Effect of combined temperature and pressure variations on the PDIV of wedge-shaped, dielectric-bounded air gaps

The variation of the partial discharge inception voltage (PDIV) of wedge-shaped, dielectric-bounded air gaps under concurrent changes of air pressure (7.5 mbar to 950 mbar) and temperature (23°C to 110°C) is investigated in this paper. Two coating materials featuring distinctly different variations of their dielectric permittivity with temperature are used. The experimentally observed variation of the PDIV is shown to be in good agreement with a physical parametrization of the PDIV in terms of the general scaling parameter p/T*s/er. The simplicity of the suggested parametrization makes it a powerful tool for insulation design considerations under a wide range of environmental conditions (pressure p and temperature T) and insulation configurations (insulation thickness s and dielectric permittivity ɛr), in particular for (more) electric aviation.