The Effect of Ambient Thermal Properties on Transient Electric Field Distribution and Life Estimation in HVDC Cable Insulation

Innovative cable designs have recently achieved high rated temperatures. Cable environment properties are getting more attention to guarantee thermally stable operation and reduced loss-of-life of the HVDC cable at all possible weather conditions. This paper aims at studying the effect of different resistivities and seasonal temperatures of the laying environment on the electric field distribution inside the insulation of HVDC cables subjected to the type test load cycles according to CIGRÉ Technical Brochure 496. Five different conditions of the laying environment are considered, set according to IEC 60287, i.e., soil saturated with water, very moist, moist, partially dry, and dry; different temperatures of the laying environment are also taken accordingly. The results show that the greater the thermal resistivity and/or the temperature of the laying environment, the shorter the life of the cable insulation.