摘要:

This paper reviews the events prior to and after the coming into being of the recent Meters Act, together with its effects upon authorized undertakers. The indirect implication of the Act, which may be regarded as essentially psychological in character, is briefly dealt with, and lastly the technical implications, such as “Approved apparatus for the examination, testing and regulating of electricity meters under Section 2 of the Act.”

DOI:10.1049/ji-2.1941.0033

出版商:IEE    

年代:1941

数据来源: IET

摘要:

The principal types of failure in light- and medium-duty electrical contacts are analysed in detail and an account is given of the characteristics of the commonly used contact materials.The effects on contact resistance of the size, shape, surface finish and closing pressure of light-duty contacts are discussed; an account is given of the resistance of contact materials to the formation of tarnish films; and attention is directed to the effects of dust and grease films in causing failure.In medium-duty contacts, when arcing occurs, the most serious cause of failure is the action known as “material transfer” which takes place when direct currents are interrupted. As a result of transfer the contact gap may close and the contacts finally interlock. The factors which influence material transfer are discussed, and curves are reproduced to show the limiting current and the rate of build-up for a number of common contact materials under given test conditions.A second cause of failure is the welding-together of the contacts by the current surge at make. The inherent tendency of a number of contact materials to weld together has been measured.In sliding contacts, excessive wear is a frequent cause of troubles. A method of testing the wear of unlubricated surfaces is described, and the results of measurements on a number of combinations are tabulated.

DOI:10.1049/ji-2.1941.0036

出版商:IEE    

年代:1941

数据来源: IET

摘要:

An important theme underlying the paper is consideration of the degree to which it is practicable or desirable to render interchangeable the numerous outdoor bushing designs now available for any given service, and to effect any measure of standardization. In developing this theme, much of the paper is devoted to the subjects of construction and testing. The paper first analyses the existing variations in construction from all aspects and discusses the relative advantages of a large number of different features of the principal types of outdoor bushings. The variations of test and service conditions which control design are then studied. Ideal test conditions are enunciated and in the light of them the author considers the tests which modern bushings have to meet. The effect of these latter tests upon design and construction are examined. Hence recommendations are made regarding the lines upon which it would be advantageous to standardize test conditions. Finally, the mechanical interchangeability of bushings is discussed and a degree, of standardization proposed. Whilst the paper relates mainly to transformer and circuit-breaker terminal bushings, and gives prominence to bushings of the bakelized-paper condenser type, it by no means confines consideration to these, and most of the conclusions are of general application.

DOI:10.1049/ji-2.1941.0039

出版商:IEE    

年代:1941

数据来源: IET

摘要:

Lightning can impress a potential on the sheath of a buried cable either by direct stroke or by induction. This fact is by itself not sufficient to explain the occurrence of voltages between the sheath and the cores, since the cores are completely enclosed by the sheath and initially take up the potential of the latter by induction. Voltages between the sheath and the cores can occur only through the formation of travelling waves; it is shown that waves of at least two different velocities must occur. Soil conductivity and wave front are important factors. Various remedies are suggested.

DOI:10.1049/ji-2.1941.0042

出版商:IEE    

年代:1941

数据来源: IET

摘要:

A new formula is developed for the proximity effect in single-phase systems of solid and hollow round conductors to replace the two formulae developed by the author and published in 1935 and 1936 respectively.Two independent formulae for the cases of solid and hollow conductors are replaced by a single formula for hollow conductors, including the solid conductor as a particular case. The new formula is simpler and can be evaluated numerically in a shorter time. It is more accurate and is valid for all possible values of the independent variables. The earlier solid-conductor formula failed for certain ranges of the independent variables. Improved formulae are also given for 3-phase systems.The discrepancies between values calculated by the new formulae and values obtained from experimental measurements are little, if any, greater than possible experimental errors.

DOI:10.1049/ji-2.1941.0043

出版商:IEE    

年代:1941

数据来源: IET

摘要:

This report is a record of a series of investigations upon the behaviour of various insulating materials under disruptive voltage surges, carried out with the object of filling serious gaps in knowledge in this important field.Particulars are given of a number of materials under different surge conditions, and a critical survey is made of the results obtained.The conditions necessary at breakdown for measurements to give the electric strength of the material under test are examined. The influence of electrode shape and immersion medium are discussed, suitable forms of test specimen for different materials are considered, and results of impulse tests at voltages up to 700 000 are given.The Director of the E.R.A. will welcome comments and suggestions from those who may have occasion to make use of this report.

DOI:10.1049/ji-2.1941.0044

出版商:IEE    

年代:1941

数据来源: IET