By W. S. Campbell, P.E., General Electric Cablevision Corporation
This paper discusses the causes of commercial power system surges and presents recorded data indicating the nature, magnitude and frequency of occurrence of surges to be anticipated on 120 volt distribution circuits. The effects these surges can have on a cable system's reliability are discussed, and the various devices available for surge protection are reviewed. Particular attention is paid to a surge problem, and the corrective measures taken, in General Electric's Decatur, Illinois cable system. In Decatur, surges in excess of 1200 volts were indicated on residential, 120 volt circuits and repetition rates up to 480 surges in a 24-hour period were recorded at the output of one of the cable system's 60 volt power supplies. Finally, a modification for cable television use of the electrical protection section of REA specification PE-60 is offered. This modification provides voltage and current surge acceptance tests for cable television amplifiers and power supplies.