Status of Joint Development and Research on Noise Frequency Induction

HE Joint Subcommittee on Development and Research is the agency through which the National Electric Light Association and the Bell Telephone System carry out technical work on problems of physical relations which vitally affect their respective growth and operating practises. In the present paper and companion papers the status of this joint development and research work is described. The present paper, Part II of the Symposium, is concerned with problems of induction in telephone circuits under normal operating conditions of power systems which results in noise. Part I I I of the Symposium treats of induction at the power system fundamental frequency, principally that occurring at the time of grounds, short circuits or other abnormal conditions of power systems. Part IV of the Symposium treats of the physical relations and of the special noise* Part II of the Symposium on Coordination of Power and Telephone Plant. Presented at the Winter Convention of the A. I. E. E., New York, N. Y., January 26-30, 1931. Published in abridged form in Electrical Engineering, April, 1931. 184 JOINT DEVELOPMENT AND NOISE FREQUENCY INDUCTION 185 frequency and low-frequency problems brought about by the close proximity of the two types of service when occupying the same poles. The Joint Subcommittee on Development and Research has subdivided its work among eleven project committees and assigned to each the actual carrying on of specific research work. Certain of the project committees are engaged on the problems described in this paper, while the remainder are concerned with the development and research problems of the companion papers, Parts I I I and IV of the Symposium.