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The paper records the development of the generation of d.c. power in aircraft by windmill- and engine-driven generators, from its inception to the present day. The developments prior to the last decade are covered only very briefly. Features of generator design which have called for special consideration, or have been the subject of failure, are discussed. Sections are devoted to the choice of speed range, brush wear at high altitude, systems of ventilation, design of end-frames, and bearing failure. Some mention is made of generators designed for power supply to radio equipment, as distinct from general power services. These generators, which include high-voltage d.c. machines and high-frequency a.c. machines, have been combined with low-voltage d.c. machines, both in tandem and with a common magnet system. The latter part of the paper deals with voltage regulation, which is inseparable from the preceding part, in so far as generator design is influenced by the system adopted; self-regulating generators of various types have been used from time to time in the past. The scope does not permit more than brief mention of the design of the several types of regulator which have been used, including Tirrill and carbon-pile types. The paper shows how the control of the system voltage has been conditioned by the inclusion of an accumulator, and how it has not been possible to devise a system which gives the constant line voltage required for current-using devices, and, at the same time, permits of adequate control of accumulator charging current. Systems of paralleling, and their effect on line voltage, are also described. The electrical equipment of lighter-than-air craft is not included in this paper.

The difficulties and complication associated with the transmission of large blocks of electric power over considerable distances have led, during recent years, to a growing interest in the possible application of direct current at high voltage for this purpose. In spite of the fact that alternating current lends itself readily to generation and potential transformation in bulk, it cannot compete with direct current where transmission on a similar scale is concerned. For this reason direct current can, under certain circumstances, form an economic link between the source of energy supply and the consumer. The paper presents a broad survey of the basic problems involved in generating, transmitting, and transforming electrical energy in the form of super-tension direct current as they appear at the present time, without attempting to add new matter to a subject which is of necessity highly specialized and the province of the transmission engineer. After a brief historical review of the subject has been given in the Introduction, the manifold advantages of high-voltage direct current as a means of power transmission are discussed and the factors limiting its direct generation are investigated. Of the several methods available for converting alternating current to direct current at high voltages, relatively few are at once technically and commercially feasible. A general account is given of those current-converting systems which seem to offer the most promising solution of the transmission problem. The general trend of opinion in favour of the super-tension direct-curent system as reflected in modern transmission projects is explained, and an outline is given of three such schemes of major importance which have been put forward during the last few years. Finally, the paper indicates the course of a rational future development and suggests how the super-tension direct current system of power transmission might with advantage be introduced and further technical data obtained. References to recent literature dealing with the transmission problem are given in a Bibliography.

The paper discusses the mode of propagation of energy under steady current conditions, and advances the view that it is only a special case of radio transmission. The electromagnetic theory governs all electrical processes, but, while the high-frequency disturbances of light, or radio-telephony, move in waves which are known to retain their individuality when superposed, the principle of independence does not seem to be applied when the disturbances are of very low frequency so as to approach steady current conditions. In the last case the electromagnetic fluxes are, even nowadays, often regarded as static, and when such fluxes are superposed it is generally assumed that they merge into a single flux. Poynting's theorem of energy flow suggested that the fluxes due to steady currents are moving through the dielectric, but tacitly assumed that the fluxes form a single stream, and that nothing of the nature of reflection occurs when this stream reaches a material surface. It would seem only to harmonize with Maxwell's theory, and with the properties of light, if such streams when incident on matter were to give rise to reflected ones, and therefore to a system of superposed streams. The aim of the paper is to show that such a view is quite consistent with the known distribution of energy to the various parts of the conducting circuit. The mathematical problem is discussed in Part 2 of the paper. The analysis is an example of Heaviside's vector methods. It is necessarily based on assumptions. The physical aspects and the justification of these assumptions are dealt with in Part 1.

This paper reviews the development and present scope of British standards, published by the British Standards Institution, for insulated power cables.It is concluded that, after taking into account the wide diversity of uses for such cables, the present multiplicity of standards is not justified, and that considerable reduction of the alternative constructions now included is desirable for economical production and in the best interests of the electrical industry as a whole. Further, that some types, not hitherto included, are now sufficiently standardized to warrant their addition to the existing ranges.Very comprehensive standards are necessary and desirable in the early stages of the development of any industry. The paper suggests that the applications of electric power cables, though more diverse than at any previous time, have now reached a point at which serious and comprehensive review is justified, with the object of reducing the number of standards to a minimum compatible with modern requirements.

The paper reviews the possible development of gas-cooled graphite-moderated reactors for power production. It is shown that larger reactors of the Calder Hall type will produce electric power at a competitive cost in the United Kingdom. A very promising line of development is towards higher-temperature operation, since this increases both the heat rating of the reactor and the overall efficiency of the plant, although it requires the development of new materials, particularly for cladding the uranium. As higher temperatures are reached, interest is stimulated in the oxide and carbide forms of uranium, and for very high temperatures an all-ceramic reactor core has been suggested. The paper describes the use of recycled plutonium as a fuel, showing that under certain circumstances this is possible with a natural-uranium fuel. Comparison is also made of the relative merits of a number of possible coolant gases. It is concluded that, given research and development effort, the gas-cooled graphite-moderated reactor is capable of considerable development. For the base-load application, cheaper power should be possible, and the range of application may be extended to smaller power units tailored for specific purposes.

The man-made-fibre industry has brought its own problems for the electrical power engineer. Power generation and distribution, special design of small motors, both asynchronous and synchronous, and control systems have all had to be developed, with special attention paid to reliability and continuity of service, combined with maximum economy. A first-hand knowledge of the industry is essential. Much the same may be said about other ‘user’ industries, and this example is used to show that there is a greater need than is perhaps realised for the professional electrical engineer as an applications engineer in a user industry. Only in this way can full and economical use, based on a balanced engineering judgment, be made of the rapid developments in electrical technology, whether power, electronics or control. Equally, the profession needs to know more of the demands and responsibilities of the user applications engineer, and a plea is made for more papers on this subject. The acceptance of informal papers increases the opportunities.

The British Electrical and Allied Industries Research Association have undertaken a comprehensive research into the problems arising in the construction and uses of overhead electric lines. The research has been productive of valuable results. The present paper deals with two sections of the work: (1) as to the strength of wooden poles, single and compound, and (2) as to the intensity of wind pressures on wires and cables such as are used for overhead power lines and on the poles and lattice structures for supporting them. The tests on wooden poles disclosed a fundamental weakness in the usual design of compound poles and led ultimately to the development of a much improved design. Accurate figures were also obtained of the rupturing strength of red fir poles. The improved design of compound pole is described and the weakness of existing designs is pointed out. The wooden poles were tested under practical conditions. The information gained was supplemented by a series of tests on small-scale models, which confirmed the claims made for the greatly increased strength of the new designs of compound poles. The tests of wind pressures were made on wires of various sizes, on cylindrical sections corresponding to those of wooden poles and on angle bars and a lattice framework. Definite values of the coefficient relating wind pressure with velocity have been recorded by these tests, the figures being of considerable value to designers. Sufficient data have been obtained to enable, for the first time, a proper allowance to be made by the designer for wind pressures on wires and cylindrical poles of the sizes commonly used for electric power lines. A series of experiments to determine the wind pressure on angle bars is described. The results indicate that the wind pressure on a fabricated frame may be estimated from the data obtained by tests on standard sections. The work of the Association described has produced valuable re

The authors begin by pointing out, with the help of a mechanical analogy, the true place which the alternating current transformer takes in the group of plant considered to-day to be standard for the generation, transmission and distribution of electric power on a large scale.They propose the use of high-voltage alternators and the partial abolition of transmforers. In support of these proposals, the authors discuss the gradual growth of conditions favourable to the introduction of the high-voltage alternator, and describe the obstacles in the way of further development at lower voltages.This discussion leads naturally to the advantages to modern alternator design to be derived from the acceptance of the principle of direct generation at high voltages.This discussion leads naturally to the advantages to modern alternator design to be derived from the acceptance of the principle of direct generation at high voltages.Apart from the design of the alternator itself, including its cable leads, there are many ways in which the adoption of such an alternator would effect financila economy in capital outlay and running expenses, and these matters the authors proceed to set out.They then taken a brief survey of what has already been done in the past in the field of direct generation at 30000 volts, and describe in detail a 33000-volt, 25000-kW, 3000-r.p.m. alternator of unique design, built for the North Metropolitan Electric Power Supply Co., for installation in the new power station at Brimsdown, North London. The operating experiences on site since the setting to work of the alternator in August 1928 are stated.As a matter of interst to those engineers and designers engaged in alternator construction and development, and outline is given of some of the experimental research carried out by the authors in the working out of the practical details of the new design, and of the tests made at works on the completed alternator.The paper concludes with some reference to the future possibilities of the extended use of direct generation at high voltages, and the authors ask for a candid expression of opinion from their critics.

The paper describes recent developments in the operation of the older types of navigational aids, lights, fog signals and radio beacons. A novel system of remote control is described and means for automatic operation of remote light stations discussed. Development of a system to give automatic indication of locally reduced visibility is described. A method of employing arc discharge lamps as navigation lights is mentioned. A new system for coding radio beacons is described. A policy for electrical power supplies at remote places is outlined, mention being made of the possible use of solar energy.

The paper consists of a description of the area supplied by the Lancashire Electric Power Co., and of the nature of supplies afforded in that area. The 11-kV distribution system and the protective arrangements employed thereon are described, and figures showing availability of supply to consumers during a period of 1 year are given. The testing necessary to ensure satisfactory functioning of the protective gear is also described.

The object of this paper is an attempt to point out the advantages of combining the production of electrical energy with that of coal by-products. It is also a plea for co-operation between the mine owners and electrical engineers, especially in districts where there already exist efficient gas-engine stations utilizing waste gas, and in other districts where they can be efficiently erected and operated.It is an admitted fact that the Electricity Act of 1926 will have a very far-reaching influence not only throughout the electrical industry but also in the homes and lives of the people, and if therefore the thermal and financial aspects of that Act are carefully considered it should lead not only to cheaper electricity but also to a greater use of the coalfields as generating centres.It has been said in the past that the general view of the generation of electricity is too parochial, and that if the country as a whole is to benefit from the proposed re-organization of the generation of electricity the widest possible outlook should be taken. This outlook must embrace the generation of electricity and also the possibility of reducing unemployment by encouraging the mining industry to cooperate, not only in the supply of fuels but also in that of surplus electrical energy.

The mining industry is one of the largest producers and users of electric power in this country. It is generally assumed that the methods of production and utilization are not as economical as they might be. The following notes of some efforts to achieve efficiency and increase reliability, together with results of tests made with this end in view, may be of general interest.For the purpose of reference the paper is divided into three parts:—Part 1 deals with the general problem of power production at mines, giving briefly the essential differences between a colliery power plant and a normal power plant.Part 2 deals with the modern methods of supplying the four main power-consuming units at mines, with particular reference in each case to the question of the utilization of synchronous motors, and also discusses the advantages and disadvantages of alternating-current and Ward-Leonard control for electric winders.Part 3 gives the results of progressive conversion of several mines from steam to electric drive for the various main units and also the effect of supplying compressed-air power from a central station in a similar way to electric power.

The paper discusses the different engineering problems associated with satellites and probes, and their launching rockets. The different set of operating conditions encountered in these two main areas of space technology are examined and the motive power and control problems which arise are dealt with. The basic requirements for the multi-stage launching rockets are discussed; rocket equipment at present under development is then reviewed, noting the limitations imposed by present rocket techniques and launching facilities. Future trends of rocket development are mentioned in relation to possible payloads. The composition of a typical satellite or space probe is then considered, with some attention being given to each of the different systems, such as structure, power, attitude and speed control, instrumentation and communication equipment, etc. Critical design criteria such as weight, and electrical power requirements are highlighted. The operating environment is then reiated to the choice of design of the various systems. Particular consideration is then given to several specific types of satellites and space probes, examining the differences which arise from the varied requirements, and assessing what integration may be achieved by the design of common systems for the various applications.

The address concerns itself with the transmission of electrical power in bulk underground principally at the voltages of 132 kV and higher. It states the basic problems of an underground system starting from the needs of the usual tortuous route and ending with the rating and high cost difficulties. There follows a review of current approaches setting these against the historical background. First, it concentrates on the severe mechanical difficulties of producing High grade cable Insulation, with paper as an Insulant, In an extremly flexible form, goes on to describe the special nature of the accessories needed to solve the electrical and pressure-retaining requirements and then deals with the many special rating solutions which are now being adopted to meet the growing demand for high MVA circuits. Bearing in mind the high relative cost of high-voltage cable much research and developement work has been in the field of the economy and the address makes reference to the many approaches. An approach is made to the problem of a transmission system which, ab initio, needs to be visualised as largerly underground and points out the strong case for d.c. transmission.

The increasing demands for electrical power in modern aircraft, and in particular 400 c/s constant-frequency supplies for various consuming devices, have emphasized the need for an electrical system which can provide the requisite amount of power for the lightest weight, the minimum maintenance and the maximum reliability. The constant-frequency a.c. system can satisfy these demands and meet the arduous conditions imposed upon it far better than any other system. The high efficiency, inherent robustness and reliability of the static transformer and induction motor contribute in large measure to the superiority of the constant-frequency system, and a further consideration is that it eases the problems associated with switching at high altitude.Methods of obtaining emergency supplies for vital services in the event of failure of the main alternators are described, together with various alternative systems of starting the main engines.The paper illustrates a typical aircraft installation and analyses the total weight; it also discusses secondary supplies, and equipment employed in the installation.

The paper describes the materials now available and in course of development which are suitable for use in components for operation at high ambient temperatures. The present and future developments of components for aircraft electrical power distribution are described.

The transmission of electrical power by overhead systems has involved electrical engineers in yet another branch of engineering, as certain specialists in the structural steelwork industry fabricate the towers which support current-carrying conductors. The initial cost of an electrical scheme embodying an overhead transmission system can be such that a high proportion of outlay is for the transmission of the current, and the deterioration rate of materials used in construction must be kept aslow as possible so that depreciation of capital value and maintenance costs are minimized. Steelwork in an unprotected state, erected in areas where rainfall and atmospheric pollution can be rated even as normal, deteriorates by corrosion quicker than is acceptable. The general method of protecting transmission structures against corrosion is hot-dip galvanizing, detailed examination ofwhich would be of interest only to those engaged in research on the subject. However, a useful working knowledge of the process and the ability to distinguish a good coat from a bad one can be obtained from a reasonably short study. The object of the paper is to give electrical engineers a brief description of the metallurgical construction of a zinc coat, together with some information on its expected life, and to offer a condensed description of the process, certain methods of quality control and to advise on the after-care of the finished product.

The paper reviews some of the factors which have influenced aircraft electrical installations. It demonstrates the complexity of present-day systems and the stringent safety precautions required. Generally it reflects the problems which constantly confront aircraft electrical engineers in meeting ever increasing demands upon electrical services.

Electrical power has been used in ships since about 1870, and until comparatively recently all marine systems have employed direct current. The past 15 years have seen a change in practice by all the leading maritime nations and a.c. systems are now becoming more popular. The paper describes the extent of this change and reviews the reasons for it. The special operating conditions applicable to a marine system are described, and also the necessary features which must be built into the electrical installation in consequence. The basic problem of voltage, frequency, size and type of generating plant, voltage regulation and protection are described. The general approach to the solution of these problems is outlined, together with some noteworthy exceptions as practised in certain shipbuilding countries. The effect of increased size of generating plant on system layout is described and current trends in various countries are noted. Mention is made of the present trend towards centralisation of control and/or automatic control for main plant items.