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Proceedings of the IEE - Part A: Power Engineering

Issue 1  Part S • Date May 1956

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Displaying Results 1 - 25 of 32
  • Opening address

    Publication Year: 1956
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    Freely Available from IEEE
  • Introduction

    Publication Year: 1956 , Page(s): 2 - 3
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    Freely Available from IEEE
  • Electrical equipment in aircraft: survey of past and present practice and future trends in design

    Publication Year: 1956
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    The paper describes briefly the development of aircraft electrical power-supply systems from the earliest days of flight until the present time. The unusual conditions which the aircraft electrical engineer has to meet in the operation of his equipment are considered, and the future problems which he will have to overcome as a result of improved aircraft performance are discussed. The review shows that aircraft electrical equipment has advanced from the position of useful but not essential equipment to that of equipment whose correct functioning may be essential to the safety of the aircraft. Electrical equipment in aircraft must conform to the highest standards of electrical engineering practice, since a small failure may have more fatal consequences than in any other field of electrical engineering. This high standard, moreover, has to be achieved under conditions of exceptional difficulty. View full abstract»

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  • Discussion on ¿Electrical equipment in aircraft: survey of past and present practice and future trends in design¿ at the Opening Session

    Publication Year: 1956 , Page(s): 14 - 17
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  • Factors in the utilization of electrical power in aircraft

    Publication Year: 1956 , Page(s): 18 - 27
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    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. View full abstract»

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  • Aircraft radio power supplies: a survey

    Publication Year: 1956 , Page(s): 28 - 33
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    The paper outlines the development of aircraft radio power supplies up to the present, and indicates some possible future trends. View full abstract»

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  • The airworthiness and reliability of aircraft electrical systems

    Publication Year: 1956 , Page(s): 34 - 49
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    Standards for the airworthiness and reliability of electrical systems and equipment are discussed in relation to the overall standards for the aircraft and its engines, and the effect of duplication of systems and equipment is considered. The control and protection of generating systems is examined in relation to experience, particularly of total power failure, and it is concluded that systems have not proved sufficiently reliable in the past to justify entire reliance on them in aircraft which depend on electrical supply for their continued flight. Various methods of providing duplicate and emergency supplies are described. The electrical controls of engines and propellers is discussed in relation to engine reliability, and recommendations are made for improvement. Inadvertent operation of some services (e.g. control-surface trimmers, propeller reversing) may constitute a major hazard to the aircraft; a detailed assessment of the causes of such operation is made and of methods of avoiding it. In an aircraft which carries large quantities of fuel and uses other inflammable fluids at high pressures, the extensive use of electricity may involve a considerable risk of fire or explosion unless the most stringent precautions are taken. Some of the risks and the measures taken to combat them are described. View full abstract»

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  • Discussion on ¿Electricity in aircraft¿

    Publication Year: 1956 , Page(s): 50 - 53
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  • The authors' replies to the discussion on on "Electricity in aircraft"

    Publication Year: 1956 , Page(s): 53 - 54
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  • The medium-voltage d.c. system in aircraft and its application in the Princess Class flying boats

    Publication Year: 1956 , Page(s): 55 - 60
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    The medium-voltage d.c. power system for aircraft is defined and its introduction described. The sources of mechanical power available are suitable for different methods of generating electrical power, but the choice of a d.c. system is supported by desirable motor characteristics, a proved range of contactors and circuit-breakers and suitable light-weight batteries. The ease of maintenance of the system, its simplicity and associated reliability in service are a considerable advantage to the economic utilization of an aircraft, whilst the safety of the system is ensured by comprehensive protective equipment. The `Princess¿ electrical installation illustrates the successful use of a d.c. system and demonstrates the reliability of the many items of d.c. apparatus. The success of any major electrical system in aircraft is attributed to thorough testing in the design stage before the aircraft installation is attempted, which is considered an essential prerequisite to reliable operation in service. View full abstract»

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  • Rectified-alternating-current generating systems in aircraft

    Publication Year: 1956 , Page(s): 61 - 71
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    The paper discusses the relative merits of alternative systems of generation for aircraft, and traces the development in particular of the rectified-a.c. system. The various kinds of supply required on modern aircraft are described, and problems associated with their distribution, as well as those of the generation of large power outputs from main-engine-driven alternators at ever-increasing speeds and altitudes, are discussed. View full abstract»

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  • A constant-frequency a.c. system for aircraft

    Publication Year: 1956 , Page(s): 72 - 80
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    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. View full abstract»

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  • Future trends in aircraft electrical systems

    Publication Year: 1956 , Page(s): 81 - 97
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    An attempt is made to devise the complete electrical system of a hypothetical civil transport aircraft, based upon the generation, utilization and distribution equipment available at the present time, or likely to be available in the immediate future. The approach used is that of an aircraft constructor's design team, and weight is used as the first criterion. Relative reliability is always more difficult to establish, but in certain kinds of equipment it becomes an overriding factor. From the assessment, and a very brief examination of existing bomber and fighter aircraft, it is apparent that before deciding upon an electrical system the particular aircraft must be considered in detail. Certain broad conclusions are, however, drawn about the desirability of certain types of utilization equipment and particular generation schemes. Of perhaps more importance are the items of equipment which are deficient in themselves, or which are limiting factors in the future development of the electrical system as a whole. An attempt has been made in the paper to indicate such items and to suggest the direction of their future development. View full abstract»

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  • Discussion on ¿Aircraft electrical systems¿

    Publication Year: 1956
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  • The authors' replies to the discussion on "Aircraft electrical systems"

    Publication Year: 1956 , Page(s): 103 - 105
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  • Trends in the development of airborne electrical equipment, with particular reference to constant-frequency alternating-current systems

    Publication Year: 1956 , Page(s): 106 - 115
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    The paper outlines the problems associated with the cooling of electrical equipment under supersonic high-altitude flight conditions. The limitations of present-day equipment are shown and recommendations are made regarding the type of equipment to meet future needs. The merits of the various types of constant-speed drive are discussed, together with the types of alternator which are likely to find favour. The need for continued development of high-temperature-resisting materials for the aircraft electrical industry is stressed. View full abstract»

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  • Electrical machines for aircraft

    Publication Year: 1956 , Page(s): 116 - 127
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    The electrical machines used in aircraft differ greatly from normal industrial machines because they must have the lowest possible weight and bulk, but must be capable of operating over a wide range of ambient temperature and air pressure at varying altitudes. Special materials and methods of construction are therefore used in order to permit a high operating temperature and a high specific loading at a high speed. Machines both for direct current and alternating current are considered and are classified as generators, motors and converting machines. The well-established engine-driven blast-cooled d.c. generator receives a good deal of attention. The use of high-temperature insulation, brazed connections, impregnated brushes, high-permeability magnetic materials and other special features are discussed in some detail. D.C. motors, while offering more variety, give rise to fewer difficult design problems. Alternating-current generators may run over a wide speed range, as in many present-day installations in which most of the output is rectified in order to provide a d.c. supply, or they may be driven at constant speed from a variable-ratio gear coupled to the main engine or from a separate turbine. The insulation and constructional problems are similar to those of the d.c. generator. A.C. motors, inverters and rotary transformers introduce their own problems in relation to starting, regulation and other requirements. The paper attempts to give a general picture of the present state of development and to indicate the ways in which further advances are likely to be made in the future. View full abstract»

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  • The cooling of aircraft electrical equipment

    Publication Year: 1956 , Page(s): 128 - 136
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    A brief review is given of the methods of cooling electrical equipment and machines at present used in aircraft. Natural cooling, comprising radiation and natural convection, augmented where necessary by the use of fins, is much used, but where a greater amount of cooling is required forced convective air cooling must be employed, the air being circulated either by fan or by the use of blast air obtained from an external air intake. The theoretical aspects of natural and forced convective air cooling and the flow of air through machines are examined, and the limitations of forced cooling on high-speed and high-altitude aircraft are determined. Assuming a hot-spot temperature of 200°C, it is shown that cooling by blast air becomes inadequate at speeds in excess of about 1 000 m.h.p. owing to kinetic heating, and at altitudes in excess of about 60000ft owing to reduction of mass flow. The introduction of an efficient local cooling circuit and a blast-cooled radiator is shown to improve the altitude performance. Alternative methods of cooling to be used in the local circuit such as air at constant pressure, liquid cooling and evaporative cooling are discussed. Finally, methods of surmounting the thermal barrier so that effective cooling at very high speeds may be achieved are reviewed. View full abstract»

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  • Discussion on "Machine equipment"

    Publication Year: 1956 , Page(s): 137 - 139
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  • The authors' replies to the discussion on "Machine equipment"

    Publication Year: 1956 , Page(s): 139 - 141
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  • Electrical characteristics and protection of aircraft power systems

    Publication Year: 1956 , Page(s): 142 - 150
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    The steady-state and transient characteristics of the utilization and power-source equipment connected to the aircraft busbar can be used to determine the response of the system to shock loading and the nature of its subsequent recovery to normal conditions. The effect of the resulting busbar disturbances on connected load can then be predicted, and limits determined for maximum permissible excursion from the controlled values. Protection of the system against generally accepted fault conditions can be achieved by a variety of types of circuit-breakers and protective circuits, the characteristics of which require to be correlated to give a co-ordinated system. View full abstract»

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  • Aircraft switchgear

    Publication Year: 1956 , Page(s): 151 - 160
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    An aircraft electrical power system involves the same control, distribution and protection problems as any land-based electrical supply undertaking, and while the design of equipment is eased by the use of lower voltages and powers, it is complicated by the necessity of operating reliably for long periods with little maintenance under widely varying atmospheric conditions, and extremes of vibration and acceleration. The paper emphasizes the importance of close co-operation between the aircraft designer and the electrical equipment manufacturer to avoid incompatibility of requirements and to ensure that all normal and abnormal operating conditions are fully appreciated. It indicates that, as generated powers increase, specialized design for most components will be necessary. The design of current-carrying elements and methods of assessing the rupturing capacity of switchgear are considered, together with the effects of voltage, frequency and altitude on these parameters. The types, functions and general methods of construction of control relays and switching equipment are discussed in relation to weight-saving and reliability. The paper concludes with a brief analysis of the problems involved in the design of equipment to operate at very high temperatures and altitudes, and demonstrates the necessity for further development work on insulating materials and constructional methods. View full abstract»

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  • Aircraft electrical cables

    Publication Year: 1956 , Page(s): 161 - 169
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    An account of early cables is followed by a statement of present-day requirements. Descriptions of the standard cables are given, together with current rating data. Further needs are indicated and possible designs are discussed. View full abstract»

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  • The development of voltage and frequency regulators for aircraft electrical systems

    Publication Year: 1956 , Page(s): 170 - 179
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    The paper surveys the development of aircraft voltage and frequency regulators from early days to the present, as aircraft generating equipment progressed from third-brush d.c. machines to constant-frequency alternators. The development of generator driving systems is reviewed, and some early d.c. voltage regulators are described. The carbon-pile regulator is discussed in some detail, and various types of voltage and frequency regulators for d.c./a.c. inverters are described and criticized. Some account is given of regulating equipment for both variable-frequency and constant-frequency a.c. systems. The underlying problems of regulator design are outlined, with an indication of possible future developments. View full abstract»

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  • Aircraft batteries and their behaviour on constant-potential charge

    Publication Year: 1956 , Page(s): 180 - 191
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    A brief survey of the present state of progress in aircraft battery development is given, followed by a discussion of constant-potential charging as it applies to aircraft practice. Improved high-rate performance and increasingly unfavourable working conditions have made aircraft batteries over-sensitive to excessive busbar voltages. The variables affecting battery stability are discussed and illustrated by examples from modern batteries. It is shown that with lead-acid batteries a worth-while improvement would be achieved if antimony could be eliminated. This change would not merely reduce the incidence of boiling but should greatly improve overall reliability, ease of servicing and tolerance towards high ambient temperatures without increasing complexity. View full abstract»

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