Proceedings of the IEE  Part C: Monographs
Volume 108, Issue 13, March 1961
Volumes & issues:
Volume 108, Issue 13
March 1961
Discussion on “Extension of the dualinput describingfunction technique to systems containing reactive nonlinearity”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, page: 1 –1
 DOI: 10.1049/pic.1961.0001
 Type: Article
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An analytical method for predicting the performance of semienclosed fuses
 Author(s): Colin Adamson and M. Viseshakul
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 2 –11
 DOI: 10.1049/pic.1961.0002
 Type: Article
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An analysis has been made and a design procedure established for fuses other than those using round wire and with, or without, a restricted crosssection for part of the fuse length. Fuses of restricted section are, however, the major interest since they may be used to give different current/time characteristics by varying their dimensions. These different characteristics may be predicted accurately by the method indicated in the paper. In all the cases of semienclosed tinstrip fuses investigated in this way very close agreement between predicted and experimental results has been obtained.
Signal flowgraph analysis and feedback theory
 Author(s): R.F. Hoskins
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 12 –19
 DOI: 10.1049/pic.1961.0003
 Type: Article
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The solution of a system of simultaneous linear equations may obtained by inspection of an associated system of nodes and connecting branches called a ‘signal flowgraph’. This provides alternative to conventional algebraic methods which is of particular interest in the case of network analysis, since the flow graph can be set up directly by inspection of the network without having to formulate the associated equations. In the paper the formal theory of flowgraph analysis is developed and applied to certain aspects of feedback theory, and it is shown that the classical results of Bode can be obtained and generalized relatively simply by this approach.
The receivedamplitude distribution produced by radio sources of random occurrence and phase
 Author(s): W.C. Bain
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 20 –24
 DOI: 10.1049/pic.1961.0004
 Type: Article
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A theoretical calculation is given of the amplitude probability distribution to be expected on an ionospheric v.h.f. forwardscatter circuit due to reflections from meteor trails alone. The analysis is based on the addition of a large number of signals with a frequency of occurrence inversely proportional to the square of their amplitude, and will therefore apply to other problems in which this relation holds. The calculated distribution is compared with a small number of practical results, and a method is outlined for deriving the relative proportion of meteoric and turbulentscattering components in the signal.
A brief review of the theory of paper lapping of a singlecore highvoltage cable
 Author(s): P. GazzanaPriaroggia ; E. Occhini ; N. Palmieri
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 25 –34
 DOI: 10.1049/pic.1961.0005
 Type: Article
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A brief outline of the theory of the lapping operation for highvoltage singlecore paperlapped cable is given, showing the stability conditions which the insulation thickness must satisfy in order that bending of the cable on the reel or capstan does not cause any damage to the insulation itself. An example of the design of a highvoltage cable is considered, showing the application of the theory outlined and its practical use.
A new type of piezoelectric flexural vibrator in the form of balanced cantilevers
 Author(s): Sheila Ayers
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 35 –49
 DOI: 10.1049/pic.1961.0006
 Type: Article
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The flexural vibrator, designed to vibrate at about 1 kc/s, basically consists of identical cantilever arms extending from a common area form a symmetrical element. Two distinct shapes have been considered—the H and the ‘zigzag’. Some of the H elements have uniform crosssection while others are arranged to have most of their mass at the free ends in order to reduce the frequency for a specimen given length. The ‘zigzags’ have folded arms of any number of sections (increasing the number of sections reduces the frequency).The theory of the various forms and their frequency equations are derived. Conditions for perfect balance of the reactions at the supports are discussed.Measurements have been made on H and ‘zigzag’ forms made from quartz slices ZYbΦ(Φ = 0−10°) and on ‘zigzag’ form from e.d.t.XYltl Φ, 90°, 90°. Frequency, temperature behaviour, Qfactor and displacement patterns of the elements are compared with theory. Since some of the conventional driving methods proved unsatisfactory short Section is included on circuits.
Chain codes and their electronic applications
 Author(s): F.G. Heath and M.W. Gribble
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 50 –57
 DOI: 10.1049/pic.1961.0007
 Type: Article
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A type of binary digital code is described which is easily generated by computer circuits. The important properties of these codes are described, and various electronic applications enumerated.
Frequency response analysis of the stabilizing effect of a synchronous machine damper
 Author(s): A.S. Aldred and G. Shackshaft
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 58 –63
 DOI: 10.1049/pic.1961.0008
 Type: Article
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The paper describes the application of frequencyresponse concepts to the analysis of a synchronous machine damper in so far as it affects the stability of the machine. The analysis of damper effects is based on Park's equations. Smalldisplacement theory is introduced toorganize the equations into the correct form for frequencyresponse computation.Nyquist diagrams are used to show the stabilizing effect of a damper and to illustrate the method of optimizing damper parameters.
The magnetic field and centring force of displaced ventilating ducts in machine cores
 Author(s): K.J. Binns
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 64 –70
 DOI: 10.1049/pic.1961.0009
 Type: Article
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This paper examines analytically the field between equal stator and rotor ducts when displaced from each other and evaluates, for any relative position, the total flux crossing the airgap and the amount entering the sides of each duct. The flux entering the sides of the stator ducts in a.c. machines varies at supply frequency and produces eddy currents the path of which is not restricted by the direction of the laminations and which consequently give rise to considerable loss. With relative displacement of the ducts the fluxes entering the two sides of a duct become unequal and produce an axial magnetic force of engineering importance.Numerical values are given for the variation of gap permeance and magnetic centring force, and are plotted in curves directly applicable to design calculation for ratios of duct to gap width varying from ½ to 5 and for any relative displacement.
An analytical review of powersystem frequency, time and tieline control
 Author(s): D. Broadbent and K.N. Stanton
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 71 –78
 DOI: 10.1049/pic.1961.0010
 Type: Article
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Over the past decade and a half there have been proposed three schemes of control for electricity supply systems interconnected through tie lines. In chronological order they are the speedgoverned system with frequency biasing, the timegoverned system and the loadphase energy control.The paper describes computer studies which compare the three systems using a performance index of the integral square error. Certain conclusions are drawn by applying this criterion both to the frequency error of the isolated system and to the tie powerflow error of the interconnected system.
The magnetic excitation inside a cylindrical thinfilm ferromagnet
 Author(s): T.H. O'Dell
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 79 –82
 DOI: 10.1049/pic.1961.0011
 Type: Article
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An expression for the magnetic excitation inside a cylindrical thinfilm ferromagnet is derived, and a Table of computed values is given. The results are considered to be relevant to work on thin ferromagnetic films for digitalstorage applications.
Discussion on “Flux distribution in a permeable sheet with a hole near an edge”
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, page: 82 –82
 DOI: 10.1049/pic.1961.0012
 Type: Article
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The conductivity of oxide cathodes. Part 9: Thermoelectric power
 Author(s): G.H. Metson and M.F. Holmes
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 83 –92
 DOI: 10.1049/pic.1961.0013
 Type: Article
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The thermoelectric power of an oxide cathode has been examined recently by J. R. Young, who finds it to be a complex function of temperature, dependent on the dual nature of oxidecathode conductivity. By an experimental artifice the present authors show that an apparently complex form of behaviour is, in fact, the result of the superposition of two quite simple phenomena. Two parallelacting thermoelectric power functions are involved, and each of these is invariant with temperature and temperature gradient. The two functions are physically separated and each is measured over an appropriate temperature range. The larger function, of magnitude 2.0 − 3.0mV/degC, is associated with the vacuum movement of electrons through the hollow pores of the oxide matrix; the smaller one, of magnitude 0.5mV/degC, occurs in the chains of contiguous solid particles of the matrix. Owing to the parallel connection and inequality of these functions, it is concluded that a temperature gradient through an oxide matrix leads to a continuous circulation of current, vacuumwise in one direction and solidwise in the other. Since the larger function is essentially one involving thermionic emission of electrons in a vacuum, it can be satisfactorily explained in terms of Richardson's law.
Forced oscillation in an oscillator with two degrees of freedom
 Author(s): B.R. Nag
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 93 –97
 DOI: 10.1049/pic.1961.0014
 Type: Article
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Resonance curves of an oscillator with two degrees of freedom and the criteria of stability of the synchronized state are determined theoretically by van der Pol's method of approximation and verified experimentally by an electronic differential analyser. An experimental method for obtaining the phase trajectories is described. Characteristics of oscillations outside the zone of synchronization are also described.
Matrix analysis of constrained networks
 Author(s): A. Nathan
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 98 –106
 DOI: 10.1049/pic.1961.0015
 Type: Article
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Following a review of nodal analysis of unconstrained lumped linear timeinvariant networks it is shown how networks with imposed unilateral constraints, i.e. transmittances and voltage sources, can conveniently be analysed by matrix methods. Their admittance matrix is equal to the product of a submatrix of the admittance matrix before the application of the constraints and a transmittance matrix which describes the constraints. Constraints lower the rank of the original admittance matrix, thus making the method quite attractive in practice. Applications included are a computing network, difference amplifiers, a d.c. amplifier and signalflow graphs.
Limitations on realizable response shapes for certain wideband bandpass amplifier circuits
 Author(s): R.A. Woodrow
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 107 –114
 DOI: 10.1049/pic.1961.0016
 Type: Article
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A procedure is described for the design of wideband bandpass amplifiers using either staggertuned stages or a chain of feedback pairs to realize Cheby̅shev or Butterworth response shapes.A graphical test has been developed by which it is possible to verify, at the outset, that a given design specification is a realizable one. Certain fundamental limitations which are imposed upon the response shapes by the choice of these circuit configurations are revealed by this test. Thus it is shown that any response shape which may be realized by a chain of feedback pairs can also be realized with staggertuned stages, while the converse is not true.An example demonstrating the application of the procedure to a design problem has been included to demonstrate that the procedure for a Cheby̅shev response is no more complicated than for a Butterworth response, neither is any additional complication introduced by increasing the number of singularities in the desired response shape beyond the first pair, since each pair of singularities is separately realized.
Application of the theory of orthogonal polynomials in two variables to a multigain equivalent linearization problem
 Author(s): J.L. Brown
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 115 –118
 DOI: 10.1049/pic.1961.0017
 Type: Article
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It is shown that the multigain representation for a singlevalued nonlinearity with multiple inputs as developed by Somerville and Atherton may be regarded as an approximation problem involving orthogonal polynomials in two variables.Consider two stationary random processes, x(t) and y(t), possibly correlated, with a given secondorder (zerodelay) joint probability density, p(x,y). If the input to a specified zeromemory nonlinear device having the input/output characteristic v_{0}(t) = f[v_{i}(t)] is x(t) + y(t), the relevant polynomials satisfy orthonormality conditions over the xyplane with respect to p(x, y) as weighting function. An inherent minimum property of these polynomials then allows the equivalent gains to be determined directly in terms of the expansion coefficients of f(x+y) with respect to the polynomials. When x and y are uncorrelated, the gains reduce to the values previously obtained by Somerville and Atherton.A further property of the polynomials is sufficient to prove that the zerodelay crosscorrelation between the input and the error involved in the approximation is zero, and that this result remains true as the order of the approximation is increased.
Unstable electron flow in a diode
 Author(s): R.J. Lomax
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 119 –121
 DOI: 10.1049/pic.1961.0018
 Type: Article
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A perturbation analysis is used to demonstrate the instability of a type of electron flow in a plane diode known as Coverlap flow, which is predicted to be a possible flow in the approximation in which electrons are emitted from the cathode with a uniform velocity.
A new approach to Kron's method of analysing large systems
 Author(s): R. Onodera
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 122 –129
 DOI: 10.1049/pic.1961.0019
 Type: Article
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Generally an electrical network is used as a model circuit for a physical field. This circuit is most complicated and the analysis of it is frequently difficult. ‘Diakoptics’, introduced by Kron, is very effective for analysis of the network. The method entails the operation of ‘cutting’, which is generally classified into opencircuiting and shortcircuiting. The latter operation is the dual of the former, but, as far as the author is aware, has not yet been reported in any of the literature. A method is described, based on Kron's diakoptics, which uses the operation of opencircuiting, and is further extended to dual diakoptics treated by the operation of shortcircuiting. Here a simplification of Kron's diakoptics is attempted and a dual method is introduced. It seems that this attempt goes backwards in tensor geometry, but forward in combinatorial topology. The first intention of the paper is to show the duality between diakoptics and codiakoptics.
Poleface losses in alternators. An investigation of eddycurrent losses in laminated pole shoes
 Author(s): J. Greig and K. Sathirakul
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 130 –138
 DOI: 10.1049/pic.1961.0020
 Type: Article
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A recent reexamination of the phenomenon of toothripple flux pulsations at laminated polefaces in alternators resulted in a new theoretical analysis by means of which the poleface eddycurrent loss can be calculated. The primary purpose of the present investigation has been to make measurements of toothripple losses which could be compared with values calculated from the new formulae. In order to make these measurements an experimental homopolar machine was built and values of eddycurrent losses were determined over a fairly wide range of flux density and frequency for four different thicknesses of lamination. It is found that there is moderately good agreement between calculation and experiment for the thicker laminations and in general the agreement is markedly better with the new formulae than with those previously developed.
Audio communication with orthogonal time functions
 Author(s): Henning F. Harmuth
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 139 –144
 DOI: 10.1049/pic.1961.0021
 Type: Article
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An audio signal may be decomposed into components having certain frequency and phase. Half the information of the signal is contained in the phase of the frequency components. Since the human ear is almost insensitive to phase, one may eliminate the phase information without causing a noticeable reduction in the signal quality. The elimination of the phase information implies a permissible reduction of the bandwidth required for the transmission of the signal to onehalf and a reduction of the signal power by 3 dB without increase of distortions due to additive white normal noise. A method for the elimination of the phase information is based on the decomposition of the audio signal by correlation with a set of orthogonal functions. These correlations yield for each orthogonal function one coefficient which is represented by a voltage. One may process these coefficients in analogue or digital computers to reduce further the bandwidth required for the transmission of audio signals with certain spectral distribution, e. g. voice signals.
The physical realization of inductionmotor equivalent circuits
 Author(s): N.N. Hancock and B.H. Karakaraddi
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 145 –152
 DOI: 10.1049/pic.1961.0022
 Type: Article
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The paper reviews the practicability of setting up physically, in the form of specialized networks, several of the equivalent circuits representing an unbalanced 2phase induction motor. This motor sufficiently general to include, as special cases, most induction machines with balanced secondary windings.
Optimum combination of pulse shape and filter to produce a signal peak upon a noise background
 Author(s): H.S. Heaps
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 153 –158
 DOI: 10.1049/pic.1961.0023
 Type: Article
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The paper concerns the generation of a signal pulse for transmission through a propagating medium and its subsequent detection as a single peak after it is received upon a noise background. It is supposed that the propagating medium behaves as a linear filter and that the noise background is independent of the signal. The pulse is conveniently described as consisting of a central portion attached to a leading edge and a trailing edge. It is found that for a given length of central portion there is an optimum combination of transmitted pulse shape and predetection filter. The results are compared with those arising from the use of certain nonoptimum systems, and it is found that the optimum system leads to a significantly high signal/noise ratio.The results of the paper imply that for the range of parameters considered it is advantageous to transmit a succession of short pulses of a determined form rather than a single smooth pulse.
The potential distribution and thermionic current between parallel plane emitters
 Author(s): F.H. Reynolds
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 159 –169
 DOI: 10.1049/pic.1961.0024
 Type: Article
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A thermionic system formed of two parallel plane emitters facing each other is analysed. By means of Tables, the distribution of potential between the emitters and the net spacechargelimited current which flows between them can be obtained for any emitter potential, temperature and saturation current density. The results are applied to practical problems including the thermoelectric and conductivity characteristics of oxide cathodes.
Propagation along unbounded and bounded dielectric rods. Part 1: Propagation along an unbounded dielectric rod
 Author(s): P.J.B. Clarricoats
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 170 –176
 DOI: 10.1049/pic.1961.0025
 Type: Article
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The paper describes a method for evaluating the propagation coefficients of an unbounded lossless dielectric rod of infinite extent. The propagation coefficients are obtained as a function of the ratio of rod radius to free space wavelength, r_{1}/λ_{0}, for the three lowest modes of propagation possessing fields with θ dependence of the form ɛ^{±jθ}. The method of solution enables the form of the complete mode spectrum to be identified. It is also established that the product of the rod permeability and permittivity, με, primarily determines the propagation behaviour; the ratio μ/ε has only a secondary effect. An expression is obtained for the distribution of transmitted power between the rod and the surrounding space, and it is also demonstrated that the product με primarily determines this quantity. Correlation between power distribution and attenuation is demonstrated for a rod possessing small losses.
Propagation along unbounded and bounded dielectric rods. Part 2: Propagation along a dielectric rod contained in a circular waveguide
 Author(s): P.J.B. Clarricoats
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 177 –186
 DOI: 10.1049/pic.1961.0026
 Type: Article
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The paper describes both approximate and exact methods for evaluating the phasechange coefficients of a circular waveguide containing an axial dielectric rod. Close correlation is found between the phasechange coefficients of this waveguide structure and those of an unbounded rod over a wide range of rod radii. The correlation enables an unambiguous classification of the modes of an unbounded rod to be made. Exact and perturbation expressions are derived for total transmitted power, power distribution and attenuation in the dielectricrodwaveguide structure. Correlation with the attenuation coefficients of an unbounded rod is again predicted. The application of the results of the paper to ferrite devices is briefly mentioned.
The launching of surface waves by a magnetic line source
 Author(s): C.M. Angulo and W.S.C. Chang
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 187 –196
 DOI: 10.1049/pic.1961.0027
 Type: Article
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The paper deals with the idealized problem of the excitation of surface waves along two infinite, identical, separate and parallel dielectric slabs by a magnetic line source (slot). The problem is reduced to a superposition of simpler ones, namely two parallel slabs with symmetrical excitation and two parallel slabs with antisymmetrical excitation.The simplified problems are solved by the modalanalysis approach, and the synthesis of the modal components is carried out to obtain the far fields excited by the magnetic line.Radiation pattern, total power of the surface waves, total radiation loss and the efficiency of launching the surface wave are derived and computed numerically for various thicknesses of the slabs, various airgaps between the slabs and different positions of the magnetic line source. The theoretical results indicate that, for each thickness of the slabs, high efficiency is obtained with an optimum location of the source and an optimum airgap. Moreover, the thicker the slabs, the higher is the maximum efficiency. The thickness of the slabs and the airgap are ultimately limited by the requirement that only one surface wave should exist for the structure.
The output spectral density of a detector operating on a f.m. c.w. radar signal in the presence of bandlimited white noise
 Author(s): J. Lait and A.J. Hymans
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 197 –207
 DOI: 10.1049/pic.1961.0028
 Type: Article
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A method of analysis suggested by Lawson and Uhlenbeck is used to examine the interaction between reference signal, echo and noise in the detector stage of a frequencymodulated c. w. radar receiver.The paper gives a method of approximation which may be used in most practical cases and states the restrictions on system parameters for which the approximations are valid.Expressions for spectral density are derived separately for both quadratic and linear detectors, and the question of optimum predetector bandwidth is examined. Finally, the authors consider how signal/noise ratio will be affected by choice of bandwidth in stages which follow the detector.
Quantitative treatment of threephase brushshifting series commutator motor
 Author(s): O.E. Mainer
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 208 –214
 DOI: 10.1049/pic.1961.0029
 Type: Article
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Previous quantitative treatments appear to have ignored the loss component of motor current. In this paper an approximate equivalent circuit, which makes allowance for this component, is developed from first principles. A method is devised for correcting the errors introduced by the approximate treatment so as to obtain an accurate solution. The average percentage errors in motor current, power factor and input obtained by both approximate and accurate treatments are given for a wide range of operating conditions.
The algebra and topology of electrical networks
 Author(s): P.R. Bryant
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 215 –229
 DOI: 10.1049/pic.1961.0030
 Type: Article
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The paper gathers together the various results and methods used in an elementary algebraic and topological study of electrical networks. Considerations are restricted to networks containing a finite number of lumped resistors, capacitors and self and mutual inductors. The result is a connected logical presentation leading, by use of the concepts of incidence, loop and cutset matrices, to the corresponding nodal, loop and cutset analysis methods.
The surge corona discharge
 Author(s): R. Davis ; R.W.E. Cook ; W.G. Standring
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 230 –239
 DOI: 10.1049/pic.1961.0031
 Type: Article
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Exploratory experiments are described followed by an account of a more systematic study of the corona discharge with concentriccylinder electrodes. From experimental records which relate the charge flow in an external circuit to the applied voltage, the corona current and energy loss were derived. An attempt is made to interpret the observations in terms of modern views on the mechanism of electrical breakdown in gases. The attenuation by corona of surges on transmission lines is examined in an Appendix.
Temperature rises in electrical machines with sustained variations in load and speed
 Author(s): B.J. Prigmore
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 240 –246
 DOI: 10.1049/pic.1961.0032
 Type: Article
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A method is presented for obtaining the temperaturerise/time curve for a given machine for an arbitrary sequence of operating currents and speeds; the method is demonstrated to give results for such a run correct to about ±2° C in 60–70° C.The method is to suppose that the equivalent thermal network of the machine is linear, its temperature/time curve thus being the sum of the temperature/time transient responses for a series of short times, δt, successive transients corresponding to the average operating conditions during successive intervals; and then to modify this curve to that for the actual nonlinear machine by adding a correction curve which is itself composed of two series of transient responses: one of these allows for the effects of nonlinearity due to temperature rise, and is based upon the succession of average temperatures, given from the first curve, during the intervals δt; the other allows for the effects of changes in dissipation coefficients due to changes in speed.The testbed procedure for obtaining the temperature/time transients for the linear machine, and the corrections for nonlinearity, is specified. It is recommended that this procedure, lasting, about 36 hours, should be applied to samples of appropriate types of machine.
The indeterminacies of measurements using pulses of coherent electromagnetic energy
 Author(s): R. Madden
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 247 –251
 DOI: 10.1049/pic.1961.0033
 Type: Article
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The measurements, on a single pulse function of electromagnetic radiation, of the position of a scatterer with polar coordinates R, φ are interdeterminate in themselves. The positional indeterminacies are related by ΔRΔφ ≃ ½λ_{t}, where λ_{t} is the wavelength of the source. The relation between the indeterminacies of range R and radial velocity V_{r} is found to be ΔRΔV_{r} ≃ ¼λ_{t}C. It is shown that vector position and vector velocity are not measurable simultaneously, and it is suggested that the 3dimensional measurement problem is basically limited to nonsimultaneous measurements which have restrictions in the presence of multiple scatterers. Similarity is noted to the quantummechanical problem.
Numerical evaluation of inductance and a.c. resistance, with particular reference to electrical machines
 Author(s): R.S. Mamak and E.R. Laithwaite
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 252 –258
 DOI: 10.1049/pic.1961.0034
 Type: Article
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The electric and magnetic circuits of electrical machines are generally so complex that the exact evaluation of such quantities as leakage reactance and a.c. resistance is virtually impossible. With the advent of digital computers it has become feasible to develop numerical methods of predetermining the flux pattern in such cases. In the paper the finitedifference equations for electromagnetic systems are obtained, and the inductance is calculated by integrating the magnetic vector potential over conducting surfaces. The same finitedifference equations are applied to the calculation of a.c. resistance of conductors in slots. The use of the method is illustrated by examples of standard transformers, a tapchanging transformer, calculation of the leakage reactance of the field winding of a salientpolealternator and the screening of d.c. poles in a new type of oscillating synchronous linear machine.
Frequency spectrum distortion of random signals in nonlinear feedback systems
 Author(s): J.C. West ; J.L. Douce ; B.G. Leary
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 259 –264
 DOI: 10.1049/pic.1961.0035
 Type: Article
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The paper considers the distortion introduced by torque saturation in a servo mechanism when responding to a randomly varying input signal, with emphasis on the spectral distribution of this distortion. It is shown that lowfrequency errors are produced by the application of an input signal whose spectrum extends beyond the pass band of the system.An approximate expression is derived which enables the magnitude of the lowfrequency errors to be evaluated in a simple manner. Experimental results are presented for a particular system.
Stability of a feedback system containing a limitedfieldofview error detector
 Author(s): D.P. Atherton
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 265 –270
 DOI: 10.1049/pic.1961.0036
 Type: Article
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A class of nonlinear errordetector characteristics is considered where, for large magnitudes of error, the error signal decreases with increased error. Sinusoidal and randominput analysis of a closedloop system containing such a nonlinearity is shown to necessitate the calculation of a family of describingfunction curves to cover operation with a d.c. input signal to the nonlinear error detector. The peculiarities of such a nonlinear system are discussed, and a simple method using a nonlinear circuit to correct the adverse behaviour is described.
Limitations of distancetype protective equipment when applied to long extremelyhighvoltage power lines
 Author(s): A. Wright
 Source: Proceedings of the IEE  Part C: Monographs, Volume 108, Issue 13, p. 271 –280
 DOI: 10.1049/pic.1961.0037
 Type: Article
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On power lines the currents which flow solely in the phase conductors travel near the velocity of light whereas those which return through the ground and overhead earth wires travel more slowly, the speed depending on the line spacings, conductor sizes and nature of the ground. The full steadystate equations for a 3phase line are developed and a particular line is examined to show the magnitude of this effect. The effect of transposing a line is also indicated.The steadystate performance of basic distance protection fitted with compensating equipment to allow for the effects of the currents in the sound phases during earth faults is studied, using the line equations. It is shown that large errors of measurement occur under earthfault conditions on long lines fed from small sources. The performance for faults which do not involve earth is satisfactory.It is shown that nontransposition of a line makes the apparent impedance of a fault on a line depend on the source impedance. This causes further errors in the assessment of the positions of faults of all types.The high transient timeconstants on long lines increase the chance of maloperation during the transient period.It is concluded that distance protection may not be satisfactory on very long lines and that a study must be made of the complete power system before a decision can be made about its suitability for any particular application.
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