摘要:

A very accurate realisation of complex transmission zeros can be achieved in an RC earthed network if the zero sections do not require subsequent adjustment of the capacitors. Zero sections of this type are characterised by the possibility of using arbitrary values for the capacitances. A synthesis method based on this property is proposed, and is illustrated by examples.

DOI:10.1049/piee.1972.0089

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The paper discusses the design requirements for a real-time programming language which may be used as a high-level language in the computer control of telecommunication switching systems. Details are given of one specific telecommunication-oriented programming language (TPL1) which has been implemented as an example of the type of language thought desirable. The main requirement of this language is that it should provide a means whereby an easily readable program may be produced, and which leads to the generation of an efficient code in both storage and central-processor utilisation.

DOI:10.1049/piee.1972.0090

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The paper extends the theory of evanescent-mode filters to include susceptance loading midway between cavities. It is shown that inductive loading may be employed to provide a substantial reduction in the length of narrowband filters without significantly increasing the insertion loss. By replacing conventional capacitive-tuning screws with quartz-rod tuning elements, losses comparable with conventional waveguide filters are obtained in filters requiring about half the volume.

DOI:10.1049/piee.1972.0091

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The paper reviews the results of a further five years' operation of 50 Hz motive power on BR. Individual classes of locomotive are considered, and details are given of the various items of equipment which have given trouble, and of the consequential modifications required. Comparisons are made between the latest class in service and earlier classes, so that the reasons for further changes in the design of this class can be clearly understood. Preliminary details are given of the new class under construction for the extension to Glasgow, and reasons are given for not selecting thyristor control at the moment. The large fleet of multiple-unit trains is reviewed, and various defects and modifications noted. In conclusion, the paper states that, after the bold initial choice of the a.c. system, development was, and must be, based on facts and past performance if a 30-year equipment life is to be achieved.

DOI:10.1049/piee.1972.0096

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The paper describes the preparatory stages that should be followed before a decision to proceed with any railway electrification is given. The purpose of such work is to provide a report to management on comparisons between the proposal and alternative courses of action. Consideration is given to capital and maintenance costs, performance characteristics, commercial appeal, train-service quality, levels of utilisation, fuel costs, track, signalling, politics and environment. Alternatives to electric traction are diesel and gas-turbine propulsion. Discounted-cash-flow appraisal is described. The position of British Railways relative to other undertakings is indicated, and it is suggested that further electrification could be justified.

DOI:10.1049/piee.1972.0097

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The current methods for reducing the effects of inductive interference in lineside telecommunication cables on railways, electrified at industrial frequency, are briefly summarised. The methods employed by British Railways for calculating induced longitudinal voltages in cables are outlined, together with standard calculated values in tabular form. The degree of electromagnetic screening which can be obtained by the use of high-conductivity cable sheaths and steel-tape armouring is illustrated. The effects of the method of traction-current control in motive-power units, with respect to the generation of noise in cables, are also discussed.

DOI:10.1049/piee.1972.0098

出版商:IEE    

年代:1972

数据来源: IET

摘要:

In the electric-arc furnace, arc motion and other factors cause a large irregular fluctuation of current. This fluctuating load results in a fluctuation of the supply voltage, which can cause annoying flicker in lamps connected to the system. The best short-term measure of the flicker severity of this voltage fluctuation is the r.m.s. value of the envelope with which the fluctuation modulates the supply-voltage wave. An instrument which indicates and records this r.m.s. voltage is described. To assess the long-term severity of the voltage fluctuation (whose amplitude varies widely during a complete furnace-operating cycle), a probabilistic method has been developed, based on a quantity called the gauge-point voltage fluctuation. Methods of estimating this quantity during the design stage of supplies to arc-furnace installations are described, including supplies to multifurnace installations. The limits for gauge-point voltage fluctuation in use in Great Britain are specified and the reasons for their choice discussed. Some comparison is made with earlier investigations in Great Britain and abroad.

DOI:10.1049/piee.1972.0099

出版商:IEE    

年代:1972

数据来源: IET

DOI:10.1049/piee.1972.0100

出版商:IEE    

年代:1972

数据来源: IET

摘要:

A procedure is presented for limiting the circulating current when changing taps, and an on-load tap changer is proposed by the author. Principles, theory, experimental results and design procedures are given. The solutions lead to simplified construction, and to some improved characteristics. Low- and medium-power applications are suggested.

DOI:10.1049/piee.1972.0101

出版商:IEE    

年代:1972

数据来源: IET

摘要:

In the first part of the paper, temperature changes in the straight joints associated with single-core oil-filled cables are determined for a number of transient operating conditions. These conditions include normal load changes and, in artificial-cooling schemes, the loss of coolant flow. In particular, 400 kV, 1935 mm2cables with several different cooling systems, i.e. normally buried separate water pipe and integral cooling, have been analysed. The thermal field in the joint and adjoining cable is examined by means of a number of finite-element networks in two dimensions. In the second part, the onset of thermal instability in e.h.v.-cable systems with integral cooling has been predicted, using a digital computer. The studies show that both the time and position at which instability occurs can be obtained for a range of input conditions. The changes in temperature prior to instability do not indicate if and when instability will occur; thus the monitoring of cable and joint temperatures will not give useful prior warning of the onset of thermal instability.

DOI:10.1049/piee.1972.0102

出版商:IEE    

年代:1972

数据来源: IET