Transmission Line Relay Protection-II

This paper is divided into three parts, the first part consisting of a list of relay nomenclature according to function and application, the second part being a general discussion on relay protection with special reference to an investigation of the Protective Devices Committee to obtain information on transmission line protective scheme and the third part, an illustrated description of the results of the investigation. The thoroughly proved methods have been given scant consideration but the operating results of new schemes have been treated in brief detail with a statement of the condition which led to the adoption of the various schemes. Many of these schemes require the use of special apparatus which is not obtainable in the open market, though in most cases it was possible to use standard apparatus. It is quite probable that some of these special schemes will be adopted by the leading manufacturers with more or less modification. In the majority of the cases cited, the actual operating results showing the number of correct and incorrect relay operations have been given and it is probable that this is the first time that such a disclosure has been so generously and frankly made. Standard names for relays as to function and application as well as qualifying terms which always have the same meaning are very desirable. The number of types of relays now in common use are so great that considerable confusion has resulted from a previous lack of uniformity of identifying designations.