**1. Introduction**

The designers of electro energetic system are thinking, to conserve the routes of 220kV transmission lines, and the transition to 400kV lines. The easiest way seems to be the placement of new overhead power lines. The other option is the use of covered conductors. Covered conductors are conductors with insulation made from two dielectrics: the first is the insulation mantel and the other is air. The covered conductors consist of a conductor which is a metal electrode (a cable), and the covering mantel which is made from a dielectric with a greater dielectric constant and higher breakdown voltage. The other dielectric with a lower dielectric constant is the surrounding air. The conductor should not be touched despite the insulation.

According to the usual labelling of conductors, we named the suggested conductor PUAC 2150/490/65 mm2. Here 2150 mm2 stands for the cross section of the polyurethane mantel, 490 mm2 for the aluminium and 65 mm2 for the core made from carbon fibbers. The saved weight (instead of steel we use carbon fibbers) can be used for the insulation. The insulation has to be thick enough so that the electric field intensity on the edge of the insulator does not exceed the critical electric field intensity of air. Such a conductor, hanged on a typical 220 kV transmission tower meets the electric load exerted. Simplified analytical calculations of the electric field intensity on the edge of the insulation match exact calculation, using the finite element method*.* This fact encourages new research, both theoretical and practical.
