DOI:10.1049/jiee-1.1936.0117

出版商:IEE    

年代:1936

数据来源: IET

摘要:

An account is given of the principal materials employed for the screens in cathode-ray tubes for television and other purposes.The fluorescent and phosphorescent phenomena displayed by willemite, calcium tungstate and cadmium tungstate, zinc phosphate, and the various preparations of zinc sulphide and zinc-jcadmium sulphide, are dealt with in detail. The method whereby the undesirable phosphorescence displayed by zinc sulphide and zinc-cadmium sulphide has been eliminated is explained.Photometric measurements of the illumination of screens composed of a variety of materials under different conditions of excitation are given. A number of spectrograms are included of the fluorescent light emitted by these substances.The results show that:—(1) Zinc sulphide and zinc-cadmium sulphide are the most suitable substances hitherto developed for fluorescent screens for cathode-ray tubes.(2) A special zinc sulphide, giving approximately white fluorescence, has been obtained.(3) A mixture of zinc sulphide and zinc-cadmium sulphide,giving a brilliant white fluorescence of high intensity, has been prepared.(4) Phosphorescence, when not required, can be entirely eliminated.(5) Zinc sulphide and zinc-cadmium sulphide giving prolonged phosphorescence can be produced, and these compounds find application for special purposes.

DOI:10.1049/jiee-1.1936.0118

出版商:IEE    

年代:1936

数据来源: IET

摘要:

The focusing and other properties exhibited by gas-focused and electron-lens-focused oscillographs when radio frequencies and ultra-high frequencies of deflection are used, are compared and contrasted. The superior focusing properties of, and absence of origin distortion in, the electron-lens-focused tube are demonstrated.Characteristics peculier to either tpe of tube are discussed, and some phenomene common to both types, when used at very high frequencies, are discribed.Finally, two applications of the cathode-ray oscillograph at very high frequencies are suggested.

DOI:10.1049/jiee-1.1936.0119

出版商:IEE    

年代:1936

数据来源: IET

摘要:

Discussion on the subject of revenue loss due to poor voltage regulation has generally been of an inconclusive nature by reason of the fact that a quantitative basis has been lacking. After making an examination of the characteristics of lowtension electricity supplies to domestic lighting and heating consumers the author puts forward a method of calculating the amount of the loss, considering only cases where the principle of revenue loss can be reasonably said to apply. The results indicate that the loss is sufficiently large to warrant closer consideration than it has hitherto been given, and in certain cases to justify expenditure on network modification, or the installation of automatic voltage-regulator equipment to prevent voltage variation.In order to show its relative importance the principle is applied to the calculations normally carried out when transformers are being purchased, and in the case considered it is shown that it completely outweighs in importance the cost of iron and copper losses.

DOI:10.1049/jiee-1.1936.0121

出版商:IEE    

年代:1936

数据来源: IET

摘要:

The importance is emphasized of being able to differentiate between an increase in the power factor of a dielectric due to gaseous ionization and an increase due to other causes. The necessity of being able to detect discharges before they have caused sufficient damage to give rise to a change in power factor is also pointed out.A description is given of various methods of discharge detection which have been investigated, together with some details of the apparatus finally adopted and used.Methods for eliminating from the measurement all discharges external to the test sample are dealt with in some detail, this being an essential feature of apparatus for use onhigh-voltage testing circuits.The last section of the paper describes some of the practical uses of the apparatus.In the Appendices the various circuit arrangements are examined mathematically, and expressions are evolved for each method which provide the means of converting the readings obtained into the actual high-frequency current flowing in the dielectric.

DOI:10.1049/jiee-1.1936.0126

出版商:IEE    

年代:1936

数据来源: IET

摘要:

Routine over-voltage testing by direct current at high voltages is considered as a means of locating and eliminating weaknesses in the insulation of high-voltage cables, which might otherwise develop into breakdowns in service. A series of tests carried out on a cable network operating at 11 kV is described, from the results of which conclusions are drawn as to the lines on which tests should be carried out and the extent to which service breakdowns may be eliminated.

DOI:10.1049/jiee-1.1936.0127

出版商:IEE    

年代:1936

数据来源: IET

摘要:

Brief introductory remarks in Section (1) draw attention to the fact that modern centralized indicator equipment isessential for the economical operation of power distribution networks. The type of equipment described in the paper is covered by two definitions, namely centralized indication equipment and supervisory control equipment. The various facilities usually demanded in practice are outlined. The choice of method and type of signalling channel to be usedare discussed, and the need for adequate protection of the signalling channel and equipment against possible high induced voltages is emphasized. A schematic diagram of typical protective apparatus is given.Section (2) contains an outline description of Strowger automatic telephone apparatus, which is employed on the various schemes of remote supervision and control described in the paper. The characteristics of telephone type relays, polarized and non-polarized, and the operational features of the uniselector (rotary switch) and two-motion selector mechanisms are outlined. The symbols employed in the diagrams are indicated.In Section (3) the layout of centralized control rooms is discussed, with particular reference to the various types of wall and miniature diagrams employed. The layout of certain control rooms of the British grid systems are given.The operation of typical circuits employing the uniselector for the remote indication of switch position is described in detail in Section (4). The function of the repeat relay in ensuring that the indications displayed are in accordance with the actual conditions prevailing, is outlined.The various methods of remote metering, including individual selections, spot readings, and photo-telemetering, are described in Section (5).The operation of a system of engine-room telegraph signals is described in Section (6).Section (7) deals with a system of protection of power networks over the signalling circuits by means of automatic telephone apparatus. Characterized by extreme rapidity of operation, with automatic self-checking features, this system is shown adapted successfully to the inter-tripping of circuit breakers.The operational features of the fundamental circuits are described in Section (8), including the processes of selection, proving the selection, remote control of selected item, and the subsequent signalling of the indication that the intended operation has been effected.In Section (9) are described the methods of a.c. voicefrequency signalling employed in circumstances where the length of line or make-up of the signalling channel prohibits the employment of d.c. signalling.The paper finishes with a Conclusion and a Bibliography.

DOI:10.1049/jiee-1.1936.0129

出版商:IEE    

年代:1936

数据来源: IET