摘要:

The paper deals with the automatic isolation or indication of earth faults on systems protected by Petersen coils. After discussing the principle of operation of this type of protection, describing the operation of a wattmeter-type relay, and enumerating the electrical constants of the system to which the protection is applied, the authors describe the application of the relay to a 66-kV distribution system.The currents in the feeders are analysed and the problem of accurate current summation is discussed in detail. Laboratory tests are given n current transformers at small percentages of rated current approximating to the capacitance currents. A comparison is made between current summation by means of a summation transformer and by direct paralleling. Further test figures are given showing the effect of load current in addition to capacitance currents. The design of the relay element is described, emphasis being laid on its constructional features and operating characteristics.

DOI:10.1049/ji-2.1944.0062

出版商:IEE    

年代:1944

数据来源: IET

DOI:10.1049/ji-2.1944.0066

出版商:IEE    

年代:1944

数据来源: IET

DOI:10.1049/ji-2.1944.0067

出版商:IEE    

年代:1944

数据来源: IET

摘要:

The paper contains an analysis of the load on the system of the Northmet Power Co. during a pre-war year. The block of annual load is split up into a basic, or all-the-year round, portion, and a seasonal portion, the latter representing all the consumption due to spaceheating, and about half that due to lighting. The basic portion is sub-divided into its principal components, and, as regards the seasonal portion, an attempt is made to separate lighting load and spaceheating load, both as to demand and annual consumption. For this purpose “seasonal demand curves” are developed, in which the load at a certain time of day is plotted for a series of days, and compared with the simultaneous conditions of outdoor temperature and illumination. The annual load factors of modern lighting and spaceheating loads are found to be normally of equal order of magnitude; in a year with a “cold snap” the load factor of the latter may even be considerably lower than that of the former.Characteristic collective and component load curves are given; and also graphs dealing particularly with the space-heating load. The paper concludes with recommendations for further research.

DOI:10.1049/ji-2.1944.0077

出版商:IEE    

年代:1944

数据来源: IET

摘要:

Although the title of the paper refers only to copper conductors, copper-alloy and steel-reinforced copper conductors for use on overhead lines are included. The creep of conductors and their initial non-elastic extension are considered in relation to their effect on sags and their compensation by an increase in erection tension as analternative to pre-stressing. A typical stress/strain curve for copper conductors is given.Information on the annealing characteristics of hard-drawn copper and copper-alloy conductors is included, with special reference to the effect of impurities in the metal. Maximum safe operating temperatures for such conductors are discussed, together with maximum permissible current loadings.Hollow copper conductors of various types for voltages up to 200–300 kV are described and some of their characteristics enumerated. The features of cadmium-copper conductors are dealt with in comparison with other types of high-tensile overhead conductor.Steel-reinforced copper conductors receive special attention, particularly in regard to the protection from corrosion of the steel wires. Results of a long-time investigation are given in full, with conclusions and recommendations. Copper-clad steel wires, their characteristics and use as reinforcement in copper conductors, are discussed.Details are given of developments in the application of compressed sleeve joints to copper and copper-alloy conductors. Suitable joints for cadmium-copper and steel-cored copper conductors are described and test results given.

DOI:10.1049/ji-2.1944.0080

出版商:IEE    

年代:1944

数据来源: IET