Loop Transients at the Customer Site

Loop Transients at the Customer Station By R. L. CARROLL and P. S. MILLER (Manuscript received April 16, 1980) Electrical transients on the customer loop are of concern because they induce stress on customer terminal equipment, as well as on the station protector. To study this problem, we have recorded transient waveforms produced by lightning on a 10-mile loop in Washington, Connecticut, and have extracted information on peak current, peak voltage, polarity, rate of rise, decay time, and energy from the waveforms. The results are of significance to designers of protectors and station equipment. I. INTRODUCTION Design o f m o d e r n s t a t i o n p r o t e c t o r s and electronic s t a t i o n a p p a r a t u s requires knowledge of the unwanted electrical transients that may appear on the telephone loop plant. Although previous studies1"3 have provided empirical descriptions of voltage transients on various types of telephone plant, the data cannot be extrapolated to measurements at a customer station in a straightforward manner. The lack of data on current transients in loop-plant cable farther restricts the usefulness of these studies for station and terminating equipment design purposes. One approach for obtaining the desired environmental information is the development of an analytical model which, for instance, might represent the loop plant as a multiport network excited by random voltage or current sources. The complexity of the loop plant and the excitation sources, however, has restricted modeling efforts to a few simple cases.