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American Institute of Electrical Engineers, Transactions of the

Issue 1 • Date Jan. 1928

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Displaying Results 1 - 25 of 61
  • Table of contents

    Page(s): nil1
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  • Preface

    Page(s): nil2
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  • Discussion

    Page(s): 20 - 22
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  • Discussion

    Page(s): 29 - 30
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  • Coupling Capacitors for Carrier Current Applications

    Page(s): 31 - 36
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    Coupling to high-voltage transmission lines for purposes of carrier-current communication was first. universally made by means of coupling wires. This type of coupling usually required high-power transmitting equipment, but when coupling capacitors were substituted it was possible to reduce the carrier input to the line without affecting the received signal strength. The paper gives an approximate method for determining the effectiveness of coupling wires and coupling capacitors. No attempt is made at refinements in calculations as it is only desired to show the effect of stray capacity. Curves show the change in practise from coupling wires to coupling capacitors. It is estimated that by the early part of 1928 the total number of the two types of coupling will be equal. The electrical characteristics for different types of insulation used in coupling capacitors, based on test results is given. Some important points of design for the new cable capacitor are included. View full abstract»

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  • Discussion

    Page(s): 36 - 37
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  • The Relation Between Frequency and Spark-Over Voltage in a Sphere-Gap Voltmeter

    Page(s): 38 - 48
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    The standard instrument for measuring crest values of high alternating voltages at 60 cycles is the sphere-gap voltmeter, which measures a voltage by the distance which it will flash between spheres. In much of the high-voltage research, however, very high frequencies are used. For measuring the voltages used in these high-frequency tests, the sphere-gap voltmeter is used, the assumption being made that its calibration at high frequency is but little, if any, different from that at 60 cycles. In the endeavor to make the sphere-gap a standard for measuring peak values of voltage at high frequencies, as it is at present a standard at commercial frequencies, experimental data were obtained from which calibration curves for the sphere-gap voltmeter were plotted for frequencies ranging from 28,000 to 425,000 cycles per sec. for standard conditions of temperature and pressure. These curves cover a voltage range from about 10,000 to 50,000 volts, the source of the high-frequency voltage being a Poulsen arc with variable inductance and capacity in, its a-c. circuit. The results show no appreciable change in voltage required to flash across a given gap as the frequency increases until a frequency of about 20,000 cycles is reached, then a gradual decrease inl required voltage as the frequency increases from 20,000 to 60,000 cycles, after which a single curve holds for all frequencies at least up to 425,000 cycles per sec., the highest frequency tested. View full abstract»

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  • Discussion

    Page(s): 48 - 49
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  • The Space Charge That Surrounds a Conductor in Corona

    Page(s): 50 - 57
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    A qualitative analysis of the nature of the space charge created about a conductor in corona, particularly with respect to relative magnitudes and polarities, rather than actual quantitative measurement, is described here. This work was the principal work on corona during the past year in the Ryan High-Voltage Laboratory. In tests with the arrangements of a wire and a plane, and of a wire and a cylinder, a decided rectifying effect was discernible in the space about the conductor in corona, in that that region was built up to a unidirectional potential above ground, the magnitude and polarity of this potential depending on the voltage applied. In both of these set-ups, this net rectification, which is evidently caused by some differential action entering into the ionization process, was of a positive sign at the start of corona, but changed over to negative as the voltage was raised. In a test made on two 1.1-in. diameter, parallel concentric strand copper conductors, 1O ft. apart, the space between them was found to have assumed a potential above ground when the conductors were in corona, the sign of this charge being negative at first, and then positive as the voltage increased. Tests were also carried out on a single brush, and on a rod fitted with ``artificial'' brushes. View full abstract»

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  • Discussion

    Page(s): 57 - 58
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  • Electric Oscillations in the Double-Circuit Three-Phase Transmission Line

    Page(s): 58 - 64
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    This paper, after referring to the results of a previous study of the electric oscillations on the three-phase aerial line obtained by Dr. Bekku, describes the additional work done by the writer concerning the electric oscillations in the double-circuit, three-phase transmission line, and shows that there are three kinds of traveling waves. The nature of these waves, and some of the important results of the induced transients, are described. In the appendixes, it is shown briefly how these results were derived and how to calculate the line constants from the construction data of the lines. A few numerical examples are given. View full abstract»

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  • Discussion

    Page(s): 64 - 67
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  • Transients Due to Short Circuits A Study of Tests Made on the Southern California Edison 220-Kv. System

    Page(s): 68 - 86
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    The paper deals with records which have been obtained during short circuits upon the Southern California Edison's 220-kv. system. The main features of the system are outlined, and such operating data as are necessary to afford an understanding of the various conditions which have to be met are included. The general scheme of relays is described, and the causes of flashovers and their times of occurrence are tabulated, together with the percentages which cause interruptions to service. Whether or not interruption is caused is found to depend, among other things, upon the load being carried at the time. With load below 150,000 kw., there are no interruptions unless relays are inoperative. A number of typical records of short circuits are shown and analyzed. It is shown that large amounts of power are consumed in short circuits, but that this is dependent upon the ground resistance. Practically all short circuits are single-phase to ground. The advantage of low-reactance machines is discussed and the various factors that prevent loss of synchronism pointed out. The records show that there is but little if any tendency for synchronous machines at either end of the line to fall out of step among themselves as a group, but that the sending end under certain conditions will get out of step with the receiving end. View full abstract»

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  • Discussion

    Page(s): 86 - 89
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  • Equipment for 220-Kv. Systems

    Page(s): 90 - 93
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    This paper discusses the characteristics of equipment which have been found most suitable for use on 220-kv. systems or on extensive lower voltage systems. Consideration is given to general system design, governors of prime movers, generators, excitation systems, transformers, high-voltage oil circuit breakers, transmission line, and the equipment of substations. The result of four years' operation of a 220-kv. system have proven it to be as reliable as a 110-kv. system. The economies of 220-kv. transmission have been realized. View full abstract»

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  • Discussion

    Page(s): 93
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  • Static Stability Limits and the Intermediate Condenser Station

    Page(s): 94 - 121
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    The principal features of this paper may be summarized as follows: For static stability calculations, power systems may be represented by a network with constant impedance and admittance branches with as many terminals as the number of synchronous machines requiring individual consideration. This method is justified because, as developed in the paper, loads may be represented by the equivalent constant admittances and synchronous machines may be replaced by their equivalent impedances. A criterion for static stability of systems is presented together with formulas for the calculation of the two-, three- and four-machine cases. It is shown that the maximum angle between machines for which synchronism can be maintained is, in general, somewhat dependent upon the inertia of the synchronous machines. Under some conditions synchronism can be maintained between two machines operating at angles greater than ??/2. The delivered power corresponding to definite excitation of machines will, in general, be a maximum for a smaller angle than the maximum stable angle. While the investigations have shown that synchronism can be maintained in regions heretofore considered inherently unstable, operation in such regions is held to be inadvisable. There are a number of generalizations which may be made as to the limiting stable condition. View full abstract»

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  • Discussion

    Page(s): 121 - 123
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  • Synchronous Condensers

    Page(s): 124 - 133
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    The paper reviews the general characteristics of large synchronous condensers, with particular reference to the possibilities of greater standardization in condenser specifications. Particular emphasis is placed on the question of the ratio of lagging to leading kv-a. capacity, and it is concluded that about 50 per cent lagging capacity is normal, while any important increase in this ratio requires special design of greater size and cost. Attention is called to the advantage to be gained by the use of reactors in place of such oversized condensers, where extra lagging capacity is needed. Separate sections of the paper are devoted to starting and stability characteristics, and to recent improvements in the design of synchronous condensers. Finally, the use of asynchronous condensers is discussed and found to be undesirable. View full abstract»

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  • Discussion

    Page(s): 133 - 134
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  • Oscillograph Recording Apparatus For Transmission Line Studies

    Page(s): 135 - 147
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    Part I is an introduction, showing the need for reliable records of power disturbances in transmission lines, and showing that the incandescent-lamp oscillograph is the only practicable recorder of such chance disturbances. Part II describes the Power Osiso which is a very compact and highly efficient oscillograph, having an instantaneous wattmeter, a permanent-magnet galvanometer, and a relay arrangement with control for automatic operation on chance disturbances. The various auxiliary apparatts, such as daylight-loading film holders, 6-volt motor, potential circuit control, etc., is also described, together with different connections for the same. Part III describes the Multi-Element Oscillograph, which gives from 3 to 9 simultaneous records on one film, also the various auxiliary apparatus and the possible combinations thereof. A detailed description is given of the automatic operation equipment and its action in recording chance disturbances. View full abstract»

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  • Discussion

    Page(s): 147
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