SF System: Power Conversion

At 7:15 A.M. on S August 196S, a technician pushed a button on a power supply in the Jacksonville Beach cable station. Within seconds another technician pushed a button on a power supply in the Magens Bay cable station. One minute later the first units of a new generation of submarine cable power supplies were in service powering the Florida to St. Thomas SF Submarine Cable System. 1 The direct current needed to power SF Submarine Cable repeaters 2 is carried to the repeaters by the coaxial cable's center conductor. The current originates in shore-based power supplies and is returned from the far cable end through sea (ocean) ground. Since the repeaters are connected in series, the current requirement is the same for all SF 749 7f>2 T H E BELL SYSTEM TECHNICAL JOURNAL, M A Y - J U N E 1970 Systems, but the end-to-end cable voltage drop is a function of system length. The new submarine cable power supplies which went into service on 8 August 1968 are direct current sources designed to accomodate a wide range of voltage loads. These supplies are powered from duplicated --48 volt battery plants. The --48 volt battery-charging rectifiers are powered from commercial power lines. The interposition of batteries between the commercial power lines and the SF Submarine Cable power supply assures continuous power availability in the event of a commercial power failure. In addition, the provision of automatically or manually started engine or turbine driven alternators extends almost indefinitely the time period over which a commercial power failure may be tolerated.