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Electrical Engineers, Proceedings of the Institution of

Issue 6 • Date June 1969

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Displaying Results 1 - 25 of 42
  • Basis for a mathematical theory of direction-defining radio beacons

    Publication Year: 1969, Page(s):901 - 904
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (716 KB)

    A study of the relative performance factors of conventional radio ground beacons provides the necessary evidence for the postulation of an `ideal¿ direction-defining beacon, and this, in turn, permits the identification of the limitations of practical systems. Theory confirms that signal-amplitude-comparison and phasecomparison systems are equivalent, but practical considerations lead to the conc... View full abstract»

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  • V.H.F. and u.h.f. propagation measurements in irregular terrain

    Publication Year: 1969, Page(s):905 - 910
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (697 KB)

    Field-strength recordings have been carried out in irregular terrain at 100, 480 and 780 MHz. At ultrahigh frequencies, the frequency dependence of propagation has been deduced in order to improve on CCIR curves. Terrain-correction values are presented which should be applied when using CCIR curves in bands IV or V. The field strengths recorded behind different obstacles show the frequency depende... View full abstract»

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  • Influence of the ground near transmitting and receiving aerials on the strength of medium-frequency sky waves

    Publication Year: 1969, Page(s):911 - 919
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1365 KB)

    The strength of the low-angle sky waves radiated by a medium-frequency aerial depends on the conductivity of the ground extending for many wavelengths in the direction of propagation. The field strength is greatest if the aerial radiates over open sea from the coast, and falls to a limiting value as the distance between the aerial and the sea increases. Measurements confirming the theoretical vari... View full abstract»

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  • Line feeds for paraboloids

    Publication Year: 1969, Page(s):920 - 922
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (325 KB)

    As a feed for a paraboloid, an endfire-line source facilitates polarisation diversity while having beamshaping potential for high efficiency. The geometrical limitations on the use of an endfire-line source as a feed for a Cassegrain aerial are examined and found to be no more stringent than those on the use of the Cassegrain system itself. In a Cassegrain aerial, the hyperboloid is usually in the... View full abstract»

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  • Antenna-system design of the ISIS-A scientific satellite

    Publication Year: 1969, Page(s):923 - 932
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1812 KB)

    ISIS-A is the first scientific satellite of the ISIS programme equipped with sufficient instrumentation for simultaneous measurements of almost all ionospheric parameters. An antenna complement of 13 radiators is used for telemetry, command, beacon and experimental purposes. This paper describes trends, and techniques used, in the design of the antenna systems on board the satellite. View full abstract»

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  • Technique for the measurement of standing-wave ratios at low power level

    Publication Year: 1969, Page(s):933 - 940
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (641 KB)

    This paper describes a technique for the measurement of large standing-wave ratios which is closely related to the standard method of Roberts and von Hippel. The latter method gives rise to errors of uncertain magnitude when the minimum field strength of the standing wave, approaching the general noise level of the detector system, can no longer be accurately established. The new method entails ma... View full abstract»

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  • Channel-dropping filter for millimetre waves in circular waveguide

    Publication Year: 1969, Page(s):941 - 946
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (764 KB)

    Low-loss waveguide, operated at millimetre wavelengths in the circular H01 mode, is likely to offer a spectrum of usable frequencies for overland trunk telecommunications, extending over more than 10 GHz. To utilise this vast bandwidth effectively requires groups of channel-dropping filters, each separating out a single channel covering 200¿500 MHz. The difficulty is to carry out this operation w... View full abstract»

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  • Three-valued digital systems

    Publication Year: 1969, Page(s):947 - 954
    Cited by:  Papers (15)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1167 KB)

    A survey is presented of the developments in algebras and techniques for the realisation of 3-valued switching functions. Digital arithmetic, ternary codes, composition algebras, minimisation, circuits and sequential circuit design are discussed. The feasibility of 3-valued digital systems is demonstrated View full abstract»

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  • Echo suppressors for telephone connections having long propagation times

    Publication Year: 1969, Page(s):955 - 964
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1512 KB)

    The paper describes the principles on which the new types of echo suppressor have been designed. The performance achieved, particularly as regards mutilation, is limited by the present condition of telephone networks; if return losses could be increased, the designcould be suitably modified to take advantage of these. The methods used for theoretical analysis of the behaviour of echo suppressors i... View full abstract»

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  • M.M.F.-harmonic effects in induction motors with phase-wound rotors

    Publication Year: 1969, Page(s):965 - 970
    Cited by:  Papers (4)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (765 KB)

    While the influence of m.m.f. harmonics on the winding inductances of practical induction motors with phase-wound secondaries is extremely small, their effect on the current waveforms may be profound. The problem posed by this phenomenon is readily stated in terms of dynamic circuit theory, but the standard transformation techniques do not facilitate a solution. A method of direct solution of the ... View full abstract»

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  • Discussion on "Statistical methods applied to the control of loadings of h.v./m.v. transformers on a distribution network"

    Publication Year: 1969, Page(s):971 - 972
    IEEE is not the copyright holder of this material | PDF file iconPDF (322 KB)
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  • Transverse edge effects in linear induction motors

    Publication Year: 1969, Page(s):973 - 979
    Cited by:  Papers (15)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (701 KB)

    Currents in the secondary member of a linear induction motor flow in roughly elliptical paths. The secondary appears to have a resistivity greater than the natural value, and the cross-gap flux density peaks towards the edges of the stators. This phenomenon is known as the transverse edge effect. In most previous work, the edge effect has been allowed for only by the use of a resistivity-increase ... View full abstract»

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  • Preliminary investigation of an invertor-fed 5-phase induction motor

    Publication Year: 1969, Page(s):980 - 984
    Cited by:  Papers (65)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (478 KB)

    The paper reports some preliminary experiments on an invertor-fed 5-phase induction motor, and shows measured values of instantaneous current and torque. These are compared with the values predicted by a dual analogue. The amplitude of the torque fluctuation is approximately one third of that of the corresponding 3-phase motor. View full abstract»

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  • Short-circuit contribution of large induction motors

    Publication Year: 1969, Page(s):985 - 990
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (689 KB)

    The relatively slow operation of short-circuit protection in the past allowed adequate time for the currents generated by induction motors to decay to an insignificant magnitude. Progress in protection techniques introduced rapid fault clearing and, in consequence of that, the fault-current contribution of induction motors can no longer be neglected. The paper describes a series of tests carried o... View full abstract»

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  • Steady-state oscillation and stabilisation of variable-frequency invertor-fed induction-motor drives

    Publication Year: 1969, Page(s):991 - 999
    Cited by:  Papers (9)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (900 KB)

    The steady-state stability of induction motors fed from variable-frequency invertors is investigated by a linearised analysis which is an extension of that given by Rogers, and experimentally from light-load tests on 30hp and 50hp machines fed from d.c.-link invertors over a frequency range of 0¿40Hz. Attention is centred on stability boundaries in terms of the d.c.-link voltage and the invertor ... View full abstract»

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  • Discussion on 'Application of rectifiers to British Railways a.c. motive power'

    Publication Year: 1969, Page(s):1000 - 1002
    IEEE is not the copyright holder of this material | PDF file iconPDF (545 KB)
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  • Approximate formula for the eddy-current loss induced in a long conductor of rectangular cross-section by a transverse magnetic field

    Publication Year: 1969, Page(s):1003 - 1008
    Cited by:  Papers (3)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (734 KB)

    A formula is derived for the eddy-current loss produced in a long conductor of rectangular cross-section, with dimensions not exceeding 6 times the skin depth of the material, by a transverse magnetic field which varies sinusoidally with time. The field is uniform and perpendicular to one side of the conductor. The derivation is based on a numerical solution of the problem, using the finite-differ... View full abstract»

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  • Discussion on "Thyristor-supplied tandem cold mill"

    Publication Year: 1969, Page(s):1008 - 1010
    IEEE is not the copyright holder of this material | PDF file iconPDF (437 KB)
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  • Travelling magnetic waves in electrical machines described by rotating vectors

    Publication Year: 1969, Page(s):1011 - 1013
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (438 KB)

    In the special case of machines with rotor dimensions small compared with the wavelength, the travelling-wave description of the magnetic field gives little insight into the forces and torques that might be expected. It is shown that a more local description of the field in terms of contrarotating vectors can lead to a simple explanation of the behaviour of these machines. View full abstract»

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  • Discussion on "Study of fault levels on supply networks"

    Publication Year: 1969, Page(s):1013 - 1017
    IEEE is not the copyright holder of this material | PDF file iconPDF (792 KB)
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  • Calculation of nonlinear circuits for surge-voltage protection

    Publication Year: 1969, Page(s):1018 - 1030
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1445 KB)

    The paper gives some general solutions of 2-element circuits involving nonlinear resistances combined with ohmic resistance, transmission lines, inductance or capacitance. Solutions are given so that many practical problems of using surge arresters for the protection of transmission lines can be readily solved for realistic surge-voltage waveforms. The inductive- and capacitative-circuit solutions... View full abstract»

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  • High-voltage distribution switchgear. Review of progress

    Publication Year: 1969, Page(s):1031 - 1045
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (2441 KB)

    The paper describes the main fields of application of switchgear in the range 1¿100kV, and the requirements of rating to which these applications give rise. After some notes on research and development, theory, standardisation and testing, some developments in materials are discussed, and the paper concludes with an account of developments in the layout and construction of switchboards. Although ... View full abstract»

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  • Static double-phase comparator for distance protection

    Publication Year: 1969, Page(s):1046 - 1047
    IEEE is not the copyright holder of this material | PDF file iconPDF (243 KB)
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  • Levitation force as a function of rate of change of impedance with respect to distance

    Publication Year: 1969, Page(s):1047 - 1048
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | PDF file iconPDF (286 KB)
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  • D.C.-switched reluctance motor

    Publication Year: 1969, Page(s):1048 - 1049
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | PDF file iconPDF (288 KB)
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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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