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Electrical Engineering

Issue 12 • Date Dec. 1942

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Displaying Results 1 - 25 of 75
  • [Front cover]

    Page(s): c1
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    Freely Available from IEEE
  • Contents

    Page(s): 1
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    Freely Available from IEEE
  • Contents

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    Freely Available from IEEE
  • Stability study of A-C power-transmission systems

    Page(s): 893 - 905
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    FOR the operation of power-transmission systems of medium and long length, the problem of stability is becoming increasingly important. This is true in the steady state of the system as well as in the transient state, during and after the occurrence of a fault on the system. Since the design of the transmission system is primarily responsible for its proper operation, and since the a-c network analyzer offers the best means for system analysis, the present study was undertaken for the purpose of correlating the design and operational data by means of the a-c network analyzer. For this purpose several power-transmission systems were selected, and their steady-state and transient-stability characteristics studied. Thus the steady-state and transient-stability limits of the system were obtained on the analyzer. View full abstract»

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  • Emergency overloading of air-cooled oil-immersed power transformers by hot-spot temperatures

    Page(s): 906 - 915
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    The paper points out that during the period of the war the need for obtaining maximum transformer overload capacity is very great, particularly under rare emergency conditions. From a thermal standpoint, the amount of overload is limited by the hottest spot in the transformer winding. To obtain accurate data 1. On the actual hot-spot temperature s under rated load conditions 2. On the increase of the hot spot with load under both ultimate moderate overload and heavy short-time overload conditions View full abstract»

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  • Induced voltages on transmission lines

    Page(s): 916 - 929
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    ABOUT the year 1929 it first became appreciated that the lightning discharge is not instantaneous. The recognition of this fact had a profound influence upon the theories of lightning protection, the emphasis being diverted from induced to direct strokes1 as the agent to be guarded against. With the meager information then available the calculations indicated that induced voltages were unimportant when the finite time of discharge was taken into account.2 The more accurate information available today calls for a critical analysis of this subject, which is the purpose of the present paper. View full abstract»

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  • Load ratings of cable — II

    Page(s): 930 - 941
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    Since the author's 1939 paper,1 further data have been obtained regarding the loading of underground power systems having impregnated-paper-insulated lead-covered underground cable. The results of the studies may be summarized as follows: 1. The factors affecting the setting of maximum safe conductor temperatures are so numerous that no fixed value (or values) can be assumed as applicable to all installations of a given design and size of cable in this country. 2. For some cables, the present temperature limits for normal day-in and day-out operation may be safely exceeded, especially for wartime conditions. 3. For emergency operation safe temperatures may be even higher than listed in the previous paper, especially for wartime operation. 4. Operation in wartimes at special temperatures will mean in some cases substantial shortening of the life of underground circuits and an accompanying increase in service interruptions. 5. Wartime increases in usual maximum daily loading and in load factors may cause large increases in duct and copper temperatures, even if past current ratings are maintained. These temperatures will sometimes exceed those in the present standards. 6. The safe temperature for emergency operation, particularly for extra-high-voltage cables, may be limited by the joints. Also, for all kinds of cable sufficient room must be provided to avoid mechanical damage of cable or joints in manholes with cable movements incidental to emergency loads. 7. Cracking of lead sheaths due to reciprocating cable movement into manholes may limit the temperature range for usual daily loading, but has little effect on the safe emergency loading. 8. For three-conductor solid-type cable, the insulation of the shielded type can safely withstand higher temperatures than the belted type, but the reverse is true as to the allowable daily temperature range with regard to its effect on the sheath in manholes. 9. Cable movement increases with length of conduit section- up to about 250 feet but shows little change with further increases in length up to 1,025 feet. 10. Changes in installation methods and the use of new types of repairs may help to mitigate troubles due to sheath cracking. 11. Copper shielding tape in three-conductor cable with relatively thin insulation has little effect in reducing the thermal drop from the conductor to the sheath. 12. In some cases considerable thermal advantage may be gained economically by making relatively deep installations of conduit. 13. In most cases, the maximum conduit temperature of 50 degrees centigrade given in the previous paper may be safely exceeded. View full abstract»

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  • Factors which influence the behavior of directional relays

    Page(s): 942 - 952
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    Very little material dealing with the factors (such as network dissymmetries) which lead to incorrect operation of directional relays has appeared in the technical literature. Practical experience has been the guide as to the relative merits of the 12 possible connections which utilize either line-to-neutral or line-to-line voltages and line currents or the differences of line currents to actuate the relay elements. In this article a graphical method for analyzing directional-relay operation is developed, utilizing circle diagrams and symmetrical components, and the method is applied to general cases to ascertain the effects of network dissymmetries. Since the relay volt-ampere expressions in terms of symmetrical components are too complicated to show the relative merits of the 12 connections, the expressions also are given in terms of the modified symmetrical components introduced by Edith Clarke and now widely used in network-analyzer studies of unbalanced faults. Circle diagrams based upon these modified components show conclusively that the ordinary 90-degree, 30-degree, and 60-degree connections are more free from disturbing influences than the other nine and therefore give more reliable operation in most practical applications of directional relays. The particular connection which will be most reliable at any given location can be determined by the methods given here when the constants of the power network are known. View full abstract»

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  • The combination of probability curves in engineering

    Page(s): 953 - 962
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    ENGINEERS are quite familiar with simple probability distributions showing the relative likelihoods of occurrence of the different values which a varying physical or electrical quantity may assume. As the complexities of machines and circuits in modern design increase, it becomes highly desirable to be able to estimate the probability distribution resulting from the joint presence of two or more sources of variation. This paper will undertake to present something of the theory of making such combinations, and its application to a number of practical examples. View full abstract»

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  • Series capacitors for transmission circuits

    Page(s): 963 - 973
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    This paper presents the results of an analytical and experimental investigation of the use of series capacitors to increase the permissible loadings of long high-voltage a-c transmission lines. Because of limitations imposed by synchronous stability and reactive kilovolt-ampere requirements, conventional lines, when extended to the higher voltages and greater lengths, cannot be loaded to values of power sufficiently high to develop maximum over-all economy. It is shown that, when suitably applied, series capacitors will make possible the desired optimum loadings and will very materially reduce transmission costs. The theoretical possibilities of using series capacitors to compensate the excessive inductive reactance of long lines have received consideration for many years. Practical series capacitors require protective equipment, but shunting of the capacitors in the earlier schemes resulted in a decrease instead of an increase in the transient-stability limits. The authors propose series capacitors of the limited-voltage type in combination with auxiliary equipment which not only protects the insulation but quickly restores the capacitors to the circuit after the faulted conductors are isolated, thus preventing a decrease in system power limit at the time of need. The application requirements of necessary apparatus are also briefly outlined. Results of analytical studies and miniature-system tests in connection with a typical application of series capacitors to one of the major lines of a typical transmission system are included. This work deals with relative transmission costs, transient stability, spontaneous hunting, and the sub-synchronous operation in the induction starting of machines. The conclusion is reached that the proposed series-capacitor scheme appears practicable for long transmission lines. View full abstract»

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  • Lightning investigation on 132-kv transmission system of the American gas and electric company

    Page(s): 974
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    Discussion and authors' closure of paper 42–18 by I. W. Gross and G. D. Lippert, presented at the AIEE winter convention, New York, N. Y., January 26–30, 1942, and published in AIEE TRANSACTIONS, 1942, April section, pages 178–85; previous discussions published in AIEE TRANSACTIONS, 1942, pages 450–3. View full abstract»

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  • Rectifier terminology and circuit analysis

    Page(s): 974 - 975
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    Discussion and authors' closure of paper 42–83 by C. H. Willis and C. C. Herskind, presented at the AIEE North Eastern District meeting, Schenectady, N. Y., April 29-May 1, 1942, and published in AIEE TRANSACTIONS, 1942, July section, pages 496–9. View full abstract»

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  • Thermal co-ordination of motors, control, and their branch circuits on power supplies of 600 volts and less

    Page(s): 975
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    Discussion of paper 42–79 by B. W. Jones, presented at the AIEE North Eastern District meeting, Schenectady, N. Y., April 29-May 1, 1942, and published in AIEE TRANSACTIONS, 1942, July section, pages 483–7. View full abstract»

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  • Selenium rectifiers and their design

    Page(s): 975 - 976
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    Discussion and author's closure of paper 42–86 by J. E. Yarmack, presented at the AIEE North Eastern District meeting, Schenectady, N. Y., April 29-May 1, 1942, and published in AIEE TRANSACTIONS, 1942, July section, pages 488–95. View full abstract»

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  • Reactance and skin effect of concentric tubular conductors

    Page(s): 976 - 977
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    Discussion and author's closure of paper 42–78 by H. B. Dwight, presented at the AIEE North Eastern District meeting, Schenectady, N. Y., April 29-May 1, 1942, and published in AIEE TRANSACTIONS, 1942, July section pages 513–18. View full abstract»

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  • Temperature-aging tests on class-a-insulated fractional-horsepower motor stators

    Page(s): 977
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    Discussion of paper 42–82 by J. A. Scott and B. H. Thompson, presented at the AIEE North Eastern District meeting, Schenectady, N. Y., April 29-May 1, 1942, and published in AIEE TRANSACTIONS, 1942, July section, pages 499–501. View full abstract»

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  • High-voltage fusing of transformer banks

    Page(s): 977 - 978
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    Discussion and authors' closure of paper 42–80 by H. H. Marsh, Jr., and G. B. Dodds, presented at the AIEE North Eastern District meeting, Schenectady, N. Y., April 29-May 1, 1942, and published in AIEE TRANSACTIONS, 1942, July section, pages 533–5. View full abstract»

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  • Sleet problems on electrified railroads

    Page(s): 978 - 980
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    Discussion and author's closure of paper 42–121 by H. F. Brown, presented at the AIEE summer convention, Chicago, Ill., June 22–26, 1942, and published in AIEE TRANSACTIONS, 1942, August section, pages 589–93. View full abstract»

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  • Electric control for steam boilers on diesel-electric and straight electric locomotives

    Page(s): 980
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    Discussion and author's closure of paper 42–127 by E. H. Burgess, presented at the AIEE summer convention, Chicago, Ill., June 22–26, 1942 and published in AIEE TRANSACTIONS, 1942, August section, pages 604–06. View full abstract»

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  • Electric facilities and operating plan for the first Chicago subway

    Page(s): 980
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    Discussion of paper 42–137 by C. E. De Leuw, presented at the AIEE summer convention, Chicago, Ill., June 22–26, 1942, and published in AIEE TRANSACTIONS, 1942, November section, pages 780–7. View full abstract»

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  • Relative expense for service restoration with different types of overcurrent protection for distribution circuits

    Page(s): 980 - 982
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    Discussion and authors' closure of paper 42–129 by G. F. Lincks and C. R. Craig, presented at the AIEE summer convention, Chicago, Ill., June 22–26, 1942, and published in AIEE TRANSACTIONS, 1942, November section, pages 813–21. View full abstract»

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  • Modern cathode-ray oscillograph for testing lightning arresters

    Page(s): 982 - 984
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    Discussion and authors' closure of paper 42–108 by E. J. Wade, T. J. Carpenter, and D. D. MacCarthy, presented at the AIEE summer convention, Chicago, Ill., June 22–26, 1942, and published in AIEE TRANSACTIONS, 1942, August section, pages 549–53 View full abstract»

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  • Modern impulse generators for testing lightning arresters

    Page(s): 984 - 985
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    Discussion and author's closure of paper 42–96 by Theodore Brownlee, presented at the AIEE summer convention, Chicago, Ill., June 22–26, 1942, and published at AIEE TRANSACTIONS, 1942, August section, pages 539–44. View full abstract»

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  • Regulated rectifiers in telephone offices

    Page(s): 985 - 986
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    Discussion and author's closure of paper 42–95 by D. E. Trucksess, presented at the AIEE summer convention, Chicago, Ill., June 22–26, 1942, and published in AIEE TRANSACTIONS, 1942, August section, pages 613–17. View full abstract»

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  • Theoretical possibilities in an internally heated bimetal type of thermal watt-demand meter

    Page(s): 986 - 987
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    Discussion and author's closure of paper 42–110 by Edward Lynch, presented at the AIEE summer convention, Chicago, Ill., June 22–26, 1942, and published in AIEE TRANSACTIONS, 1942, October section, pages 764–70. View full abstract»

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Aims & Scope

This Periodical ceased publication in 1963. The current retitled publication is IEEE Spectrum.

Full Aims & Scope