DOI:10.1049/ji-2.1945.0001

出版商:IEE    

年代:1945

数据来源: IET

摘要:

After just over fifty years' existence as a portion of the British Empire, Southern Rhodesia is now coming to life industrially. The problems of electricity supply require careful consideration if the Colony is to progress on sound economic lines, and this paper seeks to assist in laying the foundation of a policy aimed at ensuring such progress.The existing economic and geographical conditions are first outlined, together with the sources of raw materials, power and water. The probable development of basic industries in Matabeleland is discussed and other possible avenues of electricity consumption are detailed, including railway traction and the natural growth of existing load centres.The author then investigates three different methods of supplying the power demand of the future, two of which involve the transmission of large blocks of power over distances in excess of 200 miles.The peculiar problems inherent in long-distance transmission in Rhodesia are dealt with, and the economics of overhead lines operating at 250 kV are examined.The author reaches the final conclusion that the use of hydro-electric power, up to a total of 100 000 kW, from the Victoria Falls should be seriously considered as a part of a comprehensive scheme for future supplies.

DOI:10.1049/ji-2.1945.0002

出版商:IEE    

年代:1945

数据来源: IET

摘要:

Two methods of solving transmission-line problems which avoid the use of charts or tables of hyperbolic functions of complex angles are outlined. In the first method the voltage and current at any point are shown to be due to two waves, one travelling forward, and one backward, attenuating as they travel. The forward and backward wave vectors are calculated from receiving-end conditions. From these the wave vectors at any other point are derived. These, when compounded, lead to the voltage and current at that point.In the second method the (complex) angle of the load is determined from the forward and backward wave vectors. To this is added the (complex) angle of the line. The voltage and current are proportional to the hyperbolic cosine and sine respectively of the total angle. The magnitudes of these can be calculated, using circular and hyperbolic functions of real angles. In continuation of this, a semi-graphical method of finding the current and voltage at several points on the line is developed.

DOI:10.1049/ji-2.1945.0009

出版商:IEE    

年代:1945

数据来源: IET

摘要:

The war has reminded us that the ultimate necessities of life are few, namely food, shelter, and the practice of hygiene. In a civilized community it is natural that these requirements of life should expand so that the enviable amenity of one generation becomes the apparent necessity of the next. It is also natural that this expansion should be most marked in the present age when scientific discovery has penetrated so many of Nature's secrets and adapted them for the use of mankind for either destruction or survival. Electricity, the latest agent to be brought into domestic service, has fulfilled the duties required of it to a degree unapproached by any of its predecessors.Electricity in domestic service facilitates the preparation of appetizing and nutritious meals, conserves food, lights and heats the home, provides hot water for personal and household cleanliness, drives machines for washing clothes, cleaning floors and furnishings, and is the means of providing for the possibly unsocial reception of wireless broadcasts. The great majority of electrical domestic appliances perform one or other of the above duties, and their success in doing so is a measure of the enterprise of those responsible for their development.The big housing programmes following the last war were fields for electrical development which industry turned to good advantage. Much experience was gained as a result—and it must be remembered that the real test of any apparatus is its performance in the hands of the user—so that just prior to the present war ideas of electrical domestic service had begun to crystallize. Now necessarily in suspense, many improvements then ready for their final test under working conditions will, it is hoped, be released with the return of peace, while their production and efficiency will benefit from the knowledge of new materials and new manufacturing methods which has accrued during the war. In this paper the authors consider some of the improvements which may be expected and which would be most welcome. It is divided into the five sections of cooking, refrigeration, heating, hot water, and cleaning.

DOI:10.1049/ji-2.1945.0010

出版商:IEE    

年代:1945

数据来源: IET

摘要:

The paper first deals with the data and formulae necessary for evaluating the self and mutual surge-impedance values of a 3-conductor overhead system equipped with a single earth wire.It then indicates how these impedances may be used for obtaining, by an original method, the theoretical attenuation and distortion, below corona, of standard unidirectional surges. Good agreement is shown to exist between theory and experiment.Above corona, loss factors for the short surges employed are deduced from experimental results, and formulae are given to enable the corresponding factors for any single-circuit line conductor to be found.Formulae for determining the visual critical corona voltages of one, two or all three conductors of a system are also given, in terms of the relevant surge-impedance values.Finally, several values for a typical line are included.

DOI:10.1049/ji-2.1945.0013

出版商:IEE    

年代:1945

数据来源: IET

摘要:

The paper outlines the theory, method of construction and use of a family of curves allowing a rapid and accurate estimation of the average m.m.f. expended on tapered magnetic teeth. The parameters used result in less complicated relationships between the variables than with any alternative accurate method; this somewhat simplifies the calculations necessary to obtain the curves for magnetic materials having differentB/Hcharacteristics. An analysis is made of the inaccuracy of the simple “one-third” rule under varying conditions of magnetic loading and tooth profile, and it is shown that the use of this rule can lead to very considerable errors.

DOI:10.1049/ji-2.1945.0014

出版商:IEE    

年代:1945

数据来源: IET