Negative LI breakdown behavior of electrodes with thin dielectric coatings in dry air at high pressure

In gas insulated switchgear(GIS) SF
₆
gas is widely in use because it has good electrical insulation and arc interruption capabilities. Due to environmental constraints the desire to use alternative gases is continuously growing. This paper focuses on dry air as an alternative gas which unfortunately has a breakdown strength which is lower than the breakdown strength of SF
₆
at equal gas pressure. To improve the breakdown strength of dry air filled GIS, dielectric coatings can be applied to the electrodes. In this paper, the performance of GIS with thin coatings is evaluated through breakdown tests in a rod-plane electrode arrangement. Negative lightning impulse voltage is applied on the rod electrode and the gas pressure is kept constant at 0.9 MPa.