Transmission line setting calculations - beyond the cookbook

Abstract

Setting transmission line relays is fairly easy to learn-but takes years to master. With the proper education, tools, and references such as company standards available, a relatively inexperienced engineer can do good work with proper supervision and review. There are many references and training programs that provide the high-level basis for protective element setting criteria. But, the concepts have to be applied with care in context of the particular transmission line and system in question. The transmission network is complex, with many variations that must be identified to determine when deviations from cookbook guidelines are required. This paper looks at various commonly used transmission line protective elements and points out characteristics of the line and system to look for when standard reaches and margins cannot be used. While the subject is vast, the authors draw on their experience to point out some of the more common issues.