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American Institute of Electrical Engineers, Transactions of the

Issue 3 • Date Sept. 1932

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Displaying Results 1 - 25 of 45
  • Table of contents

    Page(s): nil1
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    Freely Available from IEEE
  • Preface

    Page(s): nil2
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    Freely Available from IEEE
  • Surge-Proof Transformers

    Page(s): 579 - 584
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    First Page of the Article
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  • Discussion

    Page(s): 584 - 600
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  • Effect of Transient Voltages on Power Transformer Design-IV Transition of Lightning Waves from One Circuit to Another Through Transformers

    Page(s): 601 - 615
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    Three preceding papers of the same general title have dealt with transient voltage stresses developed within high-voltage transformer windings. The most important conclusions arrived at by the author and presented in these papers and the discussions are: 1. Transformers of all conventional constructions undergo oscillations when subjected to lightning or switching surges. 2. The amplitudes of these oscillations may be dangerously high, depending on the amplitude and the shape of the applied voltage. Their frequencies range from a few thousand to a few hundred thousand cycles per second.1,2 3. A lightning wave of a given shape produces very different stresses in different transformers.1,2 4. In practical design, neither amplitude nor frequency of these oscillations can be controlled by arrangement or proportions of windings.1,2 5. A lightning wave chopped by flashover of line insulation can produce stresses in transformer windings equal to or even in excess of those produced by a long wave of the same amplitude and front.1,2 6. Unless means are taken to obtain uniform distribution under all lightning conditions it is entirely possible to design transformers that will pass A.I.E.E. test which are inadequate for service conditions. This follows because test voltages in neither magnitude nor distribution of stresses correspond to that produced by transient voltages in transformers of ordinary construction. This difference is particularly great in transformers with solidly grounded neutrals, where the potential test allows the insulation from high-voltage winding to low-voltage winding and ground to be reduced as the neutral is approached.1,2 7. View full abstract»

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  • Discussion

    Page(s): 616 - 620
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  • The Proximity Effect Its Application to the Concentration of Heating Currents in Predetermined Strips

    Page(s): 621 - 627
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    This paper describes methods of concentrating heating currents used for any industrial operation, such as welding, in predetermined strips of conducting plates, pipes, or other shapes. The method is to so place the shapes in close proximity to each other, or to auxiliary conductors, and to so interconnect the shapes with sources of alternating, or oscillatory, current of moderately high frequency that the heating current concentrates largely in adjacent strips in close proximity, in which the current flows in opposite directions in the two adjacent strips. Briefly stated, the method is to use an enhanced ``proximity effect'' to control the distribution of heating currents in bodies. The paper contains curves which have been worked out to illustrate the control of the distribution of the heating current densities by means of the proximity effect. View full abstract»

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  • Toll Switching Plan for Wisconsin

    Page(s): 628 - 633
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    This paper outlines the general plan which is being employed in the handling of intrastate toll traffic of the Wisconsin Telephone Company, including many of the transmission features involved and touching upon the relationship of the plan to that for handling countrywide toll connections. A brief discussion is included of the present and proposed toll cable network in Wisconsin. View full abstract»

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  • Discussion

    Page(s): 633 - 634
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  • Discussion

    Page(s): 639 - 643
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  • Discussion

    Page(s): 651
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  • 115,000-Kw. Turbo-Alternator

    Page(s): 652 - 656
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    Due to the increasing use of large single-shaft steam turbine units, it has been necessary to design very large generators operating at 1,800 r.p.m. The present paper describes a 115,000-kw. unit recently placed in operation. The generator is wound for 18,000 volts and the whole output of the machine, with the exception of a small part used for the operation of auxiliaries, is stepped up to 182 kv. and all switching is done on the high-voltage side of the transformers. It was possible, therefore, to design the generator for a voltage that would permit a simple two-conductor per slot winding. On account of the great axial length of the machine, ventilation required careful study and a new scheme of rotor ventilation was developed to secure uniform cooling throughout the length of the long rotor body. The stator ventilation is of the inward-outward parallel flow type with fourteen parallel paths in each half of the stator. Air circulation is provided by four single inlet motor-driven blowers mounted under the generator. A fin type radiator cooler is mounted under the generator yoke and condensate is circulated through the cooler. Excitation is furnished from a 350-kw., 250-volt coupled, shunt-wound exciter and a 7¿-kw. overhung pilot exciter is used to excite the fields of the main exciter. View full abstract»

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  • Discussion

    Page(s): 657 - 658
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  • The Mercury Arc Rectifier Applied to A-C. Railway Electrification

    Page(s): 659 - 664
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    A new commutatorless motor with series characteristics has been developed and is briefly reviewed. The motor is particularly suitable for traction purposes and can be supplied from an overhead trolley at the usual a-c. electrification voltages and any commercial frequency. It is shown how it is possible, by the use of a grid-controlled rectifier, to eliminate not merely the commutator of the motor, but practically all of the expensive control, switching, and reversing equipment commonly used on a-c. and d-c. locomotives. Regenerative braking is also made inexpensive and practicable. The first part of the paper explains the general theory of the grid-controlled rectifier which is necessary for an understanding of the commutatorless motor. The data and layout of a 1,000-hp., 50-cycle, 15,000-volt, single-phase locomotive, now under construction, are given. View full abstract»

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  • Discussion

    Page(s): 664 - 668
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  • An Improved Type of Limiting Gap for Protecting Station Apparatus

    Page(s): 676 - 681
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    The wide range of transients to which station apparatus is subjected is pointed out and the desirability shown for having adequate protection. The different breakdown characteristics of the various insulating members of a station are illustrated and the importance emphasized for considering this in choosing a voltage limiting device. The need is also shown for having protective gap discharges reduced to a minimum in order to limit the number of service interruptions. The characteristics and limitations of several forms of gaps are shown and discussed. A new form of limiting gap is described in which it is possible to change the sparkover characteristic over a considerable range to allow for the differences in time lag and polarity characteristics of station insulation. The advantage of using a limiting gap in multiple with a lightning arrester to provide maximum protection and reduce interruptions to a minimum is discussed. View full abstract»

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  • Suspension Insulator Assemblies Their Design and Economic Selection

    Page(s): 682 - 689
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    This paper presents a summary of data from extensive impulse and 60-cycle laboratory flashover tests upon suspension insulator strings relative to unit shell diameter and unit spacing. The insulating qualities and the economic advantages of the various sizes of units are discussed with due regard to the most recent lightning protection theories. Both steel tower and wood pole high-voltage transmission line insulation are given consideration from the electrotechnical and economic standpoint. View full abstract»

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  • Discussion

    Page(s): 697 - 706
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  • The Parallel Type Inverter

    Page(s): 707 - 714
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    The parallel type inverter is one of many forms which are undergoing development at the present time. It gives promise of becoming of considerable importance and therefore the principles of operation should be better and more widely known. The object of this paper is to make a qualitative analysis of the operation of this type under different conditions of loading, and to present the results largely in the form of complete sets of oscillograms for further study. Inverters of the types now being studied involve the use of hot-cathode mercury-vapor tubes called thyratrons. The characteristics of these tubes are given briefly and the data necessary for an understanding of their operation in these circuits are presented. The principle of operation of the inverter circuit is developed by means of simple diagrams and then the actual conditions throughout the circuit are studied by means of oscillograms showing the voltages and currents in all of the essential parts. It is shown that the method of operation may be considered in a different manner from that usually assumed in the development of the circuit, inasmuch as the capacitor can be thought of as performing the function of giving the correct phase relation between the input current and the induced transformer primary voltage, rather than providing a sudden reversal of potential on the anode of the tube being stopped. This reversal is provided by the induced primary voltage. The current conditions for the various steps of operation are shown by simple diagrams. View full abstract»

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  • Discussion

    Page(s): 714
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  • A General Theory of Systems of Electric and Magnetic Units

    Page(s): 715 - 727
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    A system of electric and magnetic units may be shown to be characterized by five parameters, namely: a numeric, n, which gives the ratio between the density of electric displacement used in that system and the so-called theoretical density; a numeric, p, which gives the corresponding ratio for magnetic flux densities; a physical conversion factor, k, which converts a given volume of current into the corresponding magnetomotive force; the absolute permittivity, ¿; and the absolute permeability, ¿. On the basis of these five parameters, the principal fundamental equations of electricity, magnetism, and electromagnetic waves are written in what the author calls the general system of units, without assigning definite values to these parameters. He also shows that the five parameters must satisfy the equation vk = ¿np/¿¿, where v is the velocity of propagation of electromagnetic waves in that particular medium to which ¿ and ¿ refer; otherwise the five parameters may be chosen arbitrarily. By giving these parameters specific values, seven different systems of units are derived, namely, the electrostatic, the electromagnetic, the practical, the Gauss system, the Heaviside-Lorentz system, one which the author calls the compromise system, and the ampere-ohm system introduced by him some twenty years ago. The characteristics, the advantages, and the disadvantages of each system are briefly discussed, and it is shown how to deduce a new system of units from the general system, to conform to certain desired specifications. View full abstract»

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