| 摘要 |
AN ELECTRIC POWER CABLE OF THE KIND HAVING AT LEAST ONE METALLIC CONDUCTOR (1), OPTIONALLY A CONDUCTOR SCREEN (2) OF SEMICONDUCTIVE MATERIAL, AND INSULATION (3) ALL ENCLOSED IN AN EARTH SCREEN HAVING WIRES (5) OR NARROW TAPES AND A SHEATH COMPRISING POLYMERIC MATERIAL IS CHARACTERISED BY A SHEATH CONSTRUCTION COMPRISING A FIRST EXTRUDED POLYMERIC LAYER (8) WHICH ENCLOSES THE EARTH SCREEN OF THE CABLE WITHOUT FILLING THE GAPS BETWEEN THE COMPONENTS THEREOF (THE WIRES OR STRIPS), A SECOND EXTRUDED POLYMERIC LAYER (12) ENCLOSING THE FIRST AND BETWEEN THEM BONDED TO BOTH OF THEM A MOISTURE BARRIER LAMINATE COMPRISING A METAL FOIL LAYER (10) COATED ON EACH OF ITS MAJOR FACES WITH A POLYMERIC MATERIAL (11) COMPATIBLE WITH THE MATERIAL OF THE EXTRUDED LAYER IT CONTACTS. THIS INCREASES THE RESISTANCE OF THE CABLE TO IMPACT, COMPARED WITH CONSTRUCTIONS IN WHICH A MOISTURE BARRIER FOIL LAYER IS APPLIED DIRECTLY OVER THE SCREEN WIRES, AND ALLOWS THE CABLE TO BE USED IN APPLICATIONS THAT HITHERTO REQUIRED A METAL SHEATH.
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