I’m looking for protection devices (presumably fuses) that I can use in some underwater equipment. This equipment is at the end of an underwater cable and its two main components are in parallel, sharing the two power conductors in the cable. Because they are in parallel, if one floods and starts drawing too much current, the other component will stop working. What I would like to do is to fuse each one separately so that if it shorts, its fuse will burn out, allowing the other to function. The problem is, these devices may draw up to 2 A when functioning properly and only go up to 5-7.5 A when shorted (the shore power supply maxes out at 7.5 A so that’s as high as the current can go). That’s not a great separation between operational and shorted current levels. I need the devices to be very trustable, as an unwanted blowout means that the equipment needs to be recovered, which requires a vessel and can cost hundreds of thousands of dollars.
I’ve looked at slow-blow fuses, but it’s hard to know how they will perform here, as the time/current curves in their product sheets are almost vertical. They are also temperature derated, making things a bit confusing. Any advice? Thanks in advance.
Numbers:
400 VDC
Nominal I: up to 2 A
Faulty I: 5-7.5 A
Operating temperature: 0 to 5 deg C
