power cable outer sheath

[144x]

Hi,
let's assume that we have a 66KV power cable with 500 sqmm
cross section ,metalic sheild,water sealing (both radial
and longitudinal),aluminium armour,(NO lead ,No corrugated
layer of aluminium),and it's going to be land laid directly
in ground for a distance of 4000 meter.please tell me what
the outer layer (jacket)should be made of, PVC OR PE?and why?
please give me a definite answer.

 

[gordonl]

I asked this question to a cable supplier one time and here is the reply I received:

"The other type of jacket that is used for MV cables is a linear low density polyethylene (LLDPE). It is used by many of the major utilities, but it does not offer an FT1 rating. It has better abrasion resistance and is a harder (stiff) material. It is used for encapsulated CN cables and is more suitable for direct burial."

I had to stick with PVC jacket because my cable was installed in tray and direct buried and I needed the fire resistance of PVC for the tray portion. We've been using direct buried PVC jacketed medium voltage cable in very wet terrain for over 30 years and have not had any problems with the jackets, but the manufacturer suggested that the LLDPE jacket was better yet.

Gord