摘要:

After defining the title of the paper, the author proceeds to discuss the position of telegraphs in this country, comparing it with those of Germany and the United States. Multiplex a.c. transmission is considered and the limits to its use are determined. A description of the various systems in use follows, and proposals are advanced for its wider adoption in this country. The main arguments against its adoption are economic, but some technical criticism is included.

DOI:10.1049/jiee-1.1929.0088

出版商:IEE    

年代:1929

数据来源: IET

摘要:

The paper gives a general survey of metering work in this country.Some particulars are given regarding the more usual faults found in service, and the requirements for maintained accuracy are briefly discussed.Various standard types of meters are examined and recent modifications detailed.Methods used for obtaining summated demands and consumption are discussed, together with various types of equipment for special purposes.The development of reactive kVA metering methods is traced and apparatus described. The testing of such apparatus is difficult and calls for a high degree of skill.Finally, a few remarks are made regarding special tariffs and testing procedure.

DOI:10.1049/jiee-1.1929.0093

出版商:IEE    

年代:1929

数据来源: IET

摘要:

This paper contains an account of an electromagnetic method of testing for mechanical flaws in wire ropes such as colliery winding ropes, the method comprising the use of a “search band of flux ” in combination with a search-coil system.In the introduction are detailed the advantages of the use of alternating as compared with direct current for the excitation of the magnet system.Section 1 describes the results of an experimental investigation of the penetration of magnetic flux in “locked coil” wire ropes, for a supply frequency of 50 and 20 cycles per second respectively.In Section 2 the effect of mechanical strain on magnetic permeability is considered, with special reference to a.c. excitation.In Section 3 the change in reluctance of the air space due to eccentricity of the rope in the magnet system is examined.Section 4 contains an account of the construction of the rope-testing magnet system, and the method of utilizing the search band of flux is explained.Section 5 contains the results of tests on a length of wire rope which was specially constructed for the purpose by Messrs. Latch and Batchelor, and in which a series of hidden flaws were incorporated.A complete rope-testing equipment constructed in accordance with the principles explained in this paper has been installed in one of the Carlton Main Co.'s collieries in south Yorkshire.

DOI:10.1049/jiee-1.1929.0097

出版商:IEE    

年代:1929

数据来源: IET