Discharge behavior of SF6 and air in the strong inhomogeneous field at high pressure

Sulphur hexafluoride (SF₆) is the most common insulation gas in high voltage technology because of the electron attachment (electron affinity) SF₆ has the three times higher dielectric strength at 0.1 MPa compared to air. Beside this SF₆ has the most known global warming potential (GWP) and there is demand on alternative insulation gases. SF₆ has a non-linear and air a nearly linear dependency between pressure and electric strength. Measurement results in the quasi-homogeneous field show that Paschen's law is valid for air and not for SF₆. In the strong inhomogeneous field partial discharge occurs which influences the electric field and discharge behavior. At high pressure theses corona discharge disappears and the breakdown inserts indeterminately. The strong inhomogeneous field becomes a slightly inhomogeneous field discharge behavior. At this conditions the Paschen-parameter for air and the ignition condition of SF₆ could be used to calculate the breakdown voltage of the strong inhomogeneous electric field.