摘要:

The single-phase 50c/s system of railway electrification has developed extremely rapidly and has been adopted in recent years by France, Turkey, Portugal, the Belgian Congo and Great Britain. Of the many types of locomotive possible, the rectifier type is becoming more and more widely favoured, owing to its combining the best possible traction motor with the lightest form of convertor.The paper discusses various types of power circuit which have been or could be used on rectifier locomotives, including h.v. and l.v. control systems, types of on-load tap-changing circuit, buck-boost control systems, stepless control systems, bridge and bi-phase rectifier circuits, and methods of connecting motors. Different types of tap-changer, transformer and rectifier are discussed. The operation of the motor on current with ripples is compared with d.c. operation, and the many factors which influence the choice of the ripple current are analysed.The principal aim of the paper is to bring together the characteristics of transformers, tap-changers, rectifiers and motors, and to discuss the advantages and disadvantages of the various ways in which these items can be put together to form a complete equipment.No ideal solution is found, as the authors consider that the development potential is too great for any existing equipment to be regarded as final.

DOI:10.1049/pi-a.1957.0093

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The increasing use of rectifier locomotives and motor-coaches has focused attention on the limitations of accepted rectifier theory in the calculation of performance of bi-phase and single-phase bridge-connected rectifier circuits. Most industrial rectifier installations exceeding a few kilowatts in rating are supplied from a 3-phase system, and are designed to operate with 6- or 12-phase output on the d.c. side, while sometimes in very large installations it is necessary to operate with up to 72-phase output. In these conventional multi-phase equipments the ripple current, which is associated with undulations in the output voltage, is superimposed on the output direct current, but is sufficiently small to permit, for the purpose of calculation, the assumption of a d.c. circuit of infinite inductance. This assumption leads to considerable simplification of the theory. Unfortunately it is not tenable in the circuits discussed in the paper, as it is found that the presence of the ripple current in the d.c. circuit has a profound effect on the operation of the whole equipment.The paper outlines the calculations for bi-phase and bridge circuits, based on the accepted ‘infinite inductance’ theory, and derives the direct voltage at the motor, ripple current in the motor circuit, power factor in the a.c. supply, harmonic currents in the a.c. supply and other related quantities. The inaccuracies in the results of these calculations are pointed out.A description follows of a new approach to rectifier problems, by means of which solutions to both transient and steady-state problems can be obtained, taking proper account of resistances, inductances and capacitances in all parts of the circuit. The problems are treated as circuit problems, the equilibrium equations being established in terms of mesh currents and expressed as simultaneous first-order differential equations. These are solved by means of a digital electronic computer, Deuce, whose logical facilities are used to take account of the valve action of the rectifying elements.Results of calculations are supported by tests which were carried out in conjunction with British Railways on the Lancaster-Morecambe-Heysham section. A description of this electrification has appeared elsewhere.12The operation of rectifier locomotives is discussed in the light of further calculations based on variations of a typical design.

DOI:10.1049/pi-a.1957.0094

出版商:IEE    

年代:1957

数据来源: IET

摘要:

Interconnected systems have increased considerably in recent years, and the large possible earth-fault currents resulting require further thought being given to earth system design, especially in areas of high soil resistivity. The paper discusses the special practical problems of the design, construction and testing of earth electrode systems for stations with possible earth-fault currents in excess of 3 kA. The basic components are reviewed, and principles of design are suggested for power station and large substation earthing installations. Several examples are considered in detail and brief notes are given of a number of other stations. The measurement of the dissipation resistance of large earth electrodes is discussed, and new techniques of resistance measurement which have been specially developed for use with large installations are described.

DOI:10.1049/pi-a.1957.0099

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The electrolytic tank is playing an increasing part in electrical-engineering design departments, particularly for the analogous solution of 2-dimensional field problems. The paper describes the design, construction and operation of a general-purpose deep tank for solving both 2- and 3-dimensional problems. Details are also given of the precision electronic potential and gradient measuring equipment, together with an assessment of the accuracy achieved and the precautions required.The use of the tank is illustrated by a few typical applications which have been studied by the computation group within a large electrical-engineering organization.

DOI:10.1049/pi-a.1957.0103

出版商:IEE    

年代:1957

数据来源: IET

摘要:

Reference is made to the shortage of generation, transmission and distribution capacity following the end of the 1939–45 War and upon the resumption nationally of normal activities. This prompted a renewal of interest in the storage of energy in the form of heat, and the paper describes briefly experiments that were made leading to the design and production in this country on a commercial basis of transportable unit-type thermal-storage space heaters.The suitability of buildings for this form of heating is discussed, as also are methods of planning and controlling installations.In forecasting the future of this form of heating there is reference to electricity tariffs and to the relative costs of electricity and other forms of fuel.

DOI:10.1049/pi-a.1957.0108

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The development of off-peak load is of increasing importance to the electricity supply industry, and the paper gives details of experience obtained in developing off-peak electrical floor warming in the south of Scotland. Special features in the design and control of electrical floor warming are discussed, and various methods of installation are described. Particulars are given of some representative installations, including single- and two-storey buildings, multi-storey buildings, and dwelling houses. Actual operating results are quoted and analysed. A section is included on off-peak tariff design, bringing out the South of Scotland Electricity Board's approach to this problem.Some reference is made to the comparative economics of electrical floor warming and other methods of space heating. In the conclusions it is suggested that, as this method of space heating has so much to commend it, the electricity industry can confidently take further steps in its development. It is also suggested that there is scope for further research in this field.

DOI:10.1049/pi-a.1957.0109

出版商:IEE    

年代:1957

数据来源: IET

DOI:10.1049/pi-a.1957.0113

出版商:IEE    

年代:1957

数据来源: IET