Corona Considerations in Submarine Cable Communications Systems

Underwater repeatered telephone cable systems are series powered by high-voltage dc. Each repeater and equalizer contains a power separation filter (PSF) for extracting the dc current from the center conductor of the coaxial cable while allowing signal transmission. Corona discharges occurring across the high-voltage components are coupled through reactive components to the repeater\´s terminals. Each of the experimentally observed pulse shapes emanating from a discharge in the power filter must be evaluated to determine the effect on both system data transmission and reliability objectives. The response to surface corona discharges across the dielectric of the high-voltage capacitors has been successfully duplicated without high voltage by applying current pulses to the appropriate electrodes. This technique in conjunction with artificial contamination of dielectric surfaces and cataloging of the resultant discharge waveforms has led to identification of the major corona sources in the telephone repeater and consequently, to a factory testing program for components and assembled networks that assures satisfactory corona "free" units. The experimental results have also been successfully simulated numerically with a time domain circuit analysis comiputer program which has proved useful in establishing limits for the testing program.