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Electrical Engineers, Proceedings of the Institution of

Issue 5 • Date May 1975

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Displaying Results 1 - 25 of 37
  • Corrugated rectangular horns for use as microwave feeds

    Publication Year: 1975 , Page(s): 465 - 469
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (621 KB)  

    The paper reviews and discusses the propagation and radiation characteristics of moderate-flare-angle rectangular horns which have transverse corrugations on two walls. Typical results are presented of measurements made and the extent to which the theory is able to predict the results. View full abstract»

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  • Multilayer acoustic-surface-wave program. Computer-program description

    Publication Year: 1975 , Page(s): 470 - 472
    Cited by:  Papers (11)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    A computer program is described for calculating the acoustic velocity and related field quantities for planar multilayer structures of arbitrary anisotropy and piezoelectricity. The solution method is based on a matrix approach wherein each layer is characterised by a transfer matrix relating the mechanical and electrical variables at the boundary planes. By choosing the system variables to be those quantities which must be continuous at material interfaces, formulating boundary conditions for planar multilayers is equivalent to cascading multipart networks. Thus, the transfer matrix across a multilayer is obtained by chain-multiplying the transfer matrices of successive layers. The chain-multiplication aspect, which is a fundamental consequence of this approach, guarantees that, irrespective of the number of layers, the setting of at most a 5×5 determinant to zero is all that is required to satisfy the boundary conditions. The program also calculates the mechanical and electrical field profiles as a function of depth, and metallic shorting planes can be located at any arbitrary location in the multilayer. The main program consists of four packages: a package for reading, initiating and preparing data; a package for generating the system matrices, evaluating transfer matrices, and setting up the boundary determinant for the required problem; a co-ordinate rotation package; and a mathematical package for carrying out complex eigenanalysis and function minimisation. View full abstract»

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  • Effects of pump noise in parametric amplifiers

    Publication Year: 1975 , Page(s): 473 - 478
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (841 KB)  

    A theory is presented which shows that close-to-carrier noise sidebands on a pump couple onto a signal being amplified by a parametric amplifier so that the signal also acquires noise sidebands. The appropriate coupling coefficients are derived. Experiments are described which confirm the accuracy of the maximum coefficients to within 3 db. View full abstract»

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  • Conformal antenna synthesis using spherical harmonic wavefunctions

    Publication Year: 1975 , Page(s): 479 - 486
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1050 KB)  

    A new antenna-synthesis method is described that allows the antenna surface geometry to be arbitrarily specified and the radiating current distributions to be computed directly from the radiation patterns, which can be quite general and have any type of polarisation: this latter process makes the synthesis procedure nonunique, but is of great practical value since phase information is not required. Illustrative examples based on rotational symmetry are given to show the effect of all the various sources of controllable error, and useful information is also extracted about the formulation of active conformal arrays of small closely spaced noninteracting radiating elements; in particular, a means of optimising a conformal beacon antenna and creating a wide bandwidth supergain system by utilising the closely spaced driven array principle is discussed. View full abstract»

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  • IEE Conference Publication 126. Satellite-communication-systems technology

    Publication Year: 1975
    Save to Project icon | PDF file iconPDF (167 KB)  
    Freely Available from IEEE
  • Development and field testing of a vertical-aerial lightning-flash counter

    Publication Year: 1975 , Page(s): 487 - 491
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (602 KB)  

    A vertical-aerial lightning-flash counter has been developed to replace the CIGRÉ counter, which has a horizontal aerial. Using one-tenth scale models, the relative open-circuit voltage of the two types of aerial, and their capacitances, were measured for various lengths of vertical aerial. A procedure for designing the filter circuit of the vertical-aerial counter, and for selecting the optimum vertical-aerial length was based on the results of the model tests. The objective was to ensure that the frequency response and threshold of the vertical-aerial counter were the same as those of the CIGRÉ counter. Field tests have been carried out, between 1972 and 1974, at three stations in southeast Queensland, one of each type of counter being installed at each station. Various lengths of vertical aerial, two types of aerial insulation and two filter circuits have been used. The circuit currently recommended, used with an aerial length of 3.3 m, gives registrations within 10% of those of the CIGRÉ counter when averaged over several thunderstorms, which is considered satisfactory. As a guide to installation requirements, the effect of nearby obstructions on the open-circuit voltage of both types of aerials was also measured. View full abstract»

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  • Highly reliable transmission-checking scheme for digital data links

    Publication Year: 1975 , Page(s): 492 - 493
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    The paper gives a classification of transmission errors that can affect a binary digital data-transmission system, with a discussion of methods of detecting such errors. Feedback checking offers high security with minimum transmission redundancy. A practical transmission-checking scheme, incorporating feedback, is described, intended for use over short or medium distances. The security provided by this scheme against all classes of transmission error is high, and obtainable without degradation of data-transmission efficiency. View full abstract»

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  • Sidelobe reduction of pulses compressed from pseudorandom binary words

    Publication Year: 1975 , Page(s): 493 - 494
    Cited by:  Papers (1)
    Save to Project icon | PDF file iconPDF (305 KB)  
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  • Active realisation of any stable voltage-transfer function

    Publication Year: 1975 , Page(s): 495 - 496
    Save to Project icon | PDF file iconPDF (252 KB)  
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  • Minimum spanning tree

    Publication Year: 1975
    Save to Project icon | PDF file iconPDF (137 KB)  
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  • Generalised method of assessing polarising signals for the polarised-mho relay

    Publication Year: 1975 , Page(s): 497 - 500
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    This paper considers existing methods of assessing the position of the steady-state operating characteristic of the polarised-mho relay in the R-X diagram, and puts forward an improved generalised method which is ideally suited to computer simulation studies. The new method is applied to existing schemes of protection employed by two British and two Continental relay manufacturers. Consideration is also given to the influence of system earthing on the characteristics of earth fault relays, and a compensation scheme for resistance earthed systems is suggested. View full abstract»

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  • Simulation of fuse performance for co-ordination and testing purposes

    Publication Year: 1975 , Page(s): 501 - 503
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (401 KB)  

    Simulation of fuse behaviour in short-circuit-current breaking is of use in reproducing the limiting conditions of operation, thus enabling solutions of co-ordination and protection problems to be checked. This is particularly so in the case of mechanical switching devices with fuses, (e.g. circuit breakers and fuse-combination units) where simulation is of use in determining make and break capabilities and ability to withstand current. The paper discusses the basis on which the behaviour of fuses with predetermined parameters may be simulated, and presents results for a standard and an experimental fuse. View full abstract»

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  • Simplified low-overcurrent test method for sand-filled fuses

    Publication Year: 1975
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (130 KB)  

    The summary reports on a comprehensive fuse-testing programme designed to assess the suitability of an alternative less expensive test procedure to those presently recommended in IEC standards for low-overcurrent fuse-proving tests. Statistical treatment of many circuit measurements and fulgurite quantities demonstrates the similarities between test methods and low-overcurrent arcing behaviour in fuses at 380 V, 50 Hz. View full abstract»

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  • Setting response of generalised comparators for distance protection

    Publication Year: 1975 , Page(s): 505 - 506
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (314 KB)  

    In distance protection, the magnitude of the signals from which measurements are made are subject to wide variation according to system operating and fault conditions. The necessity to preserve protective integrity precludes the use of comparator circuits with extreme sensitivities, and some deterioration in performance occurs near the setting. The paper examines the setting response of generalised phase comparators, the principles of which have been outlined in other papers. Criteria for optimising responses are given, and it is shown that the new device is inherently very accurate. The paper concludes by comparing the response with that of a practical alternative. View full abstract»

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  • Novel approach to the analysis and synthesis of modulation processes in power convertors

    Publication Year: 1975 , Page(s): 507 - 513
    Cited by:  Papers (85)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (798 KB)  

    It is axiomatic that frequency changing, whether it be in communications or power convertors, can only be achieved by a process of modulation. The paper presents a powerful method of analysing and synthesising these complex modulation processes using a 3-dimensional modulation-model approach, which provides a lucid geometric interpretation of the processes involved. The application of the new approach is demonstrated by deriving new frequency-spectra results for the p.w.m. and p.a.m. convertors, thereby providing essential design information. View full abstract»

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  • Thyristor choppers using a bridge-connected capacitor for commutation

    Publication Year: 1975 , Page(s): 514 - 516
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (443 KB)  

    A thyristor d.c. chopper may utilise a capacitor connected within a bridge of four thyristors for forced commutation instead of the more common resonant LC circuit. Consideration is given to the main forms that such chopper circuits may take, and it is shown that, of the various modes of operation, three depend upon parallel-capacitor commutation, whereas one relies solely on series-capacitor commutation. It is concluded that choppers operated in the first three modes are easier to design than more conventional choppers, although, in general, their advantages are roughly balanced by their disadvantages, except for particular applications such as traction. The fourth mode results in a chopper having inherently safe commutation, even on considerable overload, and this offers a unique advantage over conventional choppers. View full abstract»

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  • Reliability evaluation in distribution and transmission systems

    Publication Year: 1975 , Page(s): 517 - 524
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (852 KB)  

    This paper illustrates a relatively direct and sequential method of performing reliability calculations in transmission and distribution systems. The equations provided in the paper are utilised through a minimal-cut-set approach to failure modes and effects analysis, and can be used to obtain quantitative reliability indices in a wide range of systems. The equations, though complex in appearance, are fairly simple in their formulation and utilise only simple mathematical operations. This results in very efficient computer utilisation, since the equations can be permanently stored, and used when required. The application of the concepts presented in the paper are illustrated by the analysis of two practical system examples. View full abstract»

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  • IEE Conference Publication 125. Developments in power-system protection

    Publication Year: 1975
    Save to Project icon | PDF file iconPDF (143 KB)  
    Freely Available from IEEE
  • Optimal scheduling of hydroelectric-power generation by multilevel-control techniques

    Publication Year: 1975 , Page(s): 525 - 534
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (877 KB)  

    The multilevel control of large systems intended to distribute between several control levels, the calculation of optimum set points and the use and calculation of optimum control laws are based upon the concept of decomposition-co-ordination of the overall optimisation problem. For the nonseparable problem examined, it is necessary to use a fomulation of the decomposition-co-ordination principle different from that used for separable problems. Decomposition methods (recognition of coupling variables, introduction of pseudovariables) and coordination algorithms are described briefly. The problem of optimum power scheduling in an hydroelectric system, representing an example of a typical nonseparable optimisation problem, is discussed. Various decomposition co-ordination methods are proposed, and a concrete example is examined which shows the effectiveness of multilevel control techniques applied to very highly nonseparable problems. View full abstract»

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  • Generator loading limits for impulse testing low-inductance windings

    Publication Year: 1975 , Page(s): 535 - 538
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    The performance of the conventional resistance-front-control (r.f.c.) impulse generator, the inductance-frontcontrol (i.f.c.) generator and the modified resistance-front-control (m.r.f.c.) generator, during testing of lowvoltage, low-inductance windings, have been analysed. Expressions have been developed, which enable prediction of the generator parameters for the production of standard lightning impulse waves. These are then extended to find the respective loading limits, beyond which a standard wave cannot be produced. The loading range, over which each type of generator is best utilised, has been ascertained. View full abstract»

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  • Development of a new range of e.h.v. heavy-duty airblast circuit breakers

    Publication Year: 1975 , Page(s): 539 - 544
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (876 KB)  

    The paper outlines the design and development of a new range of heavy-duty high-pressure airblast circuit breakers. The interdependence of the design concept, the specifications, the testing-station capability, and testing techniques are examined. A description of the construction of the circuit breaker is given and the operating characteristics are discussed. Direct coupling of the contacts to the operating mechanism allows faster operating times to be achieved. The positioning of the blast-valves, relative to the nozzles, allows a relatively small volume of air to be discharged, and this improves the effectiveness of the integral multistage silencers which reduce the noise level to acceptable limits. The decision to operate at 6 MPa [900 lb/in2(g)] enables full advantage to be taken of the increased testingstation output which results from the establishment of synthetic-testing techniques. Type-test specifications and the type-test programme are considered, with particular attention to the short-circuit development work. The synthetic test circuits which introduced a power-frequency recovery voltage, as well as the necessary transient recovery conditions are illustrated. The value of this technique was shown by the discovery of a late-breakdown phenomenon, which would not necessarily have been apparent had the simpler d.c. synthetic testing techniques been used. The characteristics of the ancillary components and their effects on the performance are also discussed. Aspects of the insulating properties of high-pressure compressed air are discussed, together with the dielectric characteristics of the solid insulation. View full abstract»

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  • Discussion on "Lower-cost urban electricity-distribution systems by automatic control. Application to 11 kV and 33 kV systems"

    Publication Year: 1975
    Save to Project icon | PDF file iconPDF (191 KB)  
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  • Discussion on "Transformer multiflow hottest-spot rating: proposed standard specification"

    Publication Year: 1975 , Page(s): 545 - 546
    Save to Project icon | PDF file iconPDF (290 KB)  
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  • Computation of electrical field and potential around stranded conductor by analytical method and comparison with charge-simulation method

    Publication Year: 1975 , Page(s): 547 - 550
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (358 KB)  

    The electric field and potential around a stranded conductor are computed by an analytical method. The results obtained by the analytical method are compared with those obtained by the charge-simulation method to check the accuracy of the latter, which is much easier than the analytical method. View full abstract»

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  • Eddy-current losses in unbonded tubes

    Publication Year: 1975 , Page(s): 551 - 557
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (727 KB)  

    A series solution for the eddy-current loss in thin isolated cable sheaths, busbar enclosures, water cooling pipes etc. has been developed using Carter's method. The theory, which takes into account the magnetic field set up by the tube eddy currents themselves, can be applied to any system where the primary conductor current within a tube is coaxial with the tube, and the materials are nonmagnetic but not necessarily of equal dimensions or resistance. For convenience, the paper provides loss curves for the most common arrangements, i.e. 3-phase flat and trefoil. Results obtained using existing simplified formulas are compared with the computed results, and are shown to be in error by 10% and upwards for diameter/spacing ratios of more than 0.2 and values of frequency/tube-resistance greater than unity. The theory has been further extended to thick-walled tubes for which a correction factor has been derived. 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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