摘要:

The paper describes the usual methods adopted in the commercial testing of static transformers. Emphasis is laid on the need for accuracy, and methods are suggested whereby it can be obtained.The drying-out of transformers, the determination of dryness, and the measurement of insulation resistance are discussed. The measurement of the iron loss and load loss is described, together with methods for obtaining greater accuracy.The measurement of form factor and its effect on the less measurements are dealt with; and methods for determining the ohmic resistance, also corrections for the same, are detailed.The loading of transformers for a full-load test, and the temperature-rise readings obtained on this test, are discussed. Over-potential and pressure testing are described, and the methods of measuring high voltages are detailed.

DOI:10.1049/jiee-1.1926.0039

出版商:IEE    

年代:1926

数据来源: IET

摘要:

Polyphase self-excited synchronous induction motors, including the latest types, are analysed with special reference to weight efficiency, conversion efficiency, and configuration of synchronizing torque. It is shown that the weight efficiency of such machines is low compared with that of polyphase asynchronous motors, because the secondary must be designed to carry polyphase load currents as well as unidirectional load and exciting currents. The alternating currents must be carried in a polyphase winding, the unidirectional currents in a single-phase winding. Although the latter may be a part of the former, it nevertheless follows that it is practically impossible to make the maximum synchronous torque of a given frame equal to the maximum asynchronous torque of the same frame. It is further pointed out that, even with a unidirectional and pulsating synchronizing torque, such motors do not run asynchronously with a sufficiently uniform peripheral speed of the revolving member to permit of the general utilization of their asynchronous overload capacity.To overcome these drawbacks the author has conceived the idea of providing self-excited synchronous induction motors with a constant synchronizing torque, to run the machines synchronously from no load to a little beyond full load, and to run them asynchronously for all higher loads. The manner in which a constant synchronizing torque is produced is explained in detail and it is shown how the somewhat conflicting requirements of synchronizing torque and acceptable compounding characteristic are harmonized. Several embodiments of the resulting new motors are described, their synchronous performance being analysed by means of the circle diagram.

DOI:10.1049/jiee-1.1926.0045

出版商:IEE    

年代:1926

数据来源: IET

摘要:

The paper deals with temperature tests and life tests on heating-wires for electrical heating and cooking utensils and with tests on hot-plates, and describes new types of elements and utensils.

DOI:10.1049/jiee-1.1926.0046

出版商:IEE    

年代:1926

数据来源: IET

摘要:

In the first part of the paper the author reviews the conditions which an electric winch or crane should fulfil, and discusses the different ways in which these can be met and the difficulties and disadvantages entailed.An arrangement of contactors, resistances, etc., together with a patent speed-load device, is described as applied to an electric winch, and its method of working and performance under various conditions of hoisting and lowering loads are detailed.A simpler, more compact and less costly system, obtained as the result of experiment, is developed, with curves giving the various speeds obtained at different loads and a description of the safety devices, etc., incorporated.

DOI:10.1049/jiee-1.1926.0047

出版商:IEE    

年代:1926

数据来源: IET

摘要:

The paper gives the results obtained from a systematic study of the received intensities of various long-wave transmitting stations at four receiving stations over a period of nearly two years.The weekly averages of the results are studied, and it is shown that they are inconsistent with any law of steady decay. The results also show very marked periodic variations.It is suggested that all the observed effects can most easily be explained on the assumption of an upper refracting layer. This is supported by the results obtained from plotting an intensity distance curve in detail by means of a portable set, and by the study of the systematic changes which take place daily during the sunset period.Various conclusions are drawn from these results, but it is pointed out that considerable further experimental investigation of many of the observed phenomena is necessary.

DOI:10.1049/jiee-1.1926.0048

出版商:IEE    

年代:1926

数据来源: IET

摘要:

The paper describes a simple pen-writing instrument for the continuous recording of the apparent direction of arrival of atmospherics, and cites typical samples of the data obtainable from such recorders. The samples chosen show the diurnal variation of intensity of atmospheric disturbance, the diurnal variation of apparent direction of arrival, and the location of apparent sources of atmospherics by a group of recorders.

DOI:10.1049/jiee-1.1926.0050

出版商:IEE    

年代:1926

数据来源: IET

摘要:

The paper describes a visual direct-reading radiogoniometer capable of indicating the apparent azimuth of arrival of wave-trains the durations of which need not exceed 0-001 sec. The special properties of the device, which comprises essentially a combination of directional aerials with a cathode-ray oscillograph, are discussed. Amongst these properties is that of giving simultaneous bearings on two or more stations transmitting simultaneously on the same wave-length. A typical installation is described, and specimens of observations on the distribution in azimuth of received atmospheric disturbances are shown. A possible solution of the problem of navigational beacons is suggested.

DOI:10.1049/jiee-1.1926.0051

出版商:IEE    

年代:1926

数据来源: IET