Waterproof multi-core insulated cable - has elastomer-insulated conductors and centre polymer thread core enveloped in flexible crosslinked sealing polymer

摘要

A multi-core cable has its elastomer-insulated conductors enveloped in material which is cross-linked by (at least) heat; the core formed by its stranded conductors is sealed off with a polymer which fuses at the cross-linking temp.. The structure includes filaments of (pref.) polyethylene. The figure shows a cable for use in pressurised water. It has three cores (1) with the conductors (2) insulated with (e.g.) ethylene-propylene rubber which is flexible even when cross-linked. These cores (1) are embedded in the sheath (4) of (e.g.) scuff-resistant polychloroprene i.e. a rubber which also is cross-linked. The structure has a central core (5) of e.g. polyethylene, with or without e.g. polyester-carried threads. The sheath (4) is applied by coextrusion so that its polymer flows into the interstices. It is passed (after extrusion) through a continuous curing oven applying heat and pressure at over 180 deg. C to fuse the centre core (5) and press it in. ADVANTAGE - The cable has a permanently sealed interior so that even with flexible cables moisture cannot migrate inside.