摘要:

The paper is devoted chiefly to those aspects of cooker design by which cooking performance is affected. Mechanical design is reviewed, but in much less detail, and mainly with the object of recording present practice.The question of the indication of the “heating condition” of ovens is discussed, and the desirability is stressed of taking account of radiation as well as air temperature. Consideration is given to the problem of oven ventilation, particularly from the point of view of its effect on “steaming” at the vent. The Advantages offered by thermostatic oven control are outlined and an attempt is made to forecast the changes, especially in connection with methods of heating and lagging, to which it is likely to lead.The history of the development of boiling-plates is briefly reviewed, and the relative advantages and disadvantages of the various methods of construction commonly employed in this country are discussed.

DOI:10.1049/jiee-1.1938.0088

出版商:IEE    

年代:1938

数据来源: IET

摘要:

It is proposed to examine the economic aspect of electricity supply for domestic purposes, in which the electric cooker appears to offer the largest market for any individual piece of apparatus; to give reasons for the belief that the electric cooker offers the largest market for electricity supply in the domestic field; to offer suggestions on ways and means of developing this market; and to give detailed information on the maintenance cost of domestic electric cookers.

DOI:10.1049/jiee-1.1938.0089

出版商:IEE    

年代:1938

数据来源: IET

摘要:

An examination has been made of the phenomena occurring during the operation of electrical contacts, with particular reference to the destructive effects produced on the contact points. Four main stages in the break of a current have been observed, of which the resistance rise, the arc, and the spark, are well known; intermediate between the resistance rise and the arc is a stage in which the gap between the contact points is bridged by a drop of molten metal; this latter is of great practical importance since it is of almost universal occurrence, causes well-marked transference of contact material, and, as the potential difference between the contact points is then only about 2 volts, it cannot be suppressed by modifications of the interrupted circuit. The voltage-current-length characteristics of the molten bridge between electrodes of platinumiridium (25 per cent Ir) have been determined and are found to be of a similar form to those for an ordinary arc, i.e. voltage inversely proportional to current and directly proportional to length. The reason for such characteristics is not known.The conditions of voltage and current necessary for the formation of the different stages are described, and the effects produced by typical simple circuits are dealt with.Suggestions are made which should help to reduce the wear of contact points to a minimum.

DOI:10.1049/jiee-1.1938.0096

出版商:IEE    

年代:1938

数据来源: IET

摘要:

The technique of measuring impulse voltages with the aid of the high-voltage cathode-ray oscillograph and the resistor voltage-divider is discussed, and applied to the determination of the minimum impulse flashover characteristics of gaps between spheres ranging in diameters from 125 mm. to 1000 mm. Flashover measurements on sphere-gaps have also been made at power frequencies and compared with the corresponding figures for impulse voltages.The results of some previous workers are considered, and compared with those obtained by the authors.

DOI:10.1049/jiee-1.1938.0100

出版商:IEE    

年代:1938

数据来源: IET

摘要:

Since the issue of B.S.S. 358 in 1929 on the “Measurement of Voltage with Sphere-Gaps,” a number of calibrations of the sphere spark-gap have been put forward in Germany and the United States, but these differ appreciably amongst themselves and, moreover, are usually restricted to voltages of the order of 500 kV(eff.) and to spheres of 75 cm. diameter or less.The present paper is still another contribution to the literature on the subject, its justification being that it contains calibrations for larger spheres and at higher voltages than have hitherto been obtainable in this country.After a brief review of existing information the calibration at 50 cycles (a.c.) of a range of sphere spark-gaps is discussed in detail; methods of absolute measurement of high voltages are described, and calibrations are put forward for spheres up to 200 cm. diameter at voltages up to 1 million volts (effective) with one sphere earthed. These calibrations are based on a method of voltage measurement which is believed to be unique.Some attention has been directed towards the determination of the polarity of the high-voltage electrode when breakdown occurs, in view of the obvious importance of this feature in its relation to the breakdown of asymmetrical gaps under direct and impulsive voltages. A new type of polarity indicator is described.A correlation was observed between the noise of the spark and the polarity of the high-voltage electrode at breakdown.The effect of irradiation of the gap with radium and by other means is described.

DOI:10.1049/jiee-1.1938.0101

出版商:IEE    

年代:1938

数据来源: IET

摘要:

This paper describes a form of alternating-current resonance bridge suitable for measuring circuit resistances up to 30 ohms at frequencies up to 0.5 megacycle per sec. and up to 10 ohms at frequencies up to 10 megacycles per sec. The complete theory of the bridge and analysis of the errors is given, together with an account of a series of special check measurements designed to reveal the accuracy actually obtainable. The limit of error appears to be in the neighbourhood of 0.01 ohm for resistances up to 10 ohms at frequencies up to 10 megacycles' per sec.

DOI:10.1049/jiee-1.1938.0105

出版商:IEE    

年代:1938

数据来源: IET

DOI:10.1049/jiee-1.1938.0108

出版商:IEE    

年代:1938

数据来源: IET