High-voltage electric cable
A high-voltage alternate current electric cable [is provided. In the electric cable,] having at least one metallic electric conductor is surrounded by at least one extruded insulating layer. The insulating layer includes from 1 wt % to 30 wt % of a void-containing filler. The filler is made of particles having an average diameter up to 50 pm dispersed in an insulating polymeric material.
1. A high-voltage alternate current electric cable comprising at least one metallic electric conductor surrounded by at least one extruded insulating layer, wherein said insulating layer comprises from 1 wt % to 30 wt % of a void-containing filler made of particles having an average diameter of from 1 μm to 50 μm dispersed in an insulating polymeric material.
2. The high-voltage alternate current electric cable according to claim 1 , wherein said polymeric material is selected from polyolefins comprising homopolymers of a single olefin and copolymers of two or more different olefins.
3. The high-voltage alternate current electric cable according to claim 1 , wherein said insulating layer comprises from 5 wt % to 25 wt % of said void-containing filler.
4. The high-voltage alternate current electric cable according to claim 3 , wherein said insulating layer comprises from 10 wt % to 20 wt % of said void-containing filler.
5. The high-voltage alternate current electric cable according to claim 1 , wherein said particles have an average diameter up to 40 μm.
6. The high-voltage alternate current electric cable according to claim 1 , wherein said particles have an average diameter of at least 10 μm.
7. The high-voltage alternate current electric cable according to claim 1 , wherein said particles have an average diameter of from 15 μm to 20 μm.
8. The high-voltage alternate current electric cable according to claim 1 , wherein said particles are selected from hollow particles, porous particles and particles expandable at an insulation manufacturing temperature and capable of developing a spongy structure after expansion.
9. The high-voltage alternate current electric cable according to claim 1 , wherein said particles comprise inorganic or organic materials.
10. The high-voltage alternate current electric cable according to claim 9 , wherein said inorganic material is glass or silica aerogel.
11. The high-voltage alternate current electric cable according to claim 9 , wherein said organic material is a polymer selected from polypropylene, polymethyl methacrylate, poly-4-methylpentene and a fluorinated polymer.
12. The high-voltage alternate current electric cable according to claim 8 , wherein said hollow particles have a wall thickness up to 0.50 μm.
13. The high-voltage alternate current electric cable according to claim 12 , wherein said hollow particles have a wall thickness of from 0.20 μm to 0.50 μm.