Inductive Co-ordination of REA Distribution Systems and Telephone Systems

The Rural Electrification Administration and Bell System have been carrying on co-operative studies of the inductive co-ordination of REA distribution systems and rural telephone circuits since 1939. The results of these studies have indicated that the two systems can be satisfactorily co-ordinated when (a) the influence of the power system is controlled, (b) the separation in unavoidable exposures is adequate and reasonably uniform, and (c) the susceptiveness of the exposed telephone circuits is limited by care in design and maintenance. The more important factors controlling the influence of REA distribution systems and the susceptiveness of rural telephone circuits are reviewed and certain remedial measures applicable to the power system are discussed, with illustrations from the recent joint field work. Recent trends in the design of rural telephone circuits which result in improved susceptiveness are mentioned.