Uualter "Main Cable" Possibilities and Constraints ------------------------------------------------------ Initial Revision: 24-July-2026 Current Revision: 26-July-2026 The overall requirement is to minimize the cost and weight of the Main Cable(s). 1. Using one big overall "Main Cable" with many internal copper conductors will waste a lot of money and weight because we will abandon copper pairs above the Module where they are used. This realization drives us away from using one big overall cable and rather to using multiple individual small cables where each of these small cables is a separate water tight unit. 2. A major question and Uualter design concern is, what is the minimum size cable that can conveniently and economically be manufactured - specifically does a minimum size cable contain a single copper Pair or a single copper Quad ? - If the minimum cable contains a copper Pair then such a cable only needs to loop through the Modules that are powered by that one Feeder. - If the minimum cable contains a copper Quad then such a cable needs to loop through the all Modules that are powered by either of the two separate Feeders in that cable. 3. Recall that it appears to be difficult and expensive to include "Windows" in a cable. A Window is a location in a cable where its outer protective layers are opened, a subset of the internal copper conductors and/or Optical Fibers are brought out, and the outer protective layers resealed to make them water tight again. Thus the above constraint on both Feeders in a Quad needing to loop through all Modules power by either Feeder in that Quad. 4. It appears that the deep sea cable manufacturers do not like to use copper conductors that are under some minimum diameter. This minimum diameter is probably in the range of 36 mils (about #19 AWG based on the P-ONE-1 cable resistance ) up to perhaps 51 mils (#16 AWG based on Glenair connectors?). - Any diameter in this range is significantly larger than what is required to power an individual Module. Thus, to minimize the cost and weight of the cables, each Feeder must supply power to a number of Modules. - The cable manufacturer is likely to have some copper conductor diameter that is the most convenient and economical for them to work with. - To minimize the cost and weight of the cables, the Uualter power distribution system must fully utilize the current carrying capacity of the copper power Feeders - whatever their diameter happens to be. That is, each Feeder must supply as many Modules as it reliably can. - We should learn what diameter of copper conductor is most convenient and economical for a cable manufacturer to work with for our type of deep sea cable. 5. Possible numbers of Feeders and Modules powered by each Feeder: - 5 Feeders A,B,C,D,E with 4 Modules per Feeder - 4 Feeders A,B,C,D with 5 Modules per Feeder - 3 Feeders A,B,C with 8, 8, 4 Modules per Feeder or with 7, 7, 6 Modules per Feeder or with 8, 6, 6 Modules per Feeder 6. Note that if the Line Charge Soft-Start circuit is part of the DK board (and not part of the SJB Power Switch) then the design and operation of such a circuit is independent of the number of Modules per Feeder. 7. Are the Glenair "feed throughs" just a water tight feed through that is used to route a cable into a module or are they a cable mount connector and a separate fixed mount connector that is used in the side of the Module ? - If the Glenair "feed throughs" really are connectors, then the P-ONE final assembly becomes much different from what was used in P-ONE-1. Final assembly of the Modules becomes separate from the assembly of Modules into a cable String. Testing of assembled Modules becomes possible before they are connected to a String. Replacement of a Module that fails during overall String testing becomes possible. - If the Glenair "feed throughs" really are connectors, then basically all cables are the same 250 m long with a connector at each end. The only exceptions are the cables from the lowest Module on a Feeder down to the SJB which differ only in cable length. Having all cables be the same should: help control the cost, reduce cable-connector assembly errors, and make P-ONE look more like a rational customer to the cable manufacturer. 8. To minimize the overall cost - we probably want the Strength Member to be separate from the Cable that includes both the copper conductors and the Fiber Optic connections. Dual Strength Members, like Km3net, may make a lot of sense. 9. When looping a cable through a Module could both connectors (feed throughs) be in one Hemisphere (e.g. the Top) or do we need to put one feed through in each Hemisphere ? 10. Abandoning some glass optical fibers above a certain Module is a lot less expensive in terms of cost and weight compared to abandoning copper conductors. 11. Having all Fiber Optic Splitters be the same (e.g. a 1:4 in the lowest Module, a tap off in each Module, or whatever) should be a goal to minimize: cost and assembly errors. Could all Fiber Optic Splitters be in the SJB ?