The waterproof and moisture-proof performance of high-voltage cross-linked cables has always been a crucial concern for the power sector. The reliability of high-voltage cross-linked cable transmission systems largely depends on the growth of water trees within the cable. Furthermore, the growth of water trees directly affects not only the cable's longitudinal waterproofing performance but also its radial waterproofing and moisture-proofing characteristics.
The radial waterproof and moisture-proof elements of high-voltage cross-linked cables are mainly metal sheaths. Currently, the popular waterproof and moisture-proof metal sheaths for high-voltage cross-linked cables at home and abroad are mainly of three types: extruded type, welded type, and aluminum-plastic composite tape integrated sheath type. Their structures, performance, manufacturing methods, manufacturing equipment, and user evaluations are all different.
There are several ways to prevent moisture and water from entering the cable. Among them, a metal sheath can effectively prevent water or moisture from entering the cable and causing water trees to form and grow, which deteriorates the cable insulation level and shortens the cable's service life.
Based on the experience and theoretical calculations of foreign cable experts regarding cable operating time, the expected lifespan of cross-linked cables under different conditions is as follows. While some of this data is from computer simulation experiments, it still has some reference value.
15-25 years without any protection and exposed to water or moisture.
Expandable water-blocking tape lasts 20-30 years.
Water-tree resistant crosslinking material lasts 30-35 years.
Water-tree resistant cross-linked material and water-barrier tape provide 35-40 years of protection.
The metal-clad moisture barrier lasts approximately 60 years.
