A Study on Effect of Protrusion Geometry on the 400kV XLPE Cable Degradation

The presence of defects in the Extra High Voltage cables (EHV) constitutes a major concern for the cables manufacturers and electrical power utilities. The factors that decide the performance of 400kV Cross-linked polyethylene (XLPE) cables are protrusions, void and contaminants on the layers of cable. The size of these defects assess the insulation performance of XLPE cables. Here, the protrusion defect is taken into consideration. A two dimensional (2D) model geometry of ellipsoidal, spheroidal and hemispherical protrusion on cable layers has been developed using software based on Finite Element Method (FEM). This paper estimates the effect of electric stress enhancement on the various geometry of protrusions on the conductor and inner semiconductor compounds surface used with pulse voltage, say, 10 kV, with pulse width of 2ms applications. The results of EHV insulated cable reveals that ellipsoidal protrusion at a distance of 1mm from the conductor is more severe than other protrusion geometry regarding the induced electric stress are reported here as 0.411 kV/mm and also at the same distance from conductor shield the induced electric stress is 0.212kV/mm.