DOI:10.1049/jiee-1.1933.0054

出版商:IEE    

年代:1933

数据来源: IET

摘要:

The paper details the financial results that have followed the change-over from steam to electric haulage on parts of the Swedish State Railway, and shows how the traffic has been speeded up as a consequence of the electrification. The various problems associated with the change-over, and their solution, are discussed. The paper is followed by Appendices giving a technical description of the track equipment and electric locomotives, water-power resources, etc.

DOI:10.1049/jiee-1.1933.0055

出版商:IEE    

年代:1933

数据来源: IET

摘要:

The paper treats of a class of low-tension a.c. distribution system using bare conductors for electrical flexibility.A formula for self-inductance is calculated, from which it is shown that, given certain limiting conditions, the conductors must be unusually closely spaced.In practice, such a system is subject to frequent and apparently inexplicable flash-overs.Investigating this problem, the paper analyses mathematically the effect, on a steep-fronted voltage surge, of regularly localized insulator capacitance.The wave-complex arising at each reflection point is found to be divisible into groups, provisionally termed “sub-transients,” which are expressible by gamma functions.It is concluded that the insulators have a magnifying effect on voltage surges, which thereby easily attain destructive values.The researches of Steinmetz confirm the tendency for the phenomenon to persist, in systems of the type considered.Insulating barriers are suggested as being a proven, if expensive, remedy.

DOI:10.1049/jiee-1.1933.0060

出版商:IEE    

年代:1933

数据来源: IET

DOI:10.1049/jiee-1.1933.0061

出版商:IEE    

年代:1933

数据来源: IET

摘要:

Bridge methods of measurement of circuit constants at higher audible and carrier frequencies require expensive apparatus and skilful manipulation, and become difficult at higher frequencies. Prof. E. Mallett developed simpler methods to determine the resonant frequency and decay-factor of electro-mechanical vibrators, and deduced their dynamical constants. The methods were applied by Prof. Mallett and Mr. Blumleinf to find the high-frequency resistance of coils, circuits, etc. The present paper extends the application to determine the primary constants of telephone and other circuits at higher audible and carrier frequencies.Measurements were confined to the frequency band 3 to 12 kilocycles per sec. The resonant frequency and decay factor of telephone and other circuits were determined from(Z/Zd)− fcurves and derived vector diagrams (which were circles). The values ofR, L,andG,of the circuits at 6-53 kilocycles per sec. were deduced.In the case of an overhead telephone loop,RandLwere found at 6-575 andCat 11-03 kilocycles per sec. A circuit capacitance variation of the order of 0.0005 μF could be easily determined by the application of the methods at 6.6 kilocycles per sec.

DOI:10.1049/jiee-1.1933.0062

出版商:IEE    

年代:1933

数据来源: IET

摘要:

This paper is a synopsis of a report† prepared by the E.R.A. on modern practice regarding the use of reinforced concrete poles for overhead lines, considered primarily from the standpoint of factors of safety specified in official regulations.It is shown that the reduction in factors of safety and extended use of such poles in this country may be brought about only on a basis of standardization and scientifically-controlled production.The report includes most of the data required by the designer, manufacturer, and user, in addition to that needed for standardization purposes.The drafting of a British Standard Specification for poles is advocated, and this is now in preparation.

DOI:10.1049/jiee-1.1933.0063

出版商:IEE    

年代:1933

数据来源: IET

摘要:

The rapidly increasing application of mercury-arc rectifiers and the certainty of their exclusive use in the near future in the bulk conversion of alternating to direct current for railway electrification projects, require that more careful consideration be given to the peculiar nature of the load which a rectifier imposes on the supply system. Few electricity supply authorities appreciate that, in the case of rectifier substations, power-factor meters give no real indication of the additional extent to which the generating plant is loaded.The paper investigates the manner in which the mercury-arc rectifier draws power from the supply, with the object of ascertaining the degree to which the generation and distribution system is utilized.The general case of power production from currents and voltages of non-sinusoidal wave-form is considered, and, by introducing a new factor, viz. harmonic power, fresh significance is given to the conception of wattless power.The presence of harmonics in the current delivered by and supplied to the rectifier is briefly explained, and their modification due to smoothing equipment and to parallel connection of rectifiers is indicated.In dealing with the power-factor problem as applied to the mercury-arc rectifier, its treatment by previous investigators is reviewed. The relation between rectifier and system power factors is then discussed and an analytical method of determining the additional loading due to harmonics is developed. Convenient formulae for evaluating the resultant power factors and for expressing the harmonic loading in terms of the reactive power are finally deduced.The paper concludes with a suggested application of the foregoing method of analysis to the amendment of electricity supply tariffs.A bibliography of the available literature covering the problems dealt with in the paper is given at the end of the paper.

DOI:10.1049/jiee-1.1933.0065

出版商:IEE    

年代:1933

数据来源: IET