Mechanism and effect of DC charge accumulation on SF6 gas insulated spacers

Mechanism and effect of DC charge accumulation on the surface of a solid insulating support (spacer) have been studied in compressed SF₆ gas using various cylindrical model spacers. The distribution of surface charged is closely related to the normal component (gas side) E_n of electric field on the spacer surface. The ,maximum charge density can be estimated from the condition of E_n=0. When voltage is applied in a polarity opposite to prestressed DC, surface charge increases the maximum field strength in the arrangement, resulting in the reduction of the insulating ability. It is possible to estimate the lowest flashover voltage due to surface charges only from numerical fields calculations. An anticharging spacer shaped along electric lines of force is proposed and studied