Discharge Onset Voltage Prediction for a Gas-Insulated System Via the Figure-of-Merit Concept

The accuracy of discharge onset prediction via thefigur figure-of-merit concept for a strongly electronegative gas is examined. A coaxial system is employed, for which the inner electrode possesses a surface roughness of Ra=35 μm. With SF6 as the insulating medium a reference discharge-onset characteristic is obtained for gas pressures up to 0.8 MPa. From a knowledge of this onset characteristic, the direct calculation of discharge onset voltages in other strongly electronegative gases is undertaken by utilizing thefigur figure-of-merit concept. For gas pressures in the range O.02