摘要:

In order to make further progress with the solution of multimachine transient problems, it is necessary to augment the facilities of network analysers, the most convenient of the analytical tools available to the power-system engineer. The paper describes a new simulator which enables the symmetrical a.c. transient component of current or voltage of a synchronous machine, subsequent to any 3-phase disturbance, to be obtained. The simulator is based on the duals of equivalent circuits for the direct and quadrature axes of synchronous machines, and is entirely electronic in its operation.Experimental results are given and a comparison is drawn between these and the results obtained by calculation. It is concluded that such a simulator is an essential preliminary step towards a more accurate representation of machines and their associated apparatus, either individually or when interconnected in a power system.

DOI:10.1049/pi-c.1957.0038

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The paper describes certain experiments designed to investigate the mode of penetration of tooth-ripple flux pulsations in smooth laminated pole-shoes. Simple measurements made by means of search coils embedded in holes drilled axially at different radial depths from the pole face have revealed that a dynamic mode of flux pulsation, which corresponds to the static tooth-flux distribution, persists, at significant amplitude, at the normal operating speed of the machine. Measurements have been made with two sets of laminations of different thickness and material at a range of tooth-ripple frequencies. The results provide substantial evidence in support of an analysis of tooth-ripple phenomena contained in a companion paper.

DOI:10.1049/pi-c.1957.0039

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The basic theory of transient propagation in waveguides is formulated and developed. The theory is subsequently applied to the propagation of a unit-step-modulated carrier and the propagation of pulses. Formulae and graphs are outlined for various transients involved and pulse distortion is studied in detail. The results are illustrated by numerical examples.

DOI:10.1049/pi-c.1957.0040

出版商:IEE    

年代:1957

数据来源: IET

摘要:

Classical linear electromagnetic theory is used to investigate the mode of penetration of tooth-ripple flux into smooth laminated poleshoes, without making any assumption as to the thickness of the laminations employed. It is shown that, apart from the mode corresponding to the classical ‘depth of penetration’ concept, there also exists a completely different mode which penetrates to a much larger radial depth but has a non-uniform distribution across the thickness of the laminations, the maximum values occurring at the interfaces. With thicknesses usually employed in practice, at least 60% of toothripple eddy-current loss is found to arise from this latter mode of penetration, so that only a fraction of the total loss could properly be called a ‘pole-face’ loss.

DOI:10.1049/pi-c.1957.0041

出版商:IEE    

年代:1957

数据来源: IET

摘要:

In a previous paper1expressions were obtained for the distortion of the modulation when a frequency-modulated wave passes through network whose group-delay and amplitude characteristics both exhibit small departures from constancy. An ideal discriminator network has the property that when it is fed with a frequency-modulated wave the amplitude modulation of the output is an exact copy (except for scale factor) of the frequency modulation of the input. This can be achieved by a network whose group-delay characteristic is constant and whose amplitude characteristic is linear. In the present paper the theory given in the previous paper is extended to cover discriminator networks whose characteristics exhibit small departures from these ideal forms. Single-tone and noise-band modulations are considered. Two numerical examples are given, one being a design of 2-tuned-circuit discriminator, which is considered in relation to a 240-channel f.d.m. telephony system, and the other is an improved balanced discriminator suitable for a 600-channel system.

DOI:10.1049/pi-c.1957.0042

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The aim of the paper is to produce complete design data (i.e. the values of components in terms of generalized frequency and load conditions) of symmetrical equally terminated filters consisting of reactances only. The data are produced in graphical form and are carefully plotted to slide-rule accuracy; they are sufficiently dense to cover fully the usual requirements, without the use of interpolation.The filters are designed on the basis of Darlington's insertion-loss theory with Cheby̅shev behaviour both in the pass band and in the attenuation band. This allows for the unique correlation of the usual design specifications, which is displayed in a graphical form.The underlying theory of the quadripoles and of the realization procedure is explained fully and independently of the practical part of the paper.Finally, proper alignment procedure is described.

DOI:10.1049/pi-c.1957.0043

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The dispersion characteristics of periodically loaded waveguides are examined. As is well known, a loaded waveguide has the properties of a filter having infinitely many stop bands, which occur when the phase change per section for the wave is a multiple of π. For linear accelerator and other applications it is sometimes desirable to operate the structure in the π-mode but the resulting zero group velocity raises considerable difficulties.In the first part of the paper it is shown how a finite group velocity at the π-mode frequency can be obtained in a waveguide loaded with solid dielectric discs. This is accomplished by making the discs reflectionless at the required frequency; the stop band being thus eliminated, the structure can be regarded as a confluent band-pass filter.To permit the passage of an electron beam it is necessary for the discs to have central holes. Evanescent and other propagating modes are set up, but it is shown in the latter part of the paper that it is still possible to operate the structure in the π-mode with a finite group velocity. This result cannot be obtained if the guide is loaded by thin metal discs, as used in most present-day linear accelerators.

DOI:10.1049/pi-c.1957.0044

出版商:IEE    

年代:1957

数据来源: IET

摘要:

Synchronized oscillators of the feedback type, possessing low-pass and band-pass filters in the loop, are considered. It is shown that these filters can, under certain conditions, be represented by time-delay networks.Stability and the pulling effect in a synchronized oscillator with a time-delay network in the loop are investigated analytically, graphically and with the help of an analogue. The corresponding non-linear hystero-differential equation is studied, and typical solutions are presented on the phase plane. Methods of improving the performance by the use of correcting circuits are also considered.

DOI:10.1049/pi-c.1957.0045

出版商:IEE    

年代:1957

数据来源: IET

摘要:

A multi-element directional coupler is considered as a cascaded set of 2-element directional couplers, each of which, at the design frequency, is perfect in match and directivity. A characteristic impedance matrix and a voltage transfer matrix may be defined for each of the basic 2-element couplers, and these are analogous to the characteristic impedance and the propagation coefficient in iterative 4-terminal network theory.The voltage transfer matrix is shown to be a linear function of the cosine and sine of a certain angle which is related in a simple way to the coupling factor of the elemental coupler. This function has algebraic properties analogous to those of complex numbers. In particular, the use of de Moivre's theorem is shown greatly to simplify the design of multi-element couplers. An example is given of the design of a 5-slot 3 dB coupler (a binomial slot hybrid).

DOI:10.1049/pi-c.1957.0046

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The influence of the magnitude of network parameters on the waveform generated by the simplest types of circuit used in high-voltage impulse testing has been discussed at some length in the literature. These treatises are based, however, on simplifying assumptions not absolutely necessary, and no attempt appears to have been made to develop a unified approach to this problem. Moreover, some important circuits of slightly greater complexity have received particularly scanty attention, ostensibly on the grounds of mathematical complication.The present paper introduces a unified treatment, without approximations, and with application to the more complex as well as to the simplest circuits. It indicates how one of the former may be employed to achieve higher efficiencies, coupled with increased economy of parts, particularly where resistive potential dividers are used. Some light is also thrown on the discrepancy between the nominal and actual rise times of double-exponential impulse waves.

DOI:10.1049/pi-c.1957.0047

出版商:IEE    

年代:1957

数据来源: IET