DOI:10.1049/jiee-1.1933.0081

出版商:IEE    

年代:1933

数据来源: IET

摘要:

Indication of a measured quantity at a distance from the point where the measurement is carried out has become of great importance, in view of the modern practice of centralized control. At the control point, indications must be given of all quantities necessary for the efficient operation of the system, and thus remote indication is essential. This paper deals with the principles on which some electrical methods of remote indications are based. Numerous systems have been developed, in all parts of the world, and for purposes of description they may be classified according to the fundamental principles on which they are based. A description is given of at least one system in each class indicating various applications of the general principle of the class. The conditions under which an equipment is to be used, and the characteristics of the various systems, will determine which of the numerous methods described should be chosen for a particular application.

DOI:10.1049/jiee-1.1933.0085

出版商:IEE    

年代:1933

数据来源: IET

摘要:

A cheap and compact 100-megohm resistor for the measurement of direct or alternating voltages of power frequency may be constructed from thin-film resistance units similar to those commonly used as “grid leaks”. The construction and performance of such a resistor are described. Errors due to corona or leakage along supports appear to be absent. There is a change of resistance with loading, due to the self-heating of the resistor. The magnitude of this change is approximately proportional to the square of the applied voltage and amounts to −2.6 per cent at 100 kV. By taking this change into account, voltages up to 100 kV may be measured correctly to 1 or 2 parts in 1000.

DOI:10.1049/jiee-1.1933.0090

出版商:IEE    

年代:1933

数据来源: IET

摘要:

Part 1 of the paper deals with an experimental investigation of alternating-current corona discharge in air and other gases, under conditions in which the effects of space charges are negligible. The results are of theoretical and practical interest, an analysis of them resulting in a theory of electrical discharge which forms the basis of Part 2 of the paper.The results of corona discharge for all the gases are found to obey accurately the empirical relationGm=Gℴρ{1+B/√(γρ)}given by Peek, Whitehead, and others. The experimental results for air, andits principal constituents, oxygen, nitrogen, and carbon dioxide, are given in detail, and the constantsG0andBare quoted for a few of the gases which are considered later in the paper in relation to sphere-gap spark discharge.Assuming Russell's theory of sphere-gap spark discharge, it is shown that the condition for this discharge isGm=KGℴρ{1+K'B/√(γρ)}whereG0andBhave the same values as in corona discharge, andK, K, are constants which have the same values for all gases.Part 2 of the paper deals with sparking potentials as a measure of maximum voltages, and is a preliminary account of the work. A new formula is given for uniform-field spark discharge, and this form of discharge is proposed as an alternative to sphere-gap discharge for the measurement of voltages up to 300kV (r.m.s.), the limit of the experiments. Advantages and disadvantages of the two types are also considered. The results of an experimental investigation of uniform-field spark discharge are given, for variations of spacing and gas density.

DOI:10.1049/jiee-1.1933.0091

出版商:IEE    

年代:1933

数据来源: IET