摘要:

The effect of supply frequency on the speed transients of an induction motor due to small voltage and torque disturbances is discussed. The transients which depend on four nondimensional parameters are obtained by a graphical (root-locus) method which could well be followed at the design stage.The transfer functions between speed and small changes in input voltage and torque are given. It is shown that in low-frequency motors a lightly damped transient speed oscillation will occur at a frequency just below the supply frequency, which is influenced only slightly by the machine parameters.

DOI:10.1049/piee.1965.0314

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The paper describes a digital-computer programme for calculating lightning surge voltages in high-voltage power systems. The voltages due to an injected lightning current in a transmission line are calculated simultaneously in the whole system considered. The flashover characteristics of the suspension insulators, the surge impedance and earth resistance of the towers, the surge impedance for mutually coupled conductors, the surge capacitance for station equipment and the characteristic of lightning arresters are all taken into account. The programme may, for instance, be used to evaluate general rules for the location of lightning arresters as a function of a few important parameters for conventional station arrangement. It may also be applied to calculate the voltages and to determine the protection requirement necessary for each special case.

DOI:10.1049/piee.1965.0317

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The paper shows how the method of separation of variables, digital computation and Fourier synthesis may be combined to give the approximate solution of a particular field problem. The problem concerns the fringing flux at the tip of a cylindrical permeable magnetic pole face. Selected co-ordinate surfaces subdivide the volume of the field into regions within which the scalar potential may be expressed by Fourier expansions with unknown coefficients. A set of simultaneous equations for solution in these coefficients by digital computer is derived by satisfying continuity at chosen points which lie on the interfaces separating the several regions. The exact solution is approached by increasing the number of interface points.

DOI:10.1049/piee.1965.0319

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The paper is arranged in three Sections following an Introduction. Section 2 deals with factors affecting the development of electric water heating such as the increasing standards of home comfort and the effects of recent legislation calling for supplies of running hot water in the home, office, shop and factory. Progress in the development of the water-heating load is discussed, together with the scope for off-peak water heating.Section 3 covers developments in the design of electric water-heating appliances, compliance with the appropriate British Standards and approval by both electricity- and water-supply authorities. It deals with the performance of self-contained electric water heaters of both the storage and instantaneous types, and water heaters for use with off-peak supplies of electricity.Section 4 discusses developments in the design of immersion heaters, and compares their performance when installed in different positions in a storage vessel. The effects of water hardness on the life of immersion heaters are reviewed, and remedies are suggested to overcome problems of premature failure. The function of the thermostat and its performance are also considered, and the paper concludes with a consideration of the important subject of heat insulation of the water-storage vessel.

DOI:10.1049/piee.1965.0320

出版商:IEE    

年代:1965

数据来源: IET

摘要:

It is shown that, under certain conditions, a speed-control system with a back-e.m.f. nonlinearity fails to reach the demanded speed in response to a step-function input. This is equivalent to a restriction on the region of asymptotic stability of the steady state of the system. The restriction is investigated by means of the Lyapunov method, and an analytical expression is obtained for it.The nonlinearity is a function of two variables, and the functions V and V used are not sign-definite in the entire phase plane. A technique is used for deriving analytical results in this situation, and the resulting sufficient conditions are compared with exact results.

DOI:10.1049/piee.1965.0327

出版商:IEE    

年代:1965

数据来源: IET