摘要:

The design and operation of machine telegraph systems has been very considerably affected in recent years by the production of high-speed communication links of the transoceanic order of length, and by new methods of operation on land lines enabling the line plant unit—the telephone pair—with its series loading and its repeater stationsen routeto be used for either the transmission of telegraph signals or speech, or both, simultaneously and independently.The regenerative repeater, by enabling several sections of cable and land line to be interlinked, has given rise to methods of operation far reaching in their effect both from the point of view of economy to the Administration and from that of reliability and speed to the user.While the possibility of connecting two remotely situated medium-traffic offices over a single channel of a main-line high-speed multiplex system has been known for a number of years, this has not led to any considerable developments in that direction. Conditions are, however, arising in which medium traffic offices will use start-stop single-channel systems to an increasing extent, and this is being influenced by the large number of channels rendered available by the dual use of the land telephone cable. Wherever the telephone network extends, the telegraph network is ready to hand, and the single-channel system will, in course of time, replace the multiplex system for inland telegraphy.The long-distance links with their regenerative repeaters require a precision in speed and phase control not necessary heretofore, and a study of this subject therefore forms a considerable portion of this paper.The sending and receiving apparatus of the start-stop single-channel system are the inverse of each other, and the paper endeavours to establish a general underlying principle for the different variants described.The last phase of machine telegraphy will certainly be that in which intercommunication between centres will be automatically effected and intermediate manual transmission avoided. This is possible by reason of the large number of channels available through the previously-mentioned dual use of the wire plant, and by the present-day standard of automatic switching technique.

DOI:10.1049/jiee-1.1930.0152

出版商:IEE    

年代:1930

数据来源: IET

DOI:10.1049/jiee-1.1930.0157

出版商:IEE    

年代:1930

数据来源: IET

摘要:

The paper describes measurements of surge voltages made under actual working conditions on 33-kV transmission lines both overhead, underground and composite.The apparatus used for the measurements was the klydonograph, and the paper gives a description of this instrument in its final form and a discussion of its working principles. The specially designed auxiliary condensers required to subdivide the line voltage are also described.Measurements on three important transmission systems covering a year or more of continuous recording are detailed. Generally there is a large amount of oscillatory surging set up by brushing at insulators when such insulators are in a dirty condition, the over-voltage being of very high frequency and of the order of three times the normal line voltage.The atmospheric conditions under which salt is deposited on insulators are described and some of the records show the effect on the line voltage of a salt-laden insulator up to the time at which flash-over occurred and the line was put out of operation.The question of porcelain insulators to meet the prevailing foul conditions and to avoid surges due to brushing is discussed. It is shown that with proper attention to design the voltage at which brushing commences can be materially increased, and it is suggested that this factor is of even greater importance than a very high initial flash-over voltage.

DOI:10.1049/jiee-1.1930.0158

出版商:IEE    

年代:1930

数据来源: IET

摘要:

The lecture reviews briefly the provisions of the 1926 Electricity Act which relate to metering. It describes the system of measurement which has been adopted for the main classes of electricity stations connected to the “grid” system, and mentions the constructional features of the instruments used in the Central Scotland and South-East England electricity schemes which differ from recognized meter engineering practice.The novel features of the general scheme are the use of summator meters, long-scale maximum-demand indicators, special devices for recording maximum power demands, and reactive-component meters.Actual instruments were used for demonstration, and slides of typical installations were shown at the lecture.

DOI:10.1049/jiee-1.1930.0160

出版商:IEE    

年代:1930

数据来源: IET

摘要:

Although several books and many papers have been written on the subject of railway electrical signalling, it is thought that the following notes may be of interest, as they are intended to bring up points not usually mentioned.With regard to the remarks on track circuits, the author has recently heard of a new type of impedance bond track circuit employing condensers at each of the track. It would be interesting to obtain a description and criticism of this type of track circuit.

DOI:10.1049/jiee-1.1930.0162

出版商:IEE    

年代:1930

数据来源: IET

DOI:10.1049/jiee-1.1930.0167

出版商:IEE    

年代:1930

数据来源: IET