1. The primary insulation for high-voltage equipment such as switchgear, power cables, and transformers comprises gases, solids and liquids. These insulating materials can change behaviour when exposed to appropriately applied high voltage.
a) Determine the location of the void at the cross-linked polyethene (XLPE) cable given the electric field stress is \( 2.98 \mathrm{kV} / \mathrm{mm}, 3.16 \mathrm{kV} / \mathrm{mm} \), and \( 3.37 \mathrm{kV} / \mathrm{mm} \). Let the nominal cross-sectional area cable is \( 630 \mathrm{~mm}^{2} \) energized at 11 kV voltage level, while the nominal thickness of XLPE insulation is 3.4 mm and the nominal thickness of the outer sheath is 2.6 mm .
