摘要:

The Address is primarily concerned with the engineering aspects of the electricity supply industry at three points in time. The first part considers the immediate prewar years when electricity was supplied by widely varying undertakings. Aspects of generation, transmission, distribution and utilisation are considered in turn and comparisons are made with the present day where appropriate. The second Section deals with topics which are of major importance and interest today with a brief historical development being given where relevant. Particular attention is afforded to the Supergrid, the large generating sets, nuclear power, the explosion in light-current engineering techniques and equipment and to the needs of the customer and his uses for electricity. In the final part, an attempt is made to look into the future. After considering the prospects for electricity sales and the availability of various forms of energy, a review and assessment are made of the electricity-generation options open to the industry. The possibilities for the transmission and distribution of this energy are then discussed, and the paper ends with a brief review of the uses to which electricity might be put.

DOI:10.1049/piee.1977.0001

出版商:IEE    

年代:1977

数据来源: IET

摘要:

Whereas for many years electronic techniques have had wide application in telecommunication transmission equipment, until relatively recently telecommunication switching equipment has been dominated by electromechanical techniques. However, this dominance is now rapidly disappearing as electronic techniques are increasingly employed in switching, often coupled with stored program (computer) control. As electromechanical techniques were introduced well over 50 years ago, it might be assumed that progress in switching has been relatively slow until the comparatively recent technological change. With particular reference to telephone switching systems, the paper aims to show this is not the case, and that considerable changes occurred even within the constraints of an electromechanical realisation. It is argued that, although the original move from manual to automatic control was necessary for economic reasons, it was not beneficial in all respects to the subscribers, and subsequent advances were often aimed at re-introducing facilities available with adequately staffed manual systems. The paper briefly outlines the fundamental principles of switching, which are first illustrated by reference to a typical manual realisation. The evolution of automatic systems is traced from the original step-by-step dispersed-control approach, through the introduction of electromechanical common control, to the introduction of electronics and stored program control. With the introduction of electronic, stored program controlled, digitally switched systems, it is suggested that we may be about to regain the flexibility of a manual approach, with the advantage that the systems should be better able to cope with the modern network environment, more economical to operate and more reliable in service.

DOI:10.1049/piee.1977.0002

出版商:IEE    

年代:1977

数据来源: IET

摘要:

Analysis of an antenna structure which yields equalE- andH-plane patterns is presented in this paper. The structure consists of an excited slot with two symmetrically disposed and parasitically excited monopoles. The equalisation of theE- andH-plane patterns depends upon the coupling between the slot and the monopoles, which is a function of monopole height and separation from the slot. An evaluation of coupling between monople and slot is done, and an optimum configuration is obtained. The analytical results obtained as shown to be in close agreement with the experimental ones obtained by other researchers.

DOI:10.1049/piee.1977.0003

出版商:IEE    

年代:1977

数据来源: IET

摘要:

Using projection operators, a variational-bound formulation is presented which, together with some previous work, can provide both upper and lower variational bounds on the phase shifts or equivalent network elements associated with obstacles located in waveguides. The scattering parameters for dielectric rectangular-parallelepiped obstacles in single and multimode waveguides serve as numerical examples to demonstrate the applicability of the method.

DOI:10.1049/piee.1977.0004

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A large switched network has a complex pattern of interconnections which in practice is normally based on tandem connection of relatively simple units. It is shown that an alternative basis is possible, in which a large structure is built up as a Cartesian product of simple units. The resulting structure has some interesting topological properties, notably an overall homogeneity and a high connectivity for a given number of links and switches. The high connectivity implies that low blocking and high reliability should be attainable. The traffic capacity depends on the path-selection strategy used. A general theory is given for products of arbitrary dimension, assuming uniformly distributed traffic, and either of two simple strategies. A more efficient strategy is described and analysed for two-dimensional products only. The requirements of a trunking scheme for terminal and transit exchanges are summarised, and it is shown that the product network is in principle adaptable to them. The network may need to be partitioned into subsets of varied size, and it is shown that this can be done in a uniform manner. Finally, the use of a product network as a concentrator is described.

DOI:10.1049/piee.1977.0005

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The loss of the home market has forced the British switchgear, turbine generator and transformer manufacturers to produce new designs to meet specifications differing appreciably from traditional British practice. A new range of switchgear will meet the high performance requirements of the home market and also provide an economic export product for most of the common internationally agreed voltage, current and fault-breaking ratings. Turbine generators are required that are radically different in speed, rating and steam conditions from the standard UK installations. Special pass-out turbines will be required to meet the growing market requirements for combined electrical generation and water desalination projects. Transformer design is inherently flexible, but there is an increasing need for better understanding between purchaser and manufacturer regarding operational requirements and design philosophy. The total UK research effort must be co-ordinated if we are to compete effectively internationally. The private sector should probably pay more attention to the national as compared to individual interest. The public sector industries must aim for productivity levels as good as, and price inflation no worse than, those of corresponding industries in the main competing countries. If this is not achieved further economic decline is inevitable. Engineering and managerial skills are capable of meeting world competition. If political difficulties can be overcome, and the full national effort deployed, the UK can certainly gain its share of the world export market.

DOI:10.1049/piee.1977.0006

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A branch-and-bound/capacitated transhipment method for determining the optimal layout of a radial low-voltage-distribution network is presented. Branch-and-bound organisation, postoptimisation and list-processing techniques, used to solve problems of a realistically large size on medium-size computers, are discussed. Case studies and an example are also given.

DOI:10.1049/piee.1977.0007

出版商:IEE    

年代:1977

数据来源: IET

摘要:

State equations are obtained for a multimachine power system including the stator and network transient terms which are commonly neglected. Results are shown for the transient stability of a 5-machine system and the accuracy of commonly used approximations is indicated.

DOI:10.1049/piee.1977.0008

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A novel low-pass power filter is proposed, in which a d.c. machine is used as a reactive element, replacing the conventional electrostatic capacitor. The equivalent capacitance of a suitably operated d.c. machine is, typically, several times larger than commercially obtainable electrostatic capacitors, and, therefore, a filter using a machine as one of its elements should have exceptional characteristics. The primitive machine filter, i.e. one in which the machine directly replaces the capacitance, is shown to be unsatisfactory because of the rotor's leakage inductance and resistance. The critical parameters in the compensation circuit necessary to overcome the effects of these factors are derived together with the required VA ratings of the machine and inductance in a typicalL-type filter. Based on the derived principles, a machine filter, using a standard solid-iron-frame d.c. machine, has been assembled and tested, and the results show an output-voltage waveform which contains less than 0.333% total distortion. A theoretical study of the filter is presented using the proposed equivalent circuit. Finally, the machine filter is compared with classical passive-element systems under steady-state and transient conditions, and possible improvements are suggested. It is concluded that the machine filter is somewhat better than the classical filter in terms of cost and size, and that the noise and vibration problem may be offset in a number of applications by the machine filter's superior transient performance and extended temperature range.

DOI:10.1049/piee.1977.0009

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The field distribution when a thin conducting sheet moves with constant velocity between two rectangular and infinitely permeable pole pieces of an electromagnet is obtained by conformal mapping, after reduction of the problem to two dimensions. This result is used in predicting the force/speed and flux/speed characteristics of eddy-current brakes with nonmagnetic rotors. Experimental results on several brake configurations justify the validity of the analysis.

DOI:10.1049/piee.1977.0010

出版商:IEE    

年代:1977

数据来源: IET