摘要:

The phenomenon of ionization in the dielectric has been selected for detailed discussion in this paper, as it lies at the root of success or failure in the operation of high-voltage cables. The two leading features of the paper are a fairly complete co-ordination and critical examination of the published work on the subject and an account of some of the author's own investigations made with the object of confirming existing suggestions and extending our knowledge along certain lines to still wider limits. As ionization is usually-demonstrated by its effects on the variation of power factor with voltage, several pages are devoted to different phases of this important relationship, and the physical mechanism controlling the appearance or modification of ionization is then reviewed and illustrated. The close connection between ionization and long-time breakdown strength receives some attention, and tentative suggestions are made for the assessment of quality. A noteworthy feature of the paper are the data demonstrating the advance which has been made in applying a knowledge of the phenomenon of ionization to the production of reliable solid-type high-voltage cable.

DOI:10.1049/jiee-1.1933.0133

出版商:IEE    

年代:1933

数据来源: IET

摘要:

The paper deals with the relative values of those factors that impose the present practical limits to power-station efficiency.The processes involved in the generation of electricity from coal are discussed, and the relative heat-release values of steam at various temperatures and pressures are examined.A method of power-station-efficiency analysis is employed by which the values of the following factors can be separated out and compared:—(a) Steam and vacuum conditions.(b) Coincidence of plant-item efficiencies.(c) The regenerative feed-heating cycle.(d) The re-superheating cycle.The influence of the present physical limitations of the properties of metals is examined in relation to the choice between the use of higher steam temperatures and the use of the re-superheating cycle.A form of power-station-efficiency rating is discussed, with a view to expressing clearly the efficiency merit of a power station.General conclusions are drawn as to the probable lines of future development.

DOI:10.1049/jiee-1.1933.0140

出版商:IEE    

年代:1933

数据来源: IET

摘要:

Much has been written on the design of transformers to carry direct current in the primary winding in addition to alternating current, and the value of an air-gap in the magnetic circuit has also received considerable attention. In thepresent paper the subject is taken up a new, and a method is demonstrated by which graphs relating to different values of direct current and of a.c. swing are plotted on a single chart. It is shown how these charts enable the designer to obtain the nearest possible approximation to a condition of constant inductance in the face of any variations of direct current or of a.c. swing (δB). In these charts abscissae æ give the air-gap in cm and ordinates give ΔB/δ, wheregrepresents gilberts. Examples of the use of δB.Δ in the calculation of the inductance are given, and test results on transformers designed from the charts are included as illustrating the value of the procedure.Attention is drawn to the paucity or lack of data available and certain subsidiary questions relating to the use of transformers of the type in question are dealt with in conclusion.

DOI:10.1049/jiee-1.1933.0148

出版商:IEE    

年代:1933

数据来源: IET

摘要:

A fruitful procedure for the study of the ionosphere by wireless methods is the automatic registration of equivalent heights on one or more requencies, together with frequent determination, made as rapidly as possible, of the vaiation of equivalent height and echo intensity with frequency. Theoretically, the echo and frequency-change methods should measure the same quantity, the equivalent height of reflection for the waves beign use, and this is experimentalyy confirmed. The echo method, however, is the more useful since the interpretation of the records is much simpler, automatic registration is quite feasible, and the geneal operation is much more convenient.Some improvements in receiving apparatus for the frequency-change procedure are described which greatly facilitate therse experiments. For the echo work it is shown that a simple squegger osscillator is adequate as a self-modulating device for producing the short pulses of radio-frequency energy. Several thyratron circuits are described which are applicable if the recurrence frequency of the pulses must be rigidly controlled for the method of recoding adopted. A suitable receiver has been developed, using linear-law rectification and a simple valve amplifier can be added to obtain a logarithmic relation between the signal input and output amplitudes. For registration of the pulse signals a string oscillograph may be used, but photography, with a simple camera, of the synchronized patterns on a cathode-ray oscillograph is preferable for adaptation to automatic recoring, as this method minimizes the effects of interference and makes for speed and ease of operation. Linear time-scales with a scale value of 1.5 cm per millisecond are found most useful. Automatic records can be made by photographing the stationary echo pattern each minute or by making a continuous “strip” record on moving paper of the timebase itself, departures from the base line due to the signal deflections being seen on the record as white lines on a black background. The “snapshot” method is preferable for detailed examination of echo amplitudes and delay times, but the strip registrations are more economical where it is required to obtain records of equivalen heights over long periods. In the manual operation of the apparatus a schedule procedure has been developed for obtaining records of equivalent heights and echo amplitudes on a predetermined series of frequencies at an average rate of about three frequencies per minute.The Appendix describes the distortion, observed in the course of the echo experiments, of transient-modulated radio-frequency energy in tuned circuits, and shows how ht trouble may be overcome in the various cases.

DOI:10.1049/jiee-1.1933.0149

出版商:IEE    

年代:1933

数据来源: IET

摘要:

This paper gives a preliminary outline of work with a new, entirely electrical, television system having no moving mechanical parts.The registration of the image is accomplished by a special device, which is a true electric eye. The device has been named the “iconoscope,” and it consists of a vacuum tube containing an electron-emitting gun and a photo-sensitive surface of a unique type. This photo-sensitive surfa ce is scanned by an electron beam from the gun, which serves as a type of inertialess commutator.A new principle of operation permits the storing of the energy from the light of the image and enormously increases the output as compared with that of conventional types of television scanners.The sensitivity of the iconoscope, at present, is approximately equal to that of a photographic film operating at the speed of a motion picture camera. The resolution of the iconoscope is high, much higher than is necessary for television of the highest quality.The reproduction of the image is accomplished by another cathode-ray tube with a fluorescent screen, which has been named the “kinescope”. Here the impulses from the transmitter modulate the intensity of the electron beam; and this, in turn, is transformed by the fluorescent screen into variations of light.The scanning is linear and is synchronized at the end of each line. The synchronizing impulses are transmitted through the same channel as the picture signal.The whole system is completely automatic and the receiving sets are almost as easy to operate as the ordinary radio receivers.The paper describes the theory, characteristics, and mode of operation of the system.

DOI:10.1049/jiee-1.1933.0150

出版商:IEE    

年代:1933

数据来源: IET

DOI:10.1049/jiee-1.1933.0152

出版商:IEE    

年代:1933

数据来源: IET