At 06:05 PM 4/30/2008, Didier Juges wrote: >Interestingly, my company just received an RFQ for DC/DC converters >for trans-oceanic cables. Interesting specification. Among other >things, 2,000,000 hours MTBF (the converters are multi-redundant) >and, I like that part, 100% altitude tested :-) Something else you >might find interesting: all repeaters are daisy chained. The power >comes from two current limited 1A 10,000V supplies, a positive one >at one end, and a negative one at the other end, so that if the >cable is grounded accidentally in the middle (say, by a boat anchor, >just a guess...) all the repeaters still get power. One supply can >power the entire cable. Two grounds, and you can lay another cable. >The power return is through the earth. Don't swim near a head-end >cable... The capacitance of the cable is measured in Farads, and it >takes several hours to charge the cable at power up. Some time ago, >we bid on the head-end power supplies (we did not get that job). It >is interesting to observe that high reliability has a different >meaning in the under-sea cable business and in the military airborne >business. We do the latter. Didier KO4BB
I would think that the undersea cable and the deep space robotic exploration business have similar philosophies. Long life, inaccessibility for repair, etc. Jim Lux _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
