摘要:

The troubles that are beingexperienced in the use of plain 3-core cables for working at 33,000 volts are referred to and the theories advanced in explanation discussed. The various types of multi-core cable with metal sheaths over the individual cores are then enumerated and their advantages over the plain 3-core type detailed. The claims of the S.L. type in which each core is separately lead-covered, over the other metal-sheathed-core types in which a common lead sheath covers all three cores, are explained. The paper gives practical formulae for calculating sheath effects in singlecore cables, together with the results of a series of tests carried out to determine the extent of these effects in the S.L. type. Consideration is given to the temperature-rise in the various types, along with the results of a series of heating tests. As the employment of the S.L. type of cable is a move in the direction of employing single-core instead of 3-core cable, this question is also discussed and results of loading tests on both plain lead and armoured single-core cables are given. The mechanical properties of the S.L. type are also investigated and in the conclusions at the end of the paper it is shown that the presence of the sheaths, in addition to having well-known electrical advantages, produces a very distinct improvement in the thermal properties of the cable and results in a construction which is very much sounder, both mechanically and electrically, than other systems of multi-core super-tension cable.

DOI:10.1049/jiee-1.1927.0044

出版商:IEE    

年代:1927

数据来源: IET

摘要:

This paper contains a description of the 60,000-volt underground cable network which has been successfully operated in the Paris district by the Union d'Électricité for the past four years. The reasons why single-core cables were adopted for the distribution system are explained, and a number of details are given in regard to the construction of the cables, the method of laying, and the operating conditions, both electrical and thermal.

DOI:10.1049/jiee-1.1927.0049

出版商:IEE    

年代:1927

数据来源: IET

摘要:

In continuation of his previous paper on the spherical condenser † the author discusses the capacities, the mutual actions and the field in the neighbourhood of two electrified spherical conductors. After a brief introductory statement of this historical problem an attempt is made to solve it by elementary theory. The magnitudes of the errors introduced by this method are pointed out. Accurate formulæ are then obtained by the method described in the preceding paper. These formulæ enable the capacity coefficients to be computed in all cases to any required degree of accuracy without difficulty. A few simplified formulæ which will be useful in practice are also given. The discussion of the mutual actions between the spheres shows that when their potentials or charges are of like sign the force between them may be attractive or repulsive, depending on the ratio of the potentials or the charges. In this case there are always two ratios of the charges and of the potentials which make the mutual force zero. Methods of computing the forces in other cases are given. Simple formulæ are found for calculating the potential gradients at the points on the spheres where the line joining their centres cuts their surfaces. This tells us whether the charge on the spheres is all positive or all negative or partly positive and partly negative. In the Appendix a few more accurate but more elaborate formulæ are given.

DOI:10.1049/jiee-1.1927.0053

出版商:IEE    

年代:1927

数据来源: IET

DOI:10.1049/jiee-1.1927.0057

出版商:IEE    

年代:1927

数据来源: IET