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Electrical Engineers, Proceedings of the Institution of

Issue 12 • Date December 1969

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Displaying Results 1 - 21 of 21
  • H.F. oblique sounding measurements over a 6700km temperate-latitude path

    Publication Year: 1969 , Page(s): 1985 - 1991
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (881 KB)  

    Results of oblique soundings over a path from Delhi, India to Slough, England are presented. The modes of propagation are often ill-defined, but the maximum observed frequencies agree well with those deduced from measured ionospheric conditions at points along the path, using either the two-control-point method or a ray-tracing process. The study includes a discussion of measured angles of elevation and multipath time dispersions. View full abstract»

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  • Automatic interconnection system for electronic components

    Publication Year: 1969 , Page(s): 1992 - 2000
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1135 KB)  

    The printed circuit is now accepted as a convenient and economic method of interconnecting electronic components. However, the design of printed circuits (especially multilayer types) is both complicated and expensive. The system described here enables a logic or circuit diagram to be translated into a printed-circuit board within a few hours by using computer techniques. A milling machine is described which processes a standard printed-circuit board into the final circuit. However, if very large numbers of the same circuit are required, the machine can produce photographic masks to be used in the usual method of printing and etching of copper-clad laminates. View full abstract»

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  • Generation and realisation of loop and cutsets

    Publication Year: 1969 , Page(s): 2001 - 2008
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (934 KB)  

    A relationship between the transformations of trees and the corresponding basic loop and cutset matrices is established, which facilitates generation of these matrices with respect to any other or all possible trees of a graph in a routine manner. These transformation matrices can be set up directly without resorting to a series of elementary transformations. This method of generating the basic loop and cutset matrices is based on the concept of a Lagrangian tree. A method for minimising the number of nonzero entries in a loopset matrix is also discussed. Finally, two new methods for realising a given matrix as a loop or cutset matrix are proposed. These methods of analysis and synthesis will be particularly useful in dealing with complex networks which are commonly encountered in communication systems, electrical and switching networks, and models of many other physical systems. View full abstract»

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  • Transient negative torques in induction motors due to rapid reconnection of the supply

    Publication Year: 1969 , Page(s): 2009 - 2014
    Cited by:  Papers (13)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (581 KB)  

    The first part of the paper deals with a combined experimental and analytical study on a 5 hp laboratory set. It establishes the way in which the transient negative-torque peak ¿R¿ varies with the residual voltage on the machine terminals at the time of reconnecting the supply, and the phase angle that could exist between this voltage and the supply voltage which is being reconnected. An approximate expression for the peak negative torque is developed, which helps to explain why the characteristics showing how ¿R¿ varies diverge significantly from what would be expected by simple reasoning. A 100hp motor is then considered, and the variation of ¿R¿ with the time delay td in reconnecting is established. The effects of the load at which the motor is operating at the instant of supply disconnection and of external inertia are examined. Finally, for a range of machines from 100 to 2700hp, operating at various loads and with various external inertias, patterns of ¿R¿/td are computed and reduced to a single normalised curve, from which the largest possible value of ¿R¿ for any machine, under any operating conditions, can quickly be assessed for any selected delay in reclosing. The application of this normalised curve is illustrated for three motors not already used, and the results are compared with values obtained from complete-transient solutions. View full abstract»

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  • Dynamic-response analysis of interconnected synchronousߝasynchronous-machine groups. Computer correlation studies with site-test results

    Publication Year: 1969 , Page(s): 2015 - 2027
    Cited by:  Papers (12)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1419 KB)  

    Prior to instrumented site tests being carried out on a group of power-station auxiliary motors, computer studies of the site-test conditions were undertaken, and the paper reports the analytical methods developed for the pretest dynamic analyses, together with the correlation achieved between site-test and computed results. For the purposes of the tests, the motors were isolated from the turbogenerator for which they normally function as auxiliaries, and supplied from a neighbouring power station. To assess their recovery to, or divergence from, steady running conditions subsequent to disturbances in the system from which they are supplied, controlled-duration faults were applied at the power station supplying the induction-motor group. In the pretest analyses, 12 subgroups, of a total of 23 motors tested, were independently represented, as was the trubogenerator unit at the neighbouring unit at the neighbouring power station. Central to the analysis is Kron's concept of a synchronously rotating frame of reference, into which the equations of all machines in the group are transformed. It is shown, in the paper, that, after transformation, the machine equations may be arranged in a form particularly suitable for multimachine-system analysis by computer. The overall method of analysis is developed in detail, and its validity is checked by comparisons, made in the paper, of site-test recordings of the principal machine variables, and solutions obtained for them in the pretest computer studies. View full abstract»

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  • Discussion on ¿Brushless and self-excited 3-phase synchronous machine¿

    Publication Year: 1969 , Page(s): 2027 - 2028
    Save to Project icon | PDF file iconPDF (316 KB)  
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  • Electric strength of transformer insulation

    Publication Year: 1969 , Page(s): 2029 - 2037
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (959 KB)  

    High-voltage power transformers incorporate large quantities of insulation which is easily contaminated, and the dielectric strength is, in consequence, uncertain. This paper reports the results of electric-strength tests on transformer oil, alone and in combination with solid insulation, under various conditions. It is concluded that a major factor determining the maximum local oil stress at failure is the volume of oil under the highest stress, and that, from a knowledge of the failure-stress/volume characteristic for oil in uniform fields, the maximum local oil stress at failure for nonuniform fields can be predicted. View full abstract»

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  • Discussion on ¿Generalised theory of induction motors with asymmetrical primary windings, and its application to the analysis and performance prediction of shaded-pole motors¿

    Publication Year: 1969 , Page(s): 2037 - 2038
    Save to Project icon | PDF file iconPDF (237 KB)  
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  • Discussion on ¿Resin-bonded glass-fibre outdoor h.v. insulators¿

    Publication Year: 1969 , Page(s): 2038 - 2043
    Save to Project icon | PDF file iconPDF (1211 KB)  
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  • Erratum: Resin-bounded glass-fibre outdoor h.v. insulators

    Publication Year: 1969
    Save to Project icon | PDF file iconPDF (178 KB)  
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  • Discussion on ¿Cables and accessories: some trends in standardisation, rationalisation and ratings¿

    Publication Year: 1969 , Page(s): 2044 - 2049
    Save to Project icon | PDF file iconPDF (1178 KB)  
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  • Discussion on ¿Autoreclosing switchgear in distribution practice¿

    Publication Year: 1969 , Page(s): 2050 - 2055
    Save to Project icon | PDF file iconPDF (1181 KB)  
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  • Recursive generalised-least-squares procedure for online identification of process parameters

    Publication Year: 1969 , Page(s): 2057 - 2062
    Cited by:  Papers (22)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (708 KB)  

    A recursive differential correction-estimation technique is presented for online estimation of process parameters in the presence of autocorrelated noise. The technique is shown to allow adaptive estimation of changing system parameters. The experimental results of digital simulations indicate that the proposed recursive-estimation algorithm is valuable for online-control applications, and for the estimation of parameters in the presence of large amounts of data by avoiding the need for excessive data storage. View full abstract»

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  • Stability of third-order control systems with time lag using Pontryagin's method for zero determination

    Publication Year: 1969 , Page(s): 2063 - 2068
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (655 KB)  

    Pontryagin's method for determining zeros is applied to establish the stability criteria for the 3rd-order retarded system characterised by the normalised transcendental equation H(s, es) = s(s2 + as + b)es + K = 0 Various cases are considered in detail. Stability charts based on the stability criteria established are also presented. Critical values of the system parameters obtained from these stability charts agree with the results obtained by the graphical method. View full abstract»

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  • Amplitude bounds for second-order nonautonomous systems

    Publication Year: 1969 , Page(s): 2069 - 2071
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (263 KB)  

    A method is described for obtaining bounds on the response of 2nd-order nonautonomous systems. The method, which is an extension of the tracking-function method, obtains a closed bounded region in the state plane to which the system trajectories are confined. Originally conceived as a graphical procedure applicable only to autonomous systems, the method is well suited to numerical computation, which both increases its power and facilitates its application. Several examples illustrate the method and show it to be of wider applicability than previous methods. View full abstract»

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  • Study of boundedness of the response of a nuclear reactor using Volterra series

    Publication Year: 1969 , Page(s): 2072 - 2074
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    Barrett has recently suggested the use of the majorant of a Volterra series for the determination of the system-response bounds. This reduces a nonlinear differential equation to an ordinary algebraic equation, thus considerably facilitating the study of the convergence properties of a Volterra-series expansion. The author has applied this method to a practical problem to investigate the effect of temperature-feedback control on the growth of neutrons in a nuclear-power reactor. This paper determines a sufficient condition for the boundedness of the response of the nuclear reactor subjected to an arbitrary, constantly acting, bounded input. The nonzero initial conditions of the system have been taken into consideration, and their effects on the system response are clearly shown. View full abstract»

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  • Multidimensional Laplace transforms for solution of nonlinear equations

    Publication Year: 1969 , Page(s): 2075 - 2082
    Cited by:  Papers (11)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (643 KB)  

    Nonlinear multivariable differential or integrodifferential equations with terms of mixed dimensionality can be solved using multidimensional transforms. The method for two variables is presented, for which, by inspection of the original equation, an explicit solution can be written as a multidimensional Laplace transform. The inverse of the multidimensional transform is found by the method of association of the variables. Initial nonzero conditions have been taken into consideration, while obtaining the explicit solution as a Volterra-series expansion. View full abstract»

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  • Linear system optimisation with prescribed degree of stability

    Publication Year: 1969 , Page(s): 2083 - 2087
    Cited by:  Papers (45)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (735 KB)  

    The paper presents a scheme for obtaining a linear-feedback law for a linear system as a result of, minimising a quadratic-performance index; the resulting closed-loop system has the property that all its poles lie in a halfplane Re (s) < ¿ ¿, where ¿ > 0 may be chosen by the designer. The advantages of this arrangement over conventional optimal design are considered. In particular, it is shown that the reduction of trajectory sensitivity to plant-parameter variations as a result of any closed-loop control is greater for ¿ > 0 than for ¿ = 0, that there is inherently a greater margin for tolerance of time delay in the closed loop when ¿ > 0, that there is greater tolerance of nonlinearity when ¿ > 0, and that asymptotically stable bang-bang control may be achieved simply by inserting a relay in the closed loop when ¿ > 0. The disadvantage of the scheme appears to be that, with ¿ > 0, more severe requirements are put on the power level at which input transducers should operate than for ¿ = 0. View full abstract»

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  • External susceptibility tensor of magnetised ferrite ellipsoid in terms of uniform-mode ellipticity

    Publication Year: 1969 , Page(s): 2088 - 2092
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (474 KB)  

    In the paper, the components of the external susceptibility tensor in finite ellipsoidal shapes are given in terms of the uniform-mode ellipticity. This notation besides introducing the uniform-mode ellipticity simply relates the form of the external susceptibility tensor to the internal one. Measurement of the uniform-mode ellipticity provides an alternative method to the usual Kittel resonance method by which the properties of single-crystal ferrites can be obtained. The uniform-mode ellipticity is also important because it is responsible for lineshape asymmetry at low frequencies. A final advantage is that it allows a single rule for introducing the Landau-Lifshitz form of damping into the loss free components of both the internal and external susceptibilities. The paper concludes with experimental results for a hexagonal single-crystal ferrite with planar anisotropy which is biased in the easy plane. View full abstract»

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  • Review of laser microwelding and micromachining

    Publication Year: 1969 , Page(s): 2093 - 2100
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1655 KB)  

    The relevant characteristics of lasers for microwelding and micromachining applications are discussed, and practical lasers having suitable characteristics for these purposes are reviewed. The physics of the melting and machining mechanism is considered, and the limitations of heat-conduction-based models of the process are pointed out. Experimental results of microwelding and micromachining studies are presented or reviewed. The requirements of a work table for precision machining using a laser are discussed and the potentiality of a beam-deflection system is considered. View full abstract»

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  • Aspect of electric strength of a moving gas

    Publication Year: 1969 , Page(s): 2101 - 2104
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (578 KB)  

    The influence on the prebreakdown processes and the sparking voltage of a gas moving at an angle to an electric field across a uniformly stressed gap is considered quantitatively by invoking the equivalent-pressure concept. The velocity with which a moving gas displaces the charged particles taking part in the processes leading to a spark is found, and the variation of the gap strength with the gas flow is calculated. With a pure cross gas flow, no change in the electric strength is predicted, and this is in agreement with experiment where gas speeds up to 2 ×103m/s have been attained. With axial gas flow, the moving gas can either increase or decrease the gap strength depending on the direction of the gas flow relative to the field due to the direct applied voltage, and provided the gas speed is comparable in magnitude with the electron drift velocity (under a.c. conditions, a reduction in strength always occurs). A novel method for obtaining the electron drift velocity, and hence the electron-molecule-collision frequency, by the use of a moving gas is evolved. The analogy between a moving gas and an applied crossed magnetic field is pointed out. This leads to a second method for obtaining the electron drift velocity by the simultaneous application of a moving gas and a crossed magnetic field. Possible relevance to compressed-air-blast circuit breakers is considered. 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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