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American Institute of Electrical Engineers, Transactions of the

Issue 4 • Date April 1942

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Displaying Results 1 - 12 of 12
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  • A New Instrument for Recording Transient Phenomena

    Page(s): 175 - 177
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    In many cases it is of great importance to study phenomena which do not occur periodically. Such phenomena, called transients, arise, for example, at the time a short circuit appears in a power line, during the discharge of the condenser of a spot- welding machine, during the starting of electric machinery, and on very many other occasions. Most of the instruments available thus far for investigation of transients employ the method of film recording, which has the disadvantage of requiring a developing process. A new transient recorder has been developed, employing magnetic-tape recording as a means of preserving the record of a transient and steadily repeating this record on the screen of an oscilloscope. This method has the advantage that is requires no processing and that the same magnetic carrier can be used continuously without loss of material. View full abstract»

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  • Progress in Development of Trolley-Coach Overhead Reflected in Higher Service Standards

    Page(s): 185 - 191
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    The expansion of trolley coach operation to include 50 transit systems in the United States and Canada has been greatly helped by the progress made in the development of overhead distribution materials. Beginning with the installation of the first transit-type trolley coaches in Salt Lake City in 1928, the inadequacy and limitations of the earlier designs of equipment were recognized. Since 1928 it has been necessary to add many new devices and redesign many old devices to provide better reliability and permit of greater flexibility of operation. The development of trolley-coach overhead materials has been concentrated mainly on 1. Current collection 2. Hangers and insulation 3. Curve materials 4. Turnouts and crossovers The improved current collection equipment incorporating the carbon-insert shoe has been responsible for the reduction of wear on fittings and trolley wire. The carbon-insert shoe has also been responsible for the complete elimination of trolley-wire lubrication formerly required for the all-metallic shoe collector. Improvements in insulated hangers have resulted in a more dependable distribution system and have been responsible for the elimination of considerable secondary insulation formerly inserted in the supporting span wire between positive and negative trolley wires. View full abstract»

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  • The Electrical Strength of Nitrogen and Freon Under Pressure

    Page(s): 191 - 195
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    Results are given of an investigation of the electric strength of nitrogen, of dichlorodifluoromethane (Freon F-12), and of mixtures of these gases. Sparking voltages are presented as measured between spherical electrodes of brass and aluminum and between pointed electrodes of brass, at various spacings, and in gas at pressures ranging from one to several atmospheres. All measurements are for 60-cycle applied voltage. Dichlorodifluoromethane is found to withstand much higher voltages than either air or nitrogen; this advantage is more marked between points than between spheres, which suggests its use in certain types of insulation applications. A small percentage of dichlorodifluoromethane gas in nitrogen produces an anomalously large rise in the electric strength of the gas, indicating practical advantages of such mixtures. View full abstract»

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  • Supplementary Control of Prime-Mover Speed Governors

    Page(s): 209 - 214
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    It appears that the greatest improvement in over-all system frequency and tie-line regulation will be brought about by further improvement in the composite regulation of the system governing and by more widespread and co-operative application of supplementary control equipments which are already developed. View full abstract»

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  • PCC Car Operating Results In Pittsburgh

    Page(s): 214 - 217
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    The problem created by the decline in transit revenues during the depression led the Pittsburgh Railways Company to initiate a long-range service-betterment program. The most important phase of the plan was the use of modern street cars, as developed by the Presidents' Conference Committee, to replace the earlier types of rolling stock on the property. With 301 of these PCC cars in service, and 100 additional units scheduled for early delivery, sufficient data are available to show exceptionally favorable operating results. Actual experience in service has demonstrated that car maintenance comes down 28 per cent, track and roadway maintenance drops 21 per cent, accidents decrease 25 per cent, the number of cars required for specific schedules is reduced 10 per cent, and revenues increase 8 per cent. This favorable outcome has caused continued expansion in the use of such equipment and established a superior urban-transit service View full abstract»

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  • Single-phase A-C electric locomotives on the Pennsylvania Railroad - protection and tonnage rating

    Page(s): 224 - 228
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    The single-phase electric locomotive is thought of quite generally as a piece of motive power for heavy traction service. To an electrical engineer, however, it consists fundamentally of electric motors geared to wheels with means for controlling the applied voltage to handle a variable load at varying speeds. From this point of view it is interesting to consider the protective features of the motors and their associated electrical apparatus to develop devices and methods which are necessary to guard against the hazards common to the operation of all electrical devices and those special to an electric locomoive. This paper will consider these features as they apply to the electric locomotives operating on the Pennsylvania Railroad. View full abstract»

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  • Modern Electrical Equipment for Industrial Diesel-Electric Locomotives

    Page(s): 229 - 232
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    Modern electrical equipment for industrial Diesel-electric locomotives is widely different in many respects from that used five or six years ago. New and improved high-temperature insulating materials and modern synthetic varnishes have been developed and are used extensively today. Also new and improved methods of using these and the older materials have been developed. These, together with new design constants, have made possible a reduction in weight per horsepower transmitted with an improvement in the quality of the product. The Diesel engine and generator are close-coupled and mounted as a unit, thus assuring proper alignment and, at the same time, reducing the space required for mounting on the locomotive. A new and improved method of generator excitation has been developed which assures positive control of the engine speed and power. This provides a very flexible transmission of power from the prime mover to the rail. The modern traction motor has a cylindrical instead of a rectangular frame. It is a multipole instead of the conventional fourpole design. It is mounted integral with a double-reduction gear unit which is completely enclosed in an oiltight gear case. All bearings on the motor armature shaft and in the gear case are antifriction except those on the axle, which are sleeve bearings. All bearings in the gear unit are oil-lubricated with the same oil that lubricates the gearing. Both the high and low speed pinions are straddle-mounted to insure proper alignment of the gearing at all times. View full abstract»

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