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Electrical Engineers, Proceedings of the Institution of

Issue 10 • Date October 1975

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Displaying Results 1 - 9 of 9
  • Mobile v.h.f. and u.h.f. radio systems in the UK

    Page(s): 953 - 958
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (4939 KB)  

    Mobile radio systems, operating in the v.h.f. and u.h.f. bands, are widely used in the United Kingdom for short-range land, maritime and aeronautical services. In tracing the growth of these services the preponderance of land-mobile units is evident, and the review concentrates on land-mobile aspects, referring to the others mainly when differences in equipment or practice are significant. Developments in equipment and systems are reviewed, and selected units and installations are briefly described. The market for new and replacement equipment is estimated, and possible savings through the use of mobile radio are discussed. Other systems such as paging, which use the same frequency bands or techniques as mobile radio, are enumerated, and their operation and merits examined. One Section is devoted to the design of selected sections of equipment and another to the estimation of range. Typical figures for land-mobile systems are tabulated. The ever present problems of frequency selection, interference and noise are reviewed. The two main, and several proposed, systems of modulation are compared, and their future possibilities discussed. Final Sections examine reliability and testing, possible future developments and problems. Some possible lines of progress are deduced. A carefully selected, rather than a comprehensive, list of references is given. View full abstract»

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  • Telephone-traffic techniques

    Page(s): 979 - 992
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    Given well designed and reliable equipment, the efficiency of a telecommunication system depends on having sufficient equipment to meet requirements for normal service, with a reasonable margin for peak traffic. At the same time, the cost of the network must be low enough to permit the provision of an efficient service to the subscriber on acceptable terms. The determination of the amount and arrangement of equipment, so as to achieve an optimum balance between service and cost, is one of the most important aspects of telecommunication-system design, which has attracted the attention of engineers and mathematicians since the early days of telephony. Modern technical developments, including the application of electronic switching and control techniques, have posed many new traffic problems. This review deals with the general principles of telecommunication traffic, and their application to exchange and network engineering. View full abstract»

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  • Development, design and use of ripple control

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    Many of the earlier patents for ripple control were British, and the development of the single-frequency systems was pioneered in Britain. Nevertheless, interest in these systems lapsed in the UK after the Second World War, whereas in Europe it increased until in many countries ripple control of consumers' loads became standard practice. The paper reviews the history of the development of ripple control, and indicates how differences in time-switch design and the structure of the industry may have helped to create this divergence in practice. It describes the design of the main systems of control now in use, the choice of frequency, their high standard of reliability and their ability to send 1000 or more separate instructions for load or system switching. It also reviews the development on the Continent of distribution-control centres employing ripple control backed by a computer to maintain the maximum demand on the system below a target level set for the winter. This operates by dividing the consumers into groups, and switching them in turn as required to keep the total load below the target level. It also ensures that each consumer receives the energy he requires under his agreement. The economics of ripple control are reviewed, and the variety of applications for a modern sophisticated system are outlined. View full abstract»

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  • Overhead-line practice

    Page(s): 1009 - 1017
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    Overhead lines have been in use in the UK since the beginning of electricity supply, those erected prior to 1882 being based on American practice. The 1882 Act established rules regarding the consent for the erection of lines, but made no reference to technical considerations. Further Electricity Acts followed, but it was not until 1928, when the UK Electricity Commissioners issued their first general code, ELC 53, that there was any great change towards modern-day practice. The British electricity boards' specifications are developed from the BS1320 design for 11 kV and BEBS L1 for m.v. The latest work on line design is in consequence of the revised Overhead Line Regulation (statutory instrument 1355, 1970), and the industry's adoption of the metric system. The modern standards will differ from previous ones as all components will have their own standards. The supply industry produces the standards, which, where applicable, are accepted by Department of Trade and Industry as conforming to the Electricity Supply Regulations. Conductors represent some 45% of the total cost of overhead lines and for the sake of economy aluminium has replaced copper as the material used. There are problems in the use of aluminium, but these have been overcome by the development of differing designs of components and the development of fittings and connectors. The development of the bimetallic-compression joint has removed the corrosion problem in the connection of copper to aluminium. The m.v. system has changed to discrete systems around transformers with no interconnection between them, and the modern standard will cater for this, together with new methods of servicing. The advent of the BS1320 specification permitting unearthed systems, and the development of the highspeed autoreclosing circuit breaker have revolutionalised the performance of 11 kV overhead systems. Insulators have varied little over the years, but the manufacture of glass insulators has now ceased in the UK and t- - he production of porcelain ones is limited. The introduction of resin-bonded glassfibre in the construction of insulators opens up a new field in design. While earlier developments improved the operational characteristics of 11 kV lines, the addition of hot-stick maintenance techniques from America and the development of live-line connection methods by area boards in the UK is changing the maintenance philosophies of the boards and the training of the staff. It is obvious that the preservation of timber has been a problem that has exercised the minds of engineers over the years. The prime preservative has been creosote, although water-based preservatives are available and have been tested. Rot occurs in poles due to fungi, and several methods available for combating it are discussed. The rural electrification programme in the UK, as required by the 1947 Act, has been completed in the last five years, and the present construction requirement is only for short extensions and reinforcements. The emphasis in the future will be on the maintenance of lines with the consequential changes in the design of tools and equipment and the training of labour. The length of overhead lines in operation is shown in Table 1. View full abstract»

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  • Electrical standards of measurement. Part 1: D.C. and low-frequency standards

    Page(s): 1018 - 1036
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    The paper reviews recent developments in electrical masurement techniques in the context of the UK national standards maintained by the National Physical Laboratory. Part 1 describes the primary electrical standards, their derivation from the SI units, and their relation to the standards maintained by the International Bureau of Weights and Measures. From the primary standards a number of working standards are derived and used for the calibration of other laboratories' reference standards. These include the essential step of a.c./d.c. transfer. In recent years there have been a number of important advances in the techniques of accurate measurement, including the development of independent means of monitoring the stability of the primary standards and of improved null detectors, ratio devices and thermal voltmeters. These have found application not only in electrical standards but also in the measurement of the magnetic properties of materials. Parts 2 and 3 of this paper extend the discussion of standards to the microwave and submillimetre-wave regions. View full abstract»

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  • Electrical standards of measurement. Part 2: R.F. and microwave standards

    Page(s): 1037 - 1053
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    The review covers standards and measurement techniques for guided waves in the frequency range from about 1 MHz to 100 GHz. The organisation for the provision and dissemination of microwave standards, which has been established in the UK in recent years, is described. Standards have been provided for the measurement of power, attenuation, impedance and noise in coaxial line and waveguide. A brief description of the application of these standards and measurements of the dielectric properties of materials is included. View full abstract»

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  • Electrical standards of measurement. Part 3: Submillimetre-wave measurements and standards

    Page(s): 1054 - 1070
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    In the submillimetre-wave region (100GHz¿10THz), standards are not so well established as at lower frequencies. New measurement techniques are being developed and are finding application in a variety of technological fields with a consequent growth in the need for standards. This part of the paper starts by reviewing recent developments of sources, detectors and measurement systems based on Fourier-transform spectrometry. Standards of frequency have been set up using stabilised lasers, and standards of power and energy have been developed. A number of applications of submillitre-wave measurement techniques are discussed, including redetermination of the speed of light, measurement of the electrical properties of materials, environmental standards for pollution in the stratosphere, and plasma diagnosis for research on fusion reactors. View full abstract»

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  • Direct-voltage references

    Page(s): 1071 - 1076
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    Precise sources of e.m.f have existed mainly in three forms: the electrolytic cell, the gas-discharge tube and the avalanche or Zener diode. The paper attempts to place these various voltage-reference devices in historical and technical perspective. The properties of several types of cell are given, followed by a similar treatment of glow-discharge and corona-discharge tubes and finally a rather fuller account of the Zener diode and other solid-state elements. The relative merits of all these reference devices are then discussed. The paper concludes with an outline of some of the latest techniques for the successful use of these devices. The list of papers to which reference is made includes most of the original texts. View full abstract»

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  • Computer-aided management techniques

    Page(s): 1077 - 1088
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    The paper outlines the areas in which computers are of significant assistance to management, and the nature of the assistance given. The evolution of management techniques, in so far as it is relevant to the theme, is compared with the evolution of commercial data-processing systems. A progression from a state of maximum conflict between management and computer systems to a potential identity of purpose becomes apparent. Five major examples are examined, the bureau services and packages available to any user, airline-seat-reservation systems, the Stock Exchange, point-of-sale systems, and in-house systems. Each is typical of a larger group of applications. Implications of the examples are considered against a consistent framework of management requirements based on the hierarchical structure of management. Major trends over the next five years are identified, and the prospect of a senior manager `driving¿ a large organisation via a computer terminal is examined and dismissed as impracticable. 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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