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American Institute of Electrical Engineers, Proceedings of the

Issue 5 • Date May 1914

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Displaying Results 1 - 25 of 25
  • Institute meeting in Pittsfield, Mass. May 28–29, 1914

    Page(s): 147 - 148
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  • Second Institute lecture on electromagnetic theory, by Dr. M. I. Pupin, May 6, 1914

    Page(s): 148 - 149
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  • Revised standardization rules

    Page(s): 149 - 150
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  • Pittsburgh meeting of the A.I.E.E., April 9–10, 1914

    Page(s): 150
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  • Directors' meeting, New York, April 7, 1914

    Page(s): 151
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  • Membership

    Page(s): 151 - 155
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  • Past section meetings

    Page(s): 155 - 158
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  • Past branch meetings

    Page(s): 158 - 163
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  • Personal

    Page(s): 163 - 164
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  • Obituary

    Page(s): 164 - 165
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  • Abstracts of proceedings of foreign engineering societies

    Page(s): 165 - 167
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  • Library accessions

    Page(s): 167
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  • Officers and Board of Directors, 1914–1915

    Page(s): 168 - 178
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  • The future of electric heating and cooking in marine service

    Page(s): 693 - 702
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    Indications of the future point to electric motor driven propulsion and abandonment of coal-burning boilers. Electric cooking and heating is in line with this development and the source of heat for cooking and heating will be confined to the boiler room. The future of electric cooking apparatus is assured by the progress already made in the U. S. Navy in adopting electric equipment. Detail report is given of trial trip of U. S. Texas, which depends almost entirely upon electricity for cooking. Consumption of 1.25 kw-hr. per person per meal is indicated. Load factor was 50 per cent. Electric ranges and bake ovens effect considerable saving in weight and space and release cooks from being “firemen” to devote their time and effort to good cooking. Electric cooking finds greatest advantages in high temperature cooking. Electric heating on shipboard does away with the disadvantages of steam piping and gives individual and local regulation and provides, where desired, glowing heat without fire. Other accessories are the electric flatiron, the soldering iron and therapeutic devices. View full abstract»

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  • Electricity the future power for steering vessels

    Page(s): 703 - 732
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    Electrical development in the marine field has been confined in a large measure to the navy, and the best experience with electric steering gears has been obtained from navy installations. Up to the present time steam has been the universal power for operating steering gears but certain disadvantages are inherent in this system which can be overcome by the electric drive, and additional advantages obtained. The history of electric gears shows that many different schemes have been tried and proved failures owing to faulty designs and imperfectly developed apparatus. At present several different systems are in successful operation. To obtain full benefit of the advantages possible from an electric drive, much depends on the selection of apparatus with characteristics best suited to the work. The problem of electric drive is largely one of control. The calculations for rudder and motor horse powers must be carefully made, with the proper assumptions for the conditions presented. Several installations in the navy have shown excellent results; in the case of the battleship Texas the data obtained show preliminary calculations were quite accurate. Results obtained seem to justify the prediction that electric steering gears will be used quite generally in the future. View full abstract»

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  • Experiences with line transformers

    Page(s): 733 - 745
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    This paper presents an analysis of the transformer troubles for one year on a system having nearly 15,000 transformers installed. This analysis indicates that about 50 per cent of the troubles traceable to the transformer can be eliminated, with no great expense, by some slight changes in the construction details and some improvements in operating methods. Reference is made to the Standard Specifications for Line Transformers issued by the Bureau of Standards. An experiment on 1600 transformers with the connection board removed or submerged proved that the connection board above oil was responsible for about 60 per cent of the transformer troubles due to lightning. Curves showing the record of burnouts of four different makes of transformers are used as a basis for a discussion of effect of the value placed on continuous service in the selection of transformers. The results of experiment with improved lightning protection are given, showing how the troubles were reduced by two-thirds. By taking advantage of the results of the two extended experiments, it should be possible to reduce the troubles due to lightning to about 10 per cent or 20 per cent of the troubles heretofore experienced. View full abstract»

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  • Experience of the Pacific gas and Electric Co. with the grounded neutral

    Page(s): 747 - 752
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    The paper gives an outline of the distributing system of the Pacific Gas and Electric Company of California which operates at 60 kv., the transformers being Y-connected, with the neutrals solidly grounded. The company considers the grounded neutral system has a number of important advantages with regard to the transformers, the transmission lines, and operation. The fewer turns of larger capacity of the Y-connected transformers and the fixed lower average voltage to ground greatly increases their reliability. The maximum voltage on the line insulators with the grounded neutral is never more than 57.7 per cent of the line voltage, and it is possible to maintain polyphase service at a substation on a branch line with only two wires in case one wire should be cut out. This cannot be done on a delta system unless one phase of the system be grounded, which is very undesirable. With a grounded neutral, a wire down is instantly detected and power must be shut off. In a delta-connected system an arcing ground is often followed by surges which break down the insulation at other points, the cause of this disturbance being the oscillatory character of the arc. In the grounded Y system no such disturbances occur, as the frequency of an arc to ground is the same as that of the system and any damage is confined to the point of failure. It is also believed that operation with the grounded neutral causes less disturbance in telephone and telegraph lines than would be the case in delta-connected lines. View full abstract»

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  • Influence of transformer connections on operation

    Page(s): 753 - 770
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    In this paper the relative advantages and disadvantages in operation of the more important three-phase transformer connections are discussed. Three conditions of operation are given: First, normal; second, operation of a bank with one phase disabled; third, effect of line grounds on operation. The paper is not complete, particularly in that high-frequency or switching phenomena are not discussed. Its major purpose is to give a fairly adequate presentation of insulation stresses at relatively low frequencies to which transformers are subject in either normal or abnormal conditions of operation. These frequencies include the fundamental or generated frequency and its harmonics and the natural frequency of the system. The behavior of three-phase auto-transformers under the various conditions of operation given above is also analyzed. View full abstract»

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  • A study of some three-phase systems

    Page(s): 771 - 784
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    The star-star, delta-delta, delta-star and star-delta connections are taken up in order and their individual peculiarities and characteristics, precautions that must be taken in operation to avoid trouble and where and when the system may be grounded with best results, are discussed. The question of delta-delta vs. delta-star is considered: (1) For moderate voltages the delta-delta system has the advantage on account of its greater flexibility. (2) For high voltages the delta-star connection is preferable, chiefly on account of its greater strength and lower cost. There is a probability that a delta-star bank of transformers will cause less disturbance in switching than one that is delta-delta connected. (3) There are much greater possibilities of development in transformers designed for delta-star connection than for any other. (4) Past and present practise upholds the use of the delta-star connection in preference to the delta-delta for high-voltage transmission. View full abstract»

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  • Harmonic voltages and currents in Y- and delta-connected transformers

    Page(s): 785 - 789
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    The paper reviews the conditions under which triple harmonic voltages and currents are produced in Y-and delta-connected transformers. These voltages are produced by hysteresis in the core. In a single-phase transformer, increase of series resistance tends to suppress the current harmonic and produce the voltage harmonic. In three-phase transformers, a Y connection suppresses the current harmonic and allows the full flux and voltage harmonics to appear. Delta connection provides a closed path for the current harmonic, and suppresses the triple voltage. A case is cited where a Y-connected auto-transformer was used to step up from 6600 to 12,000 volts at a substation. The neutral was not grounded, and trouble resulted due to partial resonance at triple frequency between line capacity and transformer reactance. The paper shows that, although not generally recognized, a triple component can exist in the line-to-line e.m.f. wave of a three-phase system. This is possible in a case where a two-to-three-phase transformation is used, and when the e.m.f. wave of the two-phase generator contains a triple harmonic. Vector diagrams and curves are given illustrating this possible effect. View full abstract»

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  • Relative merits of Y and delta connection for alternators

    Page(s): 791 - 794
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    The main advantages obtained with the Y connection are as follows: (1) It is possible to bring out a lead from the neutral point of the winding, which is useful for various purposes. (2) The cost is less than with the delta connection, requiring approximately 58 per cent of the turns. (3) It is not possible for circulating currents of triple frequency to flow in the windings. The delta connection does not appear to have any advantages except as a convenience in design for certain voltages. When used, proper precautions must be exercised in the design to eliminate excessive circulating currents. View full abstract»

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  • The present status of aluminum-cell lightning arresters

    Page(s): 795 - 802
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    This paper gives a brief survey of the conditions of operation of aluminum-cell arresters, without any description of the forms of the arresters. References are made to recent investigations of lightning phenomena and their possible effects on the design of protective apparatus used at present. The d-c. aluminum arrester is most economical and represents the highest possible grade of protection. In connection with the a-c. aluminum arrester the following points are discussed: dielectric spark lag, dissolution of film, charging resistance, oscillations, damping, degrees of surges due to natural operations and accidents, and insulations which withstand these surges. Charging resistance on aluminum arresters is chosen to make surges harmless, and the charging resistance gives great immunity from damage to the arrester itself by any accidental and temporary local condition in the arrester. In conclusion, the aluminum-cell arrester may justly be regarded as a standardized electrical device founded on solid fundamental principles. View full abstract»

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  • Electric power

    Page(s): 803 - 818
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    The authors briefly trace the evolution of electric power up to the present time, and note various fields of application of electric power which have become specialized branches of electrical engineering. The tendency of public utilities towards consolidation, and the advantages to be derived thereby, are discussed, also the interconnection of hydroelectric plants, and the grouping of systems under a holding company. The growth of the electric power industry is illustrated by reference to the recent U. S. census report. The present practise tends to the use of very large generating units, and transmission lines are being constantly increased in length and operated at higher voltages. Applications of electric power to various industries are briefly referred to and their advantages in various fields are specified. View full abstract»

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  • Discussion on “the dielectric strength of thin insulating materials” (Farmer), New York, December 12, 1913. (see proceedings for December, 1913)

    Page(s): 819 - 839
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    F. W. Peek, Jr: Three types of insulation are in general use — gaseous, liquid, and solid. The mechanism of breakdown differs in many respects in the three types. Any insulation, under given conditions, ruptures at a given point when the dielectric flux density at that point exceeds some definite value. The total dielectric flux depends upon the capacity and the electromotive force; that is, upon the size and spacing of conductors and the voltage between them. The flux density at various points will also be different, depending upon the configuration of electrode. The flux density at any point is proportional to the gradient at that point. The strength of insulation, therefore, may also be expressed in terms of the gradient measured at the point where rupture occurs. The voltage required to rupture insulation, divided by its thickness, is not a measure of the insulation strength. It is the average gradient. The maximum gradient where rupture starts is much higher. For instance, take two pairs of spheres, one pair a half-centimeter in diameter, spaced one cm. apart, and the other pair two cm. in diameter, spaced one cm. apart. Apply a voltage of 100 kv. across pair No. 1. The gradient is maximum at the surface and is by calculation de/dx = 270 kv./cm. The average gradient e/x = 100/1. On pair No. 2, 100 kilovolts gives de/dx = 135 kv./cm.; e/x = 100 kv./cm. Thus for the same voltage and spacing the actual stress is quite different, depending upon the curvature. If 20-cm. spheres are taken, under the above conditions de/dx = 103 and e/x = 100. Thus with large radius the average gradients and de/dx are approximately equal. This is the reason that in any investigation (other than commercial testing) made to determine the strength of insulation, some electrode is taken in which the dielectric flux density and gradient at various points can be calculated — that is, spheres, parallel wires, or a wire in a cyl- nder. These may be arranged so that the break is local, as corona in air on two parallel wires at large spacings. The break starts at the surface because the flux density is a maximum there. The conducting corona extends out approximately to a point where the flux density is below the breakdown density. Only when the surfaces are close together does a complete spark-over take place before corona forms. View full abstract»

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  • Discussion on “trunk line electrification” (Kahler) and “2400-volt railway electrification” (Hobart), New York, May 20, 1913. (continued from p. 2147, proceedings for November 1913)

    Page(s): 840 - 848
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    Roger T. Smith (by letter): Mr. Kahler's paper is interesting to English electrical engineers from the complete method of analysis adopted. The examples taken do not, however, invite criticism either of the constants or of the results since they are not comparable with anything in the way of steam or electric traction that we have or are likely to have in England. View full abstract»

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Aims & Scope

This Magazine ceased publication in 1919. The current retitled publication is IEEE Spectrum.

Full Aims & Scope