On the possibility of increasing the service life of high-voltage cables

The aim of this article is to determine whether, in principle, one can use thin insulating layers with increased dielectric permittivity (barriers), located between layers of monolithic insulation, and to evaluate the effectiveness of the above. The tests were conducted using specimens of insulated conducting strands (ICS) of KGE-KhL 3 × 25 + 1 × 6 + 1 × 6 km² type cable with rubber insulation as well as ICS specimens with a barrier layer. For the main insulator both cases use rubber of type TSShM-38. Internal and external screens were made of conducting rubber of type VEP-30 and the barrier layer consisted of insulating resin filled with TiO₂. The dielectric permittivity of the insulating resin TSShM-38 is ε_i = 3.4 and for the barrier layer rubber it is ε_b = 9.2. The overall thickness of both specimen types was 4 mm and the length was 2 ± 0.15 m. Our investigations have shown the effectiveness of barriers with increased values of dielectric permittivity in high-voltage cables with the breakdown time probability P(γ) = 0.632 in test ICS specimens increased by more than a factor of 200.