Electric Field Distribution in HVDC Cable Joint in Non-Stationary Conditions

Accessories such as joints and terminations represent a weak point in HVDC cable systems. Indeed, the DC field distribution is intimately dependent on the thermal condition of the accessory and on material properties. Moreover, there is no available method to probe charge distribution in those conditions. In this work, the field distribution in non-stationary conditions, both thermally and electrically, is computed considering different insulating materials assembled in a same geometry, with focus on the tangential field distribution. We show that the position of the maximum field varies in time in a way that is not easy to anticipate. The work points to the need of precise data on materials conductivity and to the need to probe field distribution in 3D.