摘要:

The steady-state stability limit of a synchronous machine can be modified considerably by controlling field excitation and prime-mover torque by means of regulators and governors. In the paper the effects of the individual alternator parameters and controller constants on the dynamic stability limit (i. e. the steady-state limit of a controlled alternator) are investigated, and optimum operating conditions for various types of regulator and governor are established.The investigation covers a general comparison of the relative dynamic stability of the common types of large alternator. In addition, the variation in dynamic stability with a change in output rating is discussed.

DOI:10.1049/pi-c.1956.0032

出版商:IEE    

年代:1956

数据来源: IET

摘要:

Measurement has been made of the spectral intensity of the harmonic zones which exist at the output of a non-linear device fed by narrowband noise and an unmodulated carrier. The spectral shape, the maximum spectral intensity, and the carrier component in each of the first six harmonic zones (l= 0…5) have been determined both theoretically and experimentally for a half-wavevth-law rectifier withv= ½, 1 and 2, for a wide range of input carrier/noise ratios.The measuring equipment is discussed in the paper, the theoretical and experimental results are compared, and a number of computed results of practical interest are presented.

DOI:10.1049/pi-c.1956.0033

出版商:IEE    

年代:1956

数据来源: IET

摘要:

The magnetic field in the neighbourhood of coils threaded through holes in iron cylinders is calculated. The results are relevant to the estimation of the self-inductance of rotating machines and transformers and form the basis for an examination of the soundness of approximate formulae used in the design of such apparatus.

DOI:10.1049/pi-c.1956.0034

出版商:IEE    

年代:1956

数据来源: IET

摘要:

Wiener has given an explicit solution for the servo mechanism which minimizes the r.m.s. error when the system is following a signal contaminated with noise. The paper describes an elementary graphical method for evaluating Wiener's results, and makes use of a pair of transparent cursors which have already been described. An example is given, from which it appears that the accuracy of the method may be sufficient for engineering purposes.An intermediate result of the graphical method gives the minimum phase corresponding to a given attenuation characteristic.

DOI:10.1049/pi-c.1956.0035

出版商:IEE    

年代:1956

数据来源: IET

摘要:

Some properties of a general, non-reciprocal, linear network withnaccessible terminal pairs (n-port) are investigated. With the use of a symbolic notation, a unique expression for all network functions is derived. This expression can be obtained in terms of the subdeterminants of the open-circuit impedance or the short-circuit admittance matrix of then-port, and is applicable with any combination of open- or short-circuits at the network ports. Since all network functions, with such terminations of then-port, may be expressed in terms of sub-determinants of one and the same matrix, numerous relations between them may be established. Some examples illustrate the application of this method.

DOI:10.1049/pi-c.1956.0036

出版商:IEE    

年代:1956

数据来源: IET

摘要:

A theory which accounts for the well-known discrepancy between predicted eddy-current losses in electrical sheet steels and the experimentally observed values is presented. The anomaly is shown to be due partly to the magnetic inhomogeneity arising from ferromagnetic domain structure and partly to a time-lag effect caused by the finite domain boundary movements. A new experimental approach speed of to the study of the eddy-current anomaly is described. This involves the use of a method of measuring the anomaly factor as it applies instantaneously at a point in a magnetization cycle.

DOI:10.1049/pi-c.1956.0037

出版商:IEE    

年代:1956

数据来源: IET

摘要:

The discrepancy between the theoretical eddy-current effects and the actual eddy-current effects in thick steel cores is investigated. By using thick cores the magnetic inhomogeneity arising from ferromagnetic domain configuration is of little consequence and the discrepancy may be attributed to an intrinsic time-lag effect in the magnetization process. This time-lag is measured and explained in terms of a localized eddy-current action associated with the dissipation of hysteresis loss. It was found that the time-lag depended upon frequency and was less important at high frequencies.

DOI:10.1049/pi-c.1956.0038

出版商:IEE    

年代:1956

数据来源: IET

摘要:

The main purpose of the paper is to obtain a single formula for calculating feeding coefficients for optimum beam patterns. The new formula derived is equivalent to a set of formulae given by DuHamel, but is much simpler in form and more convenient for computation. It is applicable to Riblet's generalization of Dolph's procedure for finding optimum beam patterns in the design of linear arrays, for an odd number of elements when the distance between sources is less than half the wavelength. Whereas DuHamel's formulae involve a number of separate summation expressions, each of which has terms involving considerable multiplication and division, the corresponding terms in the present, more concise, expression have simpler integral coefficients involving the product of only two binomial coefficients. The mathematical problem solved is to find the explicit formula forbmin the expression of Tn(ax+b) in the form Σm=0nbmTm(x), where Tm(x) = cos(marc cosx) for m>0, T0(x) = ½.

DOI:10.1049/pi-c.1956.0039

出版商:IEE    

年代:1956

数据来源: IET

摘要:

Computed patterns are presented for thin half-wave circumferential slots on circular conducting cylinders of infinite length. The cases considered are for single and diametrically opposed slots on cylinders whose circumferences vary from 3 to 21 wavelengths.

DOI:10.1049/pi-c.1956.0040

出版商:IEE    

年代:1956

数据来源: IET

摘要:

To reduce the problems involved in the design of magnetrons of low voltage and power for operation at frequencies of the order of 10000Mc/s and higher, a system is proposed in which the anode has only a few gaps, e.g. two or four. Operation at low anode voltage and magnetic field is achieved by electron interaction with the Fourier space components of the field.A convenient and simple embodiment is described, and factors likely to result in operation different from the conventional multiple-circuit magnetrons are analysed briefly. In particular, the modes of oscillation and the magnitudes of the components of the different possible spatial harmonics are discussed for two types of anode circuit.Details of operation of valves using both types of anode with two and four gaps are given, and comparisons are made where appropriate with the earlier analysis. The simple electrical structure of the two-gap anode enables a useful tuning range to be obtained by external-circuit adjustment, and some details of tuning performance are given.The paper concludes with comments on noise performance and speed of build-up of oscillations.

DOI:10.1049/pi-c.1956.0041

出版商:IEE    

年代:1956

数据来源: IET