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American Institute of Electrical Engineers, Part II: Applications and Industry, Transactions of the

Issue 6 • Date Jan. 1959

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Displaying Results 1 - 25 of 38
  • Temperature of conducting ribbon magnet coils

    Page(s): 465 - 468
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    THIS PAPER applies the theory of heat flow to finding the steady-state temperature in excess of the surrounding iron. The ribbon coils may be either copper or aluminum, and may be either two or four in number. The magnets considered are large magnets of circular cylindrical shape such as lifting magnets. View full abstract»

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  • Equivalent circuits for 3-phase 4-wire induction motors operating on nonsymmetrical systems

    Page(s): 468 - 476
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    CALCULATION METHODS for predicting the performance of 3-phase 4-wire induction motors operating on nonsymmetrical systems are not generally known. Equivalent circuits and calculation procedures for polyphase motors with floating neutral have been available for some time. View full abstract»

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  • Graphical analysis and synthesis of feedback control systems I ¿ Theory and analysis

    Page(s): 476 - 487
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    IN THE DESIGN of high-performance feedback control systems it is necessary to consider simultaneously both the frequency and the transient response. Several methods have been developed to this end.1,2 The method proposed in this paper also operates in terms of both frequency and time domains, but it still permits the entire process to be effected in the real domain, thus greatly simplifying the practical application. View full abstract»

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  • Graphical analysis and synthesis of feedback control systems II ¿ Synthesis

    Page(s): 487 - 496
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    WITH THE USE OF the method presented in Part I,1 it is possible to develop several suitable procedures for the analysis and synthesis of feedback control systems. The purpose of all these procedures is to reduce the characteristic equation to a form where the unknown parameters would take part only in the co-ordinates of the working point M(a1, a0). It is thereby achieved that changes in the values of parameters affect only the position of the working point and not the shape of the curve ¿¿. As a consequence, it is possible to estimate almost instantaneously all roots of the characteristic equation for any set of values of the unknown parameters and to select the latter without difficulty. View full abstract»

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  • Graphical analysis and synthesis of feedback control systems III ¿ Sampled-data feedback control systems

    Page(s): 497 - 503
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    EXCEPT FOR some special methods, two main approaches are possible in the analysis of sampled-data feedback control systems: 1. Analysis in p plane, p being the complex variable of Laplace transformation;1 and 2. Analysis in z-plane, z being the complex variable of Z-transformation.2 View full abstract»

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  • Analog computer simulation of an aircraft parallel A-C generating system

    Page(s): 503 - 509
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    THE OBJECT of this paper is to present a formulation of the dynamics of complex aircraft electromechanical systems using analytical representations of components suitable for analog computation. The ability of the computer to predict system performance as well as to provide a means for system analysis and synthesis is demonstrated by correlating the results of equipment tests and computer simulation tests in the case of the parallel a-c electrical generating system used in the B-47 type of aircraft. This comparison is made to insure that all relevant information has been included in the simulation and that the simplifying assumptions adopted in the analysis are reasonably warranted. The approach used to set up the representations is detailed and generalized, with emphasis on the development of an organized procedure for studying complex aircraft electric systems rather than on providing the simplest system representation which may be valid for just one particular case. A system representation using a cascaded sequence of linear gains and time constants with associated feedbacks can give but a crude indication of actual system performance. Similarly, a representation of the dynamics of parallel alternators in terms of equivalent masses and springs, or one using the ordinary stability criteria developed for central station practice, is inadequate. View full abstract»

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  • Tramp-iron remover for a field forage harvester

    Page(s): 509 - 511
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    AN electronic tramp-iron remover for chopped hay in pneumatic conveyors has been previously described for application in fixed installations such as barns or feed-mills.1,2 When green chopped hay is fed, however, a field harvester is the only machine that handles the hay pneumatically. The tramp-iron remover can be adapted for use on a field harvester to make a self-contained unit that is in some ways simpler than the one described earlier for fixed locations. View full abstract»

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  • Artificial cooling of livestock in hot climates

    Page(s): 512 - 517
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    THE possibilities of artificially increasing the comfort, or, more correctly, the efficiency of use of feed by farm livestock, are great. The range of optimum temperatures for laying hens is 55 to 65 F (degrees Fahrenheit), for dairy cows 50 to 60 F, and for swine 65 to 75 F. Size and age of animal, sex, coat, etc., are all related to its ability to resist high or low temperatures. Adverse effects are apparent sooner from high than from low temperatures; in general, livestock are considered to be depressed by temperatures over 75 F. View full abstract»

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  • A phase-plane approach to relay sampled-data feedback systems

    Page(s): 517 - 524
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    The phase plane is used to solve second-order sampled-data feedback systems which contain a relay and zero order hold circuit. The relay quantizes the signal applied to the linear part of the system and each quantization level gives rise to a corresponding set of trajectories in the phase plane. Between sampling instants the output moves along one of these trajectories; however, the error signal which is applied to the relay depends only on the output and input at the end of the sampling interval, i.e., at the sampling instants. The output at the sampling instants is determined in the phase plane with the aid of two difference equations which are obtained from the time solution of the linear part of the system. This method of solution is not restricted to the study of such systems for step function inputs but may be used equally well to study the effects of sine wave inputs on the system as is illustrated in the examples of the paper. View full abstract»

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  • Residential heating: Electric versus gas or oil

    Page(s): 524 - 529
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    A QUERY more and more frequently made these days seeks advice on the use of electric energy as compared to the older conventional fuels for the heating of a new home. The dealer in each type of fuel will ardently argue for his product and often supply convincing evidence. While there is a great deal of information available on each type as used in different houses, a meaningful comparison is difficult if not impossible because of the great number of variables involved. View full abstract»

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  • Effect of driving source impedance on motor performance

    Page(s): 529 - 531
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    TO DATE, little attention has been focused on the resulting over-all system performance due to the effect of driving-source impedance on servomotor characteristics. The torque ¿ speed characteristics of a motor, as furnished by the manufacturer, may be correctly used for calculating the motor transfer function only when the identical test conditions relating to the driving source impedance to both phases are satisfied. View full abstract»

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  • Motor-operated switch for space heating control

    Page(s): 532 - 534
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    Resistance load (electric heaters, incandescent lights, etc.) can be switched most satisfactorily by a relatively slow moving motor-operated type of switch. Noise, contact wear, and general maintenance are all less than with the ordinary type of magnetic contactor, which is designed for switching inductive loads. View full abstract»

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  • Complex-zero signal generator for rapid system testing

    Page(s): 534 - 539
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    The expanding use of pole-zero techniques in designing feedback control systems has made paramount a simple method for determining characteristic pole-zero locations of existing systems and components. As a step in this direction, a method is presented for determining characteristic pole locations of a system. Use is made of a signal from a ¿zero generator.¿ This signal is fed into the system to cancel existing poles. A null method is used to determine when the pole is cancelled. The position of the zero given by the calibration of the zero generator then determines the location of the pole. View full abstract»

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  • Earth source heat pumps: Characteristics, design, and operation

    Page(s): 540 - 551
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    TWENTY YEARS AGO the programs of many engineering meetings included papers on air conditioning. Air conditioning was ¿billed¿ as the business which would pull the country out of the depression. Today the heat pump appears with almost equal frequency in the discussions of technical societies. The claims made for it are more realistic than were those for air conditioning. View full abstract»

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  • Determining actual power output and derating factor of electric motors that drive oil well pumping units

    Page(s): 551 - 559
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    ELECTRIC MOTORS that drive oil well pumping units cannot deliver an average horsepower output equal to name-plate rating without the effective or rms current exceeding rated current. Expressed another way, motors that drive pumping units must be derated if they are to operate without being thermally overloaded. A method is presented for determining the per cent of rated power output that electric motors can deliver when driving oil well pumping units. This requires a determination of average power output under actual operating conditions. A procedure for determining the average power output is developed that only requires measurements which can be made in the field by engineers and field testers. View full abstract»

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  • Field testing of D-C air circuit breakers on a high-capacity system

    Page(s): 559 - 563
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    AN unusual opportunity for testing d-c air circuit breakers on a high-capacity system has been made possible with use of the mercury-arc rectifier system at Alcoa's Rockdale Works. The system had a preliminary short-circuit current calculation of 880,000 amperes but the actual available current was determined at the test point, located mid-way on the d-c bus, to be slightly over 400,000 amperes. The maximum available current was obtained by connecting in parallel four potline busses without a short-circuit current-limiting test resistor. Under this extreme condition, a peak current of 220,000 amperes flowed through the breakers. These current values are greater than the interrupting rating listed in the standards for semi-high-speed d-c breakers normally used for high-capacity d-c application. However, sufficient current-limiting action of the interrupter was obtained and the clearing time was short enough to maintain a continuous power flow to the aluminum potline. Being the first known tests presented since the new rating structure was adopted, the results indicate that the standard1 is a conservative rating when used as the guide. View full abstract»

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  • Freight car tractive resistance measurements by Doppler radar

    Page(s): 563 - 566
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    MODERN classification yards permit an incoming freight train to be redistributed to tracks assigned to various destinations, with all measurements, computations, and speed control performed automatically. In such yards cars are uncoupled at the crest of a hill and then accelerate freely down a slope which is usually about 3%. This increase in speed separates the cars so that track switches may be safely thrown between cars. Some 250 feet down the hill is the master retarder, a pneumatic or electric brake, which squeezes the wheels of each car between brake beams and reduces the car speed in a controlled manner to a value which can be handled by subsequent retarders. Below the master retarder the tracks fan out to a number of group retarders; here the exit speed must be computed which will allow each car just sufficient energy to traverse the subsequent curve and travel the free roll distance down straight classification track to a gentle coupling with cars already there. A radar-controlled servo loop is closed around each retarder so that the desired exit speed is accurately attained. View full abstract»

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  • A novel generating system for railroad cabooses

    Page(s): 566 - 570
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    FOR MANY YEARS only an insignificant fraction of the cabooses operating on America's railroads have utilized any form of electric power. Most cabooses have been heated by oil stoves and illuminated by kerosene lanterns. Signaling and communications have been carried out by means of written notes or hand signals. View full abstract»

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  • Characteristics of an electric resistance furnace load

    Page(s): 570 - 572
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    IN 1899 Dr. E. G. Acheson discovered that if he overheated silicon carbide, the silicon was volatilized out and pure carbon or graphite remained. Later tests showed that graphite could be manufactured by heating petroleum coke to a high temperature [2,600 C (degrees centigrade)]. View full abstract»

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  • Differential analyzer aids design of electrical utility automatic dispatching system

    Page(s): 572 - 579
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    THIS PAPER encompasses two important aspects of the 1957 symposium theme of ¿Computers in Control.¿ First, the General Electric Automatic Dispatching System1¿3 to be described includes analog computing loops which insure that the turbine generators within the utility system are loaded according to incremental cost theories, thus resulting in minimum fuel expenditures for the utility system. Second, the application of a differential analyzer as a tool in the design of this automatic dispatching system will be described. The differential analyzer application may be outlined as follows: 1. Complete differential analyzer simulation of power system and dispatching system to determine optimum design of regulating and economic loops. 2. Differential analyzer simulation of power system tied together with prototype control components to study and evaluate the design of prototype equipment. View full abstract»

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  • Motor field control of large D-C reversing mill motors

    Page(s): 579 - 585
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    This paper analyses the performance of the field-current regulator on a large d-c reversing mill drive. A study is made of the transfer functions associated with the shunt-field-controlled d-c motor. The results obtained from an analog computer study of the problem are discussed and a brief description of the analog setup used for the study is given in Appendix I. Particular attention is paid to the performance of the current-limit control. The over-all study revealed certain weaknesses in the type of system used in practice, and the paper concludes with a brief description of a control system which embodies improved features which were an outcome of the study. View full abstract»

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  • Comparison of calculated and measured arc-back current in large power rectifier systems

    Page(s): 585 - 589
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    EVEN with the high degree of reliability which mercury-arc rectifiers possess today, there are still a few occasions when current is carried in the wrong direction in one of the rectifier tanks and hence an arc back is created. Since this arc-back current can rise to an abnormally high value in a few milliseconds, a means must be provided to limit and to cut off this abnormal current when an arc back does occur. In order to be able to specify the characteristics of the rectifier tanks, the rectifier transformer, and the anode and cathode circuit breakers, it is essential that the magnitude of this arc-back current can be calculated with a reasonable degree of accuracy. Methods and procedures for calculating this arc-back current have been described in numerous books and papers,1¿6 and these calculations have been extremely useful in permitting the design of rectifier equipments which have reliably supplied large quantities of d-c power. On occasions when field tests have been performed and measurements of this arc-back current have been made, an abnormally large discrepancy has usually been found to exist between the calculated and the measured values of this current with the calculated values being appreciably higher than the measured values. While the calculated results were on the safe side, they have, on occasions, required the installation of additional impedance in the a-c system and have therefore increased the initial installation cost and may have penalized the operating performance of this equipment. View full abstract»

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  • A dual-mode servomechanism utilizing saturation switching

    Page(s): 590 - 595
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    This paper discusses the theoretical analysis and experimental verification of a dual-mode quasi-linear servo-mechanism. After a brief review of the operation of the simple dual-mode servo system, the desirability of linear operation for small errors is pointed out. A method of producing a gradual transition from one mode of operation to the other and finally to nearly linear operation is investigated. View full abstract»

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  • Static control in automatic warehousing

    Page(s): 595 - 602
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    THE virtual elimination of relay contacts from the highly repetitive functions required for automatic warehousing was made possible by the selection of static control elements, Westing-house Cypak,1,2,3 in place of conventional relays for an extensive mechanized carton-handling installation in the Chelsea Milling Company premix food plant at Chelsea, Mich. While the basic concept of the control philosophy was determined to be the same for either relays or static control elements, the high reliability and negligible maintenance inherent in static control elements, which have no moving parts subject to wear or corrosion, dictated the choice. Interestingly, the first cost was found essentially comparable. View full abstract»

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  • General synthesis procedure for computer control of single-loop and multiloop linear systems (an optimal sampling system)

    Page(s): 602 - 609
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    This paper is concerned with the problem of designing optimal systems for the control of a plant governed by a linear differential equation with constant coefficients. Control is exerted by means of piecewise constant signals which can change only at the ¿sampling instants.¿ Optimality means here, as in some nonlinear problems, that the system achieves equilibrium with zero steady-state error from any initial state as quickly as possible. View full abstract»

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Aims & Scope

This Transaction ceased production in 1963. The current retitled publication is IEEE Transactions on Industry Applications.

Full Aims & Scope