摘要:

The history and development to 1929 of the pooling arrangement by which some 60 per cent of all the electric generating plant in the Lorraine steelworks is regulated and the electricity sold is generally described. Of the 3 600 000 cubic metres of blast-furnace gas available, half is used for processes in the various works and the other half for generating electricity. Most of this electricity is used in the works. Nominally some 100 000 kW are available for export sale.An overhead network interconnects, through substations, 10 power stations with an output of 125 000 kW, all working in parallel. Some 65 per cent of the power is developed by gas engines whose want of overload capacity throws too much of the inevitable load fluctuation on the gas-fired steam-turbine sets. These latter are being increased to a capacity of 74 000 kW distributed in 7 works, and some of the boilers are not being fired only with blast-furnace gas but, if desired, also with pulverized fuel. The whole working is controlled by telephone by a load dispatcher.

DOI:10.1049/jiee-1.1930.0038

出版商:IEE    

年代:1930

数据来源: IET

摘要:

The immersion in water of lead-covered cables, with a view to the detection of faults in the lead sheathing, is discussed. Tests of the time taken to show up these defects in power cables at different water pressures are given for various cable samples. The conclusions drawn are that, except possibly in the case of low-voltage cables, no such defects will be discovered during factory routine, and that for high-voltage cables, at least, water immersion should be definitely discontinued.

DOI:10.1049/jiee-1.1930.0040

出版商:IEE    

年代:1930

数据来源: IET

摘要:

It has been observed that the free air pressures of a sound wave may be increased at the diaphragm of a microphone in a ratio greater than 2:1 at certain frequencies, when there is concavity in the face of the microphone. A method of calculating the magnitude of this increase is applied to a condenser transmitter of the Wente type, and close agreement is found with experimental results. The calculations involve certain simplifying approximations the validity of which is discussed.

DOI:10.1049/jiee-1.1930.0041

出版商:IEE    

年代:1930

数据来源: IET

摘要:

This paper is concerned with the alternating-current characteristics of loaded telegraph cables and their relation to transmission capacity. The general principles of transmission are reviewed, and by the use of periodic theory the performance which may be expected from a cable of given a.c. characteristics is estimated.Methods of testing are described by which complete data of the a.c. constants may be obtained during the process of manufacture. The effects of frequency, current, temperature and pressure are investigated, and the results of tests on the core for a long high-speed cable are discussed and used to estimate the performance of the cable when laid.Apparatus and alternative methods for testing the laid cable are detailed and a method of deducing the primary constants from attenuation and propagation-time tests is developed; values determined are compared with results of factory tests. Deductions regarding the value and regularity of the inductance loading are made from impedance tests.Departure and arrival curves for loaded cables are constructed from theory and compared with records obtained by test.Finally, the assumed criteria for satisfactory working, expressed in terms of attenuation, are verified by transmission tests.

DOI:10.1049/jiee-1.1930.0042

出版商:IEE    

年代:1930

数据来源: IET

摘要:

The paper describes researches which have been carried out at the National Physical Laboratory for the Radio Research Board. An improved method of measuring the amplification of a radio receiver is described, together with the manner in which this method can be applied to practical cases, particularly at short wavelengths. The apparatus covers a wavelength range of from 15 to 30 000 metres, and is capable of dealing with inputs of from 0.25 to 1 000 mV over this range. After describing in detail the construction and operation of the apparatus in Section (1), the results of tests on four receivers of widely different types are given in Section (2), and some general deductions are obtained from the properties of these receivers. In conclusion, suggestions are made in Section (3) for a possible means of classifying receivers for different purposes.

DOI:10.1049/jiee-1.1930.0043

出版商:IEE    

年代:1930

数据来源: IET

DOI:10.1049/jiee-1.1930.0045

出版商:IEE    

年代:1930

数据来源: IET

摘要:

Simplified approximate formulæ are given for calculating the attenuation, wavelength constant and characteristic impedance from the “open” and “closed” impedances. The limits of error of these expressions are ascertained, and the formulæ are developed directly in terms of the bridge readings. The limitations of the “open and closed” method on long lines are discussed, and the sensitivity of the bridge necessary to obtain a given accuracy in the measurement of attenuation is found.

DOI:10.1049/jiee-1.1930.0046

出版商:IEE    

年代:1930

数据来源: IET

DOI:10.1049/jiee-1.1930.0051

出版商:IEE    

年代:1930

数据来源: IET