摘要:

After a short general discussion, a new method of polechahging, involving the use of a number of phases greater than that in the line, is explained, together with means for simplifying the connections:—(A) By the use of mutually reversed coils.(B) By a star-mesh connection.The phase transformer needed to produce the increased number of phases is next described, and it is shown that the current in the windings intermediate between the three-phase tapping points is reduced to a very low value as in the rotary converter, making the apparatus small and inexpensive.The switchgear employed is next discussed, and it is pointed out that the methods described render the squirrel-cage motor adaptable to almost all purposes, since they enable it to give good starting torque with low current.Machines with slip-ring characteristics are also described and test-results discussed.A description is given of the cascade motor, and its unique characteristic of giving gradual adjustment between speeds is explained. Two-, three- and four-speed motors having this characteristic are referred to.Some tests of large rolling-mill and other motors are given and finally a description of the application of the cascade motor as a short-circuit motor machine with slipring characteristics, and as a unity-power-factor synchronous machine of greater simplicity and less cost than any other type.

DOI:10.1049/jiee-1.1923.0036

出版商:IEE    

年代:1923

数据来源: IET

摘要:

During the past two years a great deal has been written about production problems. Some of these contributions to the subject have been penned by idealists, who claim, for instance, that such and such a shop lay-out is the first essential to successful production. Others emphasize that lack of production is caused by “ca' canny” amongst the workers. The bearing of these factors on production, or the lack of it, can be dealt with by efficient organization and management, and it is with the establishment of such a works organization that this paper will deal.With a view to interesting all sections of the industry, the author has dealt with the subject on general lines, with particular reference in places to the manufacture of electrical machinery, the object being rather to outline a general policy that has been followed in works with which he has been associated, than to go into detail which may not be applicable to any other works, as, naturally, detail must be based on the equipment in a particular works and the design of the àpparatus manufactured.

DOI:10.1049/jiee-1.1923.0042

出版商:IEE    

年代:1923

数据来源: IET

摘要:

The extent to which the rating of a cable is affected by an intermittent or fluctuating load as compared with continuous running conditions is investigated theoretically, and formulæ are given by means of which the effect of any type of loading can be calculated.It is shown by experimental determinations on various sizes and types of cables that the thermal time-constant can be calculated either from a heating or cooling curve of a particular cable, or from the specific heat and mass of the various components of the cable.Tables are given showing the rating for the cables for which load tables are given in the I.E.E. Wiring Rules, on the same basis as for motors, i.e. ½-hour and 1-hour ratings.

DOI:10.1049/jiee-1.1923.0045

出版商:IEE    

年代:1923

数据来源: IET

摘要:

In the past few years considerable strides have been made in the improvement and simplification of X-ray equipment both for medical and industrial purposes. At the same time it is a noteworthy fact that the demands of X-ray workers, are ever in advance of the apparatus at their disposal. It is for this reason that standardization is difficult, a design becoming almost obsolete as soon as perfection is approached.The comparatively sudden call for highly penetrative X-radiations of shorter wave-length, involving the maintenance of 200 000 volts at the tube terminals for continuous running, has imposed many difficult problems on the designer and manufacturer. In America these difficulties were to a great extent solved by research laboratories of large electrical corporations. The influence of sound engineering principles is, therefore, more noticeable in American practice than in that of any other country.

DOI:10.1049/jiee-1.1923.0046

出版商:IEE    

年代:1923

数据来源: IET

摘要:

A description is given of a simple method of showing the variation in the M.M.F. of a single-phase alternator winding by the shadow of a vane attached to a rotating spindle.The application of the same principle to the case of polyphase windings, and the method of arriving at the position and dimensions of the vanes, are explained.An apparatus is described which is arranged to show the M.M.F. produced in the air-gap of an induction motor by the stator and rotor windings under load conditions, with the rotor either stalled or revolving.

DOI:10.1049/jiee-1.1923.0047

出版商:IEE    

年代:1923

数据来源: IET

DOI:10.1049/jiee-1.1923.0053

出版商:IEE    

年代:1923

数据来源: IET

DOI:10.1049/jiee-1.1923.0054

出版商:IEE    

年代:1923

数据来源: IET

摘要:

In all theory, design and specifications, some assumptions are necessary and, as experience is gained, the value and accuracy of these assumptions is made apparent. The ultimate weight and cost of a structure is influenced in no small degree by the initial considerations, and in the particular field under review the question of maximum wind pressures and the law connecting such pressures with height above ground level, are of primary importance. It is the intention of this paper to review briefly the results of past experiments and endeavour to point out what are safe and economic values of wind pressures for design purposes. The need for the standardization of wind-pressure assumptions will also be brought out and it is sincerely hoped that practical action will be taken in the near future.

DOI:10.1049/jiee-1.1923.0055

出版商:IEE    

年代:1923

数据来源: IET