For our South Africa project, the rated voltage in China is 12 kV, whereas the South African standard specifies 11 kV. The lightning impulse withstand voltage is 75 kV under Chinese standards, compared with 95 kV required by South African specifications. Such discrepancies have a direct impact on primary component selection and insulation coordination, necessitating recalculation and revalidation of the full insulation system. By adopting composite insulation and electric field simulation, we have optimized our 11 kV AIS small-current switchgear: cabinet width is reduced from 800 mm to 650 mm, and the breaker pole pitch is decreased from 275 mm to 205 mm.
