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American Institute of Electrical Engineers, Proceedings of the

Issue 3 • Date March 1913

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Displaying Results 1 - 21 of 21
  • A. I. E. E. lectures on radioactivity

    Page(s): 75 - 76
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  • International electrotechnical commission

    Page(s): 76 - 78
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  • Directors' meeting, February 14, 1913

    Page(s): 78 - 79
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  • Report of special committee on past President's testimonial

    Page(s): 79
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  • The forum: Dedicated to the discussion of Institute affairs

    Page(s): 80
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  • United engineering society treasurer's report

    Page(s): 81 - 82
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  • Membership

    Page(s): 82 - 93
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  • Past section meetings

    Page(s): 94 - 99
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  • Past branch meetings

    Page(s): 99 - 110
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  • Death of John Fritz

    Page(s): 110
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  • Obituary

    Page(s): 110
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  • Library accessions

    Page(s): 111 - 113
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  • Officers and Board of Directors, 1912–1913

    Page(s): 114 - 122
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  • Thermocouples and resistance coils for the determination of local temperatures in electrical machines

    Page(s): 701 - 708
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    The paper discusses different devices for measuring temperatures in electrical machines and points out their various sources of error, and also the limitations of the uses of mercury and alcohol thermometers, thermocouples and resistance coils. Fluid thermometers can generally measure only surface temperatures, and temperatures of rotating parts must be measured after they come to rest, thereby introducing large chances of error due to equalization or rapid changes of temperature, slow rate of indication of thermometers, small contact between the bulb and the surface to be measured, emergent stem, etc. In the measurement of temperature by the electrical resistance method either the windings of the machine itself or fine wire coils placed in or about the windings are employed. In using the coils of the machine, the result depends upon the accuracy with which the coefficient of change of resistance of the copper with temperature is known. This method, of course, gives only the average temperature of the whole length of the winding and does not indicate the temperature of any part of the winding. Where coils of fine copper are used highly accurate measurements are possible, as the coefficient of temperature of the wire may be accurately known. The extent of the coil determines the extent to which the measurement is local. For accurate determinations, some sort of bridge for determining the resistance is required. The thermocouple is the most accurate device for measuring local temperatures, as the e.m.f. generated is a function of the difference in temperature between the junction of the wires of the couple and their free ends, and the temperature of the free ends can be accurately controlled. Thermocouples require the use of precision meters for reading their indications, and potentiometer arrangements may be applied to obtain any desired degree of accuracy. Ordinary thermometry is the simplest, quickest and least accurate method of temperature measurement, and usual- y applies only to surface conditions. The choice between the electrical methods of temperature measurement is largely determined by the ease of application in any particular case. The thermocouple will give the most rapid indications, although the resistance method is almost as rapid if the coil is of right proportions and is intimately applied to the parts whose temperature is to be measured. View full abstract»

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  • Generator and prime mover capacities

    Page(s): 709 - 720
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    Electric generators are of necessity driven by prime movers and the combination must be treated as a single unit when considering the questions of ratings and capacities. The importance of the proper adaptation of the capacities is fully emphasized by the fact that there are in operation in many stations in this country, units in which the output is unnecessarily limited by a discrepancy in the ratings, in that the prime mover is either too small or too large for the generator. The latter may, for example, be designed for unity power factor, while the actual operating power factor may be 0. 8, in which case the full capacity of the prime mover can not be utilized. In the past every effort was made to adjust the ratings of the generators to the station load curves, and the result was that overload capacities of 25, 50 or even 100 per cent had to be guaranteed, usually for a period of two hours. With the growth of the generating station and the improved load conditions this practice is now becoming more and more obsolete and the units are being rated on a maximum or, more properly called, constant continuous rating, which should not be exceeded except during momentary peaks. Steam turbine units have been rated according to this method for some time past, and with entirely satisfactory results. It is also becoming quite common in connection with waterwheel-driven units, and there seems to be no reason why it should not prove to be equally satisfactory for hydroelectric plants, especially for low heads, where the waterwheel efficiency falls off rapidly as the power is reduced below the normal full load. Exceptions to this may, however, be found, as, for example, where heavy short-period peak loads must be provided for, in which case it may be advisable to select a generator having a corresponding overload capacity. For the sake of standardization it seems, however, desirable to give all generators a maximum constant continuous rating at a certain specified temperature. View full abstract»

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  • The application of synchronous motors to a water power transmission system for the betterment of service standards

    Page(s): 721 - 755
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    The writer will in this paper trace the history, to some extent, of the causes leading up to the application of synchronous apparatus to the water power transmission system of the Indiana and Michigan Electric Company for the purpose of maintaining adequate and serviceable standards comparable with such as would be realized with an individual steam plant situated where power and light are to be utilized. View full abstract»

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  • Air as an insulator when in the presence of insulating bodies of higher specific inductive capacity

    Page(s): 757 - 772
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    The purpose of the paper is to show the conditions that determine the disruptive strength of an air path along the surface of a solid dielectric of higher specific inductive capacity, and what steps must be taken to insure the most efficient use of the two dielectrics in combination. Part II of the paper discusses the effect on the electric field between two given terminals of the presence of a solid dielectric. An experimental means of determining the shape of the field is given. An explanation of the conditions that exist at the surface of the dielectric when in an electric field is given. The conclusion is drawn that if the surface of the dielectric be made tangential to the lines of force at every point, the strength of the path between the two given terminals will not be weakened. Part III shows the results of applying this theory to practical purposes, such as insulating a terminal rod passing through a casing, and directing the external field on the standard form of condenser type terminals. In this portion of the paper, several curves are given, showing the distribution of potential over the surface of the dielectric. Part IV gives the summary and conclusions, which are to the effect that breakdowns of an air path over a surface have been obtained, which average as high as 9.4 kv. per cm. effective value (23,900 volts per inch) over a distance of 17.0 cm. (6.7 inches). Conditions of design are such that these same averages may be maintained for any voltage, by increasing all dimensions of the structure proportionately. The strength of the air path in this form of design is independent of the specific capacity of the dielectric, and an important thing, therefore, is to shape the terminals properly in order to obtain a high average intensity over the given path. View full abstract»

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  • The application of a theorem of electrostatics to insulation problems

    Page(s): 773 - 793
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    The arrangement of conductors so that they shall assist in insulating one another has received but little consideration. The object of this paper is to emphasize a principle of electrostatic theory by which this may be done. A statement of this principle is: “If a region in any particular electric field be isolated or cut out by any number of closed surfaces then the electric field in this region will remain unchanged, whatever change may take place in the external field, if the potentials at all points on the enclosing surfaces are maintained at their original value.” A discussion of the principle follows and illustrations of electrostatic fields produced by its means. Limitations imposed on practical applications of the principle are discussed. Application to core-type transformers is considered. Arrangements suitable for various conditions of service are described and a description is given of a transformer which was built according to this principle, and tested. Application to shell-type transformers and to outlet terminals and insulators is shown. Condenser type terminal affords an example of the advantage obtained by conforming to this principle. Suggestions are made as to its application to line insulators. This principle is capable of wide application and seems to afford a solution of some of the most perplexing problems confronting electrical engineers. View full abstract»

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  • Discussion on “notes on underground conduits and cables” (Mosman), Boston, Mass., May 15, 1912. (see proceedings for May, 1912)

    Page(s): 794 - 821
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    A. E. Kennelly: This paper manifestly embodies a large amount of valuable experimental work. It is work, as has been stated, done under very trying conditions, and we are all the more indebted to those who have done the work on that account. We have, it is true, known but little concerning the heating conditions inside ducts, although we know fairly well the heating conditions around a single cable of known dimensions buried at a given depth in the ordinary soil. I do not mean to say that we ought to be content with the knowledge which we have in that direction, but at least we have some knowledge. View full abstract»

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  • Discussion on “power requirements of rolling mills” (Sykes), and “the economical speed control or alternating-current motors driving rolling mills” (Meyer and Sykes), New York, November 8, 1912. (see proceedings for November and December, 1912.) (continued from January, 1913, proceedings, page 84)

    Page(s): 822 - 831
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    A. Dyckerhoff (communicated after adjournment): In going over the paper on The Economical Speed Control of Alternating-Current Motors Driving Rolling Mills, it occurs to me that some statements made in this paper are misleading, and also that many points are not brought out which should be mentioned. While I do not wish to invade the territory of the rolling mill engineer, whose task it is to find out the best rolling methods, and to whose needs the electrical manufacturer has to adapt his machinery in ways consistent with the best engineering practise, I wish to make a few remarks as an electrical engineer connected with steel and rolling mills. I feel myself the more qualified to speak since I had a very good opportunity during the past summer to study in Germany the question of economical speed regulation of a-c. motors, and its reliability in practical application under severe conditions. View full abstract»

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  • Discussion on “industrial lighting” (Eshleman), Cleveland, Ohio, October 23, 1911. (see proceedings for January, 1913)

    Page(s): 832
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Aims & Scope

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

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