Abridgment of the problem of service security in large transmission systems

With the rapid growth of transmission and distribution systems and the tendency to interconnect large systems, the problem of service security during abnormal conditions becomes of greatest importance. Service security is generally considered to be entirely a question of relay protection. This is an erroneous idea, as this paper will show that system layout and other factors are of equal importance, and that only the complete and simultaneous fulfillment of all component factors will bring the desired results. The ultimate goal of the problem is the creation of a transmission system which is free from service interruptions. Upon first thought, this would appear attainable either by preventive measures or by protective measures. This paper will explain briefly the impracticability of the preventive method, and will discuss the possibilities of the protective method in an endeavor to show that it is the only one promising a complete solution of the problem. The protective method depends on the creation of a strong system in which troubles are accepted but made harmless by protective means. The paper indicates also in a general way how such a perfect system can be created at no greater cost than present practise necessitates. The operating results reported in the paper are all from improved existing systems, showing that here substantial improvements can be made.