Application of $\varepsilon$ - FGM for Optimizing Electric Field Distribution in AC Cable Terminal

High voltage cable terminals play an important role in a cable transmission system and the rubber stress cone covering the cable insulation is the key component of the cable terminal. In this paper, both normal and tangential electric field (E-field) distributions along the interface between the cable insulation and the stress cone are regulated to prevent the degradations at the interface. Normal E-field is reduced by decreasing the size of the semiconductor part of the stress cone, whereas tangential E-field is homogenized by applying a permittivity functionally graded material
$\varepsilon$
-FGM) rubber to the insulation part of the stress cone. The topology optimization method is effective to obtain the optimal permittivity gradient of the
$\varepsilon$
-FGM rubber. Our simulation results show that the novel stress cone with
$\varepsilon$
-FGM performs well in regulating the E-field distributions both along the interface and inside the insulation part.