in the branch due to the loads. The latter current, of course, does not appear in the fault. Formulas and equivalent circuits for the usual threephase transformer and generator connections used in practise, are given. The use of such circuits permits the calculation of the fault current and its distribution in the power system from an equivalent singlephase network. Since currents in a threephase network under balanced conditions may also be calculated from a singlephase network, it is accordingly possible to calculate, entirely on a singlephase twowire basis, the total current in any branch of a star grounded network for a ground on any phase. The setting up of equivalent 2wire singlephase networks similar to those for the threephase case is not generally possible where the number of phases exceeds three. The value of the method lies in its enabling one to calculate on a singlephase twowire basis the short circuit current (steady state) due to a ground on a threephase grounded neutral system, as regards both magnitude and distribution and taking into account all system loads. In the usual approximate method of making shortcircuit calculations, a singlephasetoneutral network is substituted for the actual network. W ile this method involves less labor than that proposed in the paper, the results obtained by it are inexact, the effect of nongrounded loads being usually ignored. The method of the paper involves much less work than that required by threephase calculations giving equal accuracy. An illustrative example is given. View full abstract»

18. Cipher printing telegraph systems: For secret wire and radio telegraphic communications
Page(s): 109  115This paper describes a printing telegraph cipher system developed during the World War for the use of the Signal Corps, U. S. Army. This system is so designed that the messages are in secret form from the time they leave the sender until they are deciphered automatically at the office of the addressee. If copied while en route, the messages cannot be deciphered by an enemy, even though he has full knowledge of the methods and apparatus used. The operation of the equipment is described, as well as the method of using it for sending messages by wire, mail or radio. The paper also discusses the practical impossibility of preventing the copying of messages, as by wire tapping, and the relative advantages of various codes and ciphers as regards speed, accuracy and the secrecy of their messages. View full abstract»

19. The electric arc and its function in the new welding processes
Page(s): 1404  1410The subject of this paper is a phenomenon of great interest and very great complexity. The electric arc is a tool of extreme power and flexibility. The electric arc can be used to melt the most refractory substances, cut the armor plates of battleships or weld together the ends of wires no thicker than a human hair. It is a wonderful tool that makes or breaks almost anything. It may unite the most indifferent elements such as nitrogen and oxygen, or break the molecule into its constituent atoms. In this paper we shall discuss only one type of application of the electric arc; namely, the application of the arc to the welding of metals, but even in these limits the field is very wide. The electric arc was discovered by H. Davy who in 1810 was experimenting with the sparking between two horizontally disposed carbon pencils. The density of the current was such that on short circuit the tips of the carbon pencils were heated to incandescence. When the electrodes were separated the electric current continued to flow across the airgap between the carbon pencils. The airgap was bridged by some sort of an extremely bright band which under action of the accending currents of hot air was bent upwards and formed a bow or an “arc.” This is the origin of the term, the “electric arc.” For many years the electric arc was used only as a source of light. It was only years later that the electric arc was applied for the purpose of melting and welding metals together. In 1881 de Meritens for the first time used a small carbon arc for melting and welding the lead terminals of storage batteries. The more extensive application of the carbon arc was done by Bernardos. This process was modified by Dr. Zerener of Berlin, Germany, who shortly prior to 1890 invented a process of welding with a flaming arc. In this process two carbon electrodes are disposed to form a “V”. The arc is drawn between the two electrodes and caused to impinge upon th metal to be welded by being forced down by a powerful electromagnet. This arrangement caused the arc to act in a similar manner to the flame of an oxyacetylene flame. The energy developed in this arc is only partly transmitted into the weld and the efficiency of the method is very low. The third type arc welding known now as a metallic arc process was discovered about 1890 by H. Slawianoff. This engineer conceived the idea of producing steel ingots by an electrical casting process. Metal was deposited from a steel rod into a mold, an electric arc being maintained between the rod and the metal of the mold. Means were provided whereby the metal rod could be fed forward as it was consumed and a solenoid arrangement was provided for maintaining the arc length substantially constant. The ingots obtained under such conditions proved to be sound and free from shrinkage pipes. However, the cost of electrical energy in Russia in those days was very high and the process was commercially uneconomical. The information obtained by Slawianoff in this work led to the application by him of the metallic arc to the uniting together of metal plates, the repairing of cracked and broken machines, etc. Thanks to the work of Slawianoff we now possess a method of welding with metallic electrodes which at present is by far the most used of all arc welding processes. View full abstract»

20. Abridgment of arcing grounds and effect of neutral grounding impedance
Page(s): 850  854This paper was written to review and extend the theory of overvoltages due to the arcing grounds because of the increasing tendency to use impedances between the neutral point and the ground, thereby losing the advantage of the solidly grounded neutral. The “thirdclass conductor” theory of Steinmetz is touched upon very briefly and is considered as not applying to transmission line conditions. The theory when the phenomenon is controlled by normal frequency arc extinction, as presented by Peters and Slepian, is reviewed, and the maximum voltage for this analysis is found to be
$3{1over 2}$ E, where E is the normal line to neutral voltage. The theory when the phenomenon is controlled by oscillatory frequency arc extinction as originated by Doctor Petersen is given in detail but in a modified and extended form. The maximum voltage for a singlephase circuit when no damping is considered is found to be 6 E. The analysis for the threephase circuit is newly developed for the case in which there is an impedance between the neutral and ground and the maximum voltage is found to be 7.5 E when the effect of the damping factors and capacitance between lines is neglected. The method of determining the various reductions or damping factors is outlined. The effect of a neutral grounding resistor is discussed and it is pointed out that a surprisingly high value of resistance can be used without incurring the possibility of dangerous overvoltages. It is shown that the use of reactance is more liable to result in overvoltages than resistance but that relatively large values of reactance can be used in conjunction with resistance. The Petersen Coil is usually considered as causing the arc to go out by giving a balance of lagging and leading currents in the arc. It is brought out in this paper that there will be no voltages built up when the Petersen Coil is used, whether or not the arc goes out. The relation of the overvoltages on a nongrounded and an effectively grounded system is outlined, and a criterion for determining whether or not a system is effectively grounded is proposed. View full abstract» 
21. Variable armature leakage reactance in salientpole synchronous machines
Page(s): 665  669The electrical performance characteristics of a polyphase synchronous machine, that is, its voltagecurrent relations under load, depend essentially upon the nature and the extent of the magnetomotive forces of the armature currents. Broadly speaking, the effect of these magnetomotive forces is twofold; i. e., (a) they oppose and distort the field magnetomotive force and (b) they create leakage fields linked with the armature conductors. The first influence is known as the armature reaction, and the second as the armature reactance. More specifically, in a machine with salient poles, the armature reaction may be resolved for purposes of computation into the direct reaction (along the center lines of the poles) and the transverse reaction, midway between the poles. In polyphase machines of usual proportions, the armature leakage reactance, x, usually plays a secondary role, and for most purposes is assumed to be constant and independent of the power factor of the load. The vector of the reactive drop, Ix, is simply drawn in a leading time quadrature with the current I. However, in machines with considerable armature reactance, or where higher accuracy is required, the assumption of a constant x leads to noticeable discrepancies between the computed and observed data. This is of particular importance in problems which involve hunting, instability, etc., and in which the torque (or displacement) angle must be predicted. This angle depends to a considerable degree upon the leakage reactance of the machine. It has been previously proposed by others to use two distinct values of leakage reactance, one when the leakage paths around a group or belt of armature slots are closed through the center of a pole face (maximum reactance), and the other when such slots are midway between the poles (minimum reactance). However, no account has been taken apparently of a gradual change in the reactance between the two extreme positions, nor have the results been properly correlated w th the rest of the factors which enter in the performance of the machine. In the present paper, the leakage inductance is assumed to consist of two parts, one of which is constant (the average inductance), and the other, varying harmonically at a double frequency, reaches a maximum opposite the centers of the poles. A magnetic linkage equation is written, and its derivative with respect to the time angle is taken to obtain the induced voltage. The result shows that the foregoing assumption leads to two reactive drops, one, the usual average Ix drop and another a supplementary drop, leading Ix by an angle 2 ψ, where ψ is the internal phase angle at which the machine is operating. These quantities are introduced in the usual Blondel diagrams for the generator and the motor, and the relationships among the various quantities are established both graphically and analytically. View full abstract»

22. Recent developments in kilovoltampere metering
Page(s): 1176  1178W. H. Pratt: Voltampere and voltamperehour measurements seem to be occasioned almost wholly by the problem of making suitable rates for electrical energy when used at low power factor; that is of making rates that will stimulate the raising of the power factor in such cases. From this viewpoint devices of this kind should be in a measure selfeliminating, for once the power factor fairly approaches unity there is little or no excuse for the added complexity of apparatus above that of the watthour meter. View full abstract»

23. Currentlimiting reactor characteristics
Page(s): 1141To prevent in large generating and distribution systems the possible concentration of enormous amounts of electrical energies at certain critical points, makes the extensive use of the currentlimiting reactor a necessity. View full abstract»

24. The multipleradial system of cooling large turbogenerators
Page(s): 185  193The paper discusses the theoretical basis of a special turbogenerator ventilation system, in which the cooling air divides into several branches, and passes through the stator core radially in and out. An extended series of experiments on a fullsize model, embodying this system, has lately been carried out by the Westinghouse Co. The tests are described in a paper by C. J. Fechheimer under the Title: “Experimental Study of Ventilation of TurboAlternators.” The fundamental questions in regard to the flow of air in any ventilation system are: 1. How high pressure is required to force through a certain volume of air per unit time? 2. How will the air distribute, axially and radially, in the different intake and discharge vents? 3. What will be the “balanced stale” of flow, if several branches of air meet and divide in a tube, the intake and discharge taking place normal to the walls of the tube? These questions are given a thorough analysis, under certain simplifying assumptions, and it is shown that 1. The total pressure required for a certain volume of air per unit time is expressible by means of hyperbolic and trigonometric cotangents of a certain argument, which contains the geometrical dimensions of the aircircuit. 2. The air is distributed according to a simple hyperbolic or trigonometric sinelaw. 3. The “balanced state” depends on the solution of a system of simultaneous transcendental equations. A method of solution is outlined, which is applicable for such cases where the arguments are small. In such cases the transcendental equations reduce to simple algebraic equations. A numerical example is finally worked out in order to show the application of the derived formulas. View full abstract»

25. Abridgment of electric transmission and control of power from internal combustion engines for transportation
Page(s): 649  653With large internal combustion power plants in transportion service the use of electric transmission is almost a necessity. Furthermore, the interposition of the electric transmission provides a method of obtaining what is the equivalent of a wide change in gear ratio, as well as a cushioning of the characteristic power impulses of the internal combustion engine. In adapting the internal combustion engine to this character of service there has been a number of problems, such as fitting the generator to the engine curve, the question of hand or automatic control, field control arrangements, single vs. multiple motor drive, and arrangement and operation of auxiliaries. The use of the combination generatorbattery power plant has recently received considerable attention. This application employs a battery operating in parallel with the engine generator power plant, capable of supplementing the power of the engine for short periods. The characteristics of the engine used in transportation service must be well adapted to the duty required. These characteristics vary somewhat with the size of the unit and the control of the engine throttle is usually adapted to the particular problem in hand. In this paper, the principal problems connected with the operation and design of complete engine generator units are discussed in detail and many typical schemes of connection are diagrammatically shown. No attempt is made to discuss the question of multiple power plant operation, although this would mean simply the addition of the necessary cross connections to operate the two power plants in parallel; unless, as is sometimes the case, the several power plants are operating independent of each other, each engine generator furnishing power to Us own motors. In general, there is given a fairly complete summary of the operation and design of this equipment as now used in American railway practise. View full abstract»

26. The comparison of natural and artificial lighting
In connection with the efforts that are now being made to trace the relation between better lighting and higher efficiency of work, it is natural that experimenters should try to base their conclusions on the results achieved by daylight. View full abstract»

27. Stability characteristics of alternators
Page(s): 813  819During the past few years, stability characteristics of systems using long lines have been discussed at considerable length, but not so much attention has been given to the characteristics of the load. This paper shows that power limits may be reached with very short lines and certain classes of load. The characteristics of several classes of load, such as motors of various kinds with constant shaft output, variable impedance loads (synchronous converters for railways), constant impedance, and miscellaneous combinations, are discussed as they affect the stability of the generator. The criterions for the stability of an alternator as developed by this paper are “shortcircuit ratio,” saturation, power factor of the load, and character of the load. A series of curves and a formula for the minimum allowable value of shortcircuit ratio as a function of saturation and power factor are proposed for general purpose alternators which may be called upon to deliver power to any of the various classes of load. These curves are derived from characteristic curves of typical machines. It is not intended that these curves shall be used for generators which supply power over long transmission lines, as the characteristics of these lines may require considerably higher values of shortcircuit ratio, and the generator must be specially designed to meet the individual requirements. View full abstract»

28. Abridgment of effect of transient voltages on power transformer design
Page(s): 357  361When an ordinary transformer is subject to transient voltage excitation, local concentration of voltage takes place in which the capacitance charging current of the coils to ground is supplied through the winding. This is because the ratio of inductance and capacitance of the various parts throughout the winding is not constant. Calculations and tests of voltage distribution in the winding, caused by the impact of (a) damped highfrequency oscillations, and (b) unidirectional traveling waves, are given. In order to make the analysis clearer, the transformer winding is considered as a network of inductances and capacitances, and this term “network” is used throughout the paper. Certain simplified and typical networks are considered. Transformers having one terminal grounded, such as are used in threephase star connection, particularly in highvoltage systems, are frequently built with the insulation graded to other windings and ground, in the order of the normal frequency voltage stress. The danger of such a practise is shown in power transformers which are subject to transient overvoltage, since voltage oscillation in the winding may raise the voltage to ground at intermediate points above the terminal voltage, unless the design of the winding eliminates oscillation. The theoretical and experimental data given show that the distribution and magnitude of voltage stresses existing during recognized standard insulation tests are essentially different from stresses created by transient voltages. This permits the construction of transformers that would satisfactorily pass standard insulation tests but at the same time would not be suitable for average service. A new type of a transformer called “nonresonating,” for use on grounded neutral systems, is described. In transformers of this type, voltages of all frequencies distribute uniformly along the windings, as the possibility of internal voltage resonance is eliminated by a proper bala ce of distributed capacitance and inductance of the winding. This is accomplished principally by means of conducting surfaces (shields) placed outside of the winding and connected to its line terminal. The action of the shields is similar to that of the shielding ring on an insulator string. It neutralizes the effect of the capacitance current from the inside surface of the winding to ground, by supplying to every point of the winding a “charging” current equal to the “discharging” current of that point to ground. In some cases, the application of the shield reduces the local stresses to oneeightieth. Up to the present time, the total capacity of this new type of transformer exceeds half a million kva. View full abstract»

29. Power plant auxiliaries and their relation to heat balance
Page(s): 118  121In the larger central station steam plaids, efforts to increase the overall economy and ease of operation were responsible for the use of motordriven auxiliaries receiving their power from auxiliary turbogenerators, called house turbines, the exhaust from which is used for heating feed water. This scheme is reliable and economical. It is handicapped by the fact that over a considerable range of load some of the auxiliary power must be taken from the main bus or some of the energy generated must be fed to the main bus. This resulted in transfer motors generators, etc., which were additional complications. Still greater economy is possible by bleeding steam from the lowpressure stages of the main unit to heat the feed water. Considerable heat that would otherwise be rejected with the condensing water is reclaimed, thereby allowing of a smaller condenser than would otherwise be required, the performance of the main turbine also being improved due to somewhat relieving the congestion of steam in the lowpressure stages. To utilize fully the advantages of stage bleeding, the auxiliary power must be obtained from the main turbine. In order to insure an uninterrupted supply of auxiliary power to the essential drives it is suggested that an auxiliary generator be connected to and driven by the main turbine, thereby supplying the necessary reliability as long as the main turbine is available for load. Due to the advantages of variable speed drive for circulating pumps, boiler feed pumps, etc., and the necessity of having direct current for excitation, a directcurrent generator may be used to advantage. The use of the directconnected auxiliary generator with stage heating, gives a maximum of flexibility, is especially reliable in that it entirely eliminates all small turbine and gear troubles, and permits of the use of the unit scheme of grouping and supplying auxiliaries, with what appears to be a maximum of economy at no apparent increase in cost. Furthermore, the use of closed heaters with the fresh water storage located within the coiidenser hoi well seems to offer an economical and highly satisfactory solution for the deaeration of the feed water and to eliminate the possibility of the water picking up further air after leaving the condenser. View full abstract»

30. The vacuum tube rectifier: Oscillographic and vacuum tube voltmeter study of its application to Bvoltage supply for radio receivers
Page(s): 17  24This paper covers investigations made in undertaking the design of a rectifier for use as the B power supply for radio receivers. It determines the most satisfactory type of filter circuit and the appropriate values of inductance and capacitance to give a dc. output delivered with the least practicable voltage drop and having no fluctuations of sufficient magnitude to interfere with the proper operation of the set. A vacuumtube peak voltmeter used to detect very small fluctuations is described. View full abstract»

31. Abridgment of magnetic leakage and fringing flux calculations
Page(s): 340  344The object of this paper is the development of an empirical method of determining leakage and fringing fluxes in an electromagnetic system. Certain assumptions are made; namely, (a) the reluctance of the iron parts of the magnetic circuit are negligible as compared with that of the airgaps; (b) the leakage and fringing components of the flux follow paths of convenient geometric shape. Formulas are derived for leakage and fringing fluxes as percentage of the main flux which crosses the gap from the pole face, for two cases, (1) a pole core of circular section and (2) one of rectangular section. Calculations of these fluxes, in percentage of the main flux, are given over a convenient range of gap lengths, coil lengths and distance of coil from pole face. It is seen that both leakage and fringing depend to a considerable extent on all these factors. Calculations are made to determine the flux density at various points along the core length and these show a wide variation in density in accordance with the dimensions of the magnetic circuit. An experimental check was made of certain of the calculated results, and the agreement obtained was as close as could be expected, the derivation being within the limits of error of observation. The paper is not a complete discussion of the subject but it is hoped to develop it still further in a subsequent paper. View full abstract»

32. Historical review of electrical applications on shipboard
Page(s): 249  263During the year 1919, the Chairman of the Marine Committee of the Institute appointed a subcommittee with a view to compiling and recording data relative to the development and growth of electricity on shipboard. The instructions to the subcommittee included the preparation of a report, or historical review, which was to form the basis for a continuing record of such matters in the files of the Institute. After a careful investigation of the situation, the historical subcommittee found itself confronted with a task of no small proportions and one which would require, with the limited time available for such research work, probably several years to complete. An outline was prepared, however, of the ground which it was intended to cover and a preliminary report, submitted with the Marine Committee's report at the annual convention at White Sulphur Springs in 1920 and appears in the Institute's Transactions for that year. Continuing with the work for several years, the Historical Committee in April, 1923, submitted its report to the Marine Committee of the work and investigations which had been then made to date. This report of April 27, 1923 with its “Foreward” is given complete as rendered with such minor changes and corrections as shown by further investigations to be necessary. To this original report a brief section on “Electric Ship Propulsion” has been recently added. To complete this report to date, the sections on “Electrical Auxiliaries” and the appended list of references, are still to be added, although considerable work has already been done in connection therewith. Although it is regretted that the report is not complete in all details, the Marine Committee has felt that owing to the rapidly increasing interest in shipboard electrical installations that the time is opportune for the presentation of this information as at present compiled and with a view to completing the report at as early a date as prac ical. While we appreciate that this paper owing to its volume, will be read in the abstract only by those casually interested, to those who are interested in the subject, we trust the information will prove of considerable value. As information of this character has its greatest value as a historical record, we trust the Institute may be able to take steps to preserve the same in a substantial and conveniently accessible form in its files. View full abstract»

33. Mechanical forces between electric currents and saturated magnetic fields
Page(s): 897  903The general case considered is that of N independent electric circuits placed in a medium of variable permeability and subject to saturation, in parts or as a whole The problem is to determine the component (in a given direction) of the mechanical force acting upon one of the electric circuits, upon a group of circuits, or upon a group of circuits with part of the magnetic medium rigidly attached to them. It is believed that the problem has not been solved in this general form heretofore. Use is made of the expression for the stored electromagnetic energy, W, of the system, assuming all the electric circuits to be originally open and then closed one by one. Such a treatment necessitates a number of partial saturation curves, giving the linkages with each individual electric circuit when some of the remaining circuits are closed and the rest are open. A virtual displacement, δ s, is then given to the part of the system under consideration, keeping either the linkages or the currents constant, and the mechanical force, F, is determined from a comparison of the work done, F. δ s, with the change in the stored energy, δ W. It is shown that the familiar reciprocal relationship for the mutual inductance, M
12 = M21 , which holds true in a medium without saturation, can be generalized to a more involved integral expression for a saturated medium. In order to connect the general treatment with the simpler cases previously solved in the literature of the subject, some intermediate cases of one and two circuits are considered, especially those of importance in applications. The substance of the general method used was presented before the American Physical Society, at the Philadelphia Meeting, in December, 1926. View full abstract» 
34. Illumination items: Artificial lighting in foundries
It is doubtful whether in this country more than one foundry out of six obtains all the benefit that it should from artificial light. The efficiency with which many foundry operations are carried on depends to a large degree upon the workers ability to see accurately and rapidly and in semidarkness it is impossible for him to do either. Production and quality suffer from the effects of poor lighting and the accident risk is increased when vision is rendered difficult and uncertain. View full abstract»

35. Oilfilled terminals for high voltage cables
Page(s): 593  600Underground cables for transmission of power at 33,000 ft. and above have only recently come into use in America, or received much attention here. In connection with such cables suitable terminals are necessary and present an important problem in high voltage design. A marked tendency is noted toward the oilfilling of cable joints; terminal conditions make this procedure both logical and desirable. Dielectric strength must first be specified, and should exceed that of the cable; flashover should occur without puncture; lightning voltages should be guarded against in the design. Proper dc. tests are still undetermined for various combinations of solid and liquid dielectrics, and a rigid practise can not yet be established with assurance. At present, high voltage cable lines are intended for ac. operation, and safely factors should be determined for that kind of service. High voltage dc. operation may come into practise later, and research in dc. testing should be pushed. Standard ratings of terminals are proposed, corresponding to the accepted standard ratings for other high voltage apparatus. Consistency with other terminal insulation, such as apparatus bushings and line insulators, is desirable. Cable insulation may eventually experience similar standardization. The method of rating singleconductor and threeconductor cables should be harmonized, and both based on operatingline voltage. Four typical designs of high voltage cable terminals are described representing a carefully worked out and effective solution of the problem. These are (a) 37,000volt threeconductor; (b) 50,000volt singleconductor; (c) 73,000volt, singleconductor; and (d) 110,000volt singleconductor. Flashover tests and time tests, corresponding to breakdown and endurance tests on equivalent cables, are reported to illustrate the ability of the terminals to withstand factory and field tests on the cables, and to show the ample factors of safety under operating conditions. Results of  n experimental installation of the 110,000volt terminals demonstrate the safety of the design, predicted from calculations and confirmed by laboratory tests. For temporary testing purposes these oilfilled terminals are most convenient and economical, and contribute to the uniformity and reliability of the results in cable testing, which are the factors of greatest importance. View full abstract»

36. AC. elevator motor drive
Page(s): 321  327There are very few data available on the problems of using alternating current when applied directly to a motor on an elevator. It is apparent, also, that eventually there will be no dc. power transmitted for elevator service. Because of these facts and the size of this industry it seems that such data should be available. A paper covering the entire field in detail would be excessively long and it is therefore the aim of this paper to cover the subject in a general way, giving such outstanding facts as are felt to be of most interest at this time. It is hoped also to correct a false impression that is sometimes found to exist — that an ac. elevator is not practical for car speeds above 350 ft. per min. Without question, this understanding was correct six or seven years ago but it is desired to call attention to the fact that for the past five years many ac. elevators have been installed with car speeds in excess of 500 ft. per min. and today some are operating as high as 700 ft. per min., and nothing has appeared to indicate that there is a limit of car speed other than for any other type of control. A brief outline of the necessary requirements of the elevator machine is given because as yet the development of ac. elevators has depended upon the success of this unit. The desirable characteristics of the motor are given somewhat in detail, the important ones being positive speed control, elimination of exposed and sliding contacts, speed ratios of at least 6:1, a rotor of low kinetic energy, quiet under operation, allowing torque characteristic changes, smooth control of speed changes, liberal temperature range, high power factor, a maximum torque capacity and maximum practical starting torque per ampere. The desirable characteristics of the controller which permit high speed elevator operation with economical and reliable service and a minimum number of shutdowns, may be outlined as follows: Full magnetically operated but with a minimum number and ty es of magnets, types of magnets that guarantee against magnetic hum or chatter requiring no oil immersion and giving a constant pull. The controller parts in general should be as interchangeable as practical, with oilless bearings and a minimum of auxiliary parts and contacts. As a whole, the controller and its wiring must be simple and easily understood. The principles of control allowing the highspeed elevator operation are rapid but smooth acceleration and retardation, a forced slowing down of the elevator by the motor irrespective of the operator and allowing the simultaneous or overlapping braking action of the slowing down and stopping means. The brake magnet must be one guaranteeing against magnetic hum or chatter, giving a constant pull, and must be positive and rapid but not violent in action. The curves which were taken by power companies serve to show the high power factor and a minimum of line disturbance. View full abstract»

37. Traffic control
Page(s): 317  318The new Code for Standardization of Street Traffic Signs, Signals and Markings built up by a Sectional Committee wherein the American Institute of Electrical Engineers was represented has now been completed. It has been accepted by the American Engineering Council which participated during the past several years in the national conferences on street and highway safety inaugurated by Herbert Hoover when Secretary of Commerce. He cystallized consideration of the subject in a national conference on street and highway safety, in an effort to minimize the possibility of accidents and reduce the numerous loss of life and injuries resulting from accidents on the public streets and highways throughout the country. Surveys were made in 35 states and returns analyzed were collected in more than 100 cities and it is believed that the returns covering all conditions and methods of traffic control and regulation will show that this survey has been of great benefit. The final report of the Committee is now in circulation throughout the country by the American Engineering Council and efforts are being made to have the Standard Code inaugurated into laws in every state in the Union to standardize devices of every description for the regulation of traffic and safety on the public highways. View full abstract»

38. Abridgment of ventilation of revolving field salientpole alternators
Page(s): 263  267The studies were made experimentally and analytically. In the experimental study, a model of hard wood with a multiple of vent ducts of normal width of 3/8 in. each in the stator, the slots and teeth being of approximately average width was used. A fourpole rotor is distinct from one of a large number of poles; consequently two rotors were built, one of four poles and one of twelve poles, the latter being considered as representative of the greater number. The endbells and the imitations of the end windings were different for the two numbers of poles. In the test results given, data for only standard fiber wedges are included, but other forms were investigated. The vent fingers extended the full depth of the core, thereby enabling measurement to be made of the volume of air per vent per tooth, a rotating vane anemometer with a suitable funnel attachment being employed. The endbells were solid, simulating standard construction, and the entrances to the two bells were joined to a common duct, in series with which was a thermal volume meter and an external blower of readily adjustable speed. (See Fig. 6.) Pressures were measured in the inner and in the outer endbells. The rotor of the model was driven by a dc. motor. with the power input measured. By this means, windage data were obtained and many of the results are included among other data on the curve sheets. For taking a characteristic pressure volume curve, the first reading was taken with the rotor running at a suitable arbitrary speed, with the external blower stationary and its entrance closed. The pressure was then generated by the poles acting as fans, and by the internal fans. For a number of succeeding readings, cardboard orifices with various size holes were placed over the external blower entrance, until that entrance was wide open. Subsequently, the external blower was started, and readings were taken with it running at a number of speeds. The form of curves thus obtained is shown in Fig. 9, the me ning of the three curves being there indicated. One of the limitations imposed by ventilation tests as usually made on an alternator is that only one point on the inner endbell pressure — volume curve is obtained — nearly that at D in Fig. 9. The data thereby obtained do not enable the designer to estimate the volumes when conditions out of the ordinary are introduced; these would include, for example, the resistance of external ducts of a cooler, or of the influence of greater or less axial length, or of the effect of change in fan proportions, etc. The effects of these and the influence of the structural changes are treated in the paper. At one or more volumes on the pressurevolume curve, volume distribution curves were taken, and from data thereby obtained the influence of axial length was allowed for in the equations derived. In interpreting the results, it is important to eliminate some independent variables. Thus angular velocity may be eliminated, as the pressure is proportional to the square and the volume to the first power of the speed, the shape of volume distribution curve remaining the same. Ample experimental verification was obtained. Machine dimensions were more uncertain, and after many tests, it appears that for a given value of endbell pressure and angular velocity, the volume distribution for the shorter machine is substantially the same as for the longer machine with the ends removed. As those tests were many, the number of vents, (or length of machine) is considered in the following list of the 11 structural independent variables: (1) Number of poles; (2) fans; (3) number of vents; (4) wedges in stator; (5) interpolar spaces; (6) fan seals; (7) fan shroud rings; (8) field coil braces; (9) plates in endbells; (10) round and square pole corners; (11) location of fans, data for Nos. 4, 8, and 11 are not given in this paper, and not all for No. 2. There were several unusual results obtained, such as breaks in some of the pressu View full abstract»

39. Synchronous machines — III: Torqueangle characteristics under transient conditions
Page(s): 1339This is the third part of a series of papers on the subject of synchronous machines. The first two were I. An Extension of Blondel's TwoReaction Theory, II. Steady State PowerAngle Characteristics. The present paper deals with the powerangle, or torqueangle, characteristics under transient conditions, namely, A. Cyclic variation of impressed torque, B. Sudden angular displacement, C. Synchronizing out of phase. View full abstract»

40. Abridgment of critique of ground wire theory
Page(s): 780  784The complete paper consists of three parts; I — Induced Potentials, II — Direct Hits, and III — Other Effects. The work of previous investigators is briefly reviewed, and the limitations of their premises pointed out. Under Part I, a generalized theory of ideal ground wires is offered, taking into account the law of cloud discharge, the distribution of bound charge, and the formation of traveling waves. It is found that the protective ratio is independent of these factors. A more extensive theory taking the additional factors of successive reflections and tower resistance into account is then developed. Part II discusses the probability of a line's being hit, and applies a method for computing the effect of successive reflections to the calculation of potentials on the line and ground wires. Curves of these potentials at successive towers and as functions of tower resistances and of time, are given. Part III discusses the effect of ground wires on attenuation, telephone interference, zerophase sequence reactance, corona, and the reduction in surge impedance due to the introduction of extra ground wires. There are three mathematical appendixes. In Appendix I, Maxwell's electrostatic and electromagnetic coefficients are reviewed and the theory of traveling waves on any number of parallel wires, including the behavior of these waves at rather general transition points developed. While this extension to the theory of traveling waves was developed incidental to the study of ground wire theory, it is believed to be of considerable interest and value on its own account. Appendixes II and III are the mathematical analyses corresponding to Parts I and II, respectively. View full abstract»

41. Abridgment of the general circle diagram of electrical machinery
Page(s): 16  18The wellknown circle diagram of a transmission network is applied to electrical machinery, giving circle diagrams of alternators, synchronous motors, synchronous condensers, and transformers. These diagrams give a graphical representation of the machine performance under all possible conditions. Such quantities as power loss, lower input, power output, field current., etc., for any operating condition, can be obtained by inspection. These diagrams have the same field of usefulness as the circle diagram of the inductionmotor. The transmission network circle diagram can be applied to the induction motor, yielding in the approximate representation the Heyland diagram, which is merely a special case of the more general diagram. The transmission network method of attack gives a straightforward solution to many induction motor problems that would otherwise be difficult to handle; such as a motor equipped with a phase advancer. View full abstract»

42. The limitations of output of a power system involving long transmission lines
Page(s): 219  229The conditions of stability of a system are discussed and it is pointed out that while the various transmission line diagrams as used at present implicitly assume the terminal voltage at the two ends to be constant the degree of voltage regulation as determined by load conditions is an important factor in the determination of the limit of output. A type of combined diagram is proposed whereby this factor and other characteristics of the load may be included. The effect of the inherent regulation of synchronous condensers is taken up particularly with respect to compound transmission lines. A numerical example of a 300mile line is considered and various characteristic curves are drawn. The relation between the maximum output and the capacity of condensers installed at the midpoint shows the benefit obtained by increasing the condenser capacity — within certain economic limits. Mathematical analyses are presented to cover a number of different conditions. View full abstract»

43. Corona loss tests on the 202mile 60cycle 220kv. PitVaca transmission line of the Pacific gas and electric company
Page(s): 1109  1116A description is given of the physical and electrical characteristics of the PitVaca 220kv. transmission likely to affect corona loss. The line contains three distinct configurations and two sizes of conductor. Corona loss measurements were made from Pit Power House on the three configurations and from Vaca Substation on one of the configurations. Three methods of measuring corona losses were used at Pit and four at Vaca. The measured corona losses were found to follow exponential laws in three distinct phases; below visual corona, visual corona and visual corona with losses sufficiently high to produce voltage distortion. At no point did the losses follow a quadratic law. A review of the reports of the results of corona loss tests on other lines indicates that the corona losses followed exponential laws. View full abstract»

44. The use of the dynamometer wattmeter for measuring the dielectric power loss and power factor of the insulation of hightension leadcovered cables
Page(s): 746  754The use of the dynamometer wattmeter for measuring the dielectric power loss and power factor of cable and capacitor insulation is not new, but dates from about 1890. Dynamometer wattmeters as available today are suitable for making these measurements. Care and attention must be given to their application. The usual methods of application are: 1. Compensated dynamometer wattmeter method, with air capacitor, 2. Inductance variation method (phasedefect compensation method), with air capacitor, 3. Series resistor and wattmeter method, 4. Resonance wattmeter method. Comparative measurements of dielectric power loss and power factor of cable samples indicate that results are being obtained with the dynamometer wattmeter wherein the probable departure from the true value is within from 10 to 20 per cent. There is need for an effective means of standardizing any measuring equipment. Study of the calorimeter method for this purpose seems desirable. View full abstract»

45. Standards: Railway control standards revision proposed
A revision of A. I. E. E. Standard No. 16, Railway Control and Mine Locomotive Control Apparatus, has been approved by the Standards Committee and is shortly to be issued in report form in order to permit industry to familiarize itself with the suggested changes, the present Standard No. 16 to remain in force until revisions are finally accepted. Incidentally, Standard No. 16 has been split into two parts as follows: Railway Control Apparatus, and Mine Locomotive Control Apparatus. A Sectional Committee, under the joint sponsorship of the American Mining Congress, National Electrical Manufacturers Association, and A. I. E. E., is to be formed to develop an American Standard for the Mine Locomotive Control Apparatus. View full abstract»

46. Eddy current losses in twisted conductors
Page(s): 1062  1064The losses due to unequal distribution of alternating current in copper conductors in halfopen slots have been treated by numerous authors. The method given here does not disclose any new results but it shows an elementary way by which to arrive at an understanding of these not always simple phenomena. View full abstract»

47. Abridgment of the reactances of synchronous machines
Page(s): 345  348Until somewhat recently, synchronous machine theory has been satisfied with a relatively few characteristic constants, or reactances, in terms of which the behavior of machines has been calculated. Present theory, however, requires many more coefficients. There are now generally recognized two values each of leakage, synchronous, and transient reactance, which correspond to the two symmetrical axes of magnetization of the armature current and which refer to balanced operation. Negative and zero phasesequence reactances are also employed to determine operation under unbalanced conditions, and it is possible and desirable to distinguish other reactances. In view of the increasing complexity of the subject it is felt that a critical survey of it is in order and the object of the paper has been to provide that survey. The paper has been divided into two parts. Part I describes and treats of the subject with regard to those factors which are important to application or operating engineers, and to designers. In particular, the major types of reactances which include the synchronous, transient, and phasesequence reactances, are discussed. These quantities are defined and their methods of test outlined. It appears necessary to consider a second type of transient reactance; namely subtransient reactance. Both reactances may be determined from shortcircuit oscillograms as illustrated in the paper. A table is included which gives the numerical range of reactances for the various types of synchronous machines. Part II discusses the theoretical considerations, with a view to broadening and classifying existing conceptions of reactance. It includes the effect of external reactance on negative phasesequence reactance and the variation in this latter quantity, depending upon whether current or voltage is impressed on the machine. An important aspect of the division of synchronous reactance into armature reaction and leakage reactance is discussed. Transient reactance is shown to be the difference between synchronous reactance and the ratio of the mutual reactance between armature and field and the total field reactance. Calculations are included to show that the shortcircuit and opencircuit time constants are related to each other in a simple manner. The appendixes cover the following subjects: a. Application of the Principle of Superposition to Synchronous Machine Analysis. b. Replacing the Effect of Induced Field Currents by Employing Transient Instead of Synchronous Reactances. c. Significant Rotor Circuits in Addition to the Main Field Winding (which effect transient reactances). d. The Negative PhaseSequence Reactance of a Synchronous Machine with Negative PhaseSequence Voltage Impressed. e. Construction of Equivalent Circuits: Concept of Field Leakage Reactance. f. Calculation of Total Field Reactance. g. Relation of the Mutual Reactance Between Armature and Field to the NoLoad Excitation Current. h. Relation Between ThreePhase and SinglePhase Reactances. i. Discussion of the System of Notation Used in the Paper. j. PerUnit Representation of Quantities. View full abstract»

48. Papers on currentlimiting reactors
Page(s): 270  276N. L. Pollard: There are only a few points which I wish to emphasize. One is the question of thermal capacity which has been causing the committee considerable worry during the last two years. View full abstract»

49. Electrical machinery: Annual report of the committee on electrical machinery
To the Board of Directors: This committee has carried on its work during the past year according to the general plan of organization which has been in force for the past three years. The membership of the committee has been materially increased over the number of last year in an endeavor to be prepared to handle the increasing amount of work naturally resulting from the rapid growth in quantity, size, variety and quality of electrical machinery. Experience has shown that the work of a committee can be effectively carried on only when the members are able to get together and carry on a discussion across a table, following, perhaps, a preliminary exchange of views by letter. For this reason, the membership of the committee has been restricted to those living within a day's journey of New York or in the territory east of the Mississippi River. This territory embraces practically all of the manufacturers of electrical machinery, a large number of universities and large users of machinery for power generation and distribution. It is not intended, however, to exclude any members who are in a position to, or willing to, assist in any way whatsoever. In this connection, your attention is directed to the general call for volunteers which appeared on page 1 of the Journal of January, 1927, over the name of the chairman of this committee. View full abstract»

50. Recent improvements in large induction motors
Page(s): 1167  1175Like that of many other rotating electrical machines, the development of the large induction motor has been a steady and an interesting progression. From the first induction motor to the present product has been a long step, marked by the analytical ability of many capable engineers, and accompanied by continual improvements in construction, some of which are reviewed in this paper. To describe the advancement in this type of motor to its present state, it has been necessary to follow some trends in development from their beginning; thus not all of the improvements mentioned in this paper can be called recent, as time in the rapidly advancing electrical industry is measured. The paper, taking up briefly the subjects of ventilation, insulation, coil design and bracing, collectors, bearings, and manufacturing improvements, should be of interest to the many users of the large induction motor. View full abstract»
Aims & Scope
The Journal of the American Institute of Electrical Engineers (AIEE) contains articles published between 1924 and 1930. Contents are devoted to the advancement of theory and practice of electrical engineering and the allied arts and sciences.
This Journal ceased publication in 1930. The current retitled publication is IEEE Spectrum.
Further Links
Aims & Scope
The Journal of the American Institute of Electrical Engineers (AIEE) contains articles published between 1924 and 1930. Contents are devoted to the advancement of theory and practice of electrical engineering and the allied arts and sciences.
Persistent Link: http://ieeexplore.ieee.org/servlet/opac?punumber=6528086 More »
Frequency: 12
ISSN: 00959804
Subjects
 Communication, Networking & Broadcasting
 Components, Circuits, Devices & Systems
 Engineered Materials, Dielectrics & Plasmas
 Engineering Profession
 Fields, Waves & Electromagnetics
 General Topics for Engineers (Math, Science & Engineering)
 Power, Energy, & Industry Applications
 Signal Processing & Analysis
 Transportation
About this Journal
Editorial Board
Content Announcements
Author Resources
Previous Titles
 ( 1931  1963 ) Electrical Engineering
 ( 1924  1930 ) A.I.E.E., Journal of the
 ( 1920  1923 ) American Institute of Electrical Engineers, Journal of the
 ( 1905  1919 ) American Institute of Electrical Engineers, Proceedings of the