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1887

Proceedings of the Institution of Electrical Engineers

Volume 118, Issue 5, May 1971

Volumes & issues:

Volume 118, Issue 5

May 1971

Radiation from Alford aerial in a warm plasma
  • Author(s): I.L. Freeston  and  R.K. Gupta
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 118, Issue 5, p. 633 –639
  • DOI:  10.1049/piee.1971.0113
  • Type: Article
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  • p. 633 –639 (7)
    A linearised hydrodynamic theory is used to deduce expressions for the electromagnetic and plasma components of far fields, and of the radiation resistance, of a square-loop or Alford aerial immersed in an isotropic warm plasma, assuming a general value for the propagation coefficient of the current distribution. The radiation resistances predicted by this theory are compared with measurements of radiation resistance obtained in the Ariel 3-satellite experiment. It is concluded that the propagation coefficient for the current distribution on the aerial in the plasma should be close to that of electromagnetic waves propagating in the plasma.
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Regional connectivity and circuit enumeration in planar graphs
Detection of failures in combinational digital circuits
  • Author(s): Z. Kohavi  and  D.A. Spires
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 118, Issue 5, p. 643 –648
  • DOI:  10.1049/piee.1971.0115
  • Type: Article
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  • p. 643 –648 (6)
    The paper is concerned with the problem of determining, by terminal experiments, whether a given combinational switching circuit operates correctly or whether it is impaired by some malfunction. We shall be primarily concerned with permanent faults due to component failures. It is assumed that other procedures will be employed to protect the circuit against the effects of transient faults. A method is presented for the detection of failures in combinational switching circuits. The method provides minimal sets of tests for 2-level circuits and nearly minimal sets of tests for multilevel circuits.
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Design and optimisation of circuits by computer
  • Author(s): G.C.S. Bown  and  G.V. Geiger
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 118, Issue 5, p. 649 –661
  • DOI:  10.1049/piee.1971.0116
  • Type: Article
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  • p. 649 –661 (13)
    The role of optimisation in the field of circuit design is fully discussed, using some actual designs to illustrate the principles involved. A review of the more important optimisation methods is presented, and comparative tests have been carried out on realistic circuit designs. The design of these circuits would have proved difficult, if not impossible, by conventional methods. Both least-square and minimax-error criteria are discussed, and methods for dealing with constraints are considered. Attention is drawn to the partial-noise-immunity property of the simplex algorithm and its use as the basis of an experimental procedure.
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MECA: multivalued electronic-circuit analysis
Use and design of 4-wire telephone trunk concentrators
Fringe and permeance factors for segmented-rotor reluctance machines
Clock diagrams and pole-amplitude modulation
Discussion on “Rack-and-pinion motors: hybrid of linear and rotary machines” and “Low-speed brushless alternating-current motor”
Discussion on “Circulating-current pilot-wire differential protection of multiended circuits”
Discussion on “Direct supply of a large pulsed load from the e.h.v. transmission network”
Circulating-current loss within Roebel-bar stator windings in hydroelectric alternators
  • Author(s): D.C. MacDonald
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 118, Issue 5, p. 689 –697
  • DOI:  10.1049/piee.1971.0124
  • Type: Article
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  • p. 689 –697 (9)
    Circulating currents are produced within stator windings of Roebel bars by endregion leakage fields, causing voltages to arise between the strands or subconductors. A method for calculating the endregion fields arising from both rotor and stator is given, and values of voltage for a simplified bar representation are obtained. The impedance of a Roebel bar to a circulating current is discussed, and values of circulating current are obtained for one machine. It is shown that the circulating currents in each bar are substantially independent of those in other bars, but that the reactance within each bar is of the same order as the resistance. The circulating-current loss is a small component of the total loss in the machine considered (10% of the stator I2R loss), but varies with the load and the power factor. Its significance is that two-thirds of it occurs in the top layer of the stator winding, increasing the temperature rise there by 13%. The theoretical analysis from which the above conclusions are drawn is confirmed by search-coil measuremnets which show an average agreement within 18%.
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Discussion on “Stability of subconductors of smooth circular cross-section”
Realisation of convertor control using sample-and-delay method
  • Author(s): W.N.N. Cheung
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 118, Issue 5, p. 701 –705
  • DOI:  10.1049/piee.1971.0126
  • Type: Article
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  • p. 701 –705 (5)
    The design and principle of operation of a sample-and-delay circuit are described in the paper. The voltage controlled phase-delay circuit has a wide dynamic range of usable linearity. It has been successfully applied to a convertor model as a phase-delay controller for the control of constant current. An approximate method is given for the estimation of the dynamic behaviour of the closed-loop system. It is also shown that the same controller can be used in a new constant-extinction-angle control system, which has the possibility of reduced susceptibility to disturbances in the commutation voltage.
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IEE Conference Publication 74. Electrical safety in hazardous environments
Overhead-line oscillations and the effect of aerodynamic dampers
Measurement of saturated quadrature-axis reactance of synchronous machines
Near-optimal control of discrete-time nonlinear stochastic systems
Analysis of the effect of humidity on d.c. corona power losses
IEE Western Centre: Chairman's address. Professionalism and engineers
Potential and potential-gradient distributions for standard and practical electrode systems
  • Author(s): John M. Mattingley  and  Hugh M. Ryan
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 118, Issue 5, p. 720 –732
  • DOI:  10.1049/piee.1971.0133
  • Type: Article
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  • p. 720 –732 (13)
    An essential prerequisite of the so-called semiempirical method of estimating breakdown voltages for gas-insulated electrode systems is detailed information relating to potential gradients across the minimum-gap region. The paper provides formulas, and extensive tabulated potential and potential-gradient data, along the line or plane of minimum electrode separation, for several standard electrode systems for a wide range of gap/radius ratios. In addition, the paper presents various forward-, central-and backward-difference equations which, used in conjunction with digital numerical-field methods such as reported earlier by the authors, enable potential gradients (and consequently breakdown voltages) to be computed for many arbitrarily shaped practical electrode systems. Principal errors associated with these difference equations are discussed and illustrated by an example.
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Departures from Paschen's law for sulphur hexafluoride
Capacitance data for simple geometries
Erratum: High-current vacuum arcs. Part 1: An experimental study

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