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Electrical Engineers, Proceedings of the Institution of

Issue 10 • Date October 1976

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Displaying Results 1 - 5 of 5
  • High-voltage switchgear

    Page(s): 1053 - 1080
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    The paper begins by summarising the way in which the design of high-voltage (above 1 kV) switchgear has been affected by changes in the constitution of the manufacturing industry, both nationally and internationally, by advances in the knowledge and theory of arcs and circuit breaker operation, and by changing tendencies in service conditions that influence specification, rating and testing requirements. It describes the greatly increased application of circuit breakers and totally enclosed switchgear using sulphur hexafluoride as an arc-quenching medium and insulant, the commercial breakthrough of the vacuum interrupter and the universal acceptance and use of synthetic methods of testing circuit breakers. It then deals with ratings and service requirements, research and the theory of arcs and circuit breakers, standardisation and switchgear testing. It concludes by illustrating, with examples, the current trends in the design of apparatus, especially circuit breakers, and the layout and equipment of switchboards and substations. View full abstract»

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  • Active element in submerged repeaters: first quarter century

    Page(s): 1081 - 1112
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    The review links the development of British submarine telephony during the last 25 years with the development and production of the active elements, thermionic valves and silicon planar transistors, in the submerged repeater amplifiers. These devices have played a major role in determining the performance, capacity and reliability of all submarine transmission systems. While concentrating on the work of the British Post Office Research Department the complementary role played by industry, and by Standard Telephones and Cables in particular, is recognised. British effort has been encouraged and stimulated throughout by the other major submarine development organisation, Bell Telephone Laboratories in the USA. The development in France of active devices for submarine systems has also been noteworthy. The work on oxide-cathode thermionic valves between 1950 and 1965 is mainly the history of a research and development effort aimed at improving the electrical reliability of the devices. Only in the latter part of the period was any major attempt made to improve valve performance and, consequently, the capacity of submarine systems. The use of systems incorporating valves extends from shallow-water cables around the UK to transatlantic and trans-Pacific cables which have completed a transmission link more than half-way round the world. The target of a 20-year system life, free from failures arising from the decay or collapse in the performance of the valves, has already been achieved for one of the early systems. One of the major links (CANTAT-1, between the UK and Canada) has now passed the 14th year of service satisfactorily. The era of silicon planar transistors, replacing the thermionic valves in submarine systems, started in 1961 and is still continuing. The twin targets of improving performance and reliability were equally stressed during the whole period from 1961 to date. The success in improving device performance is demonstrated by the capacity of the early tran- - sistorised systems, 640 (3kHz) circuits, almost double that achieved in the last valve system. Transistor performance has improved still further to provide 1840 circuits in the last transatlantic cable (CANTAT-2, laid in 1974) and later device developments will more than double this figure. The importance of this achievement rests, however, on the maintenance of ultrahigh reliability as an essential feature of performance improvement. An advanced technique for reliability assessment has enabled predictions of less than one active-element failure in a system life of 20 years to be made. It has only been possible to reach this level of reliability by careful design of the transistor and of the processes by which it is made, supplemented by a rigorous system of quality control imposed on materials, piece parts and assembly techniques. Experience of the first eight years of operational use on the sea bed is supporting the reliability predictions. For the future, it is believed that the foundations necessary to support the British effort in this important area of international communications have been well laid. Nevertheless, technical innovation is needed more than ever before to maintain a competitive position in the face of increasing overseas interest in the art of submarine telephony. View full abstract»

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  • Noise measurement and evaluation

    Page(s): 1113 - 1137
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    This review outlines the history of noise measurement in the `pre-electronic¿ era, and then goes on to describe current practice. The first five Sections are devoted to the `engineering¿ aspects of the subject, i.e. the methods used to make physical measurements of noise parameters viewed as a series of pressure fluctuations in the air. As well as measurements at normal levels in the normal audio-frequency range, special techniques for unusually high and low frequencies and pressure levels are described, together with integrating techniques to determine the total sound output from sources. The second half of the review is devoted to techniques of noise evaluation. This subject, which is currently an area of more activity than the physical measurement side, deals with the relationship between the measurable physical parameters of the noise and its effects on the human organism. These effects include annoyance, discomfort, interference with communication, and damage to hearing. They are due not only to noise in the audible-frequency range, but also to low-frequency and infrasonic noise. Those areas are indicated where present knowledge is limited and further research and standardisation are required. View full abstract»

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  • Review of trends of large hydroelectric generating equipment

    Page(s): 1138 - 1162
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    The paper reviews the trends in the development of hydroelectric generating equipment for conventional and pumped-storage plants over the past 25 years. The growth in unit capacities, sizes and operating head ranges is outlined for various types of turbines. The features in generator design required to meet the growth of unit capacities are discussed for low-speed and high-speed machines. This review includes trends in hydraulic, mechanical and electrical design which have made the growth a reality. The mechanical and electrical auxiliaries, such as governors, static excitation equipment, static protection relays, digital controls, pump-motor starting and braking equipment, are also discussed. View full abstract»

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  • Death by lightning

    Page(s): 1163 - 1180
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    Modern knowledge of the amplitudes and waveshapes of lightning currents enables a method of determining the electrical effects of a direct lightning stroke to be established. It has been shown that this entails an initial current discharge through the body, followed by an external flashover. The amplitude and waveshape of the current flowing through a body can thus be determined. The phenomenon of a back flashover, which is a familiar concept to h.v. transmission engineers, is paralleled by the so-called side flash to a person or animal, e.g. when sheltering under a tree or in close proximity to a metal fence. Another possibility is a direct stroke to earth, producing so high a potential drop over the ground surface as to paralyse or shock people over a wide area. From the medical point of view, it is important to apply this knowledge to understand the nature of the current and its pathway through the body. It may then be possible to postulate the possible effects of the lightning stroke on the different bodily systems. While clearly it is not possible to test these conclusions by planned investigations, they may be examined in the light of reported observation from accidents. View full abstract»

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Aims & Scope

The Proceedings of the Institution of Electrical Engineers was published by the IET between 1963 and 1979.

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