DOI:10.1049/ji-2.1944.0034

出版商:IEE    

年代:1944

数据来源: IET

摘要:

The paper is a review of the performance of a group of generating stations over a 5-year period, with comments upon coal qualities, thermal efficiency, analysis of the different classes of breakdown with deductions as to probable operating life between breakdowns, plant availability and the effects of loading.The plant under review is divided into three groups, pre-1930, 1930–1937 and 1938–1942. From the results, curves for maximum probable availability are deduced.The suggestion is made that “operating efficiency” should be calculated on a uniform basis and included in station records. The need for an overall standard by which the performance of generating stations can be judged is discussed, and the term “standard merit,” based upon operating efficiency and plant availability, is suggested.

DOI:10.1049/ji-2.1944.0035

出版商:IEE    

年代:1944

数据来源: IET

摘要:

With the more general recognition of the advantages and economies to be obtained by the electrification of the surface plant and, where mining conditions permit, the underground machinery at collieries, there is likely to be a big increase in the consumption of electricity in the mining industry after the war. In the South Wales coalfield, where approximately 16% of the total output of the United Kingdom is raised, the transmission and distribution of electricity introduces special problems owing to the hilly nature of the country. To enable some idea of the potential demand at collieries to be obtained, the load for, a typical group of collieries is analysed. Some notes are included on the choice of switchgear for collieries and on the influence on this choice of the proposed amendments to the Regulations for the Use of Electricity in Mines.Information is given regarding the damage to transmission towers during the ice storm of 1940, and a proposal is made to amend the Regulations of the Electricity Commissioners governing ice-loading for conductors. A new design of cross-arm for a single-circuit 33-kV overhead line is illustrated. Recommendations are made for the standardization of equipment required for the electrification of collieries.

DOI:10.1049/ji-2.1944.0038

出版商:IEE    

年代:1944

数据来源: IET

摘要:

The paper reviews the circumstances which have led to a considerable increase in the use of thermoplastic cables within the last few months. It points out that the relative importance of such cables cannot yet be evaluated on a peace-time basis since the economic level cannot be established and since a further competitor of natural rubber, namely synthetic rubber, is now making its appearance. In order, however, to establish a basis for evaluation it is desirable to have a thorough understanding of the general characteristics of thermoplastic cables; this is attempted in the paper with particular reference to v.c. (polyvinyl chloride) cables. Indications are given of the polymer situation, the definition of a thermoplastic material and the resulting implications. The building-up and testing of p.v.c. compounds is studied, and the manufacture, characteristics and uses of cables derived therefrom are considered in detail. A brief survey of thermoplastics other than p.v.c. is followed by a comparison of v.c. with rubber.

DOI:10.1049/ji-2.1944.0042

出版商:IEE    

年代:1944

数据来源: IET

摘要:

An analysis of the nature of the air-borne particles which constitute the main source of contamination on outdoor porcelain insulators, and of the forces acting upon them in the electrostatic field around an insulator, suggests that these forces are inadequate to account completely for the observed distribution and the quantity of the deposits on insulator surfaces. Direct measurements of the field strengths close to the insulator confirm that the voltage gradients do not reach very high values under normal conditions, and that the electrical forces are proportionately weak. Investigations of the air flow over the insulators, and comparisons of the formations of air eddies observed in the flow over the geometrical forms associated with the complex shapes of insulators, show that the aerodynamic conditions have a considerable bearing upon the patterns formed by the deposits on the insulators. Wind-tunnel experiments provide results which illustrate the influence of the Reynolds' number, the applied voltage, the surface roughness, the wind velocity and the humidity, upon the distribution and amount of deposited matter. Moisture films constitute a special case of temporary contamination with sparking following the receding edges of the drying films. Finally, a method is suggested of estimating the flashover values of insulators from a consideration of the distribution of surface resistance as modified by the presence of deposited matter.

DOI:10.1049/ji-2.1944.0045

出版商:IEE    

年代:1944

数据来源: IET

DOI:10.1049/ji-2.1944.0046

出版商:IEE    

年代:1944

数据来源: IET

摘要:

The paper, after briefly considering previous work done in Great Britain, discusses the requirements of a reinforced-concrete transmission-line pole.Details are given of experimental poles, with an analysis of results of tests to destruction. A graphical method of design is developed and sufficient information is provided to enable future work to be undertaken on the bases established. An expression is obtained for the deflection of a pole under load, and it is shown that deflection cannot be taken as a criterion for proof-test purposes.Fabrication and erection methods are discussed, and the paper concludes with a survey of the advantages and disadvantages of the concrete pole, reference being made to a questionnaire issued to a number of users in this country.

DOI:10.1049/ji-2.1944.0049

出版商:IEE    

年代:1944

数据来源: IET